Investigating the impact of cryogenic treatment on the functional, micromeritic, structural and rheological properties of fish gelatin

The current study aimed to explore how cryogenic treatment affects the physical and functional properties of fish gelatin (FG) and to compare it with bovine gelatin (BG) and porcine gelatin (PG). The scanning electron microscope (SEM) confirmed the formation of nanocavities at the particle surface of modified fish gelatin (FGM) with higher oil-holding capacity than native FG. FGM showed smaller particles and particle size distribution with a higher surface area. Similarly, enhanced foam-forming capacity was observed for FGM compared to FG, while PG possesses the highest foaming capacity. In terms of micromeritic properties, FGM showed lower bulk and tapped densities than FG and presented a greater Hausner’s ratio and compressibility index. The Fourier transform infrared (FTIR) analysis indicated a decrease in the hydroxyl group and a slight shift in the amide-III, along with an increase in β-turns and random coil type secondary structures. The cryotreatment improved the thermal stability of FGM, even better than the BG and PG. X-ray diffraction (XRD) showed no drastic variations in the FGM structure, and it remained amorphous in nature with physical aggregates. The FGM solution had a lower viscosity than the FG, while the PG exhibited the highest viscosity; however, all gels demonstrated elastic behavior (G’> G”). The FGM showed softer gels than the native counterpart and remained significantly lower than BG and PG. Thus, improved thermal stability, better foaming capacity and oil absorption capacity suggest augmentation in the physico-functional properties of FGM.