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

Abstract

EnglishThe 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, HendersonPabis 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. portuguesO objetivo deste trabalho foi estudar a cinetica de secagem de fatias de maca e abobrinha enriquecidas com antocianinas e avaliar a influencia da temperatura de secagem no teor de antocianinas de discos de maca e abobrinha. Fatias de maca (Granny Smith) e abobrinha (Cucurbita pepo) foram enriquecidas com antocianinas por impregnacao a vacuo com suco de mirtilo. Em seguida, as fatias foram desidratadas a 40, 50 e 60 oC com fluxo de ar de 1,0 m / s. As amostras desidratadas foram referidas como snacks enriquecidos com antocianinas. Os valores do coeficiente de difusao melhoraram com o aumento da temperatura de secagem, na faixa de 2.81 × 10–10 a 5.78 × 10-10 m2 /s para fatias de maca e 2.02 × 10-10 a 3.99 × 10-10 m2 /s para fatias de abobrinha. A energia de ativacao foi 31.19 kJ / mol e 80.33 kJ / mol para as fatias de maca e abobrinha, respectivamente. Os modelos de Page, Weibull, Logarithmic, Henderson-Pabis e Lewis ajustaram os dados experimentais. Os snacks obtidos a 60 °C retiveram uma maior concentracao de antocianinas, atingindo valores de 592.81 ± 52.55 e 464.62 ± 48.44 mg de equivalentes de cianidina-3-glicosideo / kg de materia seca nos snacks de maca e abobrinha, respectivamente. A combinacao da impregnacao a vacuo e secagem por ar quente foi uma alternativa tecnologica para producao de lanches com propriedades funcionais.