Influence of drying techniques on the properties of gelatin derived from Atlantic salmon skin

The properties of gelatin derived from fish processing by-products, such as Atlantic salmon (Salmo salar) skin, are strongly influenced by the drying method used during production. This study investigated the impacts of four drying methods on the extraction yield, physicochemical attributes, and gel characteristics of gelatin: freeze-dried gelatin (FDG), spray-dried gelatin (SDG), vacuum-dried gelatin (VDG), and hot air-dried gelatin (HDG) extracted from Atlantic salmon (Salmo salar) skin. The yields of FDG, VDG, and HDG were similar (15.75-16.45 g/100 g; p > 0.05), and significantly higher than that of SDG at 13.23 g/100 g (p < 0.05). Proximate analysis revealed that protein was the predominant component (94.60-95.03 g/100 g), with low fat (2.35-2.78 g/100 g) and ash (2.24-2.47 g/100 g) contents. SDG had the greatest lightness, followed by FDG, VDG, and HDG (p < 0.05), while HDG and VDG displayed more brownish, yellowish, and reddish colors. FDG exhibited the highest gel strength and viscosity, comparable to SDG (p > 0.05), while HDG had the lowest (p < 0.05). VDG showed the lowest turbidity, followed by FDG, HDG, and SDG (p < 0.05). All samples exhibited predominant α- and β-chains. FTIR spectra revealed similar patterns across all samples, with major peaks in the amide region. Overall, spray drying demonstrated strong potential as a practical and scalable alternative to freeze drying for gelatin production, offering high whiteness, desirable gel strength, and favorable viscosity while supporting sustainable applications in food and industrial sectors.