The in vitro digestibility of beef varies with its inherent ultimate pH.

Animal carcasses and cuts of meat are usually differentiated and valued according to size and compositional attributes. An underappreciated variable of red meat is its inherent ultimate pH (pHu) value, which affects organoleptic and processing characteristics. This study tests the hypothesis that high pHu aged meat would be more digestible than low pHu unaged (fresh) meat. Longissimus dorsi muscles collected from 59 bull carcasses had pHu values of 5.6-6.9. These were aged for 21 days at -1.5 °C, then raw and cooked (72 °C) samples were enzymatically digested at 37 °C with pepsin (pH 1.9 for 90 min) followed by pancreatin (pH 8.0 for an additional 120 min) to simulate conditions in the stomach and small intestine, respectively. Meat proteins and peptides in the digests were separated by 1D SDS PAGE. Regardless of pHu, ageing or cooking, most sarcoplasmic and myofibrillar proteins were rapidly digested by pepsin, with concomitant release of products identified by LC-MS/MS as mainly myosin-1, -2 and -7, α-actinin-2 or -3 and tropomyosin beta and alpha chains. These products were resistant to further digestion for the entire 210 min duration of the incubation. In terms of rate and extent of digestibility of these resistant products, high pHu > low pHu (P < 0.001), whereas aged > unaged (P < 0.003), with the effect of cooking dependent on pHu and varying somewhat by protein. Overall, the digestibility of meat samples increased with increasing pHu (P < 0.001). Beef meat was highly digestible but could be further differentiated on the basis of its pHu and the ease of digestibility of proteins. Specific carcasses or cuts could be targeted to consumer groups in order to provide benefits and add value.

Composition of the non-protein nitrogen fraction of goat whole milk powder and goat milk-based infant and follow-on formulae.

The non-protein nitrogen fraction of goat whole milk powder and of infant and follow-on formulae made from goat milk was characterized and compared with cow milk powder and formulae. Goat milk infant formula contained 10% non-protein nitrogen, expressed as a proportion of total nitrogen, compared with 7.1% for cow milk formula. Goat follow-on formula contained 9.3% and cow 7.4% non-protein nitrogen. Urea, at 30%, was quantitatively the most abundant component of the non-protein nitrogen fraction of goat milk and formulae, followed by free amino acids at 7%. Taurine, glycine and glutamic acid were the most abundant free amino acids in goat milk powders. Goat milk infant formula contained 4 mg/100 ml total nucleotide monophosphates, all derived from the goat milk itself. Goat milk has a very different profile of the non-protein nitrogen fraction to cow milk, with several constituents such as nucleotides at concentrations approaching those in human breast milk.

Social anxiety as a moderator of the relationship between perceived norms and drinking.

OBJECTIVE: College students overestimate the drinking of their peers, and the more they overestimate, the more they drink. The present research was designed to evaluate social anxiety as a moderator of the relationship between perceived norms and drinking among college men and women. METHOD: Participants included 1,217 first-year residence-hall students (62.8% women) who completed Web-based assessments of social anxiety, perceived norms, and self-reported drinking. RESULTS: Results replicated previous research in that students overestimated the drinking of their peers (d = 0.75, p < .001). Students who had higher social anxiety drank somewhat more but did not differ from students who had lower social anxiety on perceived norms. However, the relationship between perceived norms and drinking was stronger among students who had higher social anxiety (d = 0.92, p < .001) relative to less socially anxious students (d = 0.02, p = NS). Higher levels of social anxiety were associated with a stronger relationship between perceived norms and drinking for both men (d = 0.86, p < .001) and women (d = 0.50, p < .001) but stronger for men (d = 0.26, p < .001). CONCLUSIONS: These results corroborate previous literature, which suggests that social factors are important determinants of drinking in this population and suggest that social anxiety is associated with susceptibility to peer influences on drinking. Additional work evaluating whether reductions in social anxiety may ameliorate the impact of perceived norms on drinking would be worthwhile.