Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
~:' 218~893
COM~INED REFORMULATION/PACKAGING TO DELAY STALING
IN BAXERY PRODUCTS.
BACKGROUND OF THE INVENTION
The present invention relates to a method for delaying staling
in backery products, which combined reformulation and modified
atmosphere packaging. The importance of the bakery industry is
well known worldwide. Bakery products are an important source of
nutrients in our diet. Consumption of bakery products in North
America is estimated at $23 billion dollars annually with roughly
50~ being spent on bread and rolls (Peat Marwick Group,
l991).However, spoilage occurs shortly after baking. After
microbial spoilage, the main spoilage problem is staling.
Therefore, methods to control staling are of great importance to
the bakery industry since staling results in millions of dollars
annually in lost revenues. It was already reported that returns
due to staling in the United States are 8% accounting for almost
50 million kg. of product returns annually. To overcome this
major spoilage problem, staling of bakery products has been the
subject of extensive investigation.
Two approaches to delay staling has been investigated so far. The
first approach is through packaging under a modified atmosphere
involving elevated CO2 levels. While packaging under 100~ CO2
delays both mold growth and staling for 6 weeks, products are
rejected by consumers after 4 weeks due to the sharp acidic taste
of CO2 dissolved in the aqueous phase of the product.
The other and more successful approach is through reformulation
involving various gums, surfactants, high fructose corn syrup
(HFCS enzymes and low protein flours. Results showed that a
highly acceptable product from both a textural and sensorial
viewpoint could be produce commercially through appropriate
levels of enzyme, gum and HFCS in the formulation. The present
invention combine both of these known technologies. As a matter
of fact, it is based on this discovery that staling and mold
growth can be prevented / delayed in bagels or any other bakery
products for at least 6 weeks through appropriate reformulation
and modified atmosphere packaging (MAP) using an oxygen
absorbent.
The estimated cost for this shelf life extension is 20-30 cents/
dozen bagels. However, the increased costs could be defrayed
through less returns and downgrading of products to croutons,
218~8g3
less production costs through bulk processing/ packaging and most
importantly extended shelf llfe, market growth and increased
profitability. Yet another cost cutting approach would be to use
the new generation of oxygen sca~enging films which are gradually
appearing on the marketplace.
Several definitions of staling have been proposed. Bechtel et al.
(1953) defined staling as a" decreasing consumer acceptance of
bakery product caused by changes in the crumb and the crust other
than those resulting from the action of spoilage microorganisms".
According to Bechtel and Meisner (1951) consumers view staling
as hardening of the crumb which has a dry mouth feel, an increase
in crumbliness, a loss of flavor and aroma, and a softening and
toughening of the crust". KuIp (1979) stated that staling was
~Ithe gross changes and the various undertying reactions, as well
as other physical or chemical phenomena which contribute to the
subjective estimate known as staling".
Staling begins immediately after the baking process is complete
(Hebeda et al., l9gO). It leads to an increase in crumb firmness,
a loss of product freshness and of consumer acceptance. However,
the process can be delayed through appropriate formulation
changes using surfactants, gums, enzymes, high fructose corn
syrup and flours of different gluten content, either a]one or in
conjunction with each others.
In accordance with the invention, it has been found that
combined ~eformulation and packaging offers the baking industry
a viable approach to inhibit two potential spoilage concerns
staling and mold growth. However, further studies are required
to determine the public health safety of these reformulated
bakery products, particularly with respect to the growth of
Clostridium ~otulinum in bagels stored under reduced oxygen
tensions and at room temperature.
Staling has been extensively studied in the past century, and
many theories have evolved. However, despite these theories,
research is still ongoing in an attempt to extend the shelf life
of the bakery products with respect to staling. Several methods
have been investigated to increase the mold free shelf life of
bakery products. These include:
- Good manufacturing practices, (Jenkins, 1975).
- U.V. light and microwave heating, (Black, 1993~.
- Incorporation of preservatives such as sorbic and
proprionic acid: or calcium salts either directly into the
product or sprayed on the product surface, (Seiler, 1989).
- Freezing, ~Matz, 1992).
- Modified atmosphere packaging, ~MAP), involving gas
packaging with mixtures of ~-O~ and N~ oxygen absorbents and
ethanol vapor generators ~Smith and Simpson, 1996).
2~893
' ~_
Water activity is one of the main factors affecting the shelf
life of the bakery products. It is directly related to microbial
spollage.
Bakery products can be divided into three major groups on the
basis of their water activity (a ):
- low moisture bakery products. i.e., products with an aw of less
than 0.6 (aw < 0.61. This group is the least affected by
lOmicrobial growth;
- intermediate moisture bakery products having an aw between 0.6
and 0.85 (aw 0.6-0.85)
- high moisture products with an ah higher than 0.85, usually
between 0.95 and 0.99 (aw 0.g5-0.99). This group is most
affected by microbial growth. ~Smith and Simpson, 1995)
Bakery products, like all processed food products, are subject
to spoilage.
20Spoilage of bakery products can be divided into:
- microbial spoilage
- chemical spoilage
- physical spoilage (Smith and Simpson, 1995)
Chemical spoilage involves both oxidative and hydrolytic
rancidity problems.
A rancid product has a musty, rank taste or smell due to fats
that have oxidized and decomposed with the liberation of short
chain fatty acids, aldehydes and ketones through an autolytic
30free radical mechanism. The free radicals and peroxides can
bleach pigments, destroy vitamins A and E, breakdown proteins and
cause darkening of fat (Smith and Simpson, 1995). They also have
a disagreable odor and flavor and are toxic in large amounts.
This kind of rancidity occurs in the absence of oxygen. It
results in the hydrolysis of triglycerides and the release of
glycerol and short chain fatty acids.
Microbial spoilage comprises of bacterial, yeast and mold
40spoilage (Smith and Simpson, 1995). All microorganisms require
three basic elements: food, temperature and moisture. Pre-
packaged bakery products provide conditions conducive to
microbial growth tJenkins, lg75).Mold spoilage is responsible for
the majority of losses in the bakery industry in the United
States.
The majority of the molds found in white ~read belong to the
genus Aspergillus and Penicillium ~Hartung, et al., 1973). Other
mold species e.g., Rhizopus, Monilia, and Mucor species have also
50been implicated (Jenkins, 1975). According to Bullerman and
Hartung ~1973), aLlatoxin producing molds have never been
detected in either flour or bread. They also stated that flour
8~'8g3
contained more toxic molds than bread, due to the fact that mold
spores are not very heat resistant. Thus, mold spoilage results
from postprocessing contamination. This occurs during cooling and
packaging from contamination by airborne spores or contact with
contaminated surfaces (Black, 1993). Contamination also results
from food handlers and raw ingredients such as glazes, nuts,
spices and sugars ISmith, 1994). Under warm humid conditions,
mold problems are even more trouhlesome and mold growth is
visible within 48 hours after baking and packaging (Black, 1993~.
Physical spoilage usually involves moisture loss or gain and
staling. Moisture loss or gain is a problem in both high and low
moisture products. Loss of moisture in high moisture bakery
products results in a loss of texture and firmness. A gain of
moisture in low moisture products also results in textural
changes and may promote enzymatic and microbial spoilage
problems. Both moisture loss and gain can be prevented by
packaging products in a film which is a high barrier to moisture
e.g., low density polyethylene ILDPE1
By definition, bread staling refers to all the changes that occur
in bread after baking. The consumer perceives staling of bread
by changes in the aroma, toughening of the crust and, most
importantly, firming of the crumb (Bechtel et aI,, 1951). Based
on market studies, the wholesale baking industry believes that
consumers equate "squeeze" softness with freshness and make their
choice at the supermarket bread rack accordingly ~ackel, lg~9~.
Thus, the bakery industry attempts to produce the most
"squeezable" bread (Jacket, 1989). Objective measurements of
30staling are complicated since 'Istaleness of bread is a subjective
quality which is ultimately assessed by the senses" (Toufeili et
al., 1994). Under optimal storage conditions, bread llstales
after 2-3 days on supermarket shelves IJackel, 1989).
Staling can be divided into crust staling and crumb staling. The
majority of research has focused on crumb staling as crust
staling seems impossible to prevent.
Crust staling is due to moisture migration from the crumb to the
40cnlst and from absorption of moisture from the atmosphere if the
relative humidity (RH) is high i.e., RH>80'~ (KuIp, 1979). If the
bread is left unpacked, it dries out completely. If packaged, the
crust soon stales (KuIp, 1979~. Crust staling is enhanced by high
moisture barrier packaging materials which do not permit moisture
to pass from the crumb to the atmosphere. Thus, it remains in the
crust IMaga, 1975).
Crumb staling is an even more complex phenomenon. The crumb
becomes firmer, less elastic, cn~mblier, harsh textured, and it
50has a dry mouth feel ~KuIp, 1979). The main factors affecting
staling are shown in table 1.10.
2188893
T~b~ F~ 0llQCIIn~ lln~.
F~ct~n6 I\I~FECtlNt3 9t~LlNt3 MAlH E~I~ECt8
Tlme ul sl~rn~3 Sit~ t)cculs dlnl~ lirsî It3~v tJtlys r)i
slc~n~t3.
r~ln~Uvlaî~re ul slcrn~t3 I~ îlnll îttl,l~,~3l~1urt3s 6l~1irlll(;~ sl011n~.
