Published in Scientific Papers. Series D. Animal Science, Vol. LXVII, Issue 2
Written by Nereida MALO (DALANAJ), Megi CAUSHAJ, Rozana TROJA, Elena MUÇA
In food science, water sorption isotherms are often used to understand the stability of food preserved in different conditions. Water activity is defined as the ratio of the vapor pressure of water in a material (p) to the vapor pressure of pure water (po) at the same temperature. In food, water activity (aw) explains how water affects the rate of microbial growth and many other chemical reactions. The paper aimed to study aw as an indicator of structuring the hysteresis cycle, its role in the changes that occur in several dried fruits in the Albanian market and to reach the hysteresis cycle through the determination of aw values in adequate conditions. Referring to physico-chemical indicators as protein, fat, and acidity, they were found to be within the limits allowed by law. So, there was no visible impact on the change of these indicators during the storage period. From the results obtained for walnuts as a specific case, it was observed that due to the dependence of moisture content on aw, the adsorption/desorption isotherms do not overlap, which refers precisely to the hysteresis cycle. It was possible to obtain a second-order desorption isotherm, with a very good approximation.
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