Mst. Sorifa Akter

Impact of α-amylase and maltodextrin on physicochemical, functional and antioxidant capacity of spray-dried purple sweet potato flour

BACKGROUND Purple sweet potato flour could be used to enhance food products through colour, flavour and nutrients. Purple sweet potato flour has not yet been prepared with maltodextrin and amylase treatment using spray drying. Thus, the investigation was to evaluate the effect of various levels of maltodextrin (30 and 50 g kg(-1) w/v), amylase (3 and 7 g kg(-1) puree) and combined with maltodextrin and amylase on the physicochemical, functional and antioxidant capacity of spray dried purple sweet potato flours. RESULTS Amylase and amylase with maltodextrin-treated flours had a higher anthocyanin and total phenolic content than the control and maltodextrin-treated flours. However, the antioxidant capacity was higher in the control and maltodextrin-treated flours compared to the amylase and amylase with maltodextrin-treated flours. The control had a higher water absorption index and lower water solubility index compared to the maltodextrin and combined with amylase and maltodextrin-treated flours. On the other hand, maltodextrin increased whereas alpha-amylase decreased the glass transition temperature. With respect to morphology, the particles of amylase-treated flours were smaller than the control and maltodextrin-treated flours. CONCLUSION The results showed that good quality flour could be prepared by combining 30 g kg(-1) maltodextrin and 7 g kg(-1) amylase treatment.

Optimization conditions for anthocyanin and phenolic content extraction form purple sweet potato using response surface methodology

Purple sweet potato flour could be used to enhance the bioactive components such as phenolic compounds and anthocyanin content that might be used as nutraceutical ingredients for formulated foods. Optimization of anthocyanin and phenolic contents of purple sweet potato were investigated using response surface methodology. A face-centered cube design was used to investigate the effects of three independent variables: namely, drying temperature 55–65°C, citric acid concentration 1–3% w/v and soaking time 1–3 min. The optimal conditions for anthocyanin and phenolic contents were 62.91°C, 1.38%, 2.53 min and 60.94°C, 1.04% and 2.24 min, respectively. However, optimal conditions of anthocyanin content were not apparent. The experimental value of anthocyanin content was 19.78 mg/100 g and total phenolic content was 61.55 mg/g. These data showed that the experimental responses were reasonably close to the predicted responses. Therefore, the results showed that treated flours could be used to enhance the antioxidant activities of functional foods.

Effect of blanching and drying temperatures on the physicochemical characteristics, dietary fiber composition and antioxidant-related parameters of dried persimmons peel powder.

The effects of blanching with hot water at 90°C for 2 min and hot-air drying temperatures (50°C, 60°C and 70°C) on the physicochemical properties, dietary fiber compositions, antioxidant activity and hydration properties of ripe, soft persimmon peels were investigated. Blanching and drying significantly reduced the retention of antioxidant-related parameters. Although there were no significant differences in total phenolics and β-carotene content at different drying temperatures for both dried unblanched and blanched peels, dried blanched peels had higher dietary fiber compositions and swelling capacity than those of dried unblanched peels at all drying conditions. In addition, blanched peels dried at 50°C had the highest dietary fiber compositions, swelling capacity and antioxidant activity compared with those at high drying temperatures (60°C and 70°C). Therefore, blanched peels dried at 50°C is suggested to obtain better quality dietary fiber powder from persimmon peel for use in food applications or in fiber-fortified foods for health promotion.