Drying kinetics modeling of apple and zucchini slices vacuum impregnated with anthocyanins

Abstract

The aim of this research was to study the drying kinetics of apple and zucchini slices enriched with anthocyanins and to evaluate the influence of drying temperature on the anthocyanin content of apple and zucchini snacks. Apple (Granny Smith) and zucchini (Cucurbita pepo) slices were enriched with anthocyanins by vacuum impregnation with blueberry juice. Then, slices were dehydrated at 40, 50 and 60 ºC with 1.0 m/s air flow. Dehydrated samples were referred to as anthocyanin enriched snacks. Diffusion coefficient values improved by increasing the drying temperature, within the 2.81×10-10 to 5.78×10-10 m2/s range for apple slices and 2.02×10-10 to 3.99×10-10 m2/s for zucchini slices. The activation energy was 31.19 kJ/mol and 80.33 kJ/mol for apple and zucchini slices respectively. Page, Weibull, Logarithmic, Henderson-Pabis and Lewis models best fitted the experimental data. Snacks obtained at 60 °C retained a higher concentration of anthocyanins, reaching values of 592.81±52.55 and 464.62±48.44 mg of cyaniding-3-glucoside equivalent/kg dry matter in apple and zucchini snacks respectively. Combination of vacuum impregnation and hot air drying was a technological alternative for producing snacks with functional properties.

Sustainable Development of Apple Snack Formulated with Blueberry Juice and Trehalose

“…Anthocyanins are also easily susceptible to the degradation during storage and especially during heat processing [47,48]. Besides, the degradation of phenolic compounds during drying has also been attributed to either the binding of polyphenols with other compounds, to alterations in the chemical structure [49] and to the drying duration [39,50,51]. In order to mitigate the losses of antioxidant compounds Barani et al [52] proposed different pre-treatments with citric acid, ascorbic acid, tartaric acid and sucrose.…”