Note: Descriptions are shown in the official language in which they were submitted.
3)31Ei
BACKGROUND OF THh INVENTION
Bitter principles in citrus juices and their products
are flavanoids, predominantly narinyin, and/or limonoids,
predominantly limonin. The chemistry and properties of these
principles have been discussed in detail by J. F. Kefford and
B.V. Chandler in Chapters 13 and 14 of "The Chemical Constituents
of Citrus Fruits" (Academic Press, 1970); V. P. Maier, R. Bo
Bennett and S. Hasegawa; and R. M. Horowitz and B. Gentili in
Chapters 9 and 10 of "Citrus Science and Technology" Volume I
~AVI Publishing Company, 1977) respectively; and N. Ao Michael
Eskin in Chapter 5. of "Plant Pigments, Flavors and Textures:
l'he Chemistry and Biochemistry of Selected Compounds" ~Academic
Press, 1977). The presence of bitterness is often accentuated
by processing of the fruit to juice or concentrate and thus
many wholesome fruits with skin blemi~hes are wasted because
they can neither be used as fresh fruit nor can they be processed
into juice.
Flavanoid bitterness is generally due to the presence of
20 naringin (4', 5, 7,-trihydroxyfla~anone-7 rhamnoglucoside).
Naringin is distribuked throughout the fruit, but occurs in
highest concentration in the albedo. Several methods have
been proposed for the reduction of naringin in citrus juices.
These methods are based on the enzymatic modification of
naringin to nonbitter compoundsj by the action o the enzyme
naringinase. D. Dinelli and F. Morisi (E'rench Patent No.
2,125,539~ discloses the use of naringinase immobilized on
cellulose esters to debitter grapefruit juice. M. Ono, T. Toso
and I. Chibata used naringinase i~mobilized on DEAE-Sephadex*
30 to debitter Natsudaidai juice (J. Fermt. Technol, Vol 55, p.
* Trademark
..~.
36~3~
493-500~ 1977). Ao C. Olson, G. M. Gray and D. G. Guadagni
debittered grapefruit juice using naringinase immobilized in
hollow fibres (J. Food Sci., Vol. 44, p. 1358-1361, 1979).
While these techniques ha~e been used to reduce naringin in
citrus juices, they are limited in their application due to
factors such as the unavailability of purified enzymes in
commercial quantities, low reaction rates associated with
immobilized enzymes and inadequate half life of immobilized
enzymes.
Limonoid bitterness is due to the presence of the dilactone,
limonin. Limonin is formed from its nonbitter precursor-
limonin A-ring lactone r which is initially present in the
albedo of citrus fruits. The formation of limonin from its
precusor takes place in the presence of an acidic environment
or upon heatingO Therefore, processes of juice extraction,
heat treatment, and storage of juice or concentrate result in
limonin induced bitterness, especially in early season orange,
Navel orange and lemon juices. Limonin levels in excess of
20 6 p.p.m. are detectable as bitterness.
Several approaches have been attempted to control limonin
induced juice bitterness. These include preharvest considerations
such as plant growth regulators~ rootstocks~ and a variety of
other horticultural factors (R. F. Albach, G. H. Redman, and
G. J~ Lime in "Limonin Content of Juice from Marrs and Hamlin
Oranges (Citrus Sinensis (L.) Osbeck)." J. Agric. and Food
Chem., Vol 29, p. 313 to 315, 1981); postharvest fruit
treatments with ethylene and plant growth regulators (V. P.
30 Maier, L. C. Brewster and A. C. Hsu in "Development of Methods
3l~
for Producing Non-Bitter Navel Orange Juice." Citograph Vol
56, p. 373 to 375, 1971): the use of relatively low pressures
in juice extraction to prevent disruption of the albedo ~J.H.
