Europaisches Patentamt European Patent Office © Publication number: 0 495 391 A1 Office europeen des brevets EUROPEAN PATENT APPLICATION © Application number: 92100260.6 int. Ci.5; A23J 3/34, A23J 3/32 @ Date of filing: 09.01.92 © Priority: 14.01.91 US 641037 © Applicant: CPC INTERNATIONAL INC. International Plaza P.O. Box 8000 @ Date of publication of application: Englewood Cliffs New Jersey 07632(US) 22.07.92 Bulletin 92/30 @ Inventor: Hamm, Donald J. © Designated Contracting States: 57 Commonwealth Avenue AT BE CH DE DK ES FR GB GR IT LI LU NL PT New Providence, New Jersey 07974(US) SE © Representative: Lederer, Franz, Dr. et al Lederer, Keller & Riederer, Patentanwalte, Lucile-Grahn-Strasse 22 W-8000 Munchen 80(DE) A process for the production of hydrolyzed vegetable proteins using gaseous hydrochloric acid and the product therefrom. @ A process for the production of hydrolyzed vegetable proteins containing no detectable level of monocholorodihydroxypropanol and substantial fla- vor enhancement characteristics by using enzymatic hydrolysis of the protein followed by mild acid hy- drolysis with gaseous hydrochloric acid and the product therefrom. 00 Rank Xerox (UK) Business Services 1 EP 0 495 391 A1 2 BACKGROUND OF THE INVENTION not for the purpose of flavor enhancement. What is taught in the existing art is generally directed to- FIELD OF THE INVENTION ward producing functionally improved proteins, such as eliminating bitter peptide formation during This invention relates to a process for the pro- 5 enzyme hydrolysis as shown in U.S. Patent No. duction of hydrolyzed vegetable proteins, contain- 4,636,388. Specifically, the patent discloses a low ing no detectable levels of monochlorodihydrox- ash protein product which is particularly adapted ypropanol. The resultant hydrolyzed vegetable pro- for enzymatic hydrolysis. A dispersion of protein is tein is clean and bland in flavor and exhibits sub- gelled and then washed in particulate form in a stantial flavor enhancement characteristics. io liquid in order to allow a portion of the non-prot- einaceous material to defuse from the gel into the DESCRIPTION OF THE PRIOR ART liquid, and then the liquid is separated from the gel. The pretreated product is then hydrolyzed en- The preparation of conventional hydrolyzed zymatically, preferably with fungal protease and vegetable proteins (HVPs) is generally carried out 75 pancreatin. by acid hydrolysis with hydrochloric acid under U.S. Patent No. 4,757,007, discloses and refluxing conditions, specifically using 6M hydro- claims a process for the preparation of hydrolyzed chloric acid at 109°C and atmospheric pressure. It products of soy protein by partially hydrolyzing soy has been demonstrated that hydrolyzing vegetable protein with protease, and then separating the re- proteins at these conditions results in the chlorina- 20 suiting hydrolyzed products by using a 5% aque- tion of glycerol, which is derived from the residual ous solution of trichloroacetic acid. The portion of fatty substances present in the crude protein, to hydrolyzed protein with low solubility possesses produce monochlorodihydroxypropanols (MCDPs) excellent emulsifying properties, while the one with and dichloropropanols (DCPs). As MCDPs and high solubility possesses excellent foaming prop- DCPs exhibit questionable properties and charac- 25 erties. teristics, their presence is not desired in food pro- In U.S. Patent No. 3,830,942, a soluble protein ducts. DCPs are readily removed during the evap- product is produced which is particularly useful in oration or concentration steps of standard pro- highly acidic foods, and an insoluble protein prod- cesses. Unfortunately, MCDPs are not removed, uct is prepared which is used in preparing protein but are concentrated in the finished product, and 30 enriched bakery goods. The patent discloses the therefore, additional processing steps must be tak- method for producing the two products by forming en to remove the MCDPs from the finished prod- an aqueous solution of defatted oleaginous seed uct. materials, adjusting the pH of the slurry to the In a conventional acid hydrolysis process for isoelectric point of the seed materials, heating the preparing HVPs, the formation of MCDPs and 35 slurry to elevated temperatures, adding an enzyme DCPs can be avoided by using sulfuric or phos- to the slurry, agitating the mixture during hydrolysis phoric acid in place of hydrochloric acid. However, of the material and thereafter, separating the the HVPs produced by hydrolyzing with sulfuric or hydrolyzed and unhydrolyzed portions of the pro- phosphoric acid are of an inferior quality in that tein product. they exhibit a bitter flavor. 