Bioaccessibility and antioxidant potential of millet grain phenolics as affected by simulated in vitro digestion and microbial fermentation

Abstract

DPPH EPRHydroxyl radicals ORAC Short chain fatty acids A B S T R A C T Dehulled and cooked grains of five millet varieties (kodo, finger, proso, foxtail and pearl) were subjected to in vitro enzymatic digestion and microbial fermentation under physiological conditions in order to determine the bioaccessibility of their phenolic compounds.Extracts recovered as supernatants from enzymatic digestion and microbial fermentation were employed for the determination of their total phenolic content (TPC) and total flavonoid content (TFC), as well as the scavenging of 2,2-diphenyl-1-picrylhydrazyl (DPPH), peroxyl and hydroxyl radicals. Furthermore, trolox equivalent antioxidant capacity (TEAC), reducing power and ferrous ion chelating activity of the extracts so obtained were evaluated. The DPPH and hydroxyl radical scavenging activities were determined using electron paramagnetic resonance (EPR) spectroscopy. The peroxyl radical activity was measured using an oxygen radical absorbance capacity (ORAC) assay. The TPC ranged from 12.7 to 35.4 and 21.2 to 47.4 lmol ferulic acid equivalents per gram of grain, on a dry weight (dw) basis at the end of intestinal digestion and colonic fermentation, respectively. All five millet varieties exhibited effective antioxidant activity and the order of efficacy differed according to the assay employed. The present study thus demonstrated that phenolic compounds of processed millets were bioaccessible and colonic fermentation released the phenolics bound to the insoluble fibre in the grain.

Antioxidant capacity and bioaccessibility of buckwheat-enhanced wheat bread phenolics

“…Different lowercase letters marked on the columns for each fraction of buckwheat enriched wheat breads indicate significant differences amongst the means (p < 0.05) soluble fraction of the reference white wheat bread was comparable to the content of these compounds in the dark wheat bread (with high difference of these compounds before digestion). This is in accordance with the results achieved by other scientists (Gawlik-Dziki et al 2009;Chandrasekara and Shahidi 2012). LiyanaPathirana and Shahidi (2005) also demonstrated that simulated gastrointestinal conditions significantly increased the TPC of extracts obtained from wheat whole grains and their flour, germ and bran fractions.…”

“…Nonetheless, food products have difficult structures where single antioxidant compounds can exist in different form: soluble and insoluble. Consequently, it is significant to investigate antioxidant activity of food after in vitro digestion process (Gawlik-Dziki et al 2009;Chandrasekara and Shahidi 2012;Li et al 2014). However, linked polyphenols are most likely disengaged later in the colon after fermentation.…”

“…Oral bioavailability of the bioactive compounds present in the pure form is typically much greater than the bioavailability of the same components contained in the matrix of the food product, because they need to be released from the matrix before absorption. In many cases, individual nutrients are chemically bound to other components, which greatly limit their release in the intestine (Delgado-Andrade et al 2010;Hur et al 2011;Chandrasekara and Shahidi 2012). Majority of food polyphenols occur in the form of esters or glycosides which are not absorbed in the native form.…”

Enhancement of Nutritional and Antioxidant Properties of Peanut Meal by Bio-modification with Bacillus licheniformis

“…Yang et al [20] reported a similar observation in soybean broth and fermented soybean broth. Meanwhile, Xiao et al [21] found that fermented soy whey extracts showed significantly higher (P < 0.05) hydroxyl radical scavenging activity at concentrations of 0.08-0.24 mg/ml (freeze-dried extracts were dissolved in 80 % ethanol and diluted to various concentrations) because of higher amounts of phenolics [46]. In this study, we considered the higher hydroxyl radical scavenging ability of FPM resulting from the increase of peanut oligopeptides according to the findings of Zheng et al [22].…”

Small Millets - Food for the Poor or Elite? - An Online Market Study in Coimbatore City of Tamil Nadu, India

“…Compared to polished Paddy rice, millets release lesser percentage of glucose over a longer period of time. Hence consumption of millets reduces risk of heart disease, protects from diabetes, improves digestive system, lowers the risk of cancer, increases immunity in respiratory health, and protective against several degenerative diseases such as metabolic syndrome and Parkinson's disease (Manach et al, 2005;Scalbert et al, 2005;Chandrasekara and Shahidi, 2012).…”