Effects of thermal pretreatment and puffing medium variously modify the microstructure and quality of crisps obtained from two banana varieties

Abstract

Fat-free crisp food products are garnering more attention from modern consumers. Hot air combined explosion puffing is one processing method that can produce a crisp food snack. Therefore, the influences of thermal pretreatment, banana variety, puffing medium, and puffing temperature upon the microstructural changes, drying time, specific energy consumption (SEC), and banana crisp qualities were studied. The banana slices, Namwa (NW) and Homtong (HT) varieties, were blanched with hot water (HW) then hot air-dried at 90 °C and combined with explosion puffing with either superheated steam (SS-puffing) or hot air (HA-puffing) from 170 to 190 °C for 2 min. The experimental results showed a stronger cellular structure and lower enzymatic activities for NW samples compared to the HT samples. This led to a harder texture, longer total drying time, and less browning for NW crisps. The cellular structure of HT was more disrupted than NW after HW pretreatment. Such modified structure characteristics caused a decrease in volume ratio and lower crispiness for HT products, whereas the NW crisp had increasing volume ratio and higher crispiness relative to the non-blanched crisps. Even though the blanching pretreatments retarded browning and improved color uniformity for both banana varieties, the process increased the total drying time and the SEC values of the drying process. By applying SS-puffing and raising the puffing temperature of blanched NW samples, higher puffed volume and crispier texture products were obtained. Additionally, the total drying time and the SEC value were also reduced. The SS-puffing also led to browner products for both NW and HT samples. Finally, the overall preference score was markedly higher for blanched NW crisp compared to blanched HT crisp; however, neither score exceeded that of commercial products.