Abstract
Shelf-life is the period of time corresponding, under certain conditions, to an acceptable reduction in food quality; it depends on various intrinsic and extrinsic factors. Food nature, its water activity, conservation process, the storage conditions and the packaging materials influence primarily the stability. This work was performed in order to establish mathematical models to predict the shelf-life of foods, by using apple samples, with different water activity: dehydrated slices, compote and fresh cut pieces, for low, medium and high water activity, respectively. To the dehydrated slices which have more stability, and depend only on the absorption of a certain amount of moisture through the packaging, the adsorption isotherm was determined at 30 °C and 65% RH; the shelf-life was predicted according to the modified Hoerl model. For baby food, such as apple compote, it was taken into account the microbiologicalrequirements and the sensory acceptance. Accelerated shelf-life study at 37 °C and 90% RH was conducted and it was performed a multivariate prediction of the characteristics pH, Brix and aroma through Labuza kinetic models. Estimation of microbial growth was completed through Gompertz equation. Refrigerated storage assays at 4°C were performed for cut fresh which quality is related with physical appearance, taste and odour. Colour and odour were monitored by instrumental sensory analysis by using colourimeter and electronic nose. Different models obtained could predict the decay time of these foods by knowing the value of the initial quality characteristic.
