ANTIOXIDANT ACTIVITY OF PEANUT FLOUR FERMENTED WITH LACTIC ACID BACTERIA

Abstract

Peanut flour (PF) was fermented with four strains of lactic acid bacteria. The effect of fermentation on the antioxidant activities (α,α-diphenyl-β-picrylhydrazyl [DPPH] radical-scavenging activity, reducing power and Fe²⁺ chelating activity) and antioxidant compounds (phenolic acids and flavonoids) was investigated. Depending on the starter organisms used, lactic acid fermentation could increase the DPPH scavenging activity, reducing power and Fe²⁺ chelating activity of PF. The content of phenolic acids had a significant decrease (P < 0.05) after fermentation. Meanwhile, a significant bioconversion (P < 0.05) of rutin into quercetin was observed after fermentation. There was a good linear correlation between the EC₅₀ value of DPPH scavenging activity (R² = 0.8893, P < 0.05) or reducing power (R² = 0.8893, P < 0.05) and the concentration of quercetin in PF. These results indicated that lactic acid fermentation might be a good process to obtain functional PF with high antioxidant activity. PRACTICAL APPLICATIONS In the present study, the antioxidant activity of peanut flour (PF) was increased after lactic acid fermentation. Meanwhile, some bioactive compounds might be produced during the fermentation. The fermented products can be taken as a nutritional supplement for the elders, infants, pregnant women and individuals with malnutrition. More important, the inexpensive fermented products can be used as a good protein source in many developing countries where protein deficiencies remain a major health problem, especially for children. In addition, the fermented PF with higher nutritional value could be developed from defatted peanut meal, which is an inexpensive by-product of peanut oil production. For these reasons, this study provides a simple and effective strategy for improving the nutritional value of PF.