I~lcur pr~lQI~ n~ rt~lt3ln llt~lrs ylQld b~e0d wllll belier
kt3eplll~ tlurJlllles.
r Itwr p~ Wtller-sclublf3 pelllcsnlls are used t~s 0nll- 81nllll~ rl~ellls,
Sllcrlellll~ eclet~ Inllltll Illm~less tll-d ~nt~ laln 11
lI-rcll~llclll sletPs~e.
Ct.. l~ol-~J~ 3 Mcllt~- nud ~llJtluellrlllJes were Iculld Ic ht1ve
rJIl t~nll-s/r~ ellecl~
SYn1PB . rDUe 10 Illelr II~ Se~UPh~ IJIUI1~IIIU3I cclJld llnve
0n rJl~ sltlllllrJ ellecl.
SrJII C~ultl 1l0vt3 tln tmll-sltlllll~ Qllecl. Ncl uo
lo mbdlly s01l It3vQls lo prevelll slnll~
E~s Invlvn3u brQt3d VUIUmQ t~ltl ~Ive 0 IlllBr~
ulll~r~r~1 Sllu~vl~)~iv~ rt31~rd slnîlllU
t3rI~ d:t1~ 3 Mllk scllds srJy prrJlQhl yv3~sl ît3vvels ~Isu
SllCWed tlllll-8ltlII11~ ~UI)U~IIV9.
Mlxln~ ct~lldlllcns Ulldellttver-llllxllltl ctln llrvl~rJ_v Ille llrml
slnee 11 Is relt~led 1~ Ille ~le c~ el i.Jle
~1~5VI î~IIV~
I ~rmelllrlllcn llrne Ullder ~nd wer-lerlnelllrJllell llnve e llnnl
ellecl.
~nklng îlme 13~klll~ llme 011ec(s mclslure cnnle~ nd r~le
c~ slall
Adapled Ir~m M~ 75).
40REFOKMULATION
Several methods have been developed to retard staling. These
include:
the addition of shortenings, the use of mono and diglycerides,
surfactants, enzymes, gums, gluten free flour. (Table 2.3)
Shortening can be defined as a "an edible fat used to shorten
50baked goods" ~Merriam Webster's Collegiate Dictionary, 1995).
' 21~889
5~ .
' ~_
Table 2.3.: I"~ dients used in lhe reformulalion and lheir pe~ nl~es~
ll~y~ 3l~ls Trade Name Suppller ~r~el~l g,ls used
Cr~ "l~s:
Genell~ y ",odlriedNovamyl Novo Nordlsk 0.031, 0.047
t~n ~ a-an"~l~se (Danbury, Ct~
i ungal and baclerlal Su~,errle~l, plus Enzyme Dl~s(e",s 0.1, 0.15, 0.2
~-a",ylas~s (BeloH, Wl)
Bac~erialc~-&""~las~hl~yal,esllplusEnzyme Bklayslems0.1 0.15 0.2
and gl~-;ul~l,a~erase (Beloil, Wl)
Gums:
Guar GuarSG25 Amcan IIl~ i . nla 0.2 0.6 1
(Lachlne, QC)
Xanthan Xanthan 100 Amcan Illyl~ i'E.115 0.2, 0.6,1
(Lachlne, QC)
Locusl bean LBG SG14 Amcan Iny,ed ~nls 0.2, 0.6, 1
(i achine, QC)
Agar Agar Agar Amcan Inyledlenls 0.2, 0.6, 1
(Lachlne, QC)
Cellulose Cellulose40 Soca Floc(Chlcago,
IL)
Cellulose 300 Soca Floc (Chlca~o,
IL)
Cellulose 900 Soca Floc(Chicago,
IL)
M~ lc~lulose Mi~ll,ocel Dowl"y~ ier,ls
,(Midland, Ml)
Algln Kelvls l<elco (Chlcago, IL) 0.2, O.ff, 1
Peclin Classic AB201 1 IErl,sl,~ oxl 0.2, 0.6,1
Amcan Illsll~d ~nls
(Lachine, QC)
SYru~s2:
HFCS Liquld HFCS Llquld ADM Corn P~ essl"g 50,100
(Decalur, AL)
H~CS Granular HFCS Granular ADM Corn Processl~,~ 50,1~0
(Decalur, AL)
Fhur:
Rice InslanlRice Flour IGT (Lincoln, NE) 25
Barley Inslanl BarleyFlourIGT (Lincoln, NE) 25
Com Instanl Corn Flour IGT (Lincoln, NE) 50
Surfact~nts:
Sodium Slearoyl Allas SSL ICI su,ra :ta"ts 0.25, 0.375
Laclylale (Lachlne, QC~
SSL and a",~rlaseAllas p51 ICI Sur~actanls 0.25, 0.375
(Lachine, QC)
1: Based on a ~lour welght basis.
2: Based on a su~ar ,eplace"~enl basis.
~188893
. ~
Most researchers agree that shortening, fat, or a combination of
vegetable oil and emulsifiers is an essential ingredient in bread
making. In commercial bakeries these are added to facilitate
dough handling and processing, to improve loaf volume and crumb
grain; and to prolong shelf life (Pomeranz et al., 1991~. When
shortening is used in the formulation an increase in loaf vol~e,
an improvement in crumb grain and a retardation of crumb firming
- during storage was observed. Crumb color depends to a large
extend on loaf volume and crumb grain (Pomeranz et al., 1966).
10However, adding shortening had no significant effect on water
absorption and mixing time.
Wheat flour lipids are important functional components in baking
since shortening acts through these lipids (Rogers et al., 1988).
Shortening had no effect on firming rate of bread made with
defatted flour ~Rogers et a/.,1 988). Defatting significantly
reduced volume and softness of bread as well as impairing loaf
volume and crumb grain of bread baked from the flour (Pomeranz
et al., 1991~. This effect is related to the amount of polar
201ipids removed from the flour during defatting. However, the
effects of shortening or of polar lipids on bread quality were
independent of wheat class or variety. Many f]ours were tested
and, in all cases, shortening resulted in improved products with
poor flour quality being improved the most (Pomeranz et al.,
1966).
The influence of shortening on firming rate is concentration
dependent ~Rogers et al., lg8B). Usually 23% shortening has shown
to be effective in providing the highest volume and softness of
30bread (Rogers et al., 1988; Pomeranz et aL, 1991). Higher levels
had no additional improving effect (Pomeranz et al., 1966). It
appears that wheat flour protein governs breadmaking properties.
Lipids, however, seem to provide certain functional properties.
Once those requirements are met, no additional benefits can be
derived by adding more lipid (Pomeranz et a~., 1966). This
lipidprotein interaction affects both the firming rate and the
loaf volume (Rogers et at, 1988). It has also been shown that 1
or 2% soy or corn oil produced bread with a volume comparable to
that with 2~ shortening ~Pomeranz et at, l99l).
Surfactants aid in the development of less tacky, more extensible
doughs which process through machinery without tearing or
sticking, or which result in baked products with finer crumb
structure and improved volume and shape. Since 1988, ~103 million
kg of surfactants have been used as foods additives, a level
which is expected to increase by 5% annually ~kamel, 1993~.
Surfactants are generally used for the following reasons:
l.To promote crumb softness;
2.To strengthen dough for good handling properties;
~ 218883~
3.To aid in water retention; and
4.To improve loaf volume.
In aqueous systems, amylose adopts a helical conformation with
the hydrogen atoms oriented to the inner side of the helix. This
result in a lipophylic region ideally suited for complex
formation with a long chain fatty acid (Osman et al., 1961).
Thus, the crumb softening effect was attributed to the surface
active properties of surfactants and their ability to form
10complexes with the amylose fraction of starch ~Figure 1.5). The
formation of these complexes with amylose affects the transfer
of water between crystallizing starch and gluten which takes
place during aging of bread. The softener complexes not only with
amylose but also with some of the outer chains of amylopectin
(KuIp, 1979).
The substantially low complex forming capacity of amylopectin has
been attributed to its limited capacity to form a helix. It has
been reported that when more than l~i monoglycerides are added and
20the free amylose is bound, interaction with the amylopectin
fraction then occurs (Hani, 1992~.
Surfactants have also been shown to act in a similar manner as
flour polar lipids. These are bound to glutenin by hydrophobic
bonding between the hydrocarbon chain of the lipid and the
lipophylic region of the protein, and to gliadin by hydrogen
bonding or electrostatic bonds between the polar groups of the
lipid and polar regions of the proteins. The binding of
surfactants to gliadin and glutenin enhances the gas retention
30capacity of gluten and results in a larger loaf volume (Hani,
1992).
The emulsifying properties of surfactants result in a more
uniform distribution of water throughout the dough and allow for
the development of gluten structures with optimum mechanical
properties. However, Pisesookbunterng and D' Appolonia (1983)
observed that the adsorption of surfactants onto the starch
surface, as well as the complex formation between starch and
surfactant, prevented starch from absorbirlg water released from
40gluten during bread aging. Consequently, the water released from
the gluten was available to migrate from the crumb to the crust
of the bread promoting crust staling.
A controversy still exists as to whether surfactants affect
initial crumb firmness (Zobel, 1973) or if, as noted by Ghiasi
et al. (1982), they only slow the rate of stallng during storage
or both effects occurs (Valjakka et aL, 1994).
Sodium tearoyl-2-lactylate,calcium stearoyl-2-Iactylate,lard,
50monoglycerides and tartaric acid ester of sucrose are the most
often employed to delay staling (Zobel, 1973). However, Krog
(1970) reported that distilled monoglycerides had the best
218~93
complexing ability among nonionic surfactants and that sodium
stearoyl-2-lactylate (SSL) and calcium stearoyl lactylate were
best among the ionic ones.
. _ . . . .
