Abstract: In order to improve the quality of compound gel as a fat substitute, the formula parameters affecting the quality of compound gel were optimized by Plackett-Burman test and steepest climbing test combined with Box-Behnken response surface method. Firstly, eight factors affecting the quality of compound gel were evaluated by Plackett-Burman test design, and four factors with significant effect were selected: the addition of carrageenan, whey protein, water and sodium carbonate, and then the maximum response area was approximated by the steepest climbing test. Finally, the response surface method was used to determine the quality ratio of each influencing factor in the best formula, Carrageenan: Whey protein: Water: Sodium carbonate: Konjac powder: Gelatin: Soybean protein isolate: vegetable oil =1.19:1:254.52:2:6:1.5:1:18.4. The hardness of compound gel was 6.96N, the sensory elasticity was 49.41%, the chewing sex was 4.14mJ, the whiteness value was 49.44, the shrinkage rate was 48.33%, the weightlessness rate was 45.77%, and the relative error was 0.85~1.7%, which was close to the predicted value.The results show that the formula parameters of compound gel can be optimized well by the Plackett-Burman test and the steepest climbing test combined with the response surface method, and the prepared compound gel can simulate the animal fat in Chinese sausage better.

Key words: Fat substitutes, Plackett-Burman design, formula optimization, response surface method