Optimization Of Nutritional Yoghurt And Ice Cream Formula And Analysis Of Nutritional Components

With the continuous improvement of living standards, consumers demand for food is not only better taste and appearance, but also to have a certain nutrition and health functions, and so on. Based on the change of consumption concept, in the process of research and development of new type of ice cream products, "health" also become the mainstream. Studies have shown that yogurt has excellent health care function, and is rich in beneficial to human body to absorb nutrients, so the yogurt become one of the raw materials of ideal to develop new ice cream. Based on fermentation of yogurt, whole milk powder, sugar, butter, composite emulsifying stabilizer etc as the raw material, production of a new type of yoghurt ice cream, and through the in vitro antioxidant activity experiment of yogurt, yogurt ice cream compared with ordinary ice cream nutrition analysis experiment etc., nutrition health care function of yoghurt ice cream was studied and evaluation. The main results were as follows:1 The fermentation process optimization of yogurtFirst, we disscussed the factors influenced the yogurt’s fermentation by using single factor experiment, and obtained the optimized scope of fermentation conditions, then using the Box-Behnken experimental design, taking the yogurt’s total number of probiotics as response value by using the response surface analysis to obtain the optimize fermentation conditions. Finally, we obtained the optimum fermentation conditions:inoculation was 4.0%, fermentation temperature was 41.9℃, fermentation time was 4.5h, under these conditions, we obtained the good quality of yoghurt, and the probiotic number is 8.8×108cfu/mL.2 Study on antioxidant activity of yogurt in vitroBy using the method of the scavenging abilities of DPPH-free radical,O2- free radical, OH free radical, the anti-lipid peroxidation ability and reduction ability to evaluat biological activity of yogurt products in vitro under the optimal conditions, the results indicated that homemade yogurt had a good antioxidant capacity:DPPH-free radical clearance rate was 43.45%, O2- free radical clearance rate was 30.59%, OH free radical clearance rate was 40.95%, inhibition of lipid peroxidation was 15.63%, reduction ability was 0.867.3 Yogurt ice cream recipe optimization processOn the basis of the optimal fermentation conditions of yogurt, then added some certain antioxidant activity yogurt sample into the basic formula of ice cream. First, selecting the addition of yogurt, whole milk, white sugar and emulsion stabilizer as four factors of orthogonal experiment optimization with L9(34) table. By the analysis of range from the L9(34) table, we learned that affecting yogurt ice creamsensory score primary and secondary order was:the addition of whole milk>the addition of yogurt>the addition of white sugar>the addition of emulsion stabilizer, affecting yogurt ice cream total number of bacteria primary and secondary order was:the addition of yogurt>the addition of white sugar>the addition of emulsion stabilizer>the addition of whole milk. Comprehensive analysis of the various factors and the actual needs of production, and the best optimization was as follow:yogurt 30%, whole milk 12%, white sugar 12%, emulsion stabilizer 0.35%. Under the best optimization, the product sensory score was 84, number of living bacterium achieves 5.2×106cfu/g. And within three months, the total number of active probiotics of yoghurt ice cream is fully compliance with national standards.4 The analysis of nutritional components of yogurt ice creamAccording to the national standard method to analyze the basic nutritional components of homemade yogurt ice cream samples, the results indicated that:the content of crude fat was 12.37%, crude protein content was 3.97%, the moisture content is 56.7%. Further analysis on the nutritional components of yogurt ice cream by using the method of atomic absorption spectrophotometer and HPLC, the results indicated that:yogurt ice cream contains some physiological activity mineral elements, such as iron, calcium, magnesium, zinc, copper ect. And the content of iron was 0.277 mg/kg, calcium was 111.802 mg/kg, zinc was 0.488 mg/kg, magnesium was 12.750 mg/kg, copper was 0.065mg/kg. Amino acid analysis showed that, yogurt ice cream samples contained 17 kinds of amino acids, the essential amino acid content was high, and the highest content of leucine was 0.479g/100g, the lowest content of cystine was 0.017g/100 g. The essential amino acids accounted for 46.07% in total amino acids, the ratio of essential amino acid and nonessential amino was 85.41%,which was in accordance with the ideals of the FAO/WHO protein model. As reference to the FAO/WHO, the yogurt ice cream first limiting amino acid is methionine and cystine, the second limiting amino acid is threonine.