Effect of preparation, freezing and thawing methods on total phenolic and vitamin c content, antioxidant activity, texture and minerals of pepper (Capsicum annuum)

Regarding to the necessity of vegetable consumption, it is necessary to examine the extent to which the nutrient content of vegetables changes during different processes. In this study the effect of various procedures; washing, blanching and six-month storage was evaluated on total phenolic, vitamin C, ash and mineral content and antioxidant activity. Two methods using boiled water or steam for blanching and domestic and semi-industrial for freezing were applied. The results showed that washing did not have any significant effect on vitamin C and total phenolic content, antioxidant activity and firmness in pepper while blanching caused a considerable reduction in these parameters as vitamin C reduced from 1498.6 in fresh pepper to 1025.4 in the samples blanched by boiled water and 392.2 mg/ 100 g db in pepper blanched by steam. Antioxidant activity also reduced from 70.5% in fresh pepper to 58.6% and 57.1% in the samples blanched by boiled water and steam, respectively. The findings revealed that washing and the type of freezing did not have any significant effect on amount of vitamin C, phenolic compounds, antioxidant activity and stiffness whereas blanching showed a significant effect.