Effects of fish collagen peptides on physical properties of mixed gels containing konjac glucomannan and kappa-carrageenan

Abstract

Konjac (konnyaku in Japanese) gels in mini plastic cups are known to pose a choking hazard for children and elderly people, mainly due to the physical properties of the gels, including their tough, elastic texture. Addition of other hydrocolloids can modify the physical characteristics and decrease the rupture load of gels containing konjac glucomannan. The efects on the texture of gels containing konjac glucomannan and kappa-carrageenan (50 : 50) of various collagens with diferent molecular weights (porcine skin gelatin and collagen peptides from tilapia scales) and at different final concentrations were evaluated in terms of dynamic viscoelasticity, an extrusion test and a human mastication test using electromyography. The elastic modulus of the mixed gels decreased following the addition of collagen, regardless of the type. Gels containing 0.8% (w/w) gelatin melted at body temperature. Electromyography revealed that gels containing high-molecular weight collagen peptides (0.8%) exhibited significantly shorter mastication times and lower muscle activity, suggesting that these gels are easier to eat ; these gels were completely separated into two pieces in the extrusion test, whereas the other nine samples could only be partly masticated.