‘2,906,628 United States .lBatent Patented ’ Sept; 2951 959i‘?

11 upon . the concentration of > the. .jsolutioia-i At? theiabfriv'ej . mentioned concentration, .namely, 3—6 %' ‘ hydrox- , 2,906,628“ = ide,skinxand the solution raises the. diffuses .PHiQf ‘rapidly1throughtheporesjof theliquidwithin .the‘skin' ,yvith the “ METHOD'OF PRESERVING'COLOR LOEGREEN the ,result _ that the, tchlorfophyll. at, the surface of ' the peas, H VEGETABLES x; retains its green colorgmore perfectlynandgfoiea , much George .J-; Maleckh- Daytnna..lieac.ll,rzl.llai-, assigns: :10 longer storage-period than when {thi‘sstepjis not ‘employed Patent; Protection Corporation, New-;Xork, NYHQQ Even with the added disodium ,glutamateLtheZjpH, corporationof New York, trustee ’ the ‘canning-solution.heeomesgraduallylower in stem NdDrawing-~Applieationi-Februarys8, ‘1956/1; 10 but,.apparently¢.the. ,pH,_of lthegliquidyvithmsthe' ‘ , .. Serial N0.~564,129: ‘ "I the peas remainsat a higher value than thehisiolut 'its'e'l ' } and‘. consequently retards'the color change: yvhichfwould; ' 7 Claims. (Cl. 99-186) .. .. otherwise occur; 4 , The above described treatment .doeswnot;jadverselyflj, T'his..inventi.qn. relates- to’ methods. .- of preserving. the 15 affect, the , taste _, or .textureaof ,‘the, 113638“ , In jjfact‘ color'of green ‘vegetables. 'It is, we'llulgno‘wnjthat finjthe. texture. .is noticeably improved; Apparently‘ thesodhir‘t... canning of green vegetables, particularly 'peas, the‘chloroi ' hydroxide. which £diffuses.;1thr0u'gh the. skin #01:‘: .th peas‘... phyll is broken down to a greater or less degree resulting effects a swelling of the starch at the surface of’t'he' peas," in a corresponding change in color from green toward the swelling being, however, insuf?cient to make the peas yellow. It is also known that this change in color is 20 mushy. materially reduced if the canning solution is maintained at Instead of adding the above speci?ed quantity of di a pH in the order of 8-8.5. sodium glutamate to the canning solution and employing It is also known that a canning solution with added the above described dip to prolong the storage period the alkali to bring the pH to this value at the time it is dip may be employed and a lesser amount of disodium added to the can will during the processing suffer a 25 glutamate added to the canning solution. change in pH to 7-7.5 with a noticeable change in the Generally speaking, when the dip as herein described greenness of the peas. Numerous attempts have been is employed the same color preservation will result with a made to employ alkalis in the canning process in a 50% reduction in the amount of disodium glutamate em manner to preserve the color of the chlorophyll and at ployed, thereby substantially reducing the added cost of the same time not adversely affect the ?avor and tex 30 the disodium glutamate process. ture of the product. The most successful process to date I have also discovered that the above described disodi is that described in US. Patent No. 2,827,382, dated um glutamate process may be further improved by adding March 18, 1958, wherein disodium glutamate is added to to the canning solution sodium sul?te in an amount in the the canning solution to increase its initial alkalinity and order of 200 parts per million. The sodium sul?te, in also serve as a buffer during the processing and subsequent 35 addition to acting as a reducing agent, also serves to storage to maintain the pH above that value where the bleach the canning solution. It has been observed that yellowing of the peas becomes pronounced. alkaline canning solutions in which peas and other vege The invention of the present application is primarily an tables are submerged develop a yellow tinge due probably improvement on the process described in my above to the action of the alkali on the glucose in the canning mentioned co-pending application, but the added steps 40 solution. Whatever the cause, this discoloration is pre hereinafter described may also be employed with the con vented by adding sodium bisul?te to the canning solu ventional canning processes involving no alkalizing steps tion. The amount which may be added is not critical. or with other processes wherein the canning solution Fifty parts per million will have a signi?cant bleaching contains added alkaline salts. When so employed such action and as much as 500 parts per million may be added steps will to a quite signi?cant extent effect the 45 used if necessary to completely prevent this discoloration. same advantageous results as when employed in conjunc The addition of the sodium