[A new method for testing the quality of food protein for maintenance metabolism. 1. Investigations into the amount of 15N excreted via the urine of 15N-labelled young rats fed various proteins].
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.
D000818:Animals; D001224:Aspartic Acid / Q000032:analysis; D002364:Caseins; D004044:Dietary Proteins / Q000032:analysis / Q000378:metabolism; D004531:Eggs; D007887:Fabaceae; D005260:Female; D005396:Fish Products; D005780:Gelatin; D005971:Glutamates / Q000032:analysis; D007553:Isotope Labeling; D008239:Lysine / Q000032:analysis; D009584:Nitrogen / Q000652:urine*; D010946:Plants, Medicinal; D051381:Rats; D013025:Glycine max; D014908:Triticum
D002364:Caseins; D004044:Dietary Proteins; D005971:Glutamates; D001224:Aspartic Acid; D005780:Gelatin; D008239:Lysine; D009584:Nitrogen
Eine neue Methode zur Prüfung der Qualität von Nahrungsproteinen für den Erhaltungsstoffwechsel. 1. Mitteilung. Untersuchungen zur Höhe der 15N-Ausscheidung über den Harn von 15N-markierten jungen Versuchsratten nach Fütterung verschiedener Proteinträger.