Study Of Whole Soymilk Applied In Ice Cream

Conventionally ice cream is a frozen product which attracts the world’s interests for its high nutrition, delicate taste and changeful flavor. However, the increasing cost of milk powder, the high calorie and the less functional components, which run counter to people’s pursuit for healthy, are the major problems of traditional ice cream. Therefore, there’s an urgent requirement to develop a fat-reduced ice cream with low cost, less calorie and comprehensive nutrition to provide more choices for the market. Soybean has been recommended for dietary supplement and protein fortification in many food products for its low cost. Researches demonstrated that the properties of ice cream could be significantly influenced by the components of soybean. Dual-protein, a combination of soybean protein and milk protein, improves nutrition, mouthfeeling and other properties of dairy products. This paper studied the substitution of milk powder with whole soymilk and evaluated the effect of soybean ingredients on ice cream.Manufacturing technique of the whole soymilk was chosen according to the particle size of the whole soymilk, the energy consumption of the equipment, and the physicochemical properties of ice cream, including the viscosity, overrun, melting rate and hardness. The best quality was obtained when 10 times water were added into the soybean and then ground at 75~85℃ for 30 min. The slurry was then processed with colloid mill for 20 times. As a result, the average particle diameter was 102.4 μm and the viscosity was 380 m Pa·s with a smooth taste.In order to ascertain appropriate time of storage to ensure the quality of whole soymilk, the relative enzyme activity of lipoxidase and the relative content of volatile flavor compounds were studied. At 4℃, the enzyme activity of lipoxidase showed no significant change and the inactivation was irreversible. Compounds such as hexanal, heptanal, 2-pentylfuran, hexanol, acetic acid were described as causing unpleasant flavor of soymilk. The total content decreased from 34.52% to 31.95% between days 0 and 3 while increased at day 6 and day 9. Nonanal, octanol, trans-octenal and so on could possess an agreeable odor and their total content decreased from 12.26% to 2.17%. Thus the most suitable storage time of whole soymilk was less than 3 d at 4℃.The main components and the physicochemical properties of whole soybean were analyzed using milk powder and soybean without bean dregs as control. The content of protein(35.56%) and dietary fiber(16.18%) of whole soybean were the highest. The soluble protein concentration of whole soymilk was 14.13 mg/m L and the viscosity was 32.48 m Pa·s, which were the highest among the three materials. In addition, the emulsion stability and foaming stability of whole soymilk were both the best, which were 272.20 min and 71.12% respectively.Sensory evaluation and physical properties, including viscosity, overrun, melting rate and hardness of the ice cream were studied to ascertain the formula. The most appropriate ratio of whole soybean substitution was 30%. Palm oil content could be reduced from 8% in traditional ice cream to 4%. Emulsifier and stabilizer content were 0.15% and 0.4% respectively.The effects of soybean protein, dietary fiber and fat on the properties of ice cream were studied respectively. The results showed that the product could obtain an overrun above 60% when the protein-fiber ratio in whole soybean was 1.50~1.65.The nutrient composition, rheological behavior, thermal properties and microstructure of the fat-reduced ice cream with 30% whole soybean substitution were studied, using the traditional fat-reduced ice cream and the fat-reduced ice cream with 30% soybean substitution without bean dregs as control. The content of dietary fiber in the ice cream with whole soybean was higher, thus the product was healthier. Rheological behavior illustrated that whole soymilk ice cream showed a more viscous and stable slurry with stronger pseudoplastic behavior. Results of the thermal characteristics analysis showed that whole soybean enhanced the thermodynamic stability of the ice cream and could be used as an ice cream stabilizer replacer to improve the T’g. The microstructure showed that air bubbles dispersed better in whole soymilk ice cream which was helpful to the sensory evaluation and storage. The cost of the ice cream with whole soymilk reduced 20.09% compared to the ice cream with milk powder.