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Abstract
Beta vulgaris, or red beetroot, is a fibrous tuber vegetable that has antioxidant power that may be utilized in the reduction of risk chronic diseases. Red beetroot has high water content in its bulb and foliage that contributes to a short shelf-life. Thermal processing techniques such as oven-drying and osmotic dehydration may be applied in order to reduce water content and potentially increase phytochemical extractability. The first objective of this study is to determine the phytochemical content (Total Flavonoid Content- TFC and Total Phenolic Content- TPC) and antioxidant activity (Nitric Oxide Radical Scavenging- NORS, Trolox Equivalent Antioxidant Capacity TEAC, and Ferric Reducing Antioxidant Power-FRAP) of the aqueous (Aq) and 5% acetic acid (Ac) extracts of red beetroot bulb (Bl) and foliage (Fo), treated with oven-drying (OD) at 40ºC and low-saline osmotic dehydration (OSD) pretreatment+oven-drying at 40ºC. Untreated (F) samples served as controls. The second objective was to determine the inhibitory effect of the red beetroot extracts (Bl and Fo) on metabolizing enzymes (α-glucosidase, α-amylase, and lipase).
Results reveal that thermal processing enhanced the phytochemical content (total phenolic and total flavonoid) of the samples. Antioxidant activity, as determined through TEAC, NORS, and FRAP assays, was reduced after thermal processing methods. It was also observed that enzyme actual (α -Glucosidase, α -Amylase and Lipase) were not significantly different between the fresh and thermally treated samples, but the solvent type greatly influenced the enzyme inhibition of the samples.
In conclusion, thermal processing such as oven-drying and low-saline osmotic dehydration pretreatment are effective in the increase in extractability of phytochemicals but may not be the best treatment for antioxidant activity. Enzyme inhibition is not greatly impacted by the thermal processing which suggests that these methods may be used to treat beetroot without detrimental effects. For future research, the use of cell models to determine the health effects may be studied. Also, further analysis of other combined thermal and non-thermal treatments may be studied for their phytochemical content and antioxidant and enzyme inhibition activities.
