[Improvement of protein hydrolysis by the pre-treatment of protein with performic acid]

[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.

Production, characterization and application of protein isolates from shark. Part 3. Characterization of protein isolates

The functional and nutritional characterization of two isolates elaborated through cleaning-extraction processes, as well as that of a third isolate obtained by means of a chemical modification (alkaline heat treatment) from one of the former, was carried out. The first two isolates exhibit in general similar properties, are nutritionally comparable with casein and show a fairly high water absorption, having a potentially great value for instance in bakery and meat products and pastes. The modified isolate is essentially different from the isolate used as raw material in many of the characterized parameters, having a high nitrogen solubility index (NSI) by pH 3.5 and 7.0 and thus offering its possible use in such food systems as soft drinks where a high solubility is desired.

Isolation of the 12 S globulin from rapeseed (Brassica napus L.) and characterization as a "neutral" protein. On seed proteins. Part 13

An isolation procedure for the 12 S rapeseed globulin is described which includes precipitation by dialysis, purification using gel chromatography on Sephadex G-200, and ion-exchange chromatography on DEAE-Sephadex A-50. The isolated globulin represents a neutral protein with an isoelectric point at pH 7.25--determined by isoelectric focusing--and a relation of the acidic to basic amino acid residues (epsilon Glu, Asp--Amide ammonia: epsilon Arg, Lys, His) of 1.0. As in other storage globulins high contents of glutamic (19%) and aspartic (10%) acid and a low content of sulphur containing amino acids are characteristic for the amino acid composition. Amongst the basic amino acids arginine has the highest percentage (7%). Opposite to results of other authors the sugar content of the globulin is low (0.5%). From the amino acid composition an average hydrophobicity according to Bigelow was calculated which amounts to be 1041 cal/res. (4.36 kJ/res.).

[Nutritional-physiological studies on acetylated fractions of protein from Vicia faba]

The nutritional-physiological value of an easily soluble and of a difficulty soluble fraction of protein from Vicia faba (showing a degree of acetylation of 0%, 43% and 94%, respectively) was characterized by determining the amino-acid content, the enzymatic amino-acid availability and the nitrogen balance in the rat. The results from both the amino-acid analysis and the animal experiments on the biological value evidenced that the nutritional-physiological value of the easily soluble fraction of protein from Vicia faba is significantly lower, which is in particular attributable to its lower content of sulphur-containing amino acids. Acetylation did not reduce the nutritional-physiological value of the easily soluble fraction of protein from Vicia faba, and impaired that of the difficulty soluble fraction but slightly. From the viewpoint of nutritional physiology, there are no objections against the use of these protein fractions as food additives.

[Relationships between the apparent digestibility of crude protein and the amino acid balance of the swine digestive tract]

A diet of equal composition (88% barley, 5% extracted sunflower meal, 3% fishmeal and 3% yeast) was subjected to 9 different forms of thermal treatment and fed to experimental pigs. The biological value of the proteins was found to decline from 65.9 below 50. The amino acid balance of the digestive tract ("true digestibility of amino acids" according to other authors) proved to deteriorate due to the thermal treatment. The individual amino acids always revealed highly significant positive correlations with the apparent digestibility of crude protein. This finding is related with the often demonstrated fact that the fecal protein always has a constant amino acid composition, irrespective of feed protein and, consequently, only influences the quantitative fecal protein secretion, i. e. the amino acid balance of the digestive tract which is suggested to be the cause of the mathematical relations shown.

[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.

[Changes in the nutritive physiological value of proteins modified by dialdehyde starch]

The reaction of dialdehyde starch with the proteins of certain model protein texturates produces changes in the nutrition physiological quality of the proteins. Under the experimental conditions chosen, these changes were barely or not at all detectable by amino-acid analysis. On using the technique of aminoacid liberation under in vitro conditions, these changes were evidenced only for lysine and arginine. The determination of the lysine availability, however, testifies to a reversible or irreversible change of lysine which reduces significantly the PER values (animal experiments) of protein texturates treated with 100% oxidized dialdehyde starch. The differences between the NPU values were but insignificant. In spite of the detectable change in protein quality, the quality of the model protein texturates tested still satisfies the criteria for proteins with a composition which is favourable from the viewpoint of nutrition physiology.

α-Aminoadipic Acid and α,ɛ-Diaminopimelic Acid in Inoculated Pea Plants (Pisum sativum) and Root Nodule Bacteria (Rhizobium leguminosarum)

Observations were made on the content of α-aminoadipic acid and α-aminophimelic acid (DAP) in pea plants, nodules and Rhizobium leguminosarum, strain HT3. The preparations were purified by ion exchange chromatography, Qualitative analyses were made by paper chromatography, and quantitative analyses by means of an automatic amino acid analysator. In the whole plant and seeds the content of α-aminoadipic acid soluble in 70% ethanol varied between 10 and 80 μg/g dry weight. The shoot and red nitrogen fixing nodules contained more of this acid than roots and green inactive nodules. In the insoluble fraction of the shoot its concentration was 0.4-0.6 mg/g dry weight. α-Aminoadipic acid was not found in free living rhizobia, which again contained a considerable amount of α-aiaminopimelic acid, about 0.5 mg/g dry weight. The synthesis of DAP was intensive also in root nodules. In red nodules, which fixed molecular nitrogen, the content of DAP was 2.1 mg/g dry weight and in green inactive nodules 1.3 mg/g dry weight. It was shown that in the nodules DAP is closely connected with cell wall peptides of bacteroids. DAP could not be found in pea plants outside the nodules.