Tatum and R. ~. Berry in "Method for Estimating Limonin Content
of Citrus Juices." J. Food Sci., Vol 38, P. 1244 to 1246, 19731;
adsorption of limonin on polyamides (B. V. Chandler, J. F. Kefford
and G. Ziemelis in "The Removal of Limonin from Bitter Orange
Juice" in J. Sci. Food Agric~, vol 19, p. 83 to 86, 1968);
adsorption of limonin on cellulose esters (B. V. Chandler and
R. L. Johnson, U.S. Patent NoO 3,989,854, 1976~; enzymatic
approaches (S. Hasegawa in "Metabolism of Limonoids, Limonin
D-Ring Lactone Hydrolase Activity in Pseudomonas" in J. Agric.
Food Chem., Vol 24, p~ 24 to 26, 1976); and the use of bitterness
modulators such as neodiosim (D. G. Guadagni, Ro N. Horowitz,
B. Gentili and V. P~ Maier, U.S. Patent 4,154t862, 1977).
U.S. Patent No. 2,681,907; Xunin, "Ion Exchange Resins,l'
2nd Edition, 1958, pp 87, 89; Gage et al, "Science, "Volume
113, pp 522-523 (~ay 4, 1951); and "Chemical Abstracts,~'
~olume 46, Abstract No. 6202f~19~ disclose removing flavanoid
compounds from aqueous solution (including plant and vegetable
extracts) by treatme~t ~ith an ion exchange resin. All of
these references specifically disclose the use of Amberlite*
IRC-50 as the ion~exchange resin. As shown in Table 13 on
page 89 o~ Kunin~ Amberlite IRC-50 is a cation exchanger of
the carboxylic (acrylic~ type which, as further disclosed
on page 87 of ~unin, is prepared by the copolymerization of
either methacrylic acid or acrylic acid with divinyl-lbenzene.
None of the above-listed references specifically disclose the
trèatment of citrus juices.
* Trademark
~ 8Ç~33~i
U.S. Patent No. 4,282~264; French Patent No. 882,796i
Swi5s Patent No. 233,394; Calmon et al., "Ion Exchangers in
Organic and Biochemistry," 1957, pp 623-625; "Abstracts,
112th Meeting, ACS," September, 1947, page 50; and "Chemical
Abstracts," Volume 40, Abstract 55039(19) disclose treating
fruit or vegetable juices (including citrus juices) with ion
exchange materials broadly.
U.S. Patent No. 2,510,797 and U.S. Patent No. 3,463,763
can disclose debittering of citrus juices by treatment with
10 various adsorbents which apparently do not have any ion
exchange properties. More specifically, U.S. Patent 2,510,797
discloses the use of activated carbon and U.S. Patent No.
3,463,763 discloses the use of the resins polyhexamethylene
adipamide and polyvinylpyrrolidone for such treatments.
.
The aforementioned methods have severe limitations and
are not practical enough to warrant commercial application.
The enzyme methods are especially undesirable because of the
unavailability of economic, commercial quantities of enzymes.
Use of polyamides to debitter citrus juices results in
a substantial loss of ascorbic acid from orange juiceO
Furthermore~ a two-stage treatment of the juice is necessary
due to the preferential adsorption of phenolic compounds by
polyamides. This techni~ue, therefore, would not appear to
be economicaily advantageous.
Partial removal of flavanoids by contacting citrus juices
with cellulose esters has been reported by K. S. Kealey and
J. E. Kinsella in "Orange Juice Quality with an Emphasis on
~L~8~'~3~ii
Flavor Components" in CRC Cxitical Reviews in Food Sci.
_trition, Vol 11, p. 1-40, 1979, with reference to U.S~
Patent No. 3,989,854 to Chandler, et al.
U.S. Patent No. 3,939,854 teaches adsorption of limonin
from fruit juices but not naringin adsorption on cellulose
esters. Said patent discloses that cellulose esters success-
fully debitter navel orange juice by adsorbing limonin.
