D. Mastrocola

Interaction between Maillard reaction products and lipid oxidation in starch-based model systems

The effect of Maillard reaction products (MRPs) on the kinetics of lipid oxidation in intermediate-moisture model systems containing pregelatinised starch, glucose, lysine and soybean oil has been studied. The samples, either containing all components or excluding one or more of them, were heated at 100 °C for different times. Lipid oxidation and browning indices were measured and the results confirmed the ability of MRPs to retard peroxide formation. Under the conditions adopted, the rate of the Maillard reaction was increased by the presence of the oil and its oxidation products. The antioxidant action of MRPs was also evaluated using a peroxide-scavenging test based on crocin bleaching. The results demonstrated that antioxidant activity developed with increased browning of the samples.

Freeze-dried strawberries rehydrated in sugar solutions: mass transfers and characteristics of final products

Sugar solutions with different sugar composition and concentration were used to reconstitute freeze-dried strawberries. The mass transfer between fruit pieces and solution during the rehydration process and the physicochemical characteristics of the reconstituted products were evaluated. The results indicated that by varying the concentration of the sugar solution and reconstitution time it was possible to obtain from the same freeze-dried product, rehydrated fruit pieces with different and peculiar characteristics such as water activity, freezing point, amount of freezable water and firmness. In addition, these characteristics were linearly correlated with soluble solids content in the rehydrated products. Using the above method, the reconstituted freeze-dried strawberries are able to be used as an ingredient in formulated foods at different levels of water activity and also in frozen dessert or ice cream.