Loss and/or formation of antioxidants during food processing and storage.

It is well known that natural antioxidants contained in foods are significantly lost during processing. Nevertheless it was recently demonstrated that thermal treatments can induce the formation of compounds with new antioxidant properties. This is the case of the Maillard reaction products (MRPs) whose presence as well as their potential effects have been scarcely investigated. In the present work the loss of natural antioxidants in relation to processing and the formation of MRPs with antioxidant activity were studied in different food systems such as tomato derivatives and coffee. Results showed that, although the concentration of natural antioxidants was significantly reduced as a consequence of the thermal treatments, the overall antioxidant properties of the food products were maintained or even enhanced by the development of MRPs.

Influence of some selected ions on system water activity and on ethanol vapour pressure and its inhibitory action on Saccharomyces cerevisiae.

The individual and interactive effects of some ionic species on the ethanol vapour pressure in equilibrium with the system, the water activity, and the fermentative performance of Saccharomyces cerevisiae were investigated. The concentrations of the ions Ca2+, Mg2+, and NH4+ were modulated according to a central composite design, within a range of values that can be individually considered optimal for S. cerevisiae. Although the temperature and ethanol and glucose concentrations were kept constant, the initial water activity and ethanol vapour pressure of the systems were remarkably affected by the interactions between the three ions studied. The data concerning the fermentative activity emphasize the role of the physical state of ethanol. In fact, when the ethanol concentration was kept constant, the highest fermentative performances of yeast were obtained when the ethanol vapour pressure, depending particularly on the Ca2+ and Mg2+ interaction, was the lowest in the matrix of values considered.

[Water activity and food stability. I. Effects on viability of Saccharomyces cerevisiae cells (author's transl)]. / Stabilità degli alimenti in funzione dell'attività dell'acqua. I. Disattivazione delle cellule di Saccharomyces cerevisiae

Biological activity of microorganism is related to water activity (aw). In this paper the effect of glicerol as humectant on Saccharomyces cerevisiae viability was considered. The irreversible loss of viability was observed only for values inferior than 0,75. The K+ presence promoted an increasing of cell viability and growth. We have evaluated the changes of the most important components of cell poll; the increasing of glicerol amount of the system induced a drastic fall of aminoacids, purines and K ions content, but it increased the Na ions content. The exposure of cells to increasing glicerol concentrations, caused an aminoacids and purines excretion related to contact time; after a few hours this material was readsorbed by cells.

[Fish as proteic food: its preservation technology and new methods of utilization (author's transl)]. / Il pesce come alimento proteico: sua conservazione e nuove tecniche di utilizzazione

This review analyses the possibility to increase fishery production in order to satisfy the always increasing requirement of protein food. The most important chemical and nutritional chracteristics of fish and its by-products, as well as the preservation and elaboration technologies are reported. Some new or unusual fish utilization processes, as protein concentrates, extracts and spread pastes productions, are proposed as human food new sources.

[Retention of volatile organic compounds in a freeze-dried model food gel (author's transl)]. / Ritenzione di composti organici volatili in un gel modello liofilizzato

In this work the results obtained during freeze-drying of a food model gel are reported. The model system was constituted by 12,5% sucrose, 2,5% pectin and five organic volatile substances: acetone, ethyl acetate, methanol, ethanol and n-propanol. In particular, it was studied the effect of granulation and the effect of frozen material thickness on retention of volatiles. Other experiments were made to study volatiles distribution inside the freeze-dried materials; the stripping action of warm air and of water vapor flux through the freeze-dried layers, and eventually the holding capacity of dried layers to "capture" the volatiles. All the data suggested a theory about the different mechanisms which influence the retention and the remotion of volatiles during freeze-drying of foods.