Abstract
The main objective of this study was to evaluate the effect of two different drying methods on physicochemical characteristics and antioxidant activity of different Brassica spp. cultivars in order to produce a dietary flour. Fresh cabbages were subjected to two drying methods: convective air-drying (80 °C, during 2h with the previous blanching) and freeze-drying. An increase in crude protein, carbohydrates and fibre was observed. Regarding protein and fibre content, there is a tendency to be higher with convective air-drying method. There were significant changes in all analysed colour parameters of dried samples. “Coração de Boi” flours, obtained with both drying methods, revealed the lowest differences compared to a fresh sample. Results from both drying methods showed the positive effect that dehydration had on antioxidant activity. Flours produced with convective air-drying with previous blanching, resulted in a decrease of EC50 values (EC50= 0.74 - 1.64 mg/mL). Although, the values of EC50 were still lower in the case of lyophilized samples and the lowest values were found for “Penca da Póvoa” and “Galega” flours (EC50= 0.47 - 0.48 mg/mL). From these results, it was concluded that both drying processes have advantages on physicochemical characteristics and antioxidant activity of the products. Brassica flours, from both drying methods, presented an antioxidant potential and therefore may constitute an important natural source of antioxidants to be applied to different food matrices, especially flours of “Galega” and “Penca da Póvoa”, from freeze-drying method, which showed the lowest EC50 values.
