Abstract
Research on the effect of processing on the retention of bioactive components with potential antioxidant activity is gaining importance. The objective of this investigation was to evaluate the effect of various processing methods (milling, boiling, pressure cooking, roasting and germination respectively) on the antioxidant components as well as the antioxidant activities in the commonly used pearl millet cultivars—Kalukombu (K) and Maharashtra Rabi Bajra (MRB). The methanolic extracts of processed pearl millet flours were analyzed for 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity, reducing power assay (RPA) and ferric reducing antioxidant power (FRAP) assays respectively. The samples were also evaluated for tannin, phytic acid and flavonoid content which was then correlated with the antioxidant activity assayed using three methods. The results indicated that the bran rich fraction showed high antioxidant activity (RPA) owing to high tannin, phytic acid and flavonoid levels. Heat treatments exhibited significantly (P ≤ 0.05) higher antioxidant activity (DPPH scavenging activity and RPA) reflecting the high flavonoid content. Processing did not have any significant effect on the FRAP activity of pearl millet. The data on the correlation coefficient suggests that DPPH radical scavenging activity and reducing power assay in the K variety was largely due to the presence of flavonoid content, however in MRB, no relationship was found between antioxidant activities and antioxidant components.
Highlights
The term “phytochemicals” or “plant chemicals” refers to every naturally occurring chemical substance present in plants, which has a potential for antioxidant activity
The methanolic extracts of raw and processed pearl millet were analyzed for DPPH free radical scavenging activity; reducing power assay (RPA) and ferric reducing antioxidant power (FRAP) assays respectively
Unlike tannins and phytic acid, the flavonoid levels considerably increased due to heat treatments while, germination did not alter the flavonoid content of pearl millet
Summary
The term “phytochemicals” or “plant chemicals” refers to every naturally occurring chemical substance present in plants, which has a potential for antioxidant activity. Used assays are reducing power assay (RPA), ferric reducing antioxidant power (FRAP) and 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity. Cereals and millets are the most commonly consumed food items in India They contain a wide range of phenolics which are good sources of natural antioxidants. Antioxidant activity of five bran extracts exhibited appreciable levels of total phenolics, flavonoids and DPPH radical scavenging activities [6]. Research on the effect of processing on retention of bioactive components with potential antioxidant activity is very important The objective of this investigation was to evaluate the effect of various processing methods (milling, heat treatments and germination respectively) on antioxidant components as well as antioxidant activities of pearl millet extracts. The methanolic extracts of raw and processed pearl millet were analyzed for DPPH free radical scavenging activity; reducing power assay (RPA) and ferric reducing antioxidant power (FRAP) assays respectively. The samples were evaluated for tannin, phytic acid and flavonoid content and were correlated with the antioxidant activity assayed using three methods
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