Efeito da germinação sobre três cultivares de amendoim.

Abstract

Peanut (Arachis hypogaea L.) is a food source of proteins, fatty acids and bioactive compounds, including phenolic compounds, flavonoids and resveratrol, which also contribute to its antioxidant activity. The seed germination process induces biochemical and nutritional changes in seeds and has been widely used to produce grains and sprouts with high antioxidant activity. Therefore, the objective of this study was to germinate, dry and obtain flour from peanut sprouts of three Brazilian cultivars (L7 Vermelho, BRS Havana and BR1). Peanut seeds were germinated: the 48 h germination sprouts were characterized, dried in a thin layer at temperatures of 50, 60 and 70 oC and crushed, giving rise to peanut sprout flours. The germination process reduced the starch content and, by almost 50%, the lipid content of the cultivars. The highest levels of total phenolic compounds were observed in the samples of the sprout of cultivar BRS Havana in 48 h (1096 mg/100 g), of the cotyledon of the cultivar L7 Vermelho in 24 h (1041 mg/100 g) and of the sprout of L7 Red in 48 h (1027 mg/100 g). The Diffusion Approximation model presented the best adjustment parameters to the shoot drying kinetics data. The effective diffusion coefficients were in the order of 10­10 m2

/s, increasing proportionally with the progression of the drying temperature temperature, with the relationship described by the Arrhenius Equation, with values between 18.54 kJ/mol and 42.33 kJ/mol. The values of enthalpy and entropy variation were reduced with increasing drying temperature, while Gibbs free energy increased in the evaluated temperature range. Drying increased the levels of lipid, protein, ascorbic acid and starch in relation to the germinated material; reduced the content of carotenoids, total phenolic compounds and tannins and affected the levels of anthocyanins and flavonoids differently, depending on the cultivar; the drying temperatures of the peanut sprouts affected the physical properties of the flours obtained, decreasing the real specific mass and wettability and increasing the solubility, hygroscopicity and angle of repose. The flours were hygroscopic and with low fluidity. Peanut bud flours dried at 70 oC had a high content of total phenolic compounds, including resveratrol, high antioxidant activity, high fiber and mineral content and no cytotoxicity. The degradation kinetics indicated that the degradation of total phenolic compounds can follow the zero­order and first­order models; k values showed that the stability of total phenolic compounds decreases with increasing storage temperature, culminating at 35 °C; cultivars BR1 and BRS Havana are more susceptible to degradation reactions. The water adsorption isotherms of the bud flours of all peanut cultivars were classified as Type II, with sigmoidal shape; the Peleg and GAB models showed the best fit to the experimental data.