Abstract

The effect of average particle size (APS), type of solvent, and extraction times (ET) on the physicochemical (moisture, pH, total soluble solids (TSS), titratable acidity, color, water activity (a_w), density), and phytochemical (total anthocyanins and phenols content)propertiesin Hibiscus sabdariffa (Roselle) calyces was analyzed. The phytochemical properties evaluation was performed using a factorial design 2×3×3: two APS (median diameters, d₅₀, of 0.55 ± 0.016 (fine powder) and 0.97 ± 0.034 (ground powder) mm), three solvents (water, 2% citric acid, and 50% ethanol) and three ET (30, 45, and 60 min). All extractions were performed at 50 °C. The APS was determined by sieve analysis using Tyler sieves of different number of mesh. Regarding physicochemical properties, no significant differences (p > 0.05) were observed in moisture content, pH, and titratable acidity; however, the 0.55 mm fine powder (FP) of Hibiscus calyces had lower a_w(0.37±0.01) and higher TSS (5.53±0.05%) than the 0.97 mm ground powder (GP). The extracts obtained fromGP showed a deeper red color than those of FP. The best combination of independent variables, in order to obtain the highest concentration of anthocyanins (451.4±28.1 mg/100 g d.s.) and total phenols (2016.2 ± 159.8 mg/100 g d.s.) were APS of 0.55 mm, 50% ethanol, and ETof 30 min.

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