Kinetic modelling of the mass and heat transfer of a plant-based fishball alternative during deep-fat frying and air frying and the changes in physicochemical properties

The mass and heat transfer of a plant-based fishball alternative (PFB) and the changes in physicochemical at-tributes within frying were researched. The effective moisture diffusivity Deff and thermal diffusivity alpha of PFB in deep-fat frying (DF) were larger than in air frying (AF), where the Deff and alpha of DF-PFB were 2.95 x 10-8 and 7.56 x 10-6 m2/s, respectively, while those of AF-PFB were 2.34 x 10-8 and 6.89 x 10-6 m2/s, respectively, indicating a more effective moisture and heat transfer in DF. The oil uptake of DF-PFB was significantly higher than fishball (FB), with the equilibrium oil content Oeq of 0.120 and 0.039 g/g, respectively; AF would reduce the oil uptake of PFB considerably (0.067 g/g). PFB had a similar trend for texture and gel strength development to FB; the hardness, chewiness, resilience, and springiness during DF developed more rapidly than in AF. Besides, DF induced a larger Delta E (total color difference) than AF, where the surface Delta E of DF-PFB was 32.25, while that of AF-PFB was 26.74. Microstructural observations illustrated that DF-PFB formed a rougher structure than DF-FB, causing more oil absorption in PFB. These results could provide a fundamental understanding of transport phenomena and physicochemical attributes of PFB during frying, demonstrating that the AF could be an alter-native way to produce healthier PFB products with less oil absorption while having equal qualities.