Effects of extrusion temperature and puffing technique on physical and functional properties of purpled third-generation snack after heat treatment.

This work aimed to investigate the effects of extrusion temperature (100 105 and 110 °C) and puffing technique (microwaving (210, 420 and 560 W.) and deep frying (170 and 190 °C)) on physical and functional properties of third-generation snack containing purple sweet potato and butterfly pea flower. Snack qualities in terms of physical properties (expansion ratio, bulk density, color and texture) and functional properties (total anthocyanin content, total phenolic content and antioxidant capacity) were subsequently determined. The results showed that extrusion temperature did not significantly affect the color of snack pellets. However, it significantly affected the functional properties of the snack pellets. Snack pellet produced from extruder at 110 °C contained significantly higher functional properties when compared to those extruded at 100 and 105 °C (p < 0.05). In addition, the study of the puffing method indicated that an increase of microwave power level and frying temperature resulted in a decrease of hardness. On the other hand, the increase of microwave power level and frying temperature caused an increase of antioxidant capacity in the puffed snacks. Moreover, microwave puffing could help preserve the color and antioxidant capacity better than deep frying. Especially, microwaved snack had total anthocyanin content twice more than that puffed by frying. Supplementary Information: The online version contains supplementary material available at 10.1007/s13197-021-05234-x. © Association of Food Scientists & Technologists (India) 2021.