Annales de la nutrition et de l'alimentation最新文献

The purpose of the study was to explain the enormous increase of nitrates in the waters of river Bèze (Côte-d'Or) belonging to a well-defined karstic basin. This paper deals with surface and underground waters, pedologic formations and their rock base. It consisted in listing the oligoelements involved in the enzymic processes of nitrate reduction, the microflora and in determining the kinetics of denitrification by column perfusion. The presence of biodegradable carbon compounds is the governing factor of denitrification; their rapid lass related to new agricultural processes and the excessive use of nitrogene fertilizers are responsible for the enormous increase of nitrates observed.

Nitrites and nitroso compounds have been incriminated in the development of abnormal colourations of "pont-l'évêque". In a preparation of these cheeses nitrites were added either to the milk or during the manufacturing procedures and in all cases were noticed pink or brown stains and bursting of the cheese pulp with formation of cavities. Our results have demonstrated it is possible to break down these nitroso-compounds with an enzyme from yeast. This enzyme detoxifies the medium following a mechanism which has been elucidated. The addition of yeasts to the cheeses during manufacturing helps to accelerate the desintegration process of the coloured compounds and to obtain a uniform shade of the crust and a total absence of deeper stains. We have shown that the nitrites present in the cheeses will form nitroso compounds. The latter are then responsible for the abnormal and irregular stains; their rapid decomposition helps to detoxify the medium as well as ameliorating the aspect of the cheeses.

Several strains of micromycetes used as fermentation agents in the cheese industry or having led to accidents during cheese making are able to favor the formation of nitrosamines in 60% of the cases. The concentrations observed are similar to those found by other authors with other microorganisms. The results obtained in a semi-synthetic medium are checked during the ripening of experimental camembert type cheese made from milk containing nitrates and cultured with a strain of Penicillium camemberti, which favors very much the synthesis of nitrosamines. The amount of nitrosodimethylamine formed in this cheese increases from 5 to 20 ppb during ripening. A tentative explanation of the mechanism of formation is outlined.

The mecanisms of resistance to starvation of adult Ceratitis capitata are analysed. This study is based on comparison of two laboratory strains: one which was previously selected for "resistance to starvation" the other which has never been selected. Resistance to starvation appears to be determined, on the one hand by reserves in the insect and their hourly rate of utilisation on the other hand by the efficiency of the antidiuretic system. The selection, which increased adult resistance to starvation acted upon these three factors. It modified the strategy of energy utilisation by inducing a more economic energy budget.

The food consumption of a sample of 10,000 French households has been under constant study by the Institut National des Statistiques et Etudes Economiques. Based on the data obtained, a representative model of the daily food consumption has been established with the help of the Nutrition Section of the Institut National de la Santé et de la Recherche Médicale. A composition table was used to define the theoretical amount of natural ascorbic acid contained in these foodstuffs, to this quantity was added the amounts of ascorbic acid incorporated as an additive in these foodstuffs. The latter amount was obtained using the maximum authorized amounts. Natural ascorbic acid plus additive gives the maximum theoretical amount of vitamin C supplied through food consumption. The mean value obtained is approximately 170-200 mg/day between 1965-1974 period. Interesting as they may be, from a nutritional point of view, it would be unrealistic to build upon these theoretical values. A critical analysis of these values based on the results of a food survey we carried out and the technological role played by ascorbic acid, led to the conclusion that food content, with this model of food intake, was somewhat between 56 to 91 mg/day and more probably between 56 to 69 mg/day. Kallner and al. in 1979 suggested that in the healthy non-smoking man the recommended dietary allowance should be 100 mg/day. In connection with this work and with nutritional studies undertaken in various industrial countries, the present study brings up the question of the level of vitamin C supply in certain groups of the French population (old people, pregnant women...).

In a first experiment, 8 groups of male rats received for 6 months diets containing 23 p. 100 casein: 1) standard semi-synthetic diet (R); 2) standard diet with 1 p. 100 potassium metabisulfite (S); 3) standard diet with 3.2 p 100 tannic acid (T); 4) standard diet with sulfite and tannic acid (ST); 5) standard diet in which ethanol replaced 30 p. 100 of the carbon-hydrate energy (E); 6) standard diet with sulfite and ethanol (SE); 7) standard diet with tannic acid and ethanol (TE); 8) standard diet with sulfite, tannic acid and ethanol (STE). In another experiment, 6 groups of male rats received for 6 months diets containing 11.5 p. 100 casein: 1) standard diet (R) fed ad libitum; 2) standard diet (R') fed in restricted amounts equal to those ingested by the rats receiving the diet with tannic acid; 3) standard diet with tannic acid (T); 4) standard diet with sulfite and tannic acid (ST); 5) standard diet with tannic acid and ethanol (TE); 6) standard diet with sulfite, tannic acid and ethanol (STE). The digestive utilization of dry matter, digestive utilization and biological value of nitrogen were determined at the beginning of the experiments and after two and six months. 1. Tannic acid caused a marked decrease in food intake in animals fed 11.5 p. 100 casein but had only a slight effect in animals fed 23 p. 100 casein. 2. Fecal excretion of dry matter was strongly enhanced in rats fed tannic acid. Sulfite and ethanol had a slight effect when given singly, but caused modifications to the effect of tannic acid when they were associated with it. 3. Fecal excretion of nitrogen was strongly increased by tannic acid, and this effect was quantitatively modified by the presence of the two other compounds, particularly by sulfite. 4. Ethanol generally increased the urinary excretion of nitrogen but interactions between the effects of the three substances were observed. Particularly, the simultaneous feeding of the three substances provoked after 6 months a poor metabolic utilization of the nitrogen, and also a lower digestive utilization of the proteins. 5. Generally all the effects of the three compounds were more marked when the dietary level of protein was low than when it was high.

Lactating female rats were fed diets A or B containing 18 and 12% of casein respectively, or similar diets but supplemented with 0.4% of methionine (diets AM or BM). The animals and their pups were sacrificed at the 18th day of lactation. Control non lactating female rats fed the same diets for the same period of time were also sacrificed. Total riboflavin and its various forms (flavin adenin dinucleotide, flavin mononucleotide + free riboflavin) were measured in various tissues as well as in the milk which was collected from the stomach of the pups after a time controlled suck. In the lactating females fed diets A and B as well as in the control animals fed the same diets the concentrations of riboflavin and of its various forms in plasma, liver and carcass are unchanged. However in group B, they are higher in milk and in tissues of the pups. These results seem to be due to a decrease in food intake by the lactating females fed diet B which results in a decrease in milk production which in turn induces a lower growth rate of the pups although the riboflavin consumption by the latter is unchanged. Addition of methionine to the diet B (diet BM) induces the same effects as diet A which contains the highest amount of proteins but addition of methionine to the diet A (diet AM) has no further incidence. Therefore the present study has not revealed any direct effect of methionine on riboflavin metabolism in lactating female rats and their pups since the effects are similar to an increase of the total protein level in the diet. In both cases they seem to be simply related to an increase of the food consumption.

The salivary and biliary excretion of nitrates has been studied in dogs. We have administered intravenously [15N] sodium nitrate (51% enrichment) and we have studied its fate in blood, bile and saliva by estimation of NO3-, NO2- and 15N at the time of 0, 30 mn, 1 h and 3 h. This experimentation, made on 9 dogs, indicates a total absence from nitrites in blood, bile and saliva and confirms the existence of biliary excretion of nitrates. Last, the evolution of 15NO3 rates, measured by mass spectrography, indicates that salivary glands produce an important endogenous accumulation of nitrate ion.