Date of Award:

1979

Document Type:

Dissertation

Degree Name:

Doctor of Philosophy (PhD)

Department:

Nutrition, Dietetics, and Food Sciences

Advisor/Chair:

D. K. Salunkhe

Abstract

The objectives of this investigation have been to study the acceptability and nutritive value of processed cabbage and to elucidate the effects of chronic administration of cabbage on the activity of a colon tumorigen, 1, 2-dimethylhydrazine (DMH). The organoleptic unacceptability of cabbage in spite of its high nutritional and economic values governed the choice of this cruciferous vegetable for this work.

Cabbage samples were blanched with steam, chemical solutions, and microwaves. Microwave blanching led to a "burnt spot" effect and to a relatively greater loss in weight of the vegetable. Blanching in solution involved boiling of cabbage with a chemical solution (or water) for 3 minutes. In steam blanching, cabbage was vacuum impregnated in a chemical solution for 5 minutes under 25 inches vacuum and then exposed to steam for 3 minutes. Blanching (without chemical treatment) was achieved within 3 minutes as judged by the inactivation of peroxidase. Among solution- and steam-blanched (without chemical treatment) products, the former had better organoleptic qualities, whereas the latter had higher ascorbic acid retention. Cabbage blanched in the presence of 0.5 percent malic acid, 0.05 percent NaHC03, and 1.2 percent NaCl was preferred for texture, color, and firmness, respectively. The results from chemical (vitamin C and chlorophyll contents), physical (firmness), and sensory evaluations of processed and stored cabbage (at -l9°C up to 24 months) indicate blanching in the presence of 1.2 percent NaCl solution to be the most generally preferred treatment.

Improvement of flavor of processed cabbage was attained by the addition of a mixture of flavor enhancers during processing and by incorporation of enzymes from fresh cabbage to processed cabbage prior to serving. The mixture consisted of monosodium glutamate, 51 -inosinate, and 51 -guanylate in the proportions of 95:2.5:2 . 5, respectively. The selective use of vacuum impregnation and blanching in conjunction with the optimum concentrations of CaC1 2, NaHC03, flavor enhancers, and NaCl was defined for both solution and steam blanching. Such solution and steam blanched products contained 22 percent and 19 percent less ascorbic acid, respectively, than their pre-blanched level at the end of one year of storage (at -l9°C). The addition of cabbage myrosinase to rehydrated freeze-dried product improved 11 Cabbage flavor strength 11 ; acceptability of the product, however, remained lower than for fresh vegetables.

Cabbage contained 35 to 42 mg percent ascorbic acid, 1.04 percent crude protein, 4.91 mg percent glucosinolate as n-butylisothiocyanate, 6.4 mg percent glucosinolate as 3-indolylmethylisothiocyanate, and 93 percent water.

Glutamic acid accounted for about 30 percent of the recovered amino acids. In vitro availability of amino acids as determined by a pepsin-pancreatin enzyme system indicated that the predicted biological value and chemical score for the available amino acids were decreased after blanching. Polyacrylamide gel electrophoretic patterns for proteins in solution and steam blanched products were similar.

Diets containing 0, 10, 20, and 40 percent dehydrated cabbage were fed to weanling male C 57 BL/6 mice for 9 months. The animals were subcutaneously injected with 20 mg of DMH per kg body weight at weekly intervals for 36 weeks. Tissues such as liver, spermatic cord, kidney, and anal skin were examined for tumor growth. Diets containing 10 and 20 percent cabbage enhanced DMH tumorigenicity, while cabbage at the 40 percent level provided a protective effect. Tumor occurrence was proportional to the activities of hexobarbital oxidase, hepatic p-nitroanisole-0-demethylase, and hepatic cytochrome P-450 content. Tumors on the spermatic cord were the most predominant, with occasional occurrence of kidney and liver tumors.

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