bisul?te also improves the tion with the process of my above mentioned application. ?avor of the peas, particularly in preventing the soapy In canning peas by the preferred process described in taste which may result from the added alkali. The my co-pending application the freshly shelled peas are sodium bisul?te is also a reducing agent and may be used ?rst blanched by soaking them in a hot water bath con 50 with advantage in lieu of the reducing agents speci?ed taining about one quarter of one percent magnesium in the aforementioned US. Patent No. 2,827,382. hydroxide for two to ?ve minutes. The cans are then In the above speci?cation I have speci?ed sodium hy ?lled with the peas and an aqueous canning solution con droxide and sodium sul?te as the compounds to be used taining by weight 4.5% sugar, 2.5% , 0.4% disodium in carrying out my improved process, but the equivalent glutamate and su?icient N/ 10 normal solution of sodium 55 compounds of the other alkali metals and alkaline earth hydroxide to bring the pH of the solution after processing metals may be used instead. to 8.5. The cans are then closed and cooked with steam It will also be understood that the above described at approximately 260° F. for 11 minutes and after cool additions to my disodium glutamate process may be used ing are labelled and packed in cartons for shipment or either separately or together, and as pointed out above, storage. 60 either or both steps may be advantageously added to con I have found that the natural color of the peas will be ventional canning processes and also to other processes more perfectly preserved if immediately before or im involving the addition of alkalis. mediately after blanching, the peas are subjected to a brief I claim: dip in an alkaline solution such as a 3-—6% solution of 1. In the canning of peas the step which consists in . The period of the dip should be be 65 dipping the peas in a 3—6% sodium hydroxide solution tween 5 and 10 seconds with the alkaline solution at for a period of approximately 5-10 seconds before plac room temperature. The chlorophyll in the outside layer ing the peas and canning solution in the cans. of the peas immediately below the skin of the peas deter 2. The process of canning peas which consists in clip mines primarily the color of the peas to the eye when the ping the peas in an alkaline solution having a concentra cans are opened. The skin of the peas is a porous mem 70 tion equivalent to 3—6% sodium hydroxide solution for brane and the rate of diffusion of the liquid in which a period of approximately 5-10 seconds, placing the peas the peas are submerged through the skin is dependent and an alkaline canning solution having a pH after 2,906,628 3 . , 4 _ processing of less than 8.0 in the cans, and heat treating for a period of approximately 5-10‘ seconds, placing the the cans. peas and an alkaline canning solution, containing sodium 3. The process of canning green peas which consists sul?te in an amount in the order of 200 parts per million in dipping the peas in a 3—6% sodium hydroxide solu in the cans, and heat treating the cans. tion for a period of approximately 5-10 seconds, placing 7. The process of claim 6 wherein the canning solution the peas and a canning solution containing disodium contains 0.3 to 0.8 percent by weight of disodium glu glutamate and having a pH after processing of 8.0-8.5 tamate and having a pH after processing of 8.0-8.5. _in the cans, and heat treating the cans. 4. In the canning of green vegetables the step which References Cited in the ?le of this patent consists in adding to the vegetables and the canning solu 10 UNITED STATES PATENTS tion a sul?te compound of an alkali metal or alkaline earth metal in an amount in the order of 200 parts per 1,666,551 Butler ______Apr. 17, 1928 million of sodium sul?te. 1,680,865 Fujii ; ______... Aug. 14, 1928 5. The process of canning green vegetables which com 2,189,774 Blair ______Feb. 13, 1940 2,305,643 Stevenson et a1 ______Dec. 22, 1942 prises placing in the vegetables a canning solution having 15 a pH after processing of 8.0-8.5 and containing a sul?te 2,417,932 Kalmar ______Mar. 25, 1947 compound of an alkali metal or alkaline earth metal in 2,589,037 Bendix et al ______Mar. 11, 1952 an amount in the order of 200 parts per million of sodium 2,628,905 Antle ______Feb. 17, 1953 sul?te and heat treating the cans. OTHER REFERENCES 6. The process of canning peas which consists in dip “Food Packer,” July 1948, p. 30, article entitled ping the peas in an alkaline solution having a concen “.” tration equivalent to 3-6% sodium hydroxide solution