CA1186936A - Preparation of citrus juices, concentrates and dried powders which are free of bitterness - Google Patents
Preparation of citrus juices, concentrates and dried powders which are free of bitternessInfo
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- CA1186936A CA1186936A CA000444327A CA444327A CA1186936A CA 1186936 A CA1186936 A CA 1186936A CA 000444327 A CA000444327 A CA 000444327A CA 444327 A CA444327 A CA 444327A CA 1186936 A CA1186936 A CA 1186936A
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Abstract
PREPARATION OF CITRUS JUICES, CONCENTRATES AND
DRIED POWDERS WHICH ARE REDUCED IN BITTERNESS
ABSTRACT OF THE DISCLOSURE
Flavanoid and/or limonoid induced bitterness, especially naringin and/or limonin induced bitterness, is reduced in citrus fruit juice by contacting the citrus fruit juice with a styrene-divinylbenzene cross-linked copolymer adsorbent resin.
DRIED POWDERS WHICH ARE REDUCED IN BITTERNESS
ABSTRACT OF THE DISCLOSURE
Flavanoid and/or limonoid induced bitterness, especially naringin and/or limonin induced bitterness, is reduced in citrus fruit juice by contacting the citrus fruit juice with a styrene-divinylbenzene cross-linked copolymer adsorbent resin.
Description
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.
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.
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 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 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 , . . .
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 .~
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.
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.
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.
-.~,,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~
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%
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 ~ A
3~;
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.
.
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 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 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 , . . .
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 .~
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.
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.
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.
-.~,,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~
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%
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 ~ A
3~;
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.
Claims (22)
1. 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, wherein said process comprises:
contacting the citrus juice for an effective period of time with an effective volume of a styrene-divinyl-benzene cross linked copolymer adsorbent resin in the absence of an added enzyme, whereby a substantial amount of flavanoid and limonoid compounds present in the citrus juice are adsorbed by the resin.
contacting the citrus juice for an effective period of time with an effective volume of a styrene-divinyl-benzene cross linked copolymer adsorbent resin in the absence of an added enzyme, whereby a substantial amount of flavanoid and limonoid compounds present in the citrus juice are adsorbed by the resin.
2. The process of claim 1, wherein the juice treated to reduce bitterness include grapefruit, Japanese summer orange, Navel orange, water extracted soluble orange solids (WESO5), early season tangerines, Valencia, Temple, and Murcot oranges, lemon and other juices, wherein the chemical constituents which contribute to bitterness comprise flavanoids and limonoids.
3. The process according to claim 1 wherein the ab-sorbent resin is packed in a column and juice passed through the column at an effective volumetric flow rate.
4. The process of claim 1, wherein pulp-free citrus juice is contacted with the adsorbent resin in a vessel at a temperature of from 1°C to 95°C and the contents of the vessel are filtered to yield filtrate with a substantial reduction in bitterness.
5. The process of claim 1, wherein the fruit juice is a whole citrus juice.
6. The process of claim 1, wherein the fruit juice is a concentrated fruit juice, diluted to a concentration of 3 to 40% solids.
7. The process of claim 6, wherein the citrus fruit juice is contacted with the adsorbent resin at 1°C to 90°C.
8. The process of claim 1, wherein the fruit juice is blended or prepared by dilution procedures.
9. The process of claim 1, wherein the fruit juice is a deacidified fruit juice.
10. The process of claim 2, wherein the water ex-tracted soluble citrus solids to be debittered are derived by washing citrus pulp.
11. The process of claim 1, wherein the juice is de-rived from a product in dried form.
12. The process of claim 1, wherein the juice is clari-fied before treatment.
13. The process of claim 1, wherein ethanolic solutions, sodium hydrozide or other alkaline solutions or hot water treatments, are employed to regenerate the spent adsorbent resin.
14. The process of claim 1, wherein the treated juice is concentrated and/or dried.
15. The process of claim 1, wherein the serum of the fruit juice is separated from the other components thereof prior to contacting the serum with said resin, and the resin is subsequently separated from the treated serum before re-combination of the treated serum with said other components.
16. The process of claim 1, wherein the citrus fruit juice is contacted with the adsorbent at 20°C to 35°C.
17. The process of claim 1, wherein the adsorbent resin contacted with the citrus fruit juice is in bead form.
18. The process of claim 17, wherein the adsorbent resin in bead form has a pore volume of 0.8 to 0.9 ml/gram and a particle size of 0.3 to 1.2 mm.
19. The process of claim 1, wherein said citrus fruit juice comprises a reduced acid citrus fruit juice.
20. A process for preparing a citrus fruit juice that is reduced in acid and bitterness comprising the steps of:
contacting the citrus juice for an effective amount of time with an effective 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.
contacting the citrus juice for an effective amount of time with an effective 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.
21. A process for the preparation of a low acid, debittered citrus juice comprising the steps of:
separating by centrifuge said fruit juice into a fraction having insoluble solid contents of less than 0.5% (v/v);
treating 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 the pulp fraction to create a reduced acid citrus juice; and contacting the reduced acid citrus juice for an effective amount of time with an effective volume of styrene-divinylbenzene cross-linked copolymer adsorbent resin in the absence of an added enzyme.
separating by centrifuge said fruit juice into a fraction having insoluble solid contents of less than 0.5% (v/v);
treating 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 the pulp fraction to create a reduced acid citrus juice; and contacting the reduced acid citrus juice for an effective amount of time with an effective volume of styrene-divinylbenzene cross-linked copolymer adsorbent resin in the absence of an added enzyme.
22. A reduced bitterness citrus juice produced by con-tacting citrus fruit juice for an effective amount of time with an effective volume of styrene-divinylbenzene cross-linked co-polymer adsorbent resin in the absence of an added enzyme.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000444327A CA1186936A (en) | 1983-12-28 | 1983-12-28 | Preparation of citrus juices, concentrates and dried powders which are free of bitterness |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000444327A CA1186936A (en) | 1983-12-28 | 1983-12-28 | Preparation of citrus juices, concentrates and dried powders which are free of bitterness |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1186936A true CA1186936A (en) | 1985-05-14 |
Family
ID=4126833
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000444327A Expired CA1186936A (en) | 1983-12-28 | 1983-12-28 | Preparation of citrus juices, concentrates and dried powders which are free of bitterness |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1186936A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103300312A (en) * | 2013-06-04 | 2013-09-18 | 华南理工大学 | Debitterized shaddock peel and production method and use thereof |
| CN109266490A (en) * | 2018-11-14 | 2019-01-25 | 重庆三峡职业学院 | A kind of preparation method of no bitter taste rose fragrant citrus fruit wine |
| CN110982659A (en) * | 2018-09-29 | 2020-04-10 | 湖北苗仙聚生物科技有限公司 | Grapefruit wine and preparation method thereof |
-
1983
- 1983-12-28 CA CA000444327A patent/CA1186936A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103300312A (en) * | 2013-06-04 | 2013-09-18 | 华南理工大学 | Debitterized shaddock peel and production method and use thereof |
| CN110982659A (en) * | 2018-09-29 | 2020-04-10 | 湖北苗仙聚生物科技有限公司 | Grapefruit wine and preparation method thereof |
| CN109266490A (en) * | 2018-11-14 | 2019-01-25 | 重庆三峡职业学院 | A kind of preparation method of no bitter taste rose fragrant citrus fruit wine |
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