Eine neue Methode zur Prüfung der Qualität von Nahrungsproteinen für den Erhaltungsstoffwechsel

Abstract

Over a period of 7 days, 38 experimental rats were fed a casein diet with a supplementation of 6.6 mg 15N-excess (15N') in the form of ammonium acetate. From the 5th experimental day, groups of 4 or 5 rats each were fed, over 5 days, different protein carriers to meet the meintenance requirement (115 kcal/kg body weight 0.75). The 15N-excretion via the urine, in terms of % of N absorbed from the food protein, served as yardstick of protein quality under maintenance conditions. The least 15N-excretion rates were reciprocally relativated for this maximum value (reciprocal 15N excretion biological value). The least 15N-excretion values from the 2nd to the 5th experimental days allowed to establish the following order for protein quality under maintenance conditions: fish meal, casein, wheat, whole egg, soybean (assayprotein), yeast peas, gelatin. The very good quality of the wheat protein for the maintenance state is seen in relation with the high content of glutamic acid (33.5 g/16 g N) and aspartic acid (5.7 g/16 gN). The found lysine content of the wheat protein (3.1 g/16 g N) proved sufficient for maintenance conditions.

Digestibility and Dietary Quality of Nonacetylated and Acetylated <i>Vicia faba </i>Proteins in Maintenance

“…absorbed but not uti lized N from the diet as distinct from N com ing from the catabolism of endogenous pro teins and amino acids. It was proposed [1] to use the urinary loss of l5N under mainte nance conditions as an indicator of the ability of a dietary protein to meet the intermediary amino acid requirement.…”

“…Table II. N balance data from collections made from the 6th to 10th days of feeding the experimental diets (n per group = 5; mean ± SE) Calculations Calculations for MFN were made as described by Hernandez et al [5] and were based on the proposals of others [2,9]. % endogenous N in feces = atom % ,5N excess in feces ^ atom % l5N excess in urine It was demonstrated [15] in animals labelled in the same way that the 1SN abundance of proteins in the pancreas and in tissues of the intestinal tract was very similar to that of nitrogen in urine.…”

“…For example, 1 The authors are grateful to Dr. K. Adam for help with l5N analysis. acetylation of Vicia faba protein improves the characteristics of gels formed by thermal denaturation [12,13].…”

“…The present study was made in order to evaluate acetylated and nonacetylated fractions of a Vicia faba protein isolate for maintenance in rats. Using an isotopic method [1,2] it was possible to estimate the loss of endogenous nitrogen via urine and feces, respectively. Whole egg, casein, and wheat were used as reference proteins.…”

Tracer and Chemical Diffusion in L1<SUB>2</SUB>-Ordered Pt<SUB>3</SUB>Fe

“…self-diffusion in Pt 15,16) and impurity diffusion of Fe in Pt. 17) The tracer diffusion coefficient of Fe in Pt 3 Fe is about three orders of magnitude smaller than the impurity diffusion coefficient of Fe in Pt. The chemical diffusion coefficient is 10-30 times larger than the tracer diffusion coefficient of Fe.…”