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Abstract: We have compared ubiquitous calpains in chicken (Gallus gallus), turkey (Meleagris gallopavo) and mammals. In chicken, we studied their distribution in different tissues. The calpain activity was determined by casein zymography, a technique avoiding any prior sample purification, thus limiting any autolysis and denaturation reactions. Our results show that two ubiquitous calpains are present in chicken: (1) a μ-calpain having a greater calcium sensitivity and a lower electrophoretic mobility than the mammalian one, (2) a μ/m-calpain, named like this by Sorimachi et al. [Sorimachi, H., Tsukahara, T., Okada-Ban, M., Sugita, H., Ishiura, S., Suzuki, K., 1995. Identification of a third ubiquitous calpain species—chicken muscle expresses four distinct calpains. Biochim. Biophys. Acta, 1261, 381–93.], having a calcium sensitivity intermediate between that of the two mammalian μ-calpain and the m-calpain. Tissue distribution of the two chicken isozymes vary and μ/m-calpain predominates, whereas μ-calpain levels are very low in some tissues, unlike in mammalian tissues. The characteristics of μ/m-calpain and its preponderance in all organs suggest that it may play a different role in chicken than in mammals. [Copyright &y& Elsevier]

Gelatin is used to make hard capsules and has to meet strict dissolution specifications to guarantee homogeneous drug delivery. The aging of gelatin induces a decrease of its dissolution rate due to the formation of intra- and intermolecular cross-links. Cross-link formation has shown to be dependent on the environmental conditions of production, such as temperature and humidity, and therefore on the geographic origin of production. Gelatin structure consists of an amorphous phase (coil structure) and a crystal phase (triple-helixes) and is very sensitive to environmental changes. The present work aims at understanding the role and effects of structural changes during aging on gelatin dissolution, taking into account the origin of production. The molecular structure of pig skin gelatins from three different production sites of the same company were studied by differential scanning calorimetry, synchrotron circular dichroism and 1 H nuclear magnetic resonance. It turned out that aging induced the melting of triple-helixes, an increase of random coils and, probably, β-turn conformations. The gelatin structure varied with the origin of production and thus affected the dissolution rate. Gelatins with non-compliant dissolution rates exhibited a higher amount of amorphous phase after aging than compliant gelatins. Although it was not possible to formulate any certain interpretation of the synchrotron circular dichroism results regarding gelatin dissolution, this technique is able to differentiate compliant dissolutions from non-compliant ones, even before gelatin aging. [ABSTRACT FROM AUTHOR]

Background: Cooking may impair meat protein digestibility. When undigested proteins are fermented by the colon microbiota, they can generate compounds that potentially are harmful to the mucosa.Objectives: This study addressed the effects of typical cooking processes and the amount of bovine meat intake on the quantity of undigested proteins entering the colon, as well as their effects on the intestinal mucosa.Methods: Male Wistar rats (n = 88) aged 8 wk were fed 11 different diets containing protein as 20% of energy. In 10 diets, bovine meat proteins represented 5% [low-meat diet (LMD)] or 15% [high-meat diet (HMD)] of energy, with the rest as total milk proteins. Meat was raw or cooked according to 4 processes (boiled, barbecued, grilled, or roasted). A meat-free diet contained only milk proteins. After 3 wk, rats ingested a (15)N-labeled meat meal and were killed 6 h later after receiving a (13)C-valine injection. Meat protein digestibility was determined from (15)N enrichments in intestinal contents. Cecal short- and branched-chain fatty acids and hydrogen sulfide were measured. Intestinal tissues were used for the assessment of protein synthesis rates, inflammation, and histopathology.Results: Meat protein digestibility was lower in rats fed boiled meat (94.5% ± 0.281%) than in the other 4 groups (97.5% ± 0.0581%, P < 0.001). Cecal and colonic bacterial metabolites, inflammation indicators, and protein synthesis rates were not affected by cooking processes. The meat protein amount had a significant effect on cecal protein synthesis rates (LMD > HMD) and on myeloperoxidase activity in the proximal colon (HMD > LMD), but not on other outcomes. The ingestion of bovine meat, whatever the cooking process and the intake amount, resulted in discrete histologic modifications of the colon (epithelium abrasion, excessive mucus secretion, and inflammation).Conclusions: Boiling bovine meat at a high temperature (100°C) for a long time (3 h) moderately lowered protein digestibility compared with raw meat and other cooking processes, but did not affect cecal bacterial metabolites related to protein fermentation. The daily ingestion of raw or cooked bovine meat had no marked effect on intestinal tissues, despite some slight histologic modifications on distal colon. [ABSTRACT FROM AUTHOR]