Sarwar G, Peace R W, Botting H G
Health and Welfare Canada, Health Protection Branch, Banting Research Centre, Ottawa, Ontario.
Am J Clin Nutr. 1989 May;49(5):806-13. doi: 10.1093/ajcn/49.5.806.
Protein and amino acid digestibility and protein quality of liquid concentrate and/or powder forms of infant formulas were studied by rat balance and growth methods. Casein plus methionine (control) and eight formulas were fed to weanling rats as the sole source of protein in diets containing 8% protein (nitrogen X 6.25). Values for true digestibility of protein, lysine, methionine, or cystine (85-92%) in liquid concentrates were up to 13% lower than those in powders. Similarly, the 2-wk relative protein-efficiency ratio values (64-85%) or the relative net protein ratio values (78-94%) of liquid concentrates were up to 25% lower than those for powders. Lower levels of bioavailable lysine and methionine plus cystine in liquid concentrates compared with powders (prepared by the same manufacturer) would suggest that inferior protein quality of liquid concentrates may be due to more heat treatment involved in their preparation.
通过大鼠平衡和生长方法研究了婴儿配方奶粉液体浓缩物和/或粉末形式的蛋白质和氨基酸消化率以及蛋白质质量。将酪蛋白加蛋氨酸（对照）和八种配方奶粉作为含8%蛋白质（氮×6.25）的日粮中蛋白质的唯一来源喂给断奶大鼠。液体浓缩物中蛋白质、赖氨酸、蛋氨酸或胱氨酸的真消化率值（85 - 92%）比粉末中的低高达13%。同样，液体浓缩物的2周相对蛋白质效率比值（64 - 85%）或相对净蛋白质比值（78 - 94%）比粉末中的低高达25%。与粉末（由同一制造商制备）相比，液体浓缩物中生物可利用赖氨酸和蛋氨酸加胱氨酸的水平较低，这表明液体浓缩物较差的蛋白质质量可能是由于其制备过程中涉及更多的热处理。
