Using Fish Skin Gelatin Hydrolysate as Stabilizer and/or Emulsifier Agent in Ice Cream Production and Melting, Textural, Rheological, and Sensory Characteristics

The increasing global interest in fish consumption leads to a greater generation of fish waste. Fish waste, rich in nutrients such as protein, bioactive compounds, and vitamins, is attracting growing attention for its potential applications in food. In this study, gelatin hydrolysate obtained from fish skin waste was utilized as a stabilizer and/or emulsifier in ice cream production. It was found that gelatin hydrolysate significantly increased the protein content of the ice cream samples. The <i>K</i> and <i>n</i> values in different ice cream compositions varied between 0.009 and 1.012 Pa.s^<i>n</i> and 0.356 and 0.863, respectively. The consistency coefficients of samples D1 (sahlep and mono-diglyceride) and D3 (sahlep and gelatin hydrolysate) were almost the same, indicating that the mono-diglyceride was replaced by an equivalent amount of gelatin hydrolysate. All the ice cream mixtures tested showed non-Newtonian, pseudoplastic flow, as indicated by their <i>n</i> values being less than 1. All mixtures demonstrated greater elasticity than viscosity, as their storage modulus (<i>G</i>') was higher than their loss modulus (<i>G</i>″). In the third interval of 3-ITT, all ice cream mixtures displayed thixotropic behavior, indicating that their viscoelastic properties could be restored after a sudden deformation. The overrun levels of the samples ranged from 9.55% to 21.74%; the use of gelatin hydrolysate resulted in a statistically significant increase (<i>p</i> < 0.05). The highest hardness and stickiness values in the samples were determined in the specific sample containing equal amounts of emulsifier, stabilizer, and gelatin hydrolysate. Furthermore, gelatin hydrolysate prolonged the first dripping time and melting rate of the samples.