Metabolism of heat-damaged proteins in the rat

Shorrock, C.; Ford, J. E.

doi:10.1079/bjn19780114

Cited by 11 publications

(1 citation statement)

References 15 publications

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“…Support for this suggestion comes from experiments on the influence of unavailable peptides on the uptake of [14C]leucine by everted sacs of rat small intestine. Shorrock & Ford (1978) found that unavailable peptides, isolated from an enzymic digest of heat-damaged fish meal, strongly depressed the uptake of leucine.…”

Section: Availability Of Methionine Tryptophan and Lysine As Measurementioning

confidence: 99%

Nutritional availability of methionine, lysine and tryptophan in fish meals, as assessed with biological, microbiological and dye-binding assay procedures

Hewitt¹,

Ford²

1985

Br J Nutr

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1. In vitro assay procedures were applied in the measurement of available amino acids in a selection of fish meals representing good-and poor-quality product. Results were assessed by comparing them with results from chick-growth assays.Available methionine and tryptophan were assayed microbiologically with Streptococcus zymogenes, after predigestion of the test samples with papain or pronase. Results for methionine were correlated with chick-growth assays (r 0.86 for papain, 0.91 for pronase; P < 0.01). Compared with the chick assays, papain tended to give lower, and pronase higher, results. Finer milling of the test samples did not influence the pronase values.Results for available tryptophan were also correlated with chick-growth assays (r 0.95 for papain, 0.96 for pronase; P < 0,001). Compared with the chick values, papain gave markedly lower results and pronase marginally higher ones. Finer milling of the test samples increased the papain values by about 50% but had no effect with pronase. Available lysine was assayed microbiologically with Tetrahymena pyriformis and with a dye-binding procedure (DBL). The results correlated with the chick-growth assays (r 0.99 for DBL, P < 0.001; 0.85 for Tetrahymena, P < 0.01) but both methods overrated the poorer-quality samples.True nitrogen digestibilities and amino acid digestibilities were determined with chickens by the 'ileal analysis' procedure: the amino acid digestibilities were significantly higher and similar to the corresponding availabilities as measured in chick-growth assays.6. Ball milling a poor-quality fish meal caused a marked fall in its N digestibility, whereas similar treatment of a good-quality meal caused a slight increase. An explanation for this finding is proposed. 7.Strep. zymogenes assays following pronase digestion of the test samples gave precise and acceptably accurate measures of the biologically available methionine and tryptophan in the test samples. For available lysine, Tetrahymena and DBL values for the poorer-quality samples were notably higher than the chick-growth assay; possible reasons for this are discussed. The ileal analysis procedure underestimated true N digestibility. 2. 3. 4.5.

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Section: Availability Of Methionine Tryptophan and Lysine As Measurementioning

confidence: 99%

Nutritional availability of methionine, lysine and tryptophan in fish meals, as assessed with biological, microbiological and dye-binding assay procedures

Hewitt¹,

Ford²

1985

Br J Nutr

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Interaction of Food Components During Processing

Hurrell

1980

Food and Health: Science and Technology

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The energetic significance of cooking

Carmody¹,

Wrangham²

2009

Journal of Human Evolution

335

220

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While cooking has long been argued to improve the diet, the nature of the improvement has not been well defined. As a result, the evolutionary significance of cooking has variously been proposed as being substantial or relatively trivial. In this paper, we evaluate the hypothesis that an important and consistent effect of cooking food is a rise in its net energy value. The pathways by which cooking influences net energy value differ for starch, protein and lipid, and we therefore consider plant and animal foods separately.Evidence of compromised physiological performance among individuals on raw diets supports the hypothesis that cooked diets tend to provide energy. Mechanisms contributing to energy being gained from cooking include increased digestibility of starch and protein, reduced costs of digestion for cooked versus raw meat, and reduced energetic costs of detoxification and defense against pathogens. If cooking indeed consistently improves the energetic value of foods through such mechanisms, its evolutionary impact depends partly on the relative energetic benefits of non-thermal processing methods used prior to cooking.We suggest that if non-thermal processing methods, such as pounding, were used by Lower Paleolithic Homo, they likely provided an important increase in energy gain over unprocessed raw diets. However, cooking has critical effects not easily achievable by nonthermal processing, including the relatively complete gelatinization of starch, efficient denaturing of proteins, and killing of foodborne pathogens. This means that however sophisticated the non-thermal processing methods were, cooking would have conferred incremental energetic benefits. While much remains to be discovered, we conclude that the adoption of cooking would have led to an important rise in energy availability. For this reason, we predict that cooking had substantial evolutionary significance.

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Metabolism of heat-damaged proteins in the rat

Cited by 11 publications

References 15 publications

Nutritional availability of methionine, lysine and tryptophan in fish meals, as assessed with biological, microbiological and dye-binding assay procedures

Nutritional availability of methionine, lysine and tryptophan in fish meals, as assessed with biological, microbiological and dye-binding assay procedures

Interaction of Food Components During Processing

The energetic significance of cooking

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