Peroxide and acid values of cake samples during storage
The changes in peroxide value (PV) and acid value (AV) of lipid extracted from cake made from substituted flour with watermelon rind and sharlyn melon peel powders during storage are given in Fig. 1 and Fig. 2. An increase in PV and AV were observed in all the cake samples on storage. The increases were considerably higher in control cake sample compared to other samples in which synthetic BHA or natural antioxidants were incorporated. A gradual increase (up to 1.62) were observed indicating the potency of antioxidant of watermelon rinds and sharlyn melon peels in inhibiting lipids oxidation and hydrolysis and the formation of peroxides and free fatty acid. In general, all the used substitution level slowed down the rate of peroxide formation and fatty acid being more effective. All samples and contained BHA were lower than that of control samples during storage. The PV and AV of lipids extracted from the control cake sample after baking did not differ considerably from the corresponding value of other samples. The PV and AV of all the treated cake samples decreased as the level of watermelon rind and sharlyn melon peel powders increased. These results are in agreement with those of Vanitha et al. (2005).