Evaluating the nutritional and bioactive composition of grape, jaboticaba, and hibiscus by-product flours as potential ingredients for the food industry

Abstract

Grapes, jaboticaba, and hibiscus are renowned for their antioxidant properties, which contribute significantly to human health. However, after industrial processing, their peel and seeds are often discarded as waste, representing up to 50% of the raw material. This study aimed to evaluate the physicochemical and nutritional composition, mineral, carbohydrates, organic acids, and phenolic profile, in addition to assessing the anti-nutritional compounds, phytochemical, and volatile compounds present in flours made from the peels and seeds of grapes, jaboticaba, and hibiscus. Moisture content ranged from 8.24 to 14.86 g/100 g, with low water activity (0.29–0.56) ensuring extended shelf life. Hibiscus flours were particularly rich in protein, providing up to 31.18% of the recommended daily intake. Grape seed oil stood out for its high unsaturated fatty acid content, while the ash content (up to 9.28 g/100 g) suggests potential for mineral fortification. Key minerals included nitrogen (658–2327 mg/100 g), potassium (480–2080 mg/100 g), and iron (4.92–15.67 mg/100 g) especially abundant in hibiscus flour, highlighting its potential in combating anemia. Phytochemical analysis revealed high levels of carotenoids and flavonoids, known for their antioxidant properties, along with significant anthocyanin and tannin concentrations. Finally, phenolic compounds, such as catechin and gallic acid, were widely detected, with emphasis on catechin in grape peel flours (149.30 mg/100 g) and ellagic acid in jaboticaba peel flours (41.40 mg/100 g), known for their antioxidant and anti-inflammatory properties. The results suggest that grape, jaboticaba, and hibiscus byproduct flours offer substantial nutritional and functional benefits, with promising applications in food industries.