Effects of hydrocolloids, acids and nutrients on gelatin network in gummies

Gelatin is a commonly used gelling agent in many confectionery gel (CG) products such as gummy candies. The rheological behaviors of gelatin in gummy products are still poorly understood. The objective of this study was to investigate how gummy formulation affects rheological behaviors of the gelatin network in both linear and nonlinear viscoelastic regions. The effects of °Brix, acids, hydrocolloids, and nutrients on gelatin gelation in gummies were investigated using both small amplitude oscillatory shear (SAOS) tests and large amplitude oscillatory shear (LAOS) tests. °Brix appeared not to impact the gelling temperature of the gelatin gummy until it reached 80 or higher when the gelling temperature decreased probably due to the extrusion of sugar from the gelatin network. Both citric acid and malic acid weakened the gelatin gummy network due to their restrictive effect on the formation of hydrogen bonds. Incorporating hydrocolloids, such as pectin and agar-agar, into the gelatin gummy showed synergistic effect on the gel network due to the nature of hydrocolloids and the ratio to gelatin in the formulation. Incorporating inulin into gelatin gummy enhanced the gel network through hydrogen bonding between inulin and gelatin. As indicated by the frequency sweep tests, incorporating whey protein isolate caused a whey protein dominated bi-continuous gel network which was enhanced by the presence of gelatin. Large deformation rheological tests showed that the gelatin gummy with 81 °Brix had greater nonlinear behaviors under large shear strains, whereas gelatin gummy with 78 °Brix was more resistant to the large deformation. These gelation and stability differences of gelatin gummy network can contribute to the differences in texture and stability of gummies during processing and storage.