Note: Descriptions are shown in the official language in which they were submitted.
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LOW D . E . STARCH HYDROLYZATES
This invention relates to starch hydrolyzate products
and to preparation of such products.
It is known that starch can be hydrolyzed by means
of acids or enzymes to produce hydrolyzate products containing
sugars and which therefore are useful in foods. The sweetening
property of the starch hydrolyzates depends to great extent
upon the degree of conversion, that is, the extent to which
the starch molecules have been hydrolyzed. A very common
method of classifying starch hydrolyzates is to measure the
deyree of h~drolysis in terms of dextrose equivalent (D~Eo)
which is a measure of the reducing sugar content of the
hydrolyzate calculated as dextrose and expressed as a per-
centage of the total dry substance. The dextrose equivalent
(D.E.) value of a starch hydxolyzate can be determined
conveniently by the method of Smogyi, M. described in the
Journal of Biological Chemistry 160, 61 (1945) and is the
method utilized herein for determining D.E. values.
The use of enzymes for hydrolyzing starch has gained
widespread application in recent years and enzymes are employed
commercially for manufacturing certain products. Enzymes have
an advantage over acid ca~alysts in that they exhibit speci-
ficity for certain linkages. One type of microbial enzyme
which is commonly employed is alpha-amylase. Alpha-amylase
has the property of splitting 1-4 linkages more or less at
random throughout the starch molecule with little effect on
- ~ ~2~
-- 2
the 1-6 linkages. Moreover, alpha-amylase does not readily
hydrolyze or split the 1-4 linkage in maltose and maltotriose.
Thus, it has been reported that when substantially complete
conversion of starch is effected with alpha-amylase, maltose
and small amounts of trisaccharides and other lower molecular
weight polysaccharides, especially those containing the 1-6
linkages, are present in the final hydrolyzate.
Low D.E. starch hydrolyzates are widely used by
the food industry as bodying agents and carriers for food
flavors, etc. For many applications the functionality or
suitability is enhanced when the D.E. of the hydrolyzate is
relatively low. Thus, low D.E. starc~ hydrolyzates generally
exhibit viscosity, film-forming and low sweetness properties
which are particularly desired for certain applications.
Although the advantages of hydrolyzates with D.E. values
less than 10 have been long recognized by the food industry,
previous attempts to produce a refined hydrolyzate of non-
waxy starch in this D.E. range have been hampered due to the
inability to filter the hydrolyzates. Unusual difficulty in
filtering such low D.E. products has been a serious problem
in the past. Non-waxy low D.E. products have been produced
as unrefined hydrolyzates, l.e., unfiltered products, but
such products have had limited usage because of incomplete
solubility and a marked tendency to hecome rancid with off
flavors and odors duxlng storage.
This invention involves the discovery that low
D.~. starch hydrolyzates having D.~. values of about 6 and
lower can be produced and filtered and refined by an extended
treatment with alpha-amylase at tem~eratures of ahout 95 C.
and above. In accordance wi~h a presently ~reEerred e~bodi-
ment of this invention, a non-waxy starch is clis~ersed in
water at a level of 10-40~ solids, preferably ~n the range
of 20-30~ solids, and liquefied by heating with either
acid or a liquefying enzyme as described in U.S. patent
No. 3,663,369. Whichever method of liquefaction is used, it
-` 12V~35~6
is important that the liquefaction be carried out so as to
provide complete gelatinization with essentially no residual
starch ~ranules, with the liquefied starch having a D.E. of
not substantially above 3. The pH of the liquefied starch
is adjusted to a pH value between about 6.5 and 8.0, prefer-
ably between 6.8 and 7.5. Bacterial alpha-amylase is added
to the liquefied starch which is adjusted to and maintained
at a temperature of about 95 C. or above, preferably at a
temperature of about 95-100 C., for a period of 10 to 60
minutes. When the desired D.E. is reached, l.e. preferably
between 3 and 6, the hydrolyzate is acidified to a pH below
4.5, preferably between 3.5 and 4.0, to inactivate the enzyme,
and the hydrolyzate recovered by filtration. The hydrolyzate
can then be treated with carbon and dried using procedures
common to the art.
Thus, the invention provides a process for producing
a starch hydrolyzate which comprises treating an aqueous
slurry of non-waxy starch with an acid or enzyme to liquefy
the starch and to provide an aqueous dispersion substantially
~0 free of residual starch granules with a measurable dextrose
equivalent value not substantially above 3, then treating
the said dispersion with a bacterial alpha-amylase at a
temperature at least about 95 C. to produce a hydrolyzate
product having a measurable dextrose equivalent value not
substantially above 10, stopping the enzyme action and re-
covering the hydrolyzate so produced. Furthermore, the
invention involves a non-waxy starch hydrolyzate having a
measurable dextrose equivalent value not substantially above
6, a saccharide composition wherein the amount of glucose
pre~ent is less than about 1~ and the amount of maltose is
less than about 1.5%, and a descriptive ratio of less than 2,
said hydrolyzate being further characterized as being filter-
able and substantially completely soluble in water at 80 C.
at solids concentrations below 35% by weight.