~nl~ Mn)t~ ?y~ s ~sed 1~ v~ nlnll~lî.
ENZYMe g~U;tt~E ~\t:1 B t~N Pl~v~U~ t 8
n~-ul~lyl~.. ,v l~h~l~r, 8in~ 80hJi7in 91
nl IJIQI)fll~ x~rll~g
Mnll
l C 13nole~ bl,n. r~
9~ I~lvllr l~xlrl~ e
M~l~
IllV13r~8g~ Y~n9~ 91lcru5~ ~llV~II 9ll~nr
M~ se Y~n~l Mnll~ X~t~S~
~ymns~ Y~n~l hlvell s~ n~ t~n~ n dl~xltJ~
2~ ~Inv~rs
P1~ 9~ Ir ~ InIl EI~bIesIn~ ItllX
~ncl~ )rep~l~llul~ xl~ lllly
Many enzymes can be added to dough to enhance its properties.
Some of the enzymes commercially used in bread dough are a -
amylases,~ -amylases, invertases, maltases, zymases and
proteinases.(Table 1.12 )
Other enzymes which could be used include lipoxygenases,
pentosanases and others.Since amylases and glucoamylases are most
often used, their mode of action will be discussed in more
detail.
Amylases are divided into a-amylases and ~-amylases. These can
be of different sources: bacterial,fungal or cereal. Different
sources give enzymes with different properties. Amylases are
usually added to increase the level of fermentable sugars, to
40increase the production of simple sugars leading to a sweeter
product and better color, since the reducing sugars produced
react with other components in bread to give Maillard reaction
products. They also improve gas and moisture retention properties
of the dough. Furthermore, heat stable amylases retard bread
staling.
Schultz et el. ~lg52) reported that small amounts of bacterial
amylases had a beneficial softening effect in bread whereas high
levels resulted in unacceptable softness. They stated that the
50main advantage of bacterial a-amylase was its thermostability
since its action occurs once starch has gelatinized. Miller et
al. (1953) studied the effect of fungal, cerea] and bacterial
2188893
~,
amylases and confirmed the results of Schultz et aL (1952~ noting
that all three types resulted in softer brea~ compared to the
control bread. Bacterial amylases did not affect the initial
bread firmness, but reduced the firming rate during storage.
Conversely, fungal amylases, decreased the initial bread firming
but did not affect the firming rate ~Valjakka et al., 199~).
~-amylases are the most widely used en%ymes. Bacterial ~-
amylases, survive baking in contrast to cereal and fungal enzymes
10and are commercially used as antistaling agents. However,
excessive amounts can produce adverse effects during storage.
Bread can turn gummy and lose desirable textural properties due
to the thermostable property of the enzyme. New improved
bacterial amylases with reduced thermostability have been
introduced to prevent these problems occurring during storage.
Bacterial a-amylase cleaves linkages in the amorphous regions of
starch where they are most accessible to enzyme attack. Once the
enzyme complexes with the starch mo]ecule and the initial
20cleavage has been made, the enzyme may remain with one fragment
and produce one or more breaks before dissociating and moving to
another substrate molecule (Martin and Hoseney, lgglb~. Prior to
baking, they only digest the damaged starch ~5~). On the other
hand, bacterial and fungal ~amylases produce small dextrins that
interfere with hydrogen bonds formation ill starchprotein
interaction and, thus, retard bread firming (Valjakka et al.,
lg94)
~ -amylase is an exoenzyme. It releases two joined glucose unit
30~maltose) from starch. amylase is normally present in flour so
that addition supplementation is not required. Still, the
addition of aamylase will enhanci the action of ~ amylases since
it will produce small dextrins on which ~-amylase can readily
act.
Glucoamylase is an exoenzyme which works on the nonreducing end
C a starch chain and releases glucose molecu]es in a step wise
process. It used in bread for glucose production since it results
in a sweeter product compared to maltose produced by ~-amylase.
Two other major groups of enzymes can also be used: non-starch
polysaccharide degrading enzymes, and the lipid modifying
enzymes. The non-starch polysaccharide enzymes consist
mainly of hemicellulases and pentosanases that have been shown
to have some effect retarding staling. The lipid modifying
enzymes group include lipoxygenases lipases and phospholipases.
These have also been the subject of many studie and appear to
have an effect on bread firming. The action of lipoxygenaseE such
as soy lipoxygenase, appear to be related with gluten
50development. It was proposed that the action of lipoxygenase
involves modification of the hydrophobic areas o~ the gluten
~KuIp and Ponte, 1981~. It was assumed that the release of gluten
. ~_ 2188893
bound lipids will provide additional free lipids for complexing
with starch during baking leading to a softer bread.
Maga (lg75) reported studies on gum carrageenan and gum karaya
an reported that they could have an antistaling effect.
Christianson and Gardner (1974) studied the effect of xanthan
gums in protein fortified starch bread. However, they found no
effect on bread firming. Mettler and Seibel(1993) worked with
guar gum carboxymethyl cellulose, mono and diglyceride and
10diacetyl tar-taric ester of monoglycerides. Their results showed
that gums had some effects in retarding the staling process.
The effect of gums on staling have not been investigated
extensively Further studies are required to determine if they
play an important role as anti- staling agents.
Most studies to date have examined the effect of softening agents
individually. However, combination treatments with these agents
could have a more pronounced effect on sta]ing.
As mentioned previously, the combination of mono and diglycerides
did not appear to give favorable results. However, emulsifiers
have been added with shortening to defatted flours to give better
results. For example, 0.1 % of ethoxylated monoglyceride ~EMG)
and 0.2~ hydroxylated lecithin, alone or in combination with 2~
shortening increased volume and improved softness of bread: each
was superior to shortening alone. EMG primarily strengthened the
dough and increased bread volume, and lecithin improved
rheological properties of the dough and crumb grain texture
30~Pomeranz et at., 1991).
The combination of an enzyme and an emulsifier resulted in a less
firm bread than bread in which these additives were used
separately ~Pomeranz e at., 1991). However, they did not have a
synergistic interaction on bread firmness of white pan bread.
Some reports indicated that enzymes alone have little effect on
bread staling, and that emulsifiers alone increase bread softness
Others have reported that when bacterial aamylase was added to
the dough together with crumb softener emulsifiers, such as
40monoglycerides, firming rate was greatly reduced. However,
Valjakka et at. ~1994) did not find major interactions between
enzymes and surfactants.
Martin and Hoseney ~199lb) reported that the amylose-lipid
complex was shown to be an obstacle to starch hydrolysis with
glucoamylase. The initial velocity of reducing end groups
released by the action of amylase was lower in the presence of
10% monoglycerides. Starch granules were less swollen in the
presence of a monoglyceride, which may have decreased the rate
50vf hydrolysis. However, their results showed that the
monoglyceride did not function by affecting the thermal stability
of the amylases. In a system with high levels of ~ -amylase,
2188893
11
monoglycerides seemed to reduce ~ -amylase activity, while
bacterial ~-amylase overcame the effect of monoglycerides on ~-
amylase activity.
Combination of many enzymes have been patented, such as
debranching enzymes ~acting on the a(1,6 ) linkages with
amylases. Bacterial and fungal amylases in combination have a
synergistic effect on softening. A glucoamylaseamylase
preparation, able to digest native starch rapidly has been
lOdeveloped in Japan. It is an enzyme originating from Aspergittus
K27. It has 70~ glucoamylase and 30~ ~-amylase activity and ;s
able to hydrolyze native corn starch comp]etely within 24 hours.
Combination of raw starch digesting enzymes and amylases led to
the conclusion that the degradation of raw starch granules is due
mainly to the glucoamylase activity, while ~amylase exert a
synergistic action (Valjakka et at., 1994).
The reduction in bread firmness due to enzymatic action has been
discussed by Dragsdorf and Varriano-Marston (~980). 'rhey showed
20that bread supplemented with bacterial amylases to be the softest
during storage. They noted that bread supplemented with barley,
malt or fungal enzyme showed the same initial softness as the
fresh product. Furthermore, they observed an order of decreasing
degree of starch crystallinity from bacterial a-amylase, cereal
~ -amylase, fungal a -amylase and unsupplemented bread,
postulating that the degree of crystallinity paralleled the heat
stability of the enzyme, which produce lower molecular weight
starch units. These will have more freedom of movement and can
more easily arrange themselves into lattice position. Thus, they
30indicated that starch crystallinity and bread firming were not
synonymous.
Martin and Hoseney (1991) also observed that bacterial ~ -amylase
and ~-amylase inhibited bread from firming during five days of
storage. Bread supplemented with amylases contained great
quantities of dextrins which appear to have an anti-firming
effect. Valjakka et al. (19g4) showed that bacterial amylases
reduced the firming rate of bread and that the rate of firming
increased with increasing concentration of enzyme confirming our
40Observations. They noted that excessive amount of the enzymes
could lead to keyholing ~weakness of loaf side walls). However,
this defect was not observed for bagels. Finally, Akers and
Hoseney (lg94) recently reported the positive effect of enzymes
on bread staling. They again concluded that the dextrins produced
by amylases are important in controlling the rate of bread
firming.
A variety of gums can be used to increase the keeping quality of
bakery products. When incorporated into a baked good formulation,
50gums have the ability to bind water into a gel to reduce water
migration and to control rheological properties resulting in an
extended shelf life. This extension of freshness can be
~ ' 2188893
12
attributed to the ability of gums to immobilize and bind water
as well as interfere with hydrogen bonding between starch and
protein i.e., the "bound" water exerts a plasticizing effect.
