Sara Da Pieve

Shelf Life Prediction of Bread Sticks Using Oxidation Indices: A Validation Study

The aim of this study was to apply the protocol for the shelf life prediction of bakery products proposed by Calligaris and others (2007a) on bread sticks. The methodology comprises 4 steps: (1) evaluation of the physical properties of fat; (2) performing the accelerated shelf life test; (3) evaluation of sensory acceptance limit and the relevant chemical index limit; (4) setting up the shelf life prediction model. The results allow validating the shelf life prediction methodology proposed. In fact, the peroxide number was found to be a representative index of the quality depletion of bread sticks during their shelf life. In addition, once again by accounting for the changes in the fat physical state, it is possible to set up a modified Arrhenius equation able to describe the temperature dependence of peroxide formation. Finally, a mathematical model to simply and quickly calculate the shelf life of bread sticks has been developed.

Effect of Lipid Physical State of Palm Derivatives on β-Carotene Bleaching

This research was addressed to study the effect of lipid physical state on bleaching kinetics of β-carotene. To this aim, β-carotene was added to palm oil and palm stearin and the samples were stored at increasing temperatures allowing different degree of crystallization. Phase transition properties of palm derivatives were studied by differential scanning calorimetry and synchrotron X-ray diffraction, whereas β-carotene bleaching kinetics were followed by measuring color changes. Bleaching proceeded at comparable rate in palm oil and palm stearin containing systems stored at 20 and -18 °C, whereas the color changes showed a maximum rate at 4 °C in palm stearin samples and at -7 °C in palm oil systems. Arrhenius plot clearly highlighted deviations from the linearity underlining the crucial role of lipid physical properties in determining the bleaching rate. The location and the compartmentalization of β-carotene in the fat lattice could affect its chemical stability.