BIOACTIVE COMPOUNDS, ANTIOXIDANT CAPACITY AND THE INFLUENCE OF THERMAL PROCESSING IN BANANA PEEL FLOURS

Banana (Musa spp) is the second most consumed fruit in the world and a large quantities of its peel is wasted by food industry and consumers. This banana by-product appears to be a good source of antioxidant compounds as phenolic acids, flavonoids and carotenoids. After thermal processing and flour production, the content of total phenols, flavonoids, carotenoids, and antioxidant capacity were evaluated. Mature fruits of four banana genotypes (‘Monthan 172’, ‘Monthan 301’, ‘Pelipita’ and ‘D’angola’), raw and thermal processed (boiling for 10 min or microwaving for 2 min - 1500 W) were used to produce peel flour. The data were submitted to analysis of variance (ANOVA) followed by Tukey test. Compared to thermal processed flour, raw flours were significantly high in bioactive compounds and antioxidant capacity. The bioactive compounds content ranged from 1.3 to 3.5 g/100g (total phenols), 0.7 to 2.2 g/100g (flavonoids), and 7.7 to 15.3 mg/100g (carotenoids). Raw flour of genotype ‘Monthan 172’ stood out with the higher levels of total phenols (3.5 ± 0.1 GAE/100g) and antioxidant capacity (DPPH: 55.6 ± 2.2 mg TEAC/g; FRAP: 291.3 ± 10.4 mmol Fe/Kg, and ABTS: 7.4 ± 0.3 mol TEAC/100g). Flours of thermal processed peels showed reduced levels of all parameters analyzed, with exception of total phenols (2.7 g/100g) and antioxidant capacity by DPPH (40.7 ± 1.1 mg TEAC/g) in flours of genotype ‘D’Angola’ after boiling. The thermal processing methods induced variable responses in the bioactive compounds and antioxidant activity of the flours. These processing methods are usual for banana consumers in home or in the food industry; however, the peel flours produced after this retain high concentrations of bioactive compounds and antioxidant capacity. Thus, raw or thermal processed banana peel flours could be a useful ingredient for new functional food formulations, supplementations or food industry products.

FAPESP (2016/00972-0, 2017/ 23488-0 and 2016/22665-2) and CNPq (305177/2015-0).