Examples of gums include guar, xanthan, locust bean gumr agar
gum, cellulose, methylcellulose, alginates and pectins. As with
other ingredients, they vary in their chemical structure and in
their ability to bind water and to maintain freshness in a
product.
~uar gum is a polysaccharide with a straight chain of
D-mannopyranose units joined by linkages with a side branching
unit of a single D-galactopyranose unit joined to every other
mannose unit by a tl,6)linkages. It has a high hydration and
water binding capacities, and forms a viscous colloidal
solutions when hydrated in cold water systems.
Xanthan gum is a high molecular weight polysaccharide produced
by the action of micro-organism on dextrose. It is very heat
20stable, it has a high moisture binding capacity and it
contributes to the elasticity of the dough and shelf life
extension of baked products.
Locust bean gum is a polysaccharide with a straight chain of
D-mannopyranose units joined by ~ (l,4) linkages with a side
branching to every fourth mannose by an ~l,6) linkage. It has
very good moisture binding capacity and it is used extensively
in frozen deserts, soft cheese and composite meat produGts.
30Agar gum is a complex polysaccharide mainly composed of agarose
lwhich is the gelling agent) and another component which is very
viscous and weak gelling. It is mainly used for its gelling and
stabilizing properties.
Algin is a high molecular weight polymer of the salts of
D-mannuronia and L-guluronic acids.
Pectin is a heteropolysaccharide which main component is the
polygalacturonic acid partially esterified with methanol. Regular
40portions of pectin macromolecules ~oin to form so-called adhesion
zones. The resulting formation of a three dimensional network
permits the trapping of large amounts of water. (Fennema, 19~5).
Current theories on the staling process involves starch-protein
interactions mainly through hydrogen bonding. Interference with
this process through the use of enzymes or water binding
ingredients such as HFCS can interfere with this hydrogen
bonding. Since gluten is implicated in the staling process,
another approach would be to replace high protein flour, either
50partially or completely with flour of lower protein content i.e.
lower gluten content to delay staling.
2188893
. ~
13
However, while the use of low protein flour (rice, corn and
bar]ey) improved the textura] shelf life of the product ~Figure
2.15), the sensory shelf life of ~he product was of 3 days
~Table 2.17). In particular, bagel volume was low showing the
importance of gluten for dough development and structure of the
final product. Some studies have been done on the effect of
different kinds of flours on bread firming. Boyacioglu and D'
Appolonia (lg94) showed that the incorporation of 25'~. durum wheat
flour resulted in a less firm crumb bread structure without
lOaffecting any of the bread's characteristics. Torres et al.
(1993) showed that the addition of up to 20~, of sorghum flours,
resulted in tortillas that were softer than the control without
affecting their sensory qualities. These results disagree with
our observations while the addition of. barley, corn or rice
flours resulted in softer products, panelists rejected the bagels
based on their characteristics.
-
Table 2.17: Sensory resulls for rlce, barley and corn.
Sensory Analysis
Flours Odor~2 Flavor Textur~ O~lerall
Days of Storag~
7 14 28 42 7 14 28 42 7 14 28 42 7 14 28 42
Barley (25%)~ 3 ~ 3~4 ~ 3 2-9 -~ - 2-5 2.4 --~ 2.6 2 4 -- --
~/_ 0.~ ~.5 -~ 0.2 --- --- ~. ---
Corn (50%) 3 28 -- 2-8 28 -- -- 2-3 2.1 -- -- 2.3 21 -- ---
Rice (25%) ~ 06 04 OM 05 0 o5 04
1 Based on a wheal ~lour .~pl~c;~"~en .
2 The sensoly was inlernJpled aner 14 days due l~ pa~ t:, request. the b~gels were mushy
and sticky.
siy~ o~ wilh pcO.05, 0.005. 0.0005.
~~ ~nly for rlce.
Avera~e Or 5 replicales roll.wod (below) by ils Slandard D~vlallon.
The incorporation of surfactants into the formulation resulted
in the following (results not shown). Atlas MDA (mono and
diglyceride and ~amylase) at 0.25~ level gave a stale free shelf
life of 25 to 35 days, according to sensorial and compressibility
tests respectively. At the 0.375% level, it increased to 30 and
40 days respectively. However, the use of Atmul500 (mono and
diglyceride, 2%), Atmul p28 (mono and. diglyceride, sodium
stearoyl21actlylate and calcium sulfate, 0.375~) and Atlas SSL
50(0.375~ resulted in a shelf life of lO days according to
sensorial tests and 25 days as shown by compressibility tests.
Thus, Atlas MDA appears to be more effective in delaying staling
218889~
~,
14
probably due to the presence of enzyme in its formulation.
Furthermore, on comparlng the results by Atlas MDA and enzyme
alolle, it was concluded that the additioII of mono and di~lyceride
were not necessary to delay staling and that enzymes alone ~ould
be used to extend the shelf life (Smith et al., l9g5, unpublished
results). Previous studies with mono and diglyceride ~Maga, 1975)
or with sodium stearoyl lactylate ~De Stephanis et aL, 1977)
showed that surfactants bind to starch thus delaying
retrogradation. However, Pisesookbunterng and D' Appolonia (19~3)
10observed that binding of surfactants to starch prevented the
latter from absorbing moisture released from gluten. Thus this
moisture migrated to the crust leading to crust staling and mold
growth. A controversy also existed on whether surfactants affect
the initial crumb firmness (Zobel, 1973) or the rate of firming
(Ghiasi et al., 1982). Our results would indicate a slight
decrease in the firming rate.
Humectants, such as high fructose corn syrup ~HFCS~ can provide
shelf life extension by enhancing the water retention of baked
20goods. Thus, the retain moisture in the crumb resulting in a less
firm, less stale fresher product. HFCS is a bright, transparent
liquid. It is produced by treating high conversion corn syrup
with immobilized glucose isomerase, an enzyme that catalyzes the
rearrangement of the sugar molecule from the aldose to the
cetose form.The transformation involves an intermolecular
transfer of hydrogen between ad~acent carbon atoms to convert
glucose to fructose. The high level of fructose gives its
hygroscopic and sweet properties. Thus, it could affect staling
by binding the moisture and/or by interfering with the hydrogen
30bond formation between protein and starch. However, at higher
levels of use, it can cause stickiness and may adhere to
packaging materials upon storage.
PACKAGlNG
Studies to date have focused on formulation changes to delay
40staling and enhance product shelf life. However, other factors
such as storage atmosphere, storage temperature and method of
production ~i.e., retarding or nonretarding) may also influence
the texture of the product. Therefore, additional studies were
done to determine if these storage processing factors had any
effect in delaying staling in bagels.
Several studies have shown that gas packaging in a CO~ enriched
atmosphere can be used to extend the mold free shelf life of
baked products. Furthermore, some studies have shown that in
50addition to its antimycotic effect, CO2 may also have an
antistaling effect, although results to date have been
contradictory.
2~8~93
, ~
MAP is a new packaging technique. Various methods can be used to
modify the gas atmosphere surrounding a product including gas
packaging, the use of oxygen absorbents or ethanol vapor
generation.
M~P has been mostly used to increase the shelf life of many food
products including bakery products where they were found to
extend the mold free shelf life of products. However, MAP may
also have some effect delaying staling.
Under ambient storage conditions, baked products can develop
visible: mold and firming within 48 hours of baking and
packaging. The main types mold causing bread spoilage are Moniha
sitophilla and members of Aspergillus, Rhizopus and Penicillium
families. Four methods are effective retarding mold growth. These
are modified atmosphere packaging ~MAP, irridiation,
preservatives and freezing ~Black et al., 1993). Only MAP wi]l
be discussed.
20Air is composed of ~78~ nitrogen ~N2), 21% oxygen ~~21 ~ and 1~
carbon dioxide (CO~). The principle of modified atmosphere
packaging is that by changing the composition of the atmosphere
around a food product,e. i., reducing the amount of O~ and
increasing the levels of CO?, shelf life of food is significantly
increased ~Doerry, 1985).
Young et at. ~1988) defined MAP as ~Ithe enclosure of food
products in high gas barrier film in which the gaseous
environment has been changed modified to slow respiration rates,
30reduce microbial growth and retard enzymatic spoilage with the
intent of extending shelf life". It is estimated that the demand
for MAP foods in North America could reach 11 billion packages
the year 2000 ~Smith and Simpson, 1995).
Several methods can be used to modify the gas atmosphere surround
bakery products. These include vacuum packaging (VP), gas
packagIng, use of oxygen absorbents and ethanol vapor generators.
Some of the methods of atmosphere modification will be discussed.
40Vacuum packaging was the earliest form of MAP. VP is not used for
most bakery products since this process causes irreversible
deformation of soft products ~Parry, 19~3). E~owever, it is used
to prevent rancidity problems in short bread (American Institute
of Baking, Personal communication).
Gas packaging consists of replacing the air with a gas or a
mixture of gases within the package, which is usually an
impermeable film. Gases commonly used in MAP are carbon dioxide,
nitrogen and carbon monoxide. Other gases, such as chlorine,
50ethylene oxide, nitrogen oxide, ozone, propylene oxide and sulfur
dioxide have been investigated but are not used commercially. The
most commonly used gases are N7 and CO2 alone or in combination
218889~
' ~"
16
with each other. The reason for this is that they are neither
toxic, nor dangerous and they are not considered as food
additives (Smith and Simpson, lg95).
N2 does not have a antimicrobial effect by itself since it is an
inert gas. However, it is usually used as a filler gas to prevent
the package collapsing in products that could absorb some CO~
upon storage. It is also used to prevent rancidity problems in
food of low a i.e., where microbial spoi]age is not a problem.
