The impact of sugar alcohols and sucrose on the physical properties, long-term storage stability, and processability of fish gelatin gels

Fish gelatin is becoming a popular alternative to mammalian gelatins due to religious restrictions, cultural preferences, ecological, and ethical concerns. Warm water fish gelatins (WWFG), as opposed to gelatins from cold water fish species, have more similar physical properties, and hence represent an alternative, to mammalian gelatins albeit a lower sol/gel transition temperature and gel strength. In warm climates, WWFG gels may therefore exhibit reduced storage stability at temperatures above this transition temperature because of e.g., a more pronounced acid hydrolysis of the sol fraction. To improve the long-term storage stability of WWFG, gels were prepared with two different sugar alcohols, sorbitol and xylitol, and a non-reducing sugar, sucrose. The change in the sol/gel transition temperature, gelling and melting kinetics, and gel strength of the gels were analyzed using small amplitude oscillatory shear measurements. Short-term and long-term storage stability tests at ambient temperature, 30 °C and 40 °C indicated improved stability of gels with co-solutes without significant differences between the type of sugar alcohol or sucrose. The stability of the gels increased with increasing concentrations of sugar alcohols. The degree of hydrolysis of the gelatin in the gels were investigated using SEC-MALS analyses which supported the bulk rheology stability results. Using sucrose led to browning and high viscosity, which may pose challenges regarding the processability and industrial applications.