Changes in Polyphenols Distribution and Antioxidant Activity during Fermentation of Some Underutilized Legumes

Abstract

The effect of fermentation on the polyphenol distribution and antioxidant activity of four underutilized legumes [Cajanus cajan L. Millsp (Pigeon pea), Vigna subterranea L. Verdc (Bambara groundnut), Sphenostylis stenocarpa Harms (African yam bean), and Phaseolus vulgaris L. (Kidney bean)] were investigated. The beans were cooked (12 h), soaked in boiled water (12 h), dehulled, and then cooked again (2 h). The cotyledons were drained, wrapped in jute sacks and left to ferment at 37°C (4 days) to produce condiments. The distribution of free and bound phenolic compounds in the fermented and unfermented beans was determined; thereafter the free radical scavenging ability, reducing power, and the ability of the free and bound phenolic compounds of the fermented and unfermented beans to inhibit lipid peroxidation were determined. The results of the study revealed that fermentation caused a significant increase (p<0.05) in the free soluble phenol content of the legumes, while there was a significant decrease (p<0.05) in the bound phenol content of the legumes. Free soluble phenol from both the fermented and unfermented legumes had a significantly (p<0.05) higher reducing power (except C. cajan), free radical scavenging ability (except C. cajan) and inhibition of lipid peroxidation than bound phenolic extract. However, free soluble phenolic compounds from the fermented beans had a significantly higher (p<0.05) reducing power, free radical scavenging ability, and inhibition of lipid peroxidation than free soluble phenols from unfermented beans. Hence, it was concluded that, fermentation could increase the free soluble phenolic content of the underutilized legumes tested and consequently enhance the antioxidant activities of the legumes; fermented V. subterranea was found to be the most promising condiment with antioxidant activity.

Fermented Pulse-Based Food Products in Developing Nations as Functional Foods and Ingredients

“…An increase in hydroxybenzoic acid and (+)-catechin content was reported in spontaneously fermented lentils [69], while similar increase in free soluble phenols observed during the fermentation of some underutilized pulses [55]. Conversely, a reduction of conjugated forms of ferulic acid, p-cumaric, hydroxycinnamic derivatives, and bound phenols was observed during the fermentation of pulses [49,55]. Surprisingly, same authors reported the synthesis of tyrosol and an increase in free quercetin due to the hydrolysis of quercetin glucosides [49].…”

“…These compounds impact pigmentation, lavor and taste in foods, and antioxidant activities and interact with proteins as a result of their radical-scavenging capacity [52]. Studies have shown that antioxidants contained in fermented pulses may mitigate the prevalence of some forms of cancer [53][54][55][56][57][58]. Ademiluyi et al [57] reported the hypoglycemic and antiacetylcholinesterase activities of fermented bambara in rats and atributed this to the presence of phenolic compounds and other phytochemicals.…”

“…Ademiluyi et al [57] reported the hypoglycemic and antiacetylcholinesterase activities of fermented bambara in rats and atributed this to the presence of phenolic compounds and other phytochemicals. Phenols in pulses and their fermented products have also been reported to exhibit strong antimutagenic, anti-inlammatory, and anticarcinogenic properties and have the capacity to modulate some important cellular enzyme functions [55,59,60]. Reduced levels of oxidative damage to lymphocytic DNA have also been linked to consumption of fermented pulse-based foods rich in antioxidants [50].…”

“…Surprisingly, same authors reported the synthesis of tyrosol and an increase in free quercetin due to the hydrolysis of quercetin glucosides [49]. Nevertheless, such documented changes have been atributed to the action of glycosidases and esterases from LABs releasing free aglycones, phenolic acids, hydroxyl-cinnamic acids, and less esteriied proanthocyanidins and the transformation of bound to free phenolics during fermentation [49,55,[70][71][72][73].…”

Hard-to-cook phenomenon in bambara groundnut (Vigna subterranea(L.) Verdc.) processing: Options to improve its role in providing food security

“…(40) Fermentation Previous researchers reported changes in composition of bambara groundnut during fermentation. (127)(128)(129)(130)(131) According to Fadahunsi and Sanni, (131) changes include an increase in crude protein, soluble solids, soluble protein in bambara groundnut tempe after 40 hour fermentation. The data obtained during tempe production showed an increase in the activities of the enzymes amylase, lipase, and proteinase as fermentation progressed.…”