Effects of the Drying Technique Used on the Contents of Total Polyphenols, Flavonoids and Antioxidant Activity of Five Varieties of Mangoes (Mangifera Indica) Dried in Senegal

Abstract

The Ziguinchor region (Kaguitte village), where the mango samples were collected, is an area that is very affected by post-school losses of seasonal fruit in general. Faced with this problem, the women in the GIE (economic interest group) have been processing mangoes into by-products for several years, particularly drying, which is one of the mwain techniques for preserving agricultural and food products. It is a process that is used in the production of many food products. To carry out this drying, three techniques were used: the one used by the women of the locality (Normal) and two others with osmotic dehydration for two hours and three hours respectively. After peeling, it was found that the improved varieties Knt and Kt had the highest pulp yields (60% of their total mass) and that the Sl variety had the lowest yield. In this work, we followed the variation of polyphenol contents and antioxidant powers according to the technique and the mango variety. For total polyphenols, the Folin-Ciocalteu method was used and antioxidant activity was assessed with 2,2-diphenyl-1-pycrilhydrazyl (DPPH°). The results showed that the antioxidant power, significantly decreases after treatment of the four varieties (example: Knt normal-AAR=0.83%, Treatment-2h-AAR=0.69% and Treatment-3h-AAR=0.59%) with the exception of Dr variety (Normal-AAR=0.68% and Treatment-2h-AAR=0.79% and Treatment-3h-AAR=0.78%). The determination of total polyphenols in these samples showed a much more obvious variation between varieties and less important after the treatment. Thus we have: Knt (Normal-0.07g/100g, treatment-2h-0.03g/100g and treatment-3h-0.19g/100g), Kt (Normal-0.27g/100g, treatment-2h-0.07g/100g and treatment-3h-0.06g/100g) and Sl (Normal-0.11g/100g, treatment-2h-0.07g/100g and treatment-3h-0.21g/100g) Analyses (of Variance and linear models) show that the varieties Knt (treatment-2h-0.0087g/100g and normal-0.0033g/100g), Dr (treatment-2h-0.0023g/100g and normal-0.0019g/100g) and Sl (treatment-2h-0.0023g/100g and normal-0.0017g/100g), respectively, have quite high flavonoid contents. These experimental results show that the technique used (Normal) by the local units preserves the antioxidant compounds well and in some cases it is necessary to treat the different varieties before drying them.