5:15 PM - 5:30 PM
[2Ep-09] Polyphenol and antioxidant analyses of sorghum and cowpea cultivars grown in Kenya and their porridges
Keywords:Antioxidants, Sorghum, Cowpeas, Polyphenols, In vitro digestion
Background
Sorghum (Sorghum bicolor) and cowpea (Vigna unguiculata) are rich in structurally different phenolics which in combined diet, may interact positively to enhance their bioactivity. This study investigated the total phenolic contents (TPC) and antioxidant activities (AA) of commonly grown and consumed sorghum and cowpea cultivars in Kenya as well as their porridge preparations. Effects of compositing and in vitro digestion on TPC and AA were also studied.
Methods
The samples comprised sorghum cultivars: two red and two white, and cowpea cultivars: a cream and three brownish-cream, and their porridge preparations. Samples were freeze-dried, pulverized, and extracted with 80% ethanol. Freeze-dried porridges were subjected to in vitro gastric and ileal digestion and colonic batch fermentation using swine fecal slurry as an inoculant. TPC was determined using Folin–Ciocalteu method while AA was evaluated using the ABTS, DPPH, and ORAC assays.
Results
The raw red sorghum cultivars showed higher AA than the white cultivars, correlating with their higher TPC. However, cooking reduced the TPC and AA of all sorghum porridge preparations. In contrast, the TPC and AA for cowpea porridges were higher than raw cultivars, suggesting enhanced extractability of phenolics. Combinations of sorghum and cowpea extracts resulted in synergistic AA effects. Gastric and ileal digestion of the porridges increased TPC and AA, suggesting that AA might be modified after ingestion. Colonic fermentation increased TPC and AA from 0-9 hrs followed by a gradual decline, suggesting phenolic extraction and degradation by gut microbiota. In conclusion, sorghum-cowpea composites or fermentation could enhance their AA against reactive oxygen species.
Sorghum (Sorghum bicolor) and cowpea (Vigna unguiculata) are rich in structurally different phenolics which in combined diet, may interact positively to enhance their bioactivity. This study investigated the total phenolic contents (TPC) and antioxidant activities (AA) of commonly grown and consumed sorghum and cowpea cultivars in Kenya as well as their porridge preparations. Effects of compositing and in vitro digestion on TPC and AA were also studied.
Methods
The samples comprised sorghum cultivars: two red and two white, and cowpea cultivars: a cream and three brownish-cream, and their porridge preparations. Samples were freeze-dried, pulverized, and extracted with 80% ethanol. Freeze-dried porridges were subjected to in vitro gastric and ileal digestion and colonic batch fermentation using swine fecal slurry as an inoculant. TPC was determined using Folin–Ciocalteu method while AA was evaluated using the ABTS, DPPH, and ORAC assays.
Results
The raw red sorghum cultivars showed higher AA than the white cultivars, correlating with their higher TPC. However, cooking reduced the TPC and AA of all sorghum porridge preparations. In contrast, the TPC and AA for cowpea porridges were higher than raw cultivars, suggesting enhanced extractability of phenolics. Combinations of sorghum and cowpea extracts resulted in synergistic AA effects. Gastric and ileal digestion of the porridges increased TPC and AA, suggesting that AA might be modified after ingestion. Colonic fermentation increased TPC and AA from 0-9 hrs followed by a gradual decline, suggesting phenolic extraction and degradation by gut microbiota. In conclusion, sorghum-cowpea composites or fermentation could enhance their AA against reactive oxygen species.