40 In U.S. Patent No. 4,665,158 to Armamet et al., The specific problem is that MCDP is derived a process is disclosed for hydrolyzing dehydrated during conventional acid hydrolysis from the protein materials with gaseous hydrochloric acid. chlorination of the glycerol derived from the resid- Partial hydrolysis is achieved by the process when ual fatty substances which are present in crude a protein material is impregnated with hydrochloric proteins. As an example, vital wheat gluten which is 45 acid and left to rest at a selected temperature until approximately 75% protein, also contains 5.0 to the desired degree of hydrolysis is obtained. If 9.5% fat and other lipid materials, is an abundant complete hydrolysis is desired, then the protein- source of glycerol in the form of a complex mixture hydrochloric acid combination is subjected to heat of mono-, di- and tri-glycerides, phospholipids and under pressure in an autoclave. glycolipids. Numerous factors which are believed to 50 Although enzyme hydrolysis and acid hydroly- effect the formation of MCDP include the presence sis are generally separate procedures, one refer- of high concentrations of chloride ions, high ence has been found which discloses the combina- amounts of excess acid, high refluxing tempera- tion of acid and enzyme hydrolysis to obtain a tures and long reaction times. It is thought that the protein hydrolyzate. In USSR Patent Application bound glycerol is more active in forming MCDPs 55 No. 442800, a method of obtaining a preparation than unbound glycerol. for parenteral protein feeding is taught. A method is Much is also known about the use of enzymes disclosed wherein the raw protein material under- to hydrolyze vegetable proteins for food use, but goes enzymatic cleavage, followed by acid hy- 2 3 EP 0 495 391 A1 4 drolysis with 5.0% sulfuric acid (4.0N), in a carbon content. Specifically, the acid hydrolysis is carried dioxide atmosphere. Thereafter, the hydrolyzate is out at significantly lower acid concentrations, at passed through an anion exchange column, treated lower temperatures, at lower moisture contents and with aluminum hydroxide and passed through a for shorter periods of time than the conventional column containing cation exchange resin. The acid 5 hydrolysis process. By controlling the conditions, hydrolysis takes place at about 100°C for about deamidation preferentially occurs; ie, the amide seven (7) hours. linkages are hydrolyzed, but the peptide bond hy- Many attempts have been made over the years drolysis is controlled or minimized. It is believed to produce hydrolyzed vegetable protein products that these conditions, combined with the reduced which are used for various purposes, however, to io fat levels from the enzyme hydrolysis, are respon- date no process has been taught which produces a sible for the lack of formation of MCDPs in the hydrolyzed vegetable protein with reduced or non- finished product. existent levels of MCDP or DCP due to preventing MCDP and DCP production by controlling the pa- DETAILED INVENTION rameters of the acid hydrolysis, and which exhibits 15 substantial flavor enhancement characteristics. The present process comprises a number of steps for the hydrolyzing of a protein to a product SUMMARY OF THE INVENTION which contains no detectable level of MCDP. The term "no detectable level" as used herein means The present invention relates to the production 20 that there is no detectable level as measured by of hydrolyzed vegetable proteins which contain no gas chromotagraphy (GC) with a sensitivity to lev- detectable levels of MCDP. This result is achieved els as low as 1 ppm. by a unique process which combines two methods According to the process, a vegetable protein of hydrolysis of the vegetable protein, enzymatic is hydrolyzed by adding it to an aqueous solution hydrolysis followed by mild acid hydrolysis with 25 of at least one protease. The protein can be any gaseous hydrochloric acid. The hydrolyzates which one of the available proteins, such as, but not result from this process are clean and bland in limited to, oil seed proteins (soy, peanut, sunflower, flavor, exhibit substantial flavor enhancement char- cotton seed), leaf proteins, grain proteins, or any acters, and contain substantial amounts of mon- combination thereof. The preferred protein for pro- osodium glutamate, up to 36% w/w of the starting 30 ducing savory flavors with substantial flavor en- protein. hancing properties is wheat gluten, due to its high The production of hydrolyzed vegetable pro- glutamic acid content, present mostly as glutamine. teins with no detectable level of MCDP begins with The protein is added to an aqueous solution of the hydrolyzing of the protein by adding it to an at least one endoprotease, which can be acidic, aqueous solution of at least one protease. The 35 neutral or alkaline in form. The protease is chosen resulting hydrolyzed soluble protein is then sepa- dependent upon a number of parameters for the rated from the insoluble mass. Thereafter, gaseous particular enzyme/substrate combination, such as hydrochloric acid is added and the mixture is heat- a) what the proper pH would be for the optimum ed, providing an acidified hydrolyzate, which is proteolytic activity; b) the peptide bond specificity, then neutralized. 40 which is best suited to meet the end product re- It is believed that the enzyme hydrolysis step quirements; and c) whether or not the substrate contributes to reducing the MCDP and DCP forma- requires debittering.