However, nowhere is it disclosed or suggested that the ad-
10 sorption technique can be used successfully to debitterjuices/pxoducts in which naringin, or naringin in conjunction
with limonin induces the bitterness. The application of
cellulose esters to debitter citrus juices is thus limited
to products in which the bitterness is induced solely by
limonin.
The use of neodiosmin as a bitterness modulator has not
found industrial application. Neodiosmin is not approved for
use as a food additive and is essentially ineffective when
20 compounds causing the bitterness are present at high levels.
Japanese Laid-Open Patent Application No 18971 January 30,
1982 discloses a process for producing a citrus fruit juice
which comprises the steps of subjecting fruit juice prepared by
squeezing and separating in a conventional manner and sterilized
as required by centrifugal separation or enzymatic treatment
followed by filtration to obtain a fruit juice having insoluble
solids contents of less than 0O5% (v/v)~ then treating same
with anion exchange resins, and mixing the thus acid removed
30 fruit juice with an nonacid removed fruit juice having insoluble
solids content of more than 0.5% (v/v) in an adequate amount.
3~
Exemplified is use of an anion exchange resin regenerated with
an aqueous sodium hydroxide solution.
Some persons exhibit a low tolerance to highly acidic
fruit juices and therefore would prefer a reduced acid product,
such as reduced acid grapefruit or orange juice. We have
observed that removal of some of the acid from grapefruit
juice by ion exchange, for example, seem to intensify the
sensation of bitterness several fold. Thereore, in order to
10 prepare a deacidified citrus juice, especially grapefruit
jiuce, it is especially desirable to employ a process for
debittering the juice, before or after deacidification.
5a
~L86~3~
Sm~MARY OF T~E INVENTION
It is the primar~ object of this invention to provide a
simple, commercially advant~geous process by which a variety of
citrus juices can be debi~ered by con~acting the juice with a
single adsorbent resin, without impairing product quality. This
bitt~rness may be due to the presence of either limonoids or
flavanoids or both of these compounds.
Thus in a broad aspect the present invention provides a
process for reducing either fla~anoid or limonoid induced bitter-
ness in citrus frui~ juice ~r both flavanoid and limonoid inducedbitterness in citrus fruit juice~ wherein said process comprises:
contac~ing the citrus juice for an e~fec~i~e period of time with
an effective ~olume of a styrene-diYinylbenzene cross-linked co~
polymer adsorbent resin in the absence of an added enzyme,
whereby a substantial amount o fla~anoid and limonoid compounds
present in the citrus juice are adsorbed by the resin.
In another aspect the presen~ invention provides a process
for preparing a citrus ~ruit juice that is reduced in acid and
bitterness comprising the steps oE: contacting the citrus juice
for an effective amount of time with an effecti~e volume of
styrene-divinylbenzene cross linked copolymer adsorbent resin to
provide a debittered citrus juice; and treating said debittered
citrus juice with an anion exchange resin to remove acid from
said debittered citrus juice to yield a debittered, deacidified
citrus juice.
In still a further aspect the invention provides a process
for the preparation of a low acid, debittered citrus juice com-
prising the steps of: separating by centrifuge said fruit juice
into a fraction having insoluble solid contents of less than
0.5% ~v/v); treatin~ said fruit juice fraction with an anion
exchange resin to remove acid from said fraction and produce a
reduced acid fraction; combining said reduced acid fraction with
.~ 6
16
the pulp fxaction to cxeate a recluced acid citrus juice; and
contacting t~e ~educed acid citxus juice ~or an e~fectiYe amount
of time with an e~fective volume of styrene-divinylbenz~ne cross-
linked copol~mer adsorbent ~esin in the absence of an added
enzyme.
In another embodiment the present invention provides a
reduced bitterness citrus juice produced by contacting citrus
fruit juice for an e~ective amount of tim~ with an effective
volume of styrene-di~inylbenzene cross~linked copolymer adsorbent
resin in the absence of an added enzyme.
