Antioxidants are substances that are able to prevent or inhibit oxidation processes in human body as well as in food products. Oxidation reactions can produce free radicals, which start chain reactions that damage cells. Antioxidants terminate these chain reactions by removing free radical intermediates and inhibit other oxidation reactions by being oxidized it selves. The protection of foods from oxygen is the basic principle upon which antioxidant protective technologies are based. Both synthetic as well as natural antioxidants are using in food industry but the application of synthetics has been reassessed due to its potential carcinogenic effects. Research is being focused on vegetable materials which are a rich source of antioxidant compounds. Various antioxidant compounds have been isolated, many of them being polyphenols. Direct relationship exists between the total phenolic contents and the antioxidant activity in fruits and vegetables. The entire tissue of fruits and vegetables are rich in bio-active compounds and in most cases the waste by-products can present similar or even higher contents of antioxidant compounds. The waste materials such as peels, seeds and stones produced from the fruit and vegetable processing unit can be successfully used as a source of phytochemicals and antioxidants. Different antioxidant sources, their mode of action, application in food industry and antioxidant activities of banana peel, watermelon peel, potato peel and cucumber peel are reviewed in this paper.

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SUMMARY :Milk yam (Ipomoea digitata L.) (Family-Covolvulaceae) or Ksheervidari is a potential medicinal cum nutraceutical agent. It is a perennial climber having tuberous roots which are medicinal. Dried and powdered tubers are used in several nutraceutical preparations. The present study focussed on different pre-treatments and drying techniques that can be adopted for improving the flour whiteness and quality of milk yam tuber powder. Peeled as well as non-peeled tubers were shredded and washed (three times, two times, single time and no washing), de-watered by keeping in bamboo basket. These tuber shreds were dried under sun and in a hot-air oven (60 0 C, 70 0 C and 80 0 C). The samples were evaluated for micronutrients, non-nutrient but beneficial components as well as sensory quality attributes.Milk yam tuber powder prepared by three times washed peeled tuber shreds dewatered by keeping in bamboo basket and dried in hot-air oven at 60 0 C recorded optimum micronutrients, non-nutrient but beneficial components and sensory (overall visual quality -OVQ) quality attributes. Micronutrients composition include, calcium-3.40 mg/100g, iron-2.47 mg/100g, sodium-2.53 mg/100g, high vitamin A (613.33g/100g) and vitamin C (7.43 mg/100g). Non-nutritional but beneficial components viz., crude fibre-7.13 g/100g and total ash-3.56 g/100g. Mean rank value for the overall visual quality (OVQ) is 288.55. KEY WORDS : Beneficial components, Ksheervidari, Micronutrients, Nutraceutical, Overall visual qualityHow to cite this paper : Sonia, N.S., Jessykutty, P.C. and Sreekala, G.S. (2017). Effect of pre-treatments and drying methods on nutrient composition and sensory quality of milk yam (Ipomoea digitata L.) tuber powder.