S & TA & NU. Rivista di scienza e tecnologia degli alimenti e di nutrizione umana最新文献

On samples of biscuits for special dietary use and rusks has been determined the protein quality with the method of enzymatic ultrafiltrate digest (EUD) at various levels of industrial production. The results have shown that the baking over again process has determined a decrease on the velocity of digestion "in vitro" against the raw material with large variations in availability of various essential aminoacids. Particularly decreased is the lysine, the limiting aminoacid of these food products.

A rapid method for sorbitol and sucrose determination by gaschromatography of their trimethylsilylderivatives is proposed. Gaschromatographic constants of these compounds are given and method riproducibility has been evaluated.

We have determined the level and the stability of the resistance of SO2 of yeast strains isolated in highly sulfitated musts. The resistance to antiseptic decreases during the storage and successive transfers of strains.

The determination of fatty acid composition of oils and fats by conventional GLC on polar columns gives satisfactory results for most of the applications. Higher precision is, however, desirable when the content of minor components is of interest. A typical example is the quantitative determination of the percentage of peanut oil in a seed oil mixture, on the basis of the content of lignoceric acid (n-C21). Lignoceric acid, wich is containen in peanut oil in the amount of 1-2%, shows, on polar columns, a very long retention time and, owing to its low percentage, flat and non well measurable peaks. A method was therefore developed which allows an accurate determination of all saturated fatty acids, particulary of those with high molecular weight. The method is based on the separation of satured fatty acids by argentation TLC followed by GLC determination on non polar columns.

In this review data are reported on the effects of rapeseed oil feeding to several animal species (mice, pigs, rats, guinea pigs, ducklings, chickens, turkeys) with particular regard to its nutritional value as compared to other vegetable fats, and to physiological and pathological modifications on different organs and tissues, namely: gonads, adrenals, thyroid, liver, myocardium. Finally, the results obtained after administration of regular rapeseed oil (i.e. with high levels of erucic acid) are compared with those obtained using the modern types Canbra, Span, Oro, Zephir (i.e. with low levels of erucic acid). From this comparison it could be inferred that erucic acid could be the major responsible for the observed modifications, but also that other long chain monoenes and the altered ratio between saturated and monounsaturated fatty acids might have a certain degree of pathogenic effects, although in this case the lesions appear later, are less frequent and less severe.

Tryptophan hydroilase in brain, normally is not saturated by its substrate; therefore the rate of tryptophan hydroxilation in brain is controlled by the concentration of tryptophan. In the other hand, brain tryptophan content is controlled by the ratio of the concentration of free tryptophan (i.e. not bound to serum proteins) to that of the other circulating amino acids, wich compete for the same transport mechanism from blood to brain. The administration of an amino acid mixture, containing all essential amino acids but not tryptophan, caused a parallel depletion of total and free serum tryptophan and of tryptophan and serotonin in brain. The mechanism of the observed fall in serum tryptophan is a rapid removed of endogenous tryptophan from circulation, secondary to an increased incorporation of tryptophan into proteins by the liver. These results suggest the hypothesis that brain serotonin synthesis is controlled by a perpherical mechanism.

Two groups of albino male rats, were fed for 90 days with a balanced and vitamin A-free diet rispectively, to observed changes, if any, in the fatty acid composition of erythrocyte membranes. The blood was separated with heparin, total lipids from erythocyte stroma were extracted and fatty acids analyzed by gaschromatography. It was noticed an increase in saturated fatty acids; at the same time mono- and, above all, polyunsaturated fatty acids decreased; the results agree with those obtained in rats fed for 30 and 60 days with Vitamin A-free diet as similar changes were observed in liver mitochondrial membranes of the rats, under study, we presume vitamin A modifies, to some extent, the biosyntesis of unsaturated fatty acids.

Undamaged cling peaches, cv. "Halford", were artificially bruised in three positions of the halves exerting a pressure of 2, 4 and 6 kg/cm2, with a hand penetrometer. These peaches were canned at different times (2, 4, 8 and 16 hours) and stored for five months. The halves were then submitted to a "panel test" which revealed that all the bruised fruits were suitable to give rise to a good canned product.