CO? is the most important gas since it is both bacteriostatic,
~ungistatic and can prevent growth of insects in the package.
However, it is highly soluble in water and fats, and forms
carbonic acid, resulting in flavor changes when used in high
concentrations. Moreover, the product can also absorb CO~ causing
the package to collapse.
The effect of CO~ can be summarized as follows:
201.The exclusion of O~ by replacement with CO~ may contribute to
the overal antimicrobial effect by slowing the growth of aerobic
spoilage microorganisms,
2.The CO2/HCO3~ ion has an observed effect on the permeability of
cell membranes,
3.CO~ is able to produce a rapid acidification of the internal pH
of the microbialcellwith possible ramifications relating to
metabolic activities,
4.CO~ appears to exert an effect on certain enzyme Systems ~Smith
and Simpson, lg95).
In bakery products, the mold free shelf life increases with
increasing concentrations of CO~ in the package headspace ~Smith
and Simpson, 1995). Extensive studies have shown that CO~:N
~60:40~ mixture is most suitable and that this concentration is
an effective one to increase the chemical and microbial shelf
life of bakery products.
However, problems, such as staling and discoloration still occurs
in some products. Also, if food is eaten directly from an MAP
pack, a bitter flavor of carbonic acid can noted. This usually
appears in the product after four days of storage. The N~ gas
also produces a noticeable offodor in bread within one day after
baking, an odor which increases with time. The control (air
atmosphere) produced a different ''stale" odor after seven days
at room temperature (Brody, 1989). However, these odors could be
overcome by toasting products prior to consumption (Smith and
50Simpson, l995)
Q~ Q ~-~
l7
Oxygen absorbents are composed of any substances, packaged iIl gas
permeable materials in the form of small pouches, which react
chemically with oxygen. Placed in sealed packed containers, they
reduce the oxygen concentration to 100 parts per million or even
lower and maintain this level, as long as the appropriate
packaging film is used. Substances commonly used are iron powder
and ascorbic acid tSmith and Simpso~, lg95). The first oxygen
absorbent was an iron powder based absorber developed by
Mitsubishi Gas Chemical Company, under the trade name of Ageless
10in 1977. In 1989, almost 7000 million sachets were sold in Japan
with sales of absorbents growing at a rate of 20~ per year (Smith
and Simpson, 1995).
The absorbing reaction is the following:
Fe~Ee +2e
1/2 ~2 + H20 + 2 ~ 20H
Fe2+ ~ 20H ~ Fe(~H)2
Fe(OH)2 + 1/4 H20 ~ Fe(OH)3 (Brody, 1989).
ZOOther types of absorbents are now available on the market. These
are Freshilizer and Freshpax absorbents all of which act in a
similar manner to Ageless (Smith and Simpson, 1995).
Oxygen absorbers should meet specific criteria. These are:
l.The ingredients should not be toxic,
2.They should absorb oxygen at an appropriate rate,
3.There should not be any unfavorable side reactions,
4.They should be of uniform quality,
305.They must be compact and uniform in size (Brody, 1989).
Many factors influence the choice of oxygen absorbents such as:
l.The nature of the food, i.e., size, shape, weight,
2.The a of the food
3.The amount of dissolved oxygen in the food,
4.The desired shelf life of the product,
5.The initial level of oxygen in the package headspace,
6.The oxygen permeability of the packaging material (Smith and
40Simpson, 1995).
In Japan, oxygen absorbents are used extensively to prevent
discoloration problems in pigmented products, and mold spoilage,
especially in intermediate moisture and high moisture bakery
products. Studies have shown that oxygen absorbents to be three
times more effective than gas packaging for increasing the mold
free shelf life of some bakery products. Five to fortyfive days
for white bread at room temperature. fourteen days at 30 C for
pizza crusts. In the United States, oxygen absorbents technology
50is still in its infancy.
8 9 3
. ~
18
Using oxygen absorbent technology, the she]f life o~ white pan
bread could be increased 5 days to 45 days at ~oom temperature
while pizza crust had a mold free shelf life of 14 days at 30 C.
The main problems with oxygen absorbents are consumer resistance
to their use in food. Two main consumer concerns are the fear of
ingesting the absorbent and the spillage of sachet contents into
the food thus adulterating the product ~Smith and Simpson, 19951.
But on the other hand, oxygen absorbents are inexpensive, non-
10toxic, fast and easy to use. They devolopment of rancid offflavors of fats and oils. Hence, the oxygen absorbent is a
preservative free method for increasing shelf life and
distribution by preventing mold growth.
Most of the studies to date with M~P have focused on extension
of the mold free shelf life of products. However studies on the
anti-staling effect of enriched CO~ atmospheres produced
conflicting results. Doerry ~lg85~ observed that the crumb of
bread became firmer irrespective of the storage atmosphere i.e.,
20storage in air, 100% CO2 or 100~ N7. Brody ~19~9) reported that
the staling rate of white and whole wheat bread was not
significantly reduced when packaged in carbon dioxide or nitrogen
as compared to air. Black et al. ~1993) also reported no clear
pattern of firming over time between packaging treatments for
pita bread packaged under various atmospheres.
However, Knorr et al. ~1985) showed that the compressibility of
bread packed under CO2 was lower than bread packed in air
suggesting that carbon dioxide delayed bread firming. Knorr
30~1957) reported that carbon dio~ide significantly decreased
compressibility of some baked goods compared to air-stored
samples and that softer products were obtained when stored under
100% CO~. While the initial compressibility of air and CO~ stored
bread was identical bread stored in CO~ for 72 hours was
significantly softer than the air-stored products ~Knorr, 1987).
Observed differences between water activity of the CO~ stored
samples and air-stored samples after 96 hours of storage suggests
that CO2 atmospheres may affect the water binding in bread
~Knorr, 1987).
Avital et al. (1990) reported that CO? delayed bread staling.
They proposed that changes in the sorption properties of MAP
baked goods were responsible for this effect. Since amylose is
in the crystalline state after one day, amylopectin is the main
component with available water binding sites. C07 appears to
block some of these sites, thus causing a reduction in hydrogen
bonding between the amylopectin branches resulting in a reduced
water sorption capacity. Since hydrogen bonding has been shown
to result in bread staling, blockage of water binding regions may
50explain bread finming. The effect of CO~ was found to exist when
water was in "the solute state". The solubility o~ CO2 in water
is 35 times higher than O~. Thus, it is possible that when water
218889~
~ ~,
19
is in the solute stage, CO2 dissolved easily and bound strongly
to amylopectin thus preventing hydrogen bonding,
Smith (1994, unpublished results) also reported that the staling
rate of white and whole wheat bread and biscuits was
significantly reduced when packaged in 100~ CO2 compared to
packaging in 100% N2 or air.
218~833
SU~MARY OP THF, II'~VF,I~lTlON
As aforesaid, the invention lies in the combination of the above
mentionned techniques.Such combination has proved to be
synergistic. The invention and its advantages will be better
understood upon reading the following non-restrictive description
made with referene to the according drawings
10BRIFF DESCRIPTION OF THE DRAWINGS
FIG. 2.1. is a schematic representation of a standard bagel
preparation.
FIG. 2.2 is a graphical representation of the compressibility
of the control bagels at different days.
FIG. 2.3 is a graphical representation of the compressibility of
bagels treated with Novamyl enzyme.
FIG.2.4 is a graphical representation of the compressibility of
bagels treated with Superfresh enzyme.
FIG.2.5 is a graphical representation of the compressibility of
bagels treated with Megafresh enzyme.
FIG.2.6 is a graphical representation of the compressibility of
bagels treated with guar gum.
FIG. 2.7 is a graphical representation of the compressibility of
bagels treated with xanthan gum.
FIG.2.8 is a graphical representation of the compressibility of
bagels treated with locust bean gum.
FIG2.9 is a graphical representation of the compressibility of
bagels treated with agar gum.
FIG.2.10 is a graphical representation of the compressibility
of bagels treated with cellulose.
FIG.2.11 is a graphical representation of the compressibility
of bagels treated with methyl cellulose
FIG.2.12 is a graphical representation of the compressibility of
bagels treated with algin gum.
FIG.2.13 is a graphical representation of the compressibility of
bagels treated with pectin gum.
FIG2.14 is a graphical representation of the compressibility of
4C bagels treated with high fructose corn syrup.
FIG.2.15 is a graphical representation of the compressibility of
bagels made of rice, barley and corn flours.
FIG.2.16 FIG2.14 is a graphical representation of the
compressibility of bagels treated with surfactants.
~ '- 21~893
21
DET~IT Fn DESCRIPTION OF THE INVENTION
Bagels can be reformulated using appropriate levels of enzymes,
gums, high fructose corn syrups and surfactants. Reformulation
can be achieved using the standard recipe and baking procedure
outlined in example 1. All ingredients were used at levels
suggested in their commercial literature. The ingredients, and
their levels of use, in the reformulated product are shown in
lOTable 2.3 (page 5a ).
The textural and sensorial changes in non-reformulated (control)
bagels were tested . The results are shown in Figure 2.2 and
Table 2.4. All bagels had an initial compression test measurement
of 0.008 MPa at day 0. This value increased steadily throughout
storage to ~0.015 -0.016 MPa as a result of crumb hardening i.e.
staling. Based on these results, bagels were deemed stale
when a compression test of 0.01 MPa was reached and this was used
as the "staling standard" for all reformulated products. However,
20staling does not just involve moisture migration and crumb
hardening but also a loss of flavor components. It is evident
that all control bagels had an unacceptable odor, flavor, texture
and overall desirability scores (<3) after 3 days. Therefore,
while a 6 weeks mold free shelf life is possible using oxygen
absorbent technology staling is still a major problem limiting
the shelf life of bagels. This problem can be addressed through
reformulation with enzymes, gums, high fructose corn syrups,
flours of varying protein content and surfactants.
