Effectiveness of plant oil in stabilizing the antioxidants, phenolic compounds and antimicrobial effects of groundnut (Arachis hypogaea L) oil

Abstract

This study appraised the biological qualities of blended groundnut (Arachis hypogaea L.) oil to determine its nutritional and pharmaceutical applications. Two sets of oils were produced; one with 100% groundnut kernels and the other produced by blending 500 g of groundnut kernels, with 100 g of onion bulbs, 100 g of ginger and 50 g of pepper. Three heavy metals (iron, lead and copper), iodine value, nitrate, thirteen phenolic compounds, thirteen antioxidants compounds, thiobarbituric acid reactive substances (TBARS), and antimicrobial actions of both the fortified (FGKO) and the unfortified (GKO) groundnut oil were quantified. The results revealed that the fortified oil developed significantly (p ≤ 0.05) higher concentrations of phenolic compounds, antioxidants parameters, iodine value, antimicrobial actions and TBARS than the unfortified oil, which it (FGKO) maintained throughout the storage period. Conversely, the GKO had significantly (p ≤ 0.05) higher heavy metals and nitrate concentrations than the FGKO. This portrayed that the combination of ginger, onions and pepper oils greatly enhanced the groundnut oil’s quality. The oils (GKO and FGKO) antioxidants followed an increasing concentration trend: ascorbic acid < proanthocyanin < β-carotene < resveratrol < isoflavonoids < Flavone < tocopherol < catechin < kaempferol < aglycone < gallocatechin < ribalinidine < lunamarin, revealing that the oils had high Gallocatechin, Ribalinidine and Lunamarin concentrations, and low ascorbic acid and proanthocyanin concentrations. Likewise, the oils phenolic compounds concentration followed this increment pattern: quercetin < naringenin < anthocyanin < rutin < ferulic acid < sapogenin < spartein < vanillic acid < luteolin < hydroxytyrosol< epicatechin < coumaric acid < ellagic acid. The findings revealed that the FGKO had a lot of preservative, medicinal and nutritional values, when compared to the GKO. These results portrayed the potential of using low-cost agricultural materials for promising and novel use in the production of nutrients rich oils. The hybridization of ginger, onions and pepper oils will be a good replacement for synthetic materials in improving oil qualities, thus eliminating the high risk factors associated with the introduction of synthetic blending materials. The FGKO has these potentials in the food industry: enhancement of food shelf life though inhibition of food spoilage agents, nutrients booster and natural flavor agent.