~L2(~8~6
The use of an extended treatment with alpha-amylase
at temperatures at least about 95 C. is a critical feature
of the present invention. Whereas the prior art has taught
the use of alpha-amylase at temperatures over 93 C. for
brief periods to accomplish liquefaction, the conventional
practice has been to reduce the temperature after liquefaction
to below 85 C. to maximize the rate of hydrolysis as measured
by D.E. increase. Under these conditions the hydrolyzate is
essentially unfilterable until the D.E. has reached a value
of 8 or higher. We have now discovered that treating the
liquefied starch with alpha-amylase ?t a temperature of
95 C. or higher produces an unexpected improvement in
filterability with very little increase in D.E. This
discovery, that filterability of hydrolyzates of 6 D.E. and
lS lower is enhanced by extending the time of amylase treatment
at 95 C. or above while the rate of D.E. increase is slowed
down, is the feature of the present invention which allows
the recovery of refined low D.E. hydrolyzates of non-waxy
starch which have not previously been available.
A variety of non-waxy starch or amylaceous materials
can be employed in accordance with the invention, such as, for
example, potato, white sweet potato, grain sorghum, tapioca,
121J8S~6
wheat, rice, sago and the like. Corn starch is a preferred
material.
The type of alpha-amylase suitable for carrying
out the pr~sent invention is we~l known to the art and is
5 available commercially under such names as Biocon Canalpha
180, Miles Tenase, or Novo BAN. These are bacte~ial enzymes
produced by Bacillus subtilis. Another type of bacterial
alpha-amylase which may be used is produced by cultures of
Bacillus licheniformis and is available commercially under
the name Novo Termamyl and Miles Taka-Therm. Amylases
derived from Bacillus licheniformis have a higher sacchari-
fying activity above 95 C. than amylases derived from
_cillus _btilis and therefore are more difficult to contrGl
to provide a final D.E. of 6 or less.
The level of alpha-amylase suitable for carrying
out the present process is generally in the range of 0.1
to 0.6~ based on starch solids when a commercial enzyme
product such as the ones listed above is employed. The
e~:act level employed will depend on the final D.E. desired,
the enzyme activity and the temperature and pH of the reac-
tion. If the final D.E. desired is in the range of 3-4, it
is ~referred to use a slightly higher temperature and pH,
1._. 97 C., pH 7.5, which requires a higher level of alpha-
amylase to provide maximum filterability than would be
requ,ired to obtain a 6 D.~. product at a lower temperature
and pH, l.e. 95 C., pH 7Ø Usually for the preparation
of hydrolyzates in the 4-6 D.E. range, we find that 0.2 to
0.4~ alpha-amylase assaying 3,000 to 4,000 SKB unit per
~ram gives satisfactory results.
The reaction time and temperature are closely
l~lated; l.e., within the relatively narrow temperature
range that the invention may be carried out t an increase
in temperature shortens the time to attain maximum filter-
ability. For the preparation of products in the less than
6 D.E. range a reaction time of 20 minutes at 95 C. is
-` lZ(~85~
usually sufficient to provide a filterable hydrolyzate,
although the time may be as short as 5 minutes or as long
as 40 minutes.
- The hydrolyzates of the present invention are
superior to non-waxy starch hydrolyzates of the prior art,
primarily with respect to better solubility and clarity of
aqueous solutions at comparable D.E. values below 6. ~hereas
non-waxy products of 6 D.E. and below of the prior art are
virtually unfilterable, the new low D.E. hydrolyzates of the
invention can ~e easily filtered and treated with carbon to
provide products which are su~stantially completely soluble
in water with the solutions being essentially colorless,
odorless and tasteless. The hydrolyzates of the present
invention have very low levels of the lower saccharides as
shown by the data in Example 5. The clarity stability is
substantially improved over products prepared by prior art
processes as shown by the data in Example 4. The new low
D.E. starch hydrolyzates may be characterized as follows:
1. A low D.E. of 6 or less.
2. Completely soluble in water at
80 C. at all solids concentra-
tions below 35~.
3. Clarity of 30~ solutions at 80 C.
measured against water in a 19
millimeter cell at 600 m~ exceeds
60~ light transmittance.
4. Contain less than 1.0~ monosaccharide
and less than 1.5~ disaccharide and
a descriptive ratio, calculated by
dividing sum of DPl DP6 saccharides
by D.E., of less than 2.
5. Can be filtered at good filtration
rate6, i.e. at rates in excess of
100 milliliters per minute. (See
Example 1.)
~2~3S~6
- 7 --
The following examples further illustrate the
invention and the advantages thereof.