To achie~e these objectives, the present invention primarily
utilizes ~ commercially a~ailable polymeric adsorbent, Duolite
S-861 (Diamond Shamrock, Inc., Redwood City, CA), chemically
defined a~ a polystyrene adsorbent resin~ cross-linked with
divinylbenzene.
Duolite*S-86l is marketed in bead form. The preparation of
a styrene-divinylbenzene cross-linked copolymer is described in
U.S~ Patent No. 3,238~153. Duolit:e*S~861 is insoluble in water,
dilute acids and bases and in con~lon solvents. The resin may be
used at temperatures above 100C. The specific surface area,
chemical nature of the resin's porous surface, and the physical
structure of the pores ~acilitate fixation of amphoteric organic
molecules. The hydrophobic part of the molecules is adsorbed on
its porous surface.
Chemically similar polymers with similar adsorption properties
axe also available in other grades and sizes (ex. Duolite ES-865,
* *
also fr~m Diamond Shamrock, Inc., SYN 42 and SYN 46, ormerly from
Immacti B.V., Holland, but now from Diamond Shamrock).
* trade markt
3i36
Sele-~ted Properties of Duoli~e S-861
Physical form white beads
Bulk density about 0.71
Specific gravity about 1.02
Moisture content 65 ~ 70~
Specific surface area about 600 m2/g dry product
* trade mark
6b
36
Pore volume about 900 mm3g dry product
Swelling about 30~ between aqueous and
methanolic form
Mean pvr~ diameter about 38 Angstroms
Particle size 0.3 - 1O2 mm
Selected Properties of Duolite Adsorbents
Surface Areal Pore Volume Mean Pore Diameter
Resin m2/g _ ml/g A
10 Duolite S-861 500-600 0.~-OO9 38
Duolite ES-865 650-700 1.3-1~5 90
determined by BET/N2
determined by Hg intrusion
Selected Properties o SYN Resins
porosity Surf. area Mean Pore diam.
Resins ml/g m2/g O
_ _ A
SYN 42 0.89 350 51
SYN 46 1.34 750 36
,
Polystyrene-divinylbenzene cross-llnked copolymer adsor-
bant resins are approved for contact with food materials.
21 C.F.R. 17702710 states as follows:
Styrene-divinylbenzene cross-linked copolymer resins
may be safely used as articles or components of articles
intended for repeated use in producing, manufacturing,
packingJ processing, pr~paring, treating, packaging, trans-
porting, or holding food, in accordance with the following
prescribed conditions:
a. The resins are produced by the copolymerization of
styrene with divinylbenzene.
~6~3~
b. The resins meet the extrac-tives limitations prescribed
in this paragraph:
1. The resins to be tested are ground or cut into
small particles that will pass through a U.S. standard
sieve No. 3 and that will be held on a U.S. STANDARD
SIEVE No. 20.
2. A 100-gram sample of the resins, when extracted
with 100 milliliters of ethyl acetate at reflux
temperature for 1 hour, yields total extractives not
to exceed 1 percent by weight of the resins.
c. In accordance with good manufacturing practice,
finished articles containing the resins shall be thoroughly
cleansed prior to their first use in contact with food.
In accordance with the pre~ent invention, it has now been
discovered a process for reducing either flavanoid or limonoid
induced bitterness in citrus fruit juice or both flavanoid and
limonoid induced bitterness in citrus fruit juice, which
consist of contacting the citrus juice with a polystyrene-
20 divinylbenzene cross-linked copolymer adsorbent resin in the
absence of an added enzymeO
By the preferred procedure of the in~ention, naringin or
limonin induced bitterness is reduced in citrus fruit juices.
Especially preferred i5 the reduction of both naringin and
limonin induced bitterness in citrus fruit juice.
While the invention will be described in connection with a
preferred procedure, it will be understood that it is not
30 intended to limit the invention to that procedure. On the
, . . .
336
contrary, it is intended to cover all alternatives, modifications,
and equivalents as may be included within the spirit and scope
of the invention as defined by the appended claims.
