Magnesium balances and plasma and blood cell concentrations were determined in 34 men and women, 20 to 53 yr of age, during each season for 1 yr while they were consuming their customary diets. Dietary records were maintained 365 days. Analysis of variance indicated no seasonal variation in intake or balance. Blood cell magnesium correlated with magnesium intake (r2 = 0.203; p less than 0.04). Daily magnesium intakes of the men (323 mg) were significantly higher (p less than 0.01) than of the women (234 mg), and reflected greater calorie consumption for their greater body weights. Daily magnesium balances for the men and women were -32 and -25 mg, respectively. Multiple regression analysis showed that magnesium balance was associated not only with magnesium intake but also with the intake of other nutrients such as fiber, protein, calcium, and phosphorus. Moreover, the effect of these nutrients on magnesium balance varied with age and sex.
A preliminary investigation was conducted to explore the use of plasma methionine and cystine for determining human sulfur amino acid requirements. Measurements of urinary methionine, cystine, taurine, and inorganic sulfate were included. After a 3-day control period, three young men were fed for 8 days a diet containing a purified -l-amino acid mixture, patterned after egg protein but devoid of methionine and cystine. Fasting plasma methionine and cystine levels showed little decrease during the 8-day period. Urinary cystine and taurine responses were inconsistent among the subjects. Urinary methionine and inorganic sulfate levels decreased markedly within a few days after feeding of the experimental diet, and may be useful criteria for determining human sulfur amino acid requirements.
Metabolic calcium and phosphorus balances, blood calcium and phosphorus levels, and alkaline phosphatase activity of 34 men and women, 20 to 53 yr of age, were determined each season during 1 yr while consuming customary diets. Dietary records were maintained 365 days. Analysis of variance indicated that serum Ca, P, and alkaline phosphatase levels were affected by season (p less than 0.0001), whereas calcium or phosphorus intakes were not. Calcium and phosphorus intakes of the men (1075 and 1533 mg, respectively) were higher (p less than 0.01) than of the women (695 and 1095 mg, respectively), but balances were not statistically different between them. Daily calcium balances for the men and women for the year were -81 and -85 mg, respectively; daily phosphorus balances were -239 and -130 mg, respectively. Stepwise regression analysis indicated that dietary calcium and protein were significantly associated with calcium and phosphorus balances, but in opposite directions, and only in women over 35 yr of age.
SUMMARY
Fifty‐four Beltsville small white male turkeys were studied either fresh‐unfrozen or frozen‐stored for 5 and 10 months. Samples of raw muscle were removed for protein analysis; the turkeys were then roasted at 325°F to end‐points of 165, 17.5, and 185°F in the thigh muscles and eating quality was evaluated.
Quantitative changes in muscle proteins as separated from extracts made with KCl‐borate buffer or with de‐ionized water were not marked. There was a decrease in actomyosin nitrogen of pectoralis major and some indication of proteolytic Changes. The magnitude of these changes in turkey muscles stored up to 10 months was not expected to alter eating quality as much as the longer cooking times required to reach the end‐point temperatures when cooking frozen‐stored turkeys.
Moisture losses were higher, and cooked thigh muscles were more tender and mealy from frozen‐stored than fresh turkeys. Cooked pectoralis major muscles required more force to shear after 5 months storage than at either 0 (fresh‐unfrozen) or 10 months storage. There was some indication that an undesirable flavor developed in thigh meat of turkeys stored 10 months.
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