Antioxidant activity of natural plant sources in dairy dessert (Sandesh) under thermal treatment

Natural sources of antioxidant viz. beet (Beta vulgaris), mint (Mentha spicata L.) and ginger (Zingiber officinale L.) have been used to fortify sandesh (a heat desiccated product of coagulated milk protein mass called chhana which is in turn a heat and acid coagulated product of milk, analogous to cottage cheese). Three sets of experiments viz. antioxidant activity, peroxide value and ultra-violet absorbance were done to evaluate the effectiveness of natural antioxidants in reducing lipid oxidation in sandesh as compared to synthetic antioxidants like tertiary butyl hydroquinone (TBHQ), butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) under thermal treatment. Among the natural sources, ginger has the highest antioxidant activity and it was similar to TBHQ and BHA–BHT combined. Results of the antioxidant activity differed from those of the oven test at 63 °C particularly for ginger and BHA–BHT combined. Control sandesh (without any antioxidants) showed the highest peroxide value and ultra-violet absorption. All the natural sources and their combinations significantly improved the oxidative stability of sandesh and their effectiveness was comparable with synthetic antioxidant TBHQ, a combination of BHA and BHT. Among the natural sources, although ginger had the highest antioxidant activity but mint showed better effectiveness in the inhibition of lipid oxidation. Regarding antioxidant activity and lipid oxidation, combination of mint or ginger with beet showed better result as compared to beet alone. Besides, sensory evaluation of freshly prepared natural source fortified sandesh samples was done as compared to control sandesh in order to commercialize the herbal sandesh in market. Sandesh containing beet, ginger, combination of beet with ginger or mint, or combination of mint with ginger were more acceptable to panelist than control sandesh.