~ble 2.4: Sensory resulls for conlrol bagels.
Sensory Analysls
Control OdorFlavor Texture Overaîl
Days of Storage
7 14 28 42 7 14 28 42 7 14 28 42 7 14 28 42
4 ~ Control 2.2 2.2 1.8 1.6 2.8 2.ff 2.4 2.2 2.4 2.2 2.2 2 2.2 1.8 i.8 1.4
0.4 0.8 0.4 O.S 0.4 0.5 0.5 0.4 0.5 0.4 0.4 0.~ 1 0.4 0.8 0.5
A\~erage of S replicales IOIIJ~d (below) by lls Slandard Deviallon.
~0
21~9~
22
Thus, it appears that enzymes have a beneficial effect on crumb
firmness, i.e., they delay the staling process. This can be
attributed to the ability of these enzymes to "cut" the amylase
and amylopectin branches of starch resulting in smaller branches
which prevents starch-protein interaction. They also create low
molecular weight sugars and dextrins improving the water
retention capacity of the baked good. Furthermore, the three
types of enzymes did not result in "stickiness" or "gumminess"
in the end product.
The results for the various levels of gums included in the
reformulated bagel recipes and their effect on freshness are
shown in Figures 2.6-2.13 and Tables 2.8-2.15.The effect of two
levels of guar gum ~0.2 and 0.6~) on bagel softness is shown in
Figure 2.6. Textural shelf life could be extended to ~20 days at
the 0.2~ level ~flour weight basis) whereas at higher levels
~0.6~) bagels were stale after 30 days ~shown by compressibility
test of 0.01 MPa). However, for sensory analysis of products only
bagels formulated with 0.6~ guar gum were marginally acceptable
20after 28 days at ambient temperature.
The effect of three different types of cellulose (Type 40, 300
and 900) end methylcellulose, all used at the 1~ level ~flour
weight basis) on the softness of bagels throughout storage are
shown in Figures 2.10 and 2.11, and Table 2.12 and 2.13
respectively. The textural shelf life of bagels using cellulose
40 was terminated after 14 days. However, the shelf life could
be extended to day 25 using cellulose 300 and 900 at the 1~
level ~Figure 2.10). Methylcellulose had an even greater effect
30On textural shelf life and bagels were still acceptable until day
30 using 1~ methylcellulose in the formulation. Furthermore,
methylcellulose also had a more pronounced effect on the sensory
qualities of the reformulated bagel as compared to cellulose
~Tables 2.12 and 2.13). With methylcellulose, products were still
acceptable after 28 days at ambient temperature (Table 2.13).
Mold growth was visible in all air packaged bagels after 56 days
at ambient storage temperature. However, by packaging bagels in
either 100~ CO2 or with an Ageless type FX100 oxygen absorbent
40mold growth could be inhibited throughout the 42 day storage
period. These results are in agreement of previous studies by
Smith et al. (1996) and confirm the antimycotic effect of high
C02 levels and low ~2 levels on mold growth. The antimycotic
effect of various gas atmosphere on mold growth on bagels are
shown in table 5.1.
;.1 s Elrecl Or ~ , c~ s~ e ~r l~ els
F~r~tllllell~l Pllcî~ ly ~ Uny~ ~ vl~lble~
~ wll~
r.)~/0 ~07 N~
13~yeless ~X ~bs~rbQI1l NC~
C 1WSb C02 NG
ele~s l:X ~bs~belll NC~
E ~Ir ~-~
N(l- N~ uruwll~ r ~12 dnys.
21~g3
23
~he results for textural and sensory changes throughout storage
are summarized in Table 5.2. Shelf life in days was determined
from graphical results when a compressibility of 0.01 MPa and a
sensory score of <3 was reached (results not shown).
Inl~lc~.2lllre~t~rlr-cknhlllgc~ ns~ e.~ nln~ el~s~lnlsl~elr~ r ~n~cl~
~mlul0tl~l~ D~u~ll Pn~heg~ 8l~ellllrQ
l wlll~nu~pl)QrQt~xlure 8Qn~y
ct:)2
b C02 ~14 ~14
B ~ I~gel~s ~X ~1'1 ~14
C 1Wo~o CC~ ~21
t~ - A~eles~ I~X ~Z8 -2
E~ Alr ~? c7
Air packaged bagels are stale in <7 days as observed previously.
Flushing bagels with 100% CO2 during mixing and subsequently
packaging in 100% CO2 or with oxygen absorbents have little
effect on either the textural or sensory shelf life. Indeed,
bagels are staler than non flushed bagels packaged in either CO2
or with an oxygen absorbent (C and D).
Furthermore,bagels were rejected after 14 days due to an acidic
sharp taste which can be attributed to either the CO2 in the
30dough or absorption of CO~ from the packaging atmosphere
~Formulation A). These results are contrary to the observations
of knorr (1987) who reported that flushing enriched white bread
dough under a CO2 atmosphere resulted in a softer bread. However,
in these studies knorr (1987), flushed CO2 during the
fermentation (proofing) stage and not during mixing as in our
study. This latter route was taken as bagels formulated in our
study had a limited proofing or fermentation time. However, our
results agree with the observations of knorr and Tomlins (1985)
who reported that French bread and white bread packaged under
40100% CO2 were significantly softer than air stored samples.
As shown in Figure 5.1. bagels packaged under 100~ C~2 have a
compressibility of 0.009 after 42 days at room temperature i.e.,
within the "staling standard" of 0.01 MPa. However, while
textural shelf life is acceptable, bagels are rejected after 21
days again due to sharp acidic taste probably caused in
dissolution of headspace CO2 in the aqueous phase of the
product.Finally, bagels packaged with an oxygen absorbent
(Formulation D) had a textural and sensory shelf life of 28 days.
In conclusion, the results confirm that flushing CO2 into the
dough during the mixing stage does not have a beneficial effect
~1~$~ 3
' ~,
24
on crumb texture i.e., staling. It has also shown that packaging
bagels in 100~ CO2 could be a useful alternative to reformulation
to delay staling. While the exact antistaling mechanism of CO2 is
not known, it may affect the hydrogen capacity of proteins which
would have a plasticizing effect on starch-protein interactions.
Hence, bagels reformulated with enzymes, gums and HFCS in
combination with modified atmosphere packaging ( e.g. elevated
levels of CO2) have an anti-staling effect for 42 days and are
lOedible within 21 days after packaging.
2 1~ 3
~,
E~ PLEl (reformulation)
Bagels were reformulated with the ingredients mentioned
hereinabove in "reformulation" so as to monitor their effect on
the textural and sensorial qualities of baggels over a 6 weeks
period at ambient storage temperature ~25 C).
All ingredients were added to a Hobart mixer ~D300, Hobart
10Canad~Inc., Don Mills, Ontario~ and mixed at a high speed, for
~10 mins until the dough was formed and then at low speed for
5 mins until the dough was properly developed i.e., indicated by
dough temperature (30 C~ and by the feel of the dough. The dough
was then removed from the mixer, kneaded, and proofed at room
temperature for ~10 minutes. After proofing, the dough was cut
into 75g pieces and shaped manually into a bagel form. The bagels
were then proofed for an additional 5 minutes prior to being
boiled in a kettle filled with boiling water containing honey (4
tablespoons in lOL water) until they floated to the surface.
20Bagels were then removed from the kettle using a wire sieve and
drained of excess water. The bagels were coated with sesame seeds
or both sides, placed on wire racks and baked for ~18 minutes ~g
minutes on each side) in a convection oven at 400 F (Garland
Convection Oven (TE3,4CH Commercial Ranges Ltd., Mississauga,
Ontario).
After baking, bagels were cooled to room temperature and packaged
(2 per bag) in Cryovac barrier bags (size 210x210 mm, Cryovac,
Mississauga, Ontario, Canada). An Ageless type FX100 oxygen
30absorbent ~Mitsubishi Gas Chemical Co., Tokyo, Japan) was added
to each bag to prevent mold growth during storage. All packaged
bagels were stored at 25 C for 6 weeks, and monitored for
textural and sensorial qualities at regular intervals (days 0,
3, 7, 14, 28 and 42). A flow process of bagel preparation is
shown in Figure 2.1.
Based on this initial study, the estimated shelf life of bagels
for all reformulated products stored at 25 C are shown in Table
2.18. The textural shelf life was based on the time (days) to
40reach a compressibility of 0.01 MPa. While sensory shelf life was
based on time (days) to reach an overall acceptability score of
~3. It is evident from these results that certain ingredients may
result in a desired textural shelf life of 42 days, yet have a
lower sensory shelf life, and vice versa.
However, certain formulation involving enzymes (Superfresh, and
Megafresh at the 0.150.2% level) resulted in a 42 day extension
in textural and sensorial shelf life of bagels. Algin gum at the
0.2~ level also produced similar extensions in shelf fife. While
50HFCS at the 50% level delayed staling for 42 days, sensory shelf
life was regarded unacceptable after 28 days. Pectin also gave
a favorable extension in both textural and sensory shelf life.
