Synthesis of Aroma Compounds as a Function of Different Nitrogen Sources in Fermentations Using Non-Saccharomyces Wine Yeasts.

Non-Saccharomyces yeasts are prevalent at the onset of grape must fermentations and can have a significant influence on the final wine product. In contrast to Saccharomyces cerevisiae, the biosynthetic pathways leading to aroma compound formation in these non-conventional yeasts, in particular those that are derived from amino acid metabolism, remains largely unexplored. Within a synthetic must environment, we investigated the amino acid utilization of four species (Hanseniaspora uvarum, Hanseniaspora osmophila, Zygosaccharomyces rouxii, Starmerella bacillaris) and S. cerevisiae. We report on the differential uptake preferences for amino acids with H. uvarum displaying the most rapid uptake of most amino acids. To investigate the fate of amino acids and their direct contribution to aroma synthesis in H. uvarum, H. osmophila and Z. rouxii, musts were supplemented with single amino acids. Aroma profiling undertaken after three days showed the synthesis of specific aroma compounds by the respective yeast was dependent on the specific amino acid supplementation. H. osmophila showed similarities to S. cerevisiae in both amino acid uptake and the synthesis of aroma compounds depending on the nitrogen sources. This study shows how the uptake of specific amino acids contributes to the synthesis of aroma compounds in wine fermentations using different non-Saccharomyces yeasts.

Fist fractures at child's age.

The aim of this work is to confirm or deny the hypothesis that the fist fracture medical treatment at child's age in the General Hospital in Zadar does not differ much from the medical treatment method in other centers which have already published their results. The work is based on the retrospective study. The examinees are children with fist fractures in the General Hospital in Zadar from 1999 to 2003. The control group is formed by the examinees of the published studies about children fist fractures, which have been collected and statistically elaborated. The examinees of our group and the control group are classified by the same criterion: age, sex, place, sort and type of fracture as well as the method of medical treatment. The used statistical methods are the testing of frequency differences and chi2 test. Statistically essential differences between our group and the control group have been noticed. There are also differences among the control group subgroups. The difference in the method of medical treatment is statistically essential and shows that the methods are not the same as in our group and the control group. The surgical way of treatment is less represented by our results than in those of the control group. The different attitude in medical treatment is conditioned by the attitude that surgical intervention of finger bones does not always give us the expected functional result.