Effects of sugars on the gelation kinetics and texture of duck feet gelatin

Gelatin extracted from avian sources, such as duck feet is a potential alternative to mammalian-derived gelatin. The effects of sugars (sucrose and lactose) at different concentrations (0, 5, 10, 20 and 40%) on the gelation kinetics, and thermal and rheological properties of duck feet gelatin (DFG) (6.67% w/w) were investigated using a mechanical rheometer. The secondary structure of the gelatin was investigated using Fourier transform infrared (FTIR) spectroscopy. The results showed that the addition of sugars affected the physicochemical and structural properties of the gelatin. The gelation rate constant (k(gel)) and gel strength decreased with increasing amounts of sugars at low concentration (i.e., 5-20% for sucrose and 5-10% for lactose). These data suggest that the addition of sugars at these concentrations prevented gelatin chains from approaching each other kinetically during gelation. However, the kgel and gel strength increased upon further addition of sugars, likely due to the formation of additional small junction zones that led to development of a more rigid gel. Additionally, gelling and melting temperatures increased as the concentration of added sugars increased. Sucrose had more pronounced effects than lactose, probably because of its greater solubility and number of e-OH groups. These results illustrate the potential for use of DFG in confectionery products. (C) 2016 Published by Elsevier Ltd.