_YMP E 1
Two 3-liter samples of acid-liquefied, non-waxy
corn starch were obtained from a co~nercial jet cooker. The
liquefied starch contained 25% solids, had a pH of 7.2 and a
D.E. of 2.2. One sample was held at 80 D C . and the other at
96~ C. Bacterial alpha-amylase (Canalpha~180) was added to
both samples at a level of 0.2% based on starch solids. This
level was equivalent to 800 SKB units of alpha-amylase per
100 grams of staroh. Two hundred milliliter portions were
removed at 5, 10, 20, 30 and 40 minutes, acidified to pH
3.5 4.0, and checked for filterability by the following test:*
A 9 centimeter, jacketed, filtering funnel heated
with circulating water at 80 C. was equipped with ~1 Whatman
filter paper and attached to an aspirator. Two grams of
filteraid (Celatom) was added to 200 milliliters of crude
hydrolyzate at 75-77 C. and poured into the funnel. A
stop watch was used to measure the time to filter the entire
samE~le or the volume filtered in 5 minutes. The filtration
time was used to calculate the filtration rate in milliters
per minute.
The results comparing alpha-amylase treatment at
80 and 96~ C. are reported below. It is readily apparent
that the rate of D.E. increase is much higher at 80 C. than
at 96 C. while the filtration rate is much higher after
amylase treatment at 96 C. than at 80 C.
~ _ __ __ ___ ~ __ __ _ _
* This test method is used throughout
to obtain data on filtration.
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EXAMPLE 2
A six-liter sample of acid-liquefied starch,
23.3~ solids, was obtained from a production jet cooker
and divided into two 3-liter samples for treatment with
Biocon Canalpha~180 alpha-amylase as shown below. One
sample was held at 80 C. and the other at 95 C~ Samples
, were removed periodically for measurements of D.E. and
filterability after adjusting to pH 3~5-4.0 to inactivate
enzyme.
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The results show that the D.E. increased fastest
in the 80~ C. sample; however, the filtra ion rate increased
faster at 95 C.
EXAMPLE 3
A dispersion of non-waxy starch was treated with
alpha-amylase and liquefied in a commercial jet cooker. Two
samples of liquefied starch were adjusted to pH 7.0 and
heated to 80 C. and 95 C. for treatment with alpha-amylase
as follows:
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The results show that D.E. increased faster at
S0 C. than at 95 C. while the filtration rate for the
low D.E. products (~ 6) was much faster using a 95 reaction
temperature than at 80 C. For example, at 80~ the D.E.
reached 5.88 after 5 minutes and provided a filtration rate
of 81 milliliters per minute. At 95 the D.E. reached 5.6
, at 30 minutes and had a filtration rate of 160 milliliters
per minute.
EXAMPLE 4
Four 3-liter samples of acid-liquefied starch were
drawn from a commercial, steam jet cooker. The liquefied
starch contained 22% solids and had a D.E. of 2.2. The p~l
was adjusted to 7.2 and the temperature held at 85, 90, 95
and 99 C. as shown below. Alpha-amylase (Biocon Canalpha
15 180) was added at a level of 0.3% based on solids. Samples
were removed periodically, acidified with hydrochloric acid
to pH 4 and tested for filterability using the Standard
Filtration Test described previously. A portion of the
filtrate was used to determine D.E. and checked for clarity
after heating to 80 C., then cooling to 60 C. Ciarity was
determined by measuring the light transmittance against water
at 600 m~u using a 19 millimeter B~L test tube ln a Spectronic
20 Colorimeter.
The results are given in the table below. The
data show that treatment with alpha-amylase at temperatures
of 95 or 99 C. produced filtrable hydrolyzates in the 3-5
D.E. range while at 85u filterable products were not obtained
until thc D.E. reached 6 or 7. The clarity data show that
increasinc3 the temperature of amylase treatment from 85 to
3G ~'3 produced a substantial improvement in c~arity stability
of samples in the 3-6 D.E. range.
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- 15 -
EXAMPLE 5
Scveral samples of non-waxy hydrolyzates with D.~.'s
between 4 and 6 were prepared by the process of the invention
and analyzed for D.~. and saccharide profile as shown in
the following table,
- lZ~S~36
-- 16 --
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- 17 -
EXAMPLE 6
Three liters of acid-cooked starch paste from a
production steam jet cooker were adjusted to pH 7.0 with
sodium carbonate and cooled to 96 C. Forty-eight milli-
liters of diluted Biocon Canalpha bacterial alpha-amylase
(equal to 0.4~ on starch dry substance) were added and the
solution held at 95-96 C. for 27 minutes. Hydrochloric acid
was added to adjust the pH to 4.2 and 2.5 grams carbon added.
After 10 minutes at 95 C., the solution was cooled to
85 C. and filtered with the aid of a filter aid. The
filtrate was water-clear at temperatures above 75~ C. and
had a D.E. of 4.3.
Those modifications and equivalents which fall
within the spirit of the invention are to be consldered a
part thereo~.
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