~ 2t8~893
26
F.X~IPI F.~ (reformulation)
Novamyl is a genetically modified maltogenic amylase produced by
a genetically modified strain of Bacillus subtilis (host) which
has received the gene for maltogenic amylase from a strain of
Bacillus stearothermophilus. When used at a level of 0.031%
lO(flour weight basis~ it had a pronounced effect on the textural
shelf life of bagels (Figure 2.3). At the end of the 6 week
storage period, bagel texture had changed very little (from 0.006
MPa to 0.007 MPa~ over this time period. This was well below the
textural standard of O.Ol MPa used as an indicator for staling.
However, higher levels ~0.047~i) did not result in an improved
textural shelf life. Indeed, product was regarded as stale after
~14 days as indicated by a compressibility test of O.Ol MPa
(Figure 2.3).
20The results for the sensory scores of bagels reformulated with
Novamyl are shown in Table 2.5. Based on a "cut-offl
acceptability score of 3, it is evident that bagels reformulated
with 0.031% Novamyl, had a sensory shelf life-of 28 days which
is interesting. Thus, while objective measurements resulted in
a shelf life of ~42 days, product had a stale flavor and odor
after 28 days and was considered "stale" by panelists.
Table 2.5: Sensoly results for Nov~myl enzyme.
Sensory Analysis
Novamyl Odor Flavor Texture Overall
Days of Storage
7 14 28 42 7 14 28 42 7 14 28 42 714 28 42
0 031% 3.63.73.83.53.83.83.82.23.83.73.~ 2.73.83.73.72.n
+/_ 0.91.20.70.8100.70.910.50.71.50.~ 0.50.81.1
o 047% 3.~ 3.43.73.43.23.23.23.53.12.92.52.5 ~.43.63.73.3
~/_ O.B 0.81110.71.1 ~.8110.81.210.510.8
The compressibility results were highly significant with a
p-value of <0.0005 (normally a p-value of <0.05 is considered
significant). However, the sensory results were not significant
and this is mainly due to the nature of the sensory analysis and
the difficulty of the judging task. The p-value measures the
relation between the variables and the outcome. When the p-value
is 0.05,the results are considered statistically significant,
i.e., indicating that the results are not due to chance, but
50there is a real relation between the days of storage, the level
used and compressibility outcome. Furthermore, as expected less
than 2596 correlation was observed between compressibility and the
21~1 9 3
2~
sensory results, showing once more that even if texture is an
important cause of sample rejection, flavor and odor still
influence panelistls perception of freshness.
.
EX~PLE3 (refonmulation)
Similar trends were observed for bagels reformulated with
lOSuperfresh and Megafresh enzymes.Superfresh is a mixture of
fungal and bacterial amylases which act by hydrolyzing the (l,4)
glycosidic linkages of starch by hydrolyzing maltose units into
simple sugars. Its effect on the textural and sensorial shelf
life of bagels at levels ranging from O.l to 0.2~ ~flour weight
basis~ are shown in Figure 24 and Table 2.6. At lower levels of
use (0.1%) firmness was fairly constant over the storage period.
At higher usage levels (0.15-0.2%), firmness measurements
increased slightly from an initial level of 0.006 MPa but were
well below the "staling standard" of O.Ol MPa after 42 days.
20Sensory results showed that optimum results could be achieved
with 0.15 or 0.2% Superfresh in the formulation ~Table 2.6), i.e.
a textural and sensorial shelf life of 6 weeks was possible using
this level of enzyme in the reformulated product.
Table 2.6: Sensory results for Sl,perr.~sl~ enzyme.
Sensory Analysis
Sup~.rl~,sh Odor Flavor Texture Overall
Days of Storage
7 14 28 42 714 28 42 7 14 28 42 7 14 28 42
01% 3.93.73.63.43.~ 3.73 2.63.43 3.22.63.93.53.22.~1
+/_ 0.60.41.10.50.50.41.50.81 0.81.31.10.60.51.30.8
0.15% 3.23 3.23.64 2.62.62.84 3.23.23.83.93.23.63.4
+/_ 0.40.70.80.80.30.81.11.50.60.81 1.30.50.41.11.3
0 2% 3.63.63.63.43.73.63.63.23.43.23 3.23.63.43.23.4
+/_ 0.91.11.10.51 1.11.11.31.10.81 1 1 1.10.80.5
Averaqe of s ,.~I'cqtes ~ n,~d (below) bv lls Slandard Devialioll.
Superfresh followed the same trend as Novamyl i.e., the
compressibility results were highly significant with a p-value
~0.0005, while the sensory results were not significant. The
correlation between the compressibility and the sensory was
50also less than 25%.
2~18~ 8 9 3
F.X~MPI F 4 (refornwlation)
The effect of Megafresh, a bacterial a-amylase and
glucotransferase enzyme system on staling are shown in Figure 2.5
and Table 2.7. At the lower level of use ~0.1~) bagels had a
compressibility measurements of 0.006 MPa after 42 days. At the
100.1596 level, results were similar to those obtained with 0.159~
Superfresh and 0.031% Novamyl i.e., products became slightly
firmer throughout the 42 days storage period. At the higher level
of use (0.2%) bagels reformulated with Megafresh reach their
max;mllm firmness after 35 days ~Figure 2.5). Sensory analysis
showed that optimum results were obtained using 0.159~ Megafresh
i.e., a textural and sensorial shelf life of 6 weeks was
possible using this level of enzyme in the reformulated product
(Table 2.7).
--
. Table 2.7: Sensory resulls for M~ar,esl, enzyme.
- Sensory Analysis
MegafreshOdor Flavor Texture Overall
Days of St~rage
7 14 28 427 14 28 42 7 .14 28 42 714 28 42
01% 3.63.63.6 --'3.33 3 - 3.53.43.2 --3.43 3 --
+/1 0.5 ~).8 ---1.41 0.7 --- 1.10.51 -1.30.70.~ ---
0.15% 3.73.E~ 3.83.63.93.43.43 4 3.43.43.43.~ 3.43.43.4
~/_ 0.60.80.~ 0.50.~11.10.50.71.10.50.50.80.70.50.50.5
0 2% 3.43.43.4 ~ 2.82.82.8 2.82.82.8 - 3 3 2.8 --
+/_ 0.70.51.1 - 0.70.81.4 --- 0.90.81.3 --- 0.80.70.8 ---
1. The sensory was inlerrupled due to mold growth.
Averaye of 5 ~-."c les ~ollowed (below) by ils Slandard Dcvialion.
Compressibility results were again highly significant with a
p-value however the sensory results were also significant with
a p-value ~0.005. However, here again, statistically, no
correlation was found between the compressibility and sensory
50results.
21~1~893
E~ PLE5 (refonmulation)
Compressibility and sensory analysis test results for three
levels of xanthan gum 10.2, 0.6 and 1%) are shown in Figure 2.7
and Table 2.9.
Table 2.9: Sensory results for xanthan gum.
Sensory Analysis
1 0 Xanthan Odor~ Flavor* Texture*~ Overall~
Days of Storage
7 14 28 42 7 14 28 42 7 14 28 42 7 14 28 42
02% 3.73.8333.43.232.53.132.82.63.232.62.4
~/_ 0.90.41.31.30.70.71.511.311.61.30.80.61.21
06% 3.532.82.22.72.62.422.82.621.62.62.~ 2.82
+/_ 0.80.70.80.811.31.611.40.80.70.81.40.80.80.7
2.52.52.52.62.521.621.71.51.61.62.2222.2
+/_ 0.81.211.210.80.50.81.20.70.50.80.410.90.8
Texturally, products were rejected after day 12 at lower and
upper levels of xanthan gum i.e., 0.2 and 1~ ~Figure 2.7 ).
However, at the 0.6~ level, bagels had a textural shelf life of
~25 days. Sensorially, however, products were rejected after 7-14
days for all levels of xanthan gum used. Favorable
compressibility results were observed for bagels reformulated
with locust bean gum (Figure 2.8) with the best results being
obtained at the 0.6% level of use ~Figure 2.8). However, with the
30exception of odor scores, products containing locust bean gums,
were rejected by panelists after 7 days of storage as shown by
the sensory results in Table 2.10.
Table 2.10: Sensory results for locust bean gum.
Sensory Analysis
Locust bean Odor~ Flavor Texture Overall
Days of Storage
7 14 28 42 7 14 28 42 7 14 28 42 7 14 28 42
02% 2.63 ~ 2.42.2 - - 2.22 - - --- 2.42.2 - - ---
+/_ 0.80.8 - - - - 0.50.9 ~ - - 0.80.8 - - - - 0.50.9 --- ~
0 6% 3.53.73.7 --- 2.72.73 --- 2.52.72.2 -- 3.12.72.6 ---
0.50.50.8 - 0.90.51.5 --- 1.21.20.4 ~ 0.61.20.8 --
33.23.5 -- 333 ~- 2.72.52.8 --- 2.42.72.8 ---
~/_ 0.70.50.8 - - 0.801.2 ~ 0.~ o.s o.g - - O.S 0.50.9
1. The sensory was interrupted due to mold growth.
si~ll'fica..l with p~0.05, 0.005, 0.0005.
Averaue Or 5, . pl.' ~ dlcs followed (below) by its Standard Dcviallon.
21~'8g3
rXA~LE6 (reformulation)
A similar trend in textural and sensorial shelf life was observed
for bagels re~ormulated with agar gum (Figure 2.9 and Table
2.11). Thus, while gums appeared to inhibit staling due to their
water binding capacity they fail to enhance the organoleptic
quality of bagels as shown by the low sensory evaluation scores.
These results confirm the controversy effect of gums to decrease
bread firmness (Maga, 1975, Mettler and Seibel, 1993) while
lOothers found that gums had no effect on firmness (Christianson
and Gardner, 1974).