DETAILED DESCRIPTION OF THE INVENTION
.
This invention relates to the treatment of citrus fruit
]uices to reduce bitterness by adsorption of the bitter
principles in the ~uices onto an insoluble polymeric adsorbent
resin.
The citxus juices or concentrates that may be treated in
accordance with the present invention to reduce bitterness
include grapefruit, Japanese Summer Orange, Navel orange, water
extracted soluble orange solids IWESOS), early season tangerines,
Valencia, Temple, and Muscott oranges, lemon and other juices,
wherein the chemical constitutents contributing to bitterness
are either flavanoids and/or liminoids.
The distribution of bitter principles in citrus varies from
20 fruit to fruit. Falvanoid bitterness is dominant in grapefruit,
Seville oranges and Natsudaidai ~Japanese Summer Orange);
limonoid bitterness is dominant in Navel oranges, grapefruits
and in ~emons. Limonin bitterness is particularly severe in
early season fruit, for example, earIy se~son tangerines, Valencia,
Temple and Navel oranges. Limonin bitterness is also associated
with seyeral citrus byproducts, for example, WESOS (Water
Extracted Soluble Orange Solids?, hereafter referred to as pulp
wash solids.
The term "citrus juices" as used throughout this description
.~
36
includes not only whole juices extracted from citrus fruit
but also juice that has been further processed by methods such
as concentration, dilution, blending, drying, etc. The term
also includes juices which may have been treated by the addition
of preservatives, coloring, sweeteners, flavoringsl and
similar materials, it also includes deacidified citrus juices
and pulp wash solids.
As a result of thi5 invention naringin can be effectively
10 adsorbed from grapefruit and Japanese Summer Oranges (Natsudaidai)
juices; limonin can be successfully adsorbed from early season
i tangerine and orange, Navel orange, grapefruit and lemon
juices - as well as pulp wash solids (extracts~. Other bitter
flavanoids analogous in chemical structure to naringin, such as
poncirin, and limonoids analogous in chemical structure to
limonin, such as nomilin, which are present in minor quantities
in citrus products are presumably removed by the adsorption
process.
In a preferred embodiment of the present invention, the
adsorbent is packed in a column, preferably a glass column.
Citrus juice, either freshly extracted, heat processed,or diluted
from concentrate is centrifuge~ in order to remove coarse pulp
particles. The centrifuged juice is passed through the
column. Pulp is added back to the juice after debittering.
The process may also be applied in the batch mode. Pulp-
ree citrus juice is contacted with the adsorbent in a vessel.
Thereafter~ the contents of the vessel are filtered to yield
30 filtrate with a substantial reduction in bitterness. The
fruit juice is contacted with the adsorbent resin at a temper-
ature in the range of 1C to 95C, preferably 2QC to 35~C.
369~
Because of the small bead size of the adsorbent employed,
it is preferred to centrifuge the juice in order to minimize
the possibility of clogging the column. If larger, yet
uniformly sized beads with greater interstitial spaces are
available, preclarification of the juice would be less important
to the practical application of the processO Within the scope
of the invention, the juice may be treated with fine or coarse
resin using other techniques known in the art, such as placing
the resin in a porous bag and contacting the bag with the juice.
The treated juice may or may not be blended with other juices.
However, it may be desirable to blend the treated juice with
untreated juices to attain a controlled, constant and highly
acceptable level of bitterness in the final product. The
product may be packaged as a liquid, processed into concentrate
or into a dry powder, and distributed and stored under conven-
tional conditions.
Use of a styrene divinylbenzene cross-linked copolymer
adsorben~ resin as a means to debitter citrus juices is
exemplifiedl in the column and batch modes, in the following
~xamples:
SPECIFIC EMBODIMENTS
EXAMP_ES 1 TO 8
In these examples the adsorbent resin employed was Duolite
ES-861. Prior to experimentation, the resin was soaked in
tap water overnight, drained and rinsed the next morning with
three (3) washes of distilled water.
