A study of the chromatographic determination of amino acids in the presence of large amounts of carbohydrate

Formation of labeled sugars from L-tyrosine-C14 in some higher plants

Radioactive sugars and organic acids, including glutamic and aspartic acids, were synthesized in leaf disks of live species of angiosperms from administered uniformly labeled L-tyrosine. The synthesis of sugars was appreciable in light; in the dark there was virtually no conversion to carbohydrate. In three different experiments, 28%, 36%, and 46% of the total activity of tyrosine-U-C14, administered to leaf disks of Pyrus communis, could be accounted for in identifiable aliphatic compounds. These results indicate that tyrosine is a glucogenic amino acid in higher plants and suggest also that three or more carbons of the tyrosine molecule are utilized. Ring cleavage is a possibility.

[The quality of protein-enriched products from sunflower seeds. 1. The effect of various production processes on the nutritive value of meals and protein isolates]

Globulin isolates from native sunflower seed and industrial extraction meal obtained by extraction with different electrolyte solutions and subsequent isoelectric precipitation are relatively poor in the essential amino acids lysine, threonine, and methionine as compared to defatted seed meals. On the other hand, albumins separated by means of polyanionic complexing agents (sodium alginate and aluminium potassium sulphate) are relatively rich in these amino acids, and albumin-globulin-co-precipitates have a correspondingly balanced amino-acid composition, being also reflected by nutrition physiological values as BW, NPU, and EAA-index. As compared to seed meals protein isolates are characterized furthermore by a better protein digestibility.

An energy response curve for a commercial white Leghorn laying-strain cross

Individually-caged White Leghorn hens, 235-d-old, were given daily metabolisable energy (ME) intakes ranging from 707 to 1321 kJ for 8 two-week periods. Energy was the first limiting nutrient, in those cases where the differences in egg output between treatments were sufficiently large. Body weight, egg number and egg weight all responded (P less than 0.001) to energy intake, and as judged by regression analyses, these responses had stabilised by the fifth period. For a near-maximum egg output of 48 g/bird d, the difference between the ME requirement of the average bird and of the flock, estimated from linear and curvilinear models respectively, was 20.5%. The ME requirement (Y, kJ/bird d) of the average bird for egg production (E, g/bird d) and maintenance of metabolic body size (kg W0.75) corrected to an ambient temperature of 22 degrees C is given by the equation, Y = 440W0.75 + 8.96 E.

[Development and testing of protein mixtures based on blood and collagen]

Using the results of the chemical amino acid analyses of the unconventional proteins blood, collagen and wool and the conventional proteins soya, maize and casein, protein mixtures were developed. The quality of the protein mixtures was estimated in feeding experiments with growing male Sprague-Dawley rats and expressed as protein efficiency ratio (PER). Different blood parameters and the weight of some organs were also recorded. Blood, collagen and wool protein are very poor in different essential amino acids, therefore their quality is very low, it can however be significantly improved when they are fed in mixtures with other animal or plant proteins of higher quality. In mixtures of three components only containing blood (10--40%), collagen (10--25%) and casein (50 to 70%) the deficit in the content of essential amino acids cannot be compensated. Rats fed with such diets showed, however, decreased food intake and depressed growth. The relative PER values of those mixtures were 44--69% of that of casein. The best supplementing effect on the imbalanced amino acid patterns was achieved when the protein mixture was developed from 4 or 5 different proteins. The quality of these five-component-mixtures amounted to 94--100% of that of casein. In these mixtures the percentage of casein in the protein mixture amounted to only 35% and soya or maize to 15%. Exactly 50% of the protein supply could be derived from hydrolysates of the unconventional proteins blood, collagen and wool.

[Nutritive-physiological study of sunflower seed protein isolate and spun sunflower seed protein-casein fibers]

Compared with defatted sunflower seeds, in sunflower seed globulin isolates the content of lysine and sulphur containing amino acids is decreased, the content of phenylalanine is increased. The content of the whole essential amino acids of sunflower seed globulin isolate in relation to casein is decreased. The value of the enzymatic invitro available amino acids of sunflower seed globulin is comparable with casein. The digestibility is good, the biological value is in relation to defatted sunflower seed lower. Apart from the lower content of sulphur-containing amino acids the amino acid composition of spun sunflower seed globulin/casein (I:I) fibers corresponds with the calculated value; in relation to sunflower seed globulin isolate the content of lysine and the whole essential amino acids of the spun protein fibers is increased. The enzymatic in-vitro-hydrolysis results altogether in a comparable availability of the amino acids between spun protein fibers and sunflower seed globulin isolates. The digestibility and the biological value of spun protein fibers corresponds with that of casein.

[Nutritional study of field bean protein isolate and of spun field bean protein-casein fibers]

The amino acid composition of the different field bean protein isolates shows a good correspondence. In relation to casein the content of the whole essential amino acids is low. In the first line the low content of methionine and cystine limits the biological value of this proteins. The content of lysine is relatively high. The enzymatic in vitro-hydrolysis results in a corresponding availability of the amino acids between the field bean proteins and casein. The digestibility is very good, the biological value with less than 50 relatively low. Apart from the low content of the sulphur containing amino acids the amino acid composition of the spun field bean protein/casein(I:I) fibers corresponds with the calculated value; the enzymatic availability of the fibers is also comparable with casein. The digestibility in the nitrogen balance test is very good and the biological value of the fiber corresponds with that of casein.