Developing Novel Combination Drying Method for Jackfruit Bulb Chips: Instant Controlled Pressure Drop (DIC)-Assisted Freeze Drying

Jackfruit chips are very popular in South Asia; however, the quality of traditional hot air-dried jackfruit chips is not desirable due to brown color and high hardness. The effects of three drying methods, instant controlled pressure drop-assisted freeze drying (FD-DIC), instant controlled pressure drop-assisted hot air drying (AD-DIC), and freeze drying (FD), on the physicochemical characteristics, color, antioxidant activity, expansion ratio, texture, rehydration, hygroscopicity, and microstructure of jackfruit (Artocarpus heterophyllus L.) chips were investigated. The FD-DIC-dried jackfruit chips showed the highest expansion ratio (119 %), the best color (△E, 6.5) and texture (hardness 42 N, crispness 19) compared with the FD- and AD-DIC-dried samples. A substantial increase in pore size was observed in the microstructure of the FD-DIC-dried chips. Compared with AD-DIC, the FD-DIC-finished jackfruit chips exhibited stronger antioxidant capacities (DPPH· free radical scavenging activity, ferric reducing power, and ABTS·+ radical cation scavenging activity) and higher retention of phenolics (1.2 mg GAE g−1) and carotenoids (3.1 μg CE g−1). In conclusion, the jackfruit chips produced by FD-DIC obtained a superior overall quality than the AD-DIC- and FD-dried samples. Considering the relatively high production cost of FD, this novel combination (FD-DIC) could be an alternative method for obtaining high-quality fruit chips or processing valuable agro-products.