Example l
A small glass column (18 cm long x 2 cm i.d.~ was packed
with washed Duolite ES-861 adsorbent resin. The bed volume
'~
9~
(BV) occupied by the adsorbent rPsin was 14 mls. Reduced
acid grapefruit juice containing 762 p.p.m. naringin and 11.5
pOp.m. limonin ~10.5 Brix, 31.5 Brix/Acid Ratio (B/A) -
prepared from concentrate, and previously processed to reduce
the acid by ion-exchange1 was centrifuged. The clear juice
was passed through the column at a flow rate of approximately
5 to 6 BV/hr. ~about 1.5 ml/min.). Approximately 7Q0 mls of
juice were treated and collected. The ratio of the volume of
adsorbent resin used to the juice treated was 1:50. Treated
10 and untreated juice were assayed for naringin and limonin by
High Pressuxe ~iquid Chromatography ~HPLC). The juice had a
naringin content of 143 p.p.m.; the limonin content was 1.2
p.p.m. This translated to a naringin and limonin reduction
(adsorption) of approximately 80% and 90~, respectively. The
results of this experiment are presented in Table I. The
treated juice (with the pulp added back) was subjected to
organoleptic evaluation against untreated juice using a 14
member laboratory panel. The panelists unanimously identified
the treated juice as tasting substantially less bitter than
20 the untreated juice and they agreed that the treated juice
tasted virtually nonbitter.
Table 1
__
Debittering Reduced
Acid Grapefruit Juice
.
Volume of Juice Treated 700 mls.
Volume of Juice Treated50 Bed Volumes
Initial Naringin Content of Grapefruit
Juice 762 p~p.m.
Naringin Content of Treated Juice 143 p.p.m.
Naringin Removed (%), Treated Juice 80
Initial Limonin Content of
Grapefruit Juice 11.5 p.p.m.
12
3~i
Limonin Content of Treated Juic~ 1.2 p.p.m.
Limonin Removed (%), Treated Juice 90~
The experiment was repeated several times, with minor
modifications. Between each experiment, the adsorbent was
successfu]ly regenerated by washing the column either with
ethanolic or alkaline (NaOH~ solutions or with hot water. The
reactivated resin was successfully used to debitter more
citrus juice.
Since the presence of ascorbic acid in citrus ~uices is
nutritionally significantp the ascorbic acid content of reduced
acid grapefruit juice was determined before and after treatment
in oxder to study the effect of the adsorption pxocess on
ascorbic acid levels in the juice. As can be seen from Table II
only a 6.6~ loss in ascorbic acid was observed upon treat~ent.
Table II
Retention of Ascorbic Acid in
in Grapefruit Juice After Treatment
20 A5corbic Acid Content of Untreated
Juice 34.0 mg/100 mls
Ascorbic Acid Content of Treated
Juice 31.7 mg/100 mls
Ascorbic Acid Lost Upon Treatment 6.6%
Exam~e 2
A small glass column (18 cm long x 2 cm i.d.) was packed
with washed Duolite ES-861. The bed v~lumeoccupied by the
column was 15 mls. Navel orange juice containing 8.2 p~p.m.
of limonin (11.5 Brix, 15.3 B/A ratio, prepared from concentrate)
was centrifuged. The ciear juice was passed through the column
at a flow rate of approximately 7 Bed Volumes (BV) per hour.
Approximately 800 mls of the juice were treated and collected.
13
3~j;
The ratio of the volume of adsorbent used to the juice treated
was 1:53. Treated and un~eated juice were assayed for limonin.
The treated juice had a limonin level of 1.2 p.p.m. A reduction
of 85% in the limonin content was achieved using the adsorption
process. The results of the experiment are shown in Tabl~ III.
As judged by the sensory panel described in Example ], a majority
of the panelists identified the treated juice as tasting
substantially nonbitter.
Table III
Debittering Navel
Orange Juice
Volume of Juice Treated 800 mls.
