Optimization of ratio of refrigerants for quick liquid freezing of aquatic product by response surface methodology

In order to develop a safe food-grade quick-freezing liquid formulation suitable for rapid freezing of aquatic products, we designed a low-temperature quick freezing liquid which composed of ethanol, oligofructose, citric acid, calcium chloride and propylene glycol. Then, we analyzed the variation of freezing point with different mass fractions of that composition by single factor test. Based on that, taking the freezing point and viscosity as response values, we optimized the addition amount of the refrigerants in the quick freezing liquid by Box-Behnken response surface method. The optimum formula of quick-freezing liquid was 19.9% ethanol, 9.5% fructooligosaccharide, 3% citric acid, 5% calcium chloride and 10% propylene glycol. The quick-freezing liquid prepared by the formula had a freezing point of –63.50 ℃ and a viscosity of 4.64 mPa·s, characterized by low freezing temperature, small viscosity, low formulation cost and convenient operation, suitable for rapid freezing of aquatic products and frozen convenience foods.