Secagem de folhas de aroeira (Schinus terebinthifolius raddi.) com aquecimento por micro-ondas: avaliação da retenção de cor e qualidade dos extratos etanólicos

Abstract

In this study, the drying of aroeira leaves (Schinus terebinthifolius Raddi) with microwave heating was evaluated in order to reduce moisture, color retention and chlorophyll concentration, as well as preserving total phenolic compounds (TPC) and antioxidant activity (AA) in the dried leaf extracts. The leaves were first characterized for their morphological and physical properties. Drying tests were performed in a White-Whestinghouse microwave, model EM 3500B, with specific powers ranging from 0.56 W/g to 4.35 W/g. To verify the drying conditions, a Central Rotational Composite Design (CCRD) 22 was performed with 4 tests under axial conditions and 3 repetitions at the central point, totaling 11 tests. The color intensity was determined by the colorimetric method based on the CIE L*a*b* color system. The bioactive compounds were extracted through maceration in ethanol for 7 days. The concentration of total phenolic compounds (TPC) was determined evaluated by the Folin-Ciocalteu method and antioxidant activity was determined by the DPPH method. Through the analysis of multiple regression coefficients, the effects of specific power and drying time on quality parameters final moisture, TPC, AA, and effective energy consumption. The results showed that higher power levels reduced drying times as they resulted in higher heating rates. Statistical analysis showed that the power and drying time have significant effects on the responses final moisutre, TPC content, AA and effective energy consumption. Based on by the Tukey test the color parameters L*, a*, b*and ∆E* showed no significant differences as applied power and drying timewere increased. There was no statistically significant differences in the chlorophyll contents of dried leaves, regardless of the applied power and drying time. Based on the response surfaces generated by the regression models, an optimization procedure was performed based on the desirability function to identify the operating condition that would best preserve the bioactive compounds with lower effective energy consumption. It was identified that the optimum drying condition would be obtained at the power of 1.5 W/g and time of 275 min.