Volume of Juice Treated53 Bed Volumes
Initial Limonin Content of
Navel Orange Juice 8.2 p.p.m.
Limonin Content of Treated Juice 1.2 p.p.m.
Limonin Removed (%?, Treated Juice85%
Example 3
- A small glass column ~1~ cm long x 2 cm i.d.) was packed
with washed Duolite ES~861. The bed volume (BV) occupied by
the resin was 15 mls. Juice from Japanese summer oranges
(Natsudaidai) having a naringin content of 915 pOp.m. (11
Brix; 4.8 B/A ratio ; prepared from concentrate) was centri-
fuged. The clear juice was passed through the column at a
flow rate of approximately 7BV/hx. Approximately 850 mls of
juice were treated and collected. The ratio of the volume of
resin used to the juice treated was 1:57. Both treated and
untreated juice were assayed for naringin. The treated juice
had a naringin content of 280 p.pOm. A reduction of 70% in
the naringin content was achieved by the adsorption process.
These results are presented in Table IV.
14
-.~,,l'
gL~ 36
Table IV
Debittering oE Japanese
Summer Oranges
Volume of Juice Treated 850 mls
Volume of Juice Treat d57 Bed Volumes
Initial Naringin Content of Japanese
Summer Orange Juice 915 p.p.m.
Naringin Content of Treated Juice280 p.p.m.
Naxingin Removed (%~, Treated Juice 70%
Example 4
One gram of washed Duolite ES 861 was weighed into a
standard 250 ml. flask. Fifty mls, of pulp-free lemon juice
having a limonin content of 12.1 p.p.m. ~11 Brix; 1.28 B/A
ratio; prepared from concentrate) were introduced into the
flask. The flask was shaken on a rotary shaker ~or 1 hour,
the contents of the flask were f iltered, and the filtrate
was assayed for limonin. The limonin content of the treated
juice was 0.8 p.p.m. This corresponds to a 94% reduction in
the limonin content. These results are presented in Table V.
Tab}e ~
Debittering of Lemon Juice
Weight of Resin Used 1 gram
Volume of Juice Treated 50 mls
Initial Limonin Content of pulp-free
lemon juice 12.2 p.p.m.
Limonin Content o~ Treated Juice 0.8 p.p.m.
Limonin Removed (%) 94%
Example 5
One gram of washed Duolite ES-861 was weighed into a
standard 250 ml flask. Fifty mls of pulp-free early season
, ..
,, . ,, .~
~6~3~
tangerine juice containing 34.7 p.p.m. limonin (11 Brix; 9.9
B/A ratio; prepared from concentrate) were introduced into
the flask. The flask was shaken on a rotaxy shaker for 1
hour, the contents of the flask were filtered, and the
filtrate assayed for limonin. The limonin content of the
treated juice was 2.7 p.p.m. This corresponds to a 92%
reduction in the limonin content. The results of -t~ experiment
appear in Table VI.
Table VI
Debittering of Early Season
Tangerine Juice
-
Weight of Resin Used l gram
Volume of Juice Treated 50 mls.
Limonin Content of Untreated Juice 34~7 p.p.m.
Limonin Content of Treated Juice2.7 p.p.mO
I,imonin Removed (~), Treated Juice 92%
Example 6
One gram of washed Duolite ES-861 was weighed into a
standard 250 ~1, flask. Fifty mls. of pulp-free early season
Valencia orange juice containing 9.7 p.p.m. of limonin (11~
Brix; 12.9 B/A ratio ; prepared from concentrate) were intro-
duced into the flask. The flask was shakenon a rotary shaker
~or 1 hour~ the contents of the flask wexe filtered, and the
filtrate assayed for limonin. The limonin content of the
treated juice was 1.4 p.p.m. This corresponds to an 86~
reduction in the limonin content. The xesults of this experiment
are shown in Table VII.
l~
36
Table VII
Debittering of Valencia Orange Juice
Weight of Resin Used 1 gram
Volume of Juice Treated 50 mls.
