Nutritional Evaluation of Food Proteins by Measuring Availability of Amino Acids to Microorganisms I. Cottonseed Proteins

Availability of amino acids. A methionine-fructose compound and its availability to microorganisms and rats

“…The diminished availability of methionine in DMF to microorganisms (20%) compared to the unavailability of the methionine to rats (100%) is disappointing in view of the need for a rapid method for studying availability. Flowever, in earlier work on cottonseed proteins (Horn et a/., 1952) the microbiological method gave satisfactory results when compared with the results of animal feeding. The difference in availability to the microorganism between compounds of the type described here and the complexes formed in heated carbohydrate foods after proteolytic enzyme digestion, suggests that the complexes obtained in the food hydrolyzates are different from those of the simple DMF type.…”

Cottonseed Meal Extracts, Electrophoretic Patterns of Buffer Extracts of Different Nutritive Value

“…On the basis of their nutritional value for chicks, the meals of series 1 fall into three groups, the highest values being given by meals 6, 7, and 8, intermediate values by meals 1, 3, and 4, and a poor value by meal 5 (8). Rat feeding tests in which the laboratory-prepared, solvent-extracted meal was included indicated that there were four significant groups in the following decreasing order of protein efficiency: (1) solventextracted meal; (2) series 1, meals 6, 7, and 8; (3) meals 1, 3, and 4; and (4) meal 5 (4).…”

Measurement of lysine damage in proteins heated with gossypol

“…Here we extend the study to complexes of protein with gossypol both in cottonseed flours (CF), where the dialdehyde gossypol occurs naturally and can bind to the protein during processing, and in a purified protein-gossypol mixture. The low value of protein-gossypol complexes as a source of lysine has already been shown in studies of animal growth (Baliga and Lyman, 1957;Smith et al, 1958;Frampton, 1965; Major and Batterham, 1981) and digestibility, both in vitro (Ingram et al, 1950; Horn et al, 1952; Cater and and in vivo (Kuiken, 1952 and Broderick, 1981; Tanksley et al, 1981). However, it has not been clear which of the possible chemical procedures is to be preferred for estimating the biologically available lysine.…”