Table 2.11: Sensory resulls lor agar ~um.
Sensory Analysis
Agar Odor~Fîavor*~ Texture~ Overall~
Days of Storage
7 14 28 42 7 14 28 42 7 14 28 42 7 14 28 42
0.2% 3.7 3.5 3 --' 3.5 3 2.8 -- 3.5 3.2 3 -- 3.3 3 2.4 --
2 0 +/- 0.5 0.5 0 ~ 0.8 0.6 0.4 -- 0.8 0.7 0.7 0.5 0.~ 0.5
06% 2.~ 2.8 2.~ 3.3 2.3 2.2 -- 3.1 1.8 1.5 -- 3.4 2.2 2.1
+/_ 0.7 0.4 0.4 -- 1.1 0.8 0.7 --- 1 1.1 0.5 --- 0.9 0.4 0.4
% 3.7 3.5 3,2 --- 3 2.9 2.a - 2.8 2.7 2.6 -- 3 2.S 2.~ --
+/_ 0 5 ~ S 0 4 -- 1 0.~ 0.4 -- 1 .4 0.8 0.8 -- 0.~ 0.4 0 4
1 The sensory was interrupled due lo mold growlh.
si~ "lc~lll ~th p~O.05, 0.005, 0.0005.
Avern~e o~ S ~~ rl_s r~llJ~vc~ (below) by its Standard Devlation.
30~XA~PT.F. 7 (reformulation)
Both algin and pectin ggums also gave ~avorable results from a
textural viewpoint, particularly at the lower levels of use i.e.,
0.2 and 0.6~ (Figure 2.1 and 2.13). However, as with other gums,
sensory shelf life was always less than the textural one as
shown in Tables 2.14 and 2.15. Thus, while gums have a beneficial
effect on staling, its effect varies from gum to gum. This is
expected since the chemical structure of each gum is different
and hence the water binding capacity and plasticizing effect will
40vary. However, it is evident that gums appear to have a greater
effect on the textural quality of bagels compared to their
sensory effect as shown by the consistently lower sensory scores
for bagels reformulated with gums.
Statistically, most gums followed the same pattern. The~
compressibility results were highly significant with p-values of
less than 0.005 to 0.0005, while the sensory results were not
significant with p-value of less than 0.5. However for agar and
xanthan gums, the compressibility results were not significant
50values of 0.5 (xanthan) or less (agar), while their sensory
results were significant with p-values of 0.0005 (agar~ and 0.005
(xanthan). Very low correlations were found between
218~893
~_ 3~
compressibility and sensory results in most of the gums studied.
However, correlations > 5096 were observed for agar, guar and
locust bean gums. This again shows that when the texture,
measured objectively, is "acceptablen, other subjective
attributes such as flavor and odor influence shelf life.
.
Table 2.14: Sensory resulls for algin gum.
Sensory Analysis
Algin Odor Flavor Texture Overall
Days of Storage
7 14 28 42 7 14 28 42 7 14 28 42 7 14 28 42
02% 3.5 3.6 4 4 3.5 3.2 3.43 2.7 2.6 2.72.6 3 - 3.2 3.2 3
~/ o.s 0.s 1 0.6 0.5 1 0.80.61.5 0.8 0.7 0.4 1.1 0.8 0.8 0.7
06% 3.s 2.7 4.2 4 2.7 2.2 3.43 3.2 2 3.4 3.2 3 3.s 3.6 3.4
+/ 0.s o.s o.s 0.60.s o.s 1.10.60.s o.s 0.s o.40.s 0.s 0.s 0.4
1 % 3.2 3.4 3.8 3.53.7 3.8 3.43 3.7 3.8 3.4 3 3.s 3 3 2.9
+/ 0.5 0.8 0.9 0.50.5 1 1 0.60.2 0.7 0.6 0 0.8 1.1 1.1 0.4
Average of 5 r.,' ~ ~'es ~ollowed (below) by its Slandard Dcv;alion.
Table 2.16: Sensory results ~or pèctln ~um.
Sensory Analysis
Pectin Odor Flavor~ Texture Overall
Days of St~r~e
7 14 28 42 7 14 28 42 7 14 28 42 7 14 28 42
02% 3.33.3 3.73.53.6 3.5 3.3 3 3.4 3 2.7 2.73.4 3.2 2.9 2.7
+/ 0.41.2 0.5 0.80.5 0.8 0.5 0 0.2 0.8 0.5 0.70.9 0.g 0.4 0.8
06% 3.13.8 3.7 3.42.7 4 3.3 3 3 3.3 3 2.73.s 3.s 3.2 2.9
~/ 1 0.7 0.5 0.40.4 0.6 0.8 0 1 1 1.2 0.6 0.6 1 1.1 0.4
1 % . 3.43.s 3.s 3.23.63.72.82.s 3.s 332.s 2.s 3.6 3.7 3.22.9
+/ 0.90.7 0.5 0.40.71 0.70.s 0.30.s 0.70.s 0.71 0.7 0.4
nirica"l wilh p~0.05,0.005, .0005.
Avera~e of S l~r~ les followed Sbelow) by its Slandard Dcv;alion.
.
.
2188893
.
E~ PLE8 (reformulation)
The effect of HFCS (liquid or granular) as sugar replacement in
the bagel formulation is shown in Figure 2.14 and Table 2.16.
Both granular and liquid HFCS had a significant effect on crumb
staling as shown by compressibility tests (Figure 2.14).
After 42 days, products refonmulated with liquid HFCS (50%) were
almost as fresh as day 1 bagels while bagels containing granular
lOHFCS ~100%) were only slightly firmer than day 1 bagels. However,
while higher levels also delayed firming, products were very
sweet and sticky due to the hygroscopic nature of HFCS. From a
sensory view point, only the 50~ liquid HFCS gave acceptable
scores with sensory shelf life being acceptable at the end of the
42 days storage period. Thus, HFCS at this level has the
potential to delay staling and to produce an organoleptically
acceptable product. High fructose corn syrups compressibility
results were highly significant with p-values of 0.0005, while
the sensory results were not significant, i.e., similar results
20to enzymes and gums.
Table 2.16: Sensory results for hlgh fruclose corn syrup.
Sensory Anaîysis
High r~ 5Q Odor Fîavor~ Texture Overaîl
corn syrup
Days of Storage
7 14 28 42 714 28 42 7 14 28 42 7 14 28 42
Liquid 5o%1 3-536353 2.83.63.43 3 343 3 2.53.23 3
+/_ 0.~10.50.70.70.50.50.50 0.80.82 0.72 0.80.71
Liquid 100% 3.53.53.23 3.33.53 2.53.83.23 2.53.53.23 2.6
+/_ 1 1.21 0.50.91.51.51.40.51.51.20.70.71.51.10.7
Granular 50% 373 2;8263-7262-42 2.72.62 2 3 2.62.42
+/_ 1 1.21 0.50.91.51.51.40.51.51.20.70.71.51.41.7
Granular100% 3 333 2-5322-82-4.2 2.62.52.22 3.23 2.62
+/_ 1.10.50.70.50.90.80.80.71.20.50.80.71.20.80.51
1. Based on a sugar leplace.,.enl basis.
The producls wilh high fruclose corn syrup were sweeler and slickier Ihan lhe ones using sugar
siy~ ic6lll wilh pc0.05l 0.005, 0.0005.
Average of 5 I~p'ica'cs lo'l.J/cd (below) by ils Slandard Dcvialioll.
8893
~,
33
EX~PLE9 (Combined)
This present essay is to confirm the antimycotic effect of CO2
and to determine its effect on staling.
A standard bagel recipe, as outlined in example 1, was used
through this study. To determine the effect of CO2 on shelf life,
104 processing packaging conditions were investigated. These were:
A. Flushing dough with CO2 during mixing packaging in 100% CO2;
B. Flushing dough with CO2 during mixing packaging with an
Ageless FX 100 oxygen absorbent;
C. Packaging baked bagels in 100~ CO2;
D.Packaging bagels with an Ageless FX oxygen absorbent; and
E.Packaging bagels in air.
In A and B, CO2 was flushed directly into the dough in the Hobart
20mixer for 10 mins until dough was properly developed. The dough
was then proofed at room temperature for 10 mins, cut in 75g
portions, formed, boiled, dipped in sesame seeds and baked as
described in example 1.
In C, D and E, bagels were mixed, proofed, cut, formed, boiled,
dipped in sesame seeds and baked as described in example 1.
All bagels were packaged in 20x20 cm Cryovac bags (2 per bags).
Formulations A and C were packagedi sealed with 100% CO2 in a
30Multivac chamber type heat seal packaging machine (Model 4300/4s,
Multivac Wolfertachwenden, Germany). A Smith proportional gas
mixer, model 299028 (Tescom Corporation, Minneapolis, Minnesota
55441, USA), was used to give the desired proportion of CO2 in
the package headspace. Gases (CO2 and N2) were obtained from
Medigas Ltd (Quebec, Canada). Formulations B and D were packaged
with an Ageless FXlO0 oxygen absorbent taped inside the bag. All
packages were sealed manually using an impulse heat sealer.
Control bagels (E) were packaged in air as described above.
40All packaged bagels were stored at 25 C and monitored for visible
signs of mold growth. Textural and sensory analysis were done at
day 0, 7, 14, 28 and 42. The results ~or textural and sensory
changes throughout storage are summarized in table 5.2. The
antimycotic effect of various gas atmosphere on mold growth on
bagels are shown in table 5.1.