Initial Limonin Content of Valencia
orange juice 9.7 p.p.m.
Limonin Content of Treated Juice1.4 p.p.m.
Limonin Removed 86%
Example 7
One gram of washed Duolite ES-861 was weighed into a
standared 250 ml. flask. Fifty mls of pulp-free early season
pulp wash solids (WESOS), also known as water extracted
soluble orange solids containing 12.2 p.p.m. limonin. (16
Brix; 17.9 B/A ratio ; prepared from concentrate) were intro-
duced into the flask. The flask was shaken in a rotary shaker
for 1 hour, the contents of the flask were filtered, and the
filtrate was assayed for limonin. The limonin content of the
treated material was 1.4 p.p.m. This corresponds to an 88~
reduction in the limonin content. I'he results of this experiment
appear in Table VIII. The experiment was repeated on a larger
scale. Both treated and untreated samples were subjected to a
taste test by a six-member panel. The panelists unanimously
identified the treated sample as tasting considerably less
bitter than the untreated juice.
Table VIII
Debitterin~ of Pulp Wash Solids
Weight of Resin Used 1 gram
Volume of WESOS Treated 50 mls.
Initial limonin content of (WESOS) 12.2 p.p.m.
30 Limonin Content of Treated Material1.4 p.p.m.
Limonin Removed t%) in Treated material 88%
17
3~
Example 8
A two hundred milliliter portion of pulp-free debittered
grapefrui~ juice and non debittered grapefruit juice, respectively,
were dried in a laboratory freeze drier. Ten grams of each
dried sample were formulated into beverages and organoleptically
compared by a six me~ber laboratory panel. The beverage prepared
from the debittered dried juice was rated as being significantly
less bitter than the beverage prepared from regular, dried
grapefruit juice. Debittered dried citrus juices were
successfully used in formulating be~erages.
In Examples 1 to 8, fruit juice serum, i.e. pulp-free,
was treated with Duolite ES-861. It was observed that treatment
o~ only the serum ~as adequate to substantially debitter the
juices. This observation was supported by analytical work
which revealed that flavanoids and limonoids are present in
the serum in excess of 90% rather than in the pulp in most
citrus juices. When pulp is removed Erom the juice by centri~
fugation/filtration prior to treatment with the adsorbent re~in,
it may not be necessary to recover the pulp in such a way
~ that it need be added back to the juice from which it came.
However, the economics are improved by saving and using the
pulp because it is relatively low in bitterness.
Citrus products are relatively thermal labile in that
they de~elop off-flavors if abused during processing. The
experiments described above were conducted at room temperature.
In a commercial operation, the upper temperature range employed
in conducting the adsorption would most likely be limited by
the formation of abused flavors, rather than the effect of
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temperature on adsorption. The maximum temperature of applicatiOn
is further controllable by the size of the column, the type of
processing, e.g. size of a batch in a batch process and the
flow rate or duration of processing. Abused flavor development
is caused by a combination of time and temperature effects.
The lower temperature range employed in conducting the adsorption
may be primarily affected by product viscosity considerations.
With regard to product concentration, the upper range may
10 be limited by viscosity to 30 to 40~ solids. The lower
concentration range may be as low as 3 to 5~ solids, wherein said
concentration is determined by the volume to be processed and
later concentrated.
Thus, it is apparent that there has been provided, in
accordance with the invention, a process for the reduction of
flavanoid and/or limonoid induced bitterness that fully
satisfies the objects, aims, and advantages set forth above.
While the in~ention has been described in oonjunction with
2~ specific embodiments thereof, it is evident that many alter-
natives, modifications~ and variations will be apparent to
those skilled in the art in light of the foregoing description.
~ccordingly, it is intended to embrace all such alternatives,
modi~ications, and variatio~s as fall within the spirit and
broad scope of the appended claims.
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