The solubilities of sarcoplasmic and myofibrillar proteins were determined at the time of slaughter, onset of rigor mortis, completion of rigor mortis and 24 hr after death in muscles exhibiting a wide range of physiological conditions during the post-mortem period.Muscle protein solubility was grossly altered by the conditions of both temperature and pH which existed at the onset of rigor mortis or during the first few 'hours after death. Sarcoplasmic protein solubility at 24 hr was decreased to 55% of that found at 0 hr in muscle groups exhibiting high temperature and low pH at the onset of rigor mortis.Conversely, only a 17% reduction of sarcoplasmic protein solubility was noted in groups with high pH at onset. Myofibrillar protein solubility ranged from no reduction during the first 24 hr after death when pH remained high at onset to 75% reduction in muscle with low pH and high temperature at the onset of rigor mortis.The 24-hr pH of th e muscle appeared to have only a minor influence on protein solubility. Muscle protein solubility appeared to be one of the major factors affecting the juice-retaining properties of muscle.
This study was conducted to determine the relative cholesterol-lowering effects of several levels of full-fat rice bran in hamsters. In addition, the separate effects of defatted rice bran and/or crude rice bran oil were investigated at levels equivalent to those present in 43.7% full-fat rice bran. Diets containing 10.9, 21.8, 32.8 or 43.7% full-fat rice bran, 35% defatted rice bran and/or 9% rice bran oil were fed to 4-wk-old male hamsters. All diets contained 10% total dietary fiber, 9% fat and 3.2% nitrogen; hypercholesterolemic diets contained 0.3% cholesterol; two diets were cholesterol-free, i.e., 10% cellulose and 43.7% full-fat rice bran. After 21 d, plasma and liver cholesterol, plasma triglycerides and liver weights were significantly greater in hamsters fed the 10% cellulose diet with 0.3% cholesterol compared with those fed the cholesterol-free cellulose diet. In animals fed cholesterol-free diets, plasma cholesterol values were significantly lower in those fed the 43.7% full-fat rice bran diet than in those fed the cellulose diet. In animals fed cholesterol-containing diets, plasma and liver cholesterol were significantly lower in animals fed the 43.7% full-fat rice bran diet than in those fed the cellulose diet. Plasma cholesterol reductions were significantly correlated to the level of rice bran in the diet. In cholesterol-fed hamsters, total liver cholesterol content was significantly lower in those fed the defatted rice bran diet with rice bran oil compared with those fed the cellulose diet. Full-fat rice bran was the only treatment that significantly lowered both plasma and liver cholesterol.(ABSTRACT TRUNCATED AT 250 WORDS)
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