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Antioxidant activities of different vegetables Bitter gourd, Tomato and Spinach (Momordica charantia, Lycopersicon esculentum, Spinacia oleracea) were determined. In addition, rapid visual estimation of tannin content, total phenolic, tested for their free radical scavenging activity (FRSA) in the DPPH (1, 1-dephenyl-2-picrylhydrazil radical) of those samples were assessed. A new technique was used to quickly distinguish between intermediate, moderately high and high tannin content by the development of shades of purple, light blue and deep blue colors (Bitter gourd, Tomato and Spinach) respectively. The total phenolics in methanol solution for all the samples were analyzed with slightly higher value for spinach paste. The % of condensed tannin of all the three vegetables were low as determined by the Vanillin-HCl method respectively. The antioxidant activity with DPPH-method expressed as per percent inhibition of oxidation ranged from a high of 88% in bitter gourd extract to near about 70% in tomato and spinach respectively. The studies can be further extended to exploit their possible application for the preservation of food products as well as health supplements and neutraceuticals.

Purified tannin from sorghum grain (NK 300) was provided by Dr. Haslam. Tannin from a high-tannin sorghum grain (BR 54) was purified by our standard technique (Hagerman and Butler, 1980) by A. Hagerman. Samples to be used for determining extinction coefficients were dried overnight over P205 at room temperature.Assays. Vanillin assays in methanol were carried out as recommended by Price et al. (1978), in a 30 °C water bath with a reaction time of 20 min. The vanillin reagent contained 4% concentrated HC1 and 0.5% vanillin in methanol. Absorbance was read in a Zeiss PMQ-II spectrophotometer, at 500 nm, the wavelength of maximum

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Treatment of high-tannin sorghum grain with moist, alkaline conditions was shown to substantially reduce the amount of tannin as measured by three chemical assays. Chicks fed a high-tannin grain (Savannah III), treated as the whole grain with dilute ammonium hydroxide for 30 days, showed 3-week weight gains and feed efficiencies which were statistically equivalent to those of chicks fed an untreated low-tannin control (RS-610). A shorter treatment of a ground high-tannin grain (BR-54) with a 0.5 M aqueous solution of K2C03 resulted in a comparable improvement in weight gains and a substantial improvement in feed efficiencies. Treatment of the same grain with moisture and CaO gave an improvement of a lesser magnitude. Increases in available protein after treatments did not appear sufficient to account for the nutritional improvements.