Effect Of Processing Technology And Formula Composition On Quality Of The Neutral Dairy Desserts

The effects of preparation technology, carrageenan, KCl, konjac gum, gelatin, locust bean gum and xanthan gum on the texture characteristics, including hardness, elasticity, par-ticle size(d4,3,d3,2), bleeding capacity and taste of dairy desserts had been investigated. Main influencing factors on the hardness of dairy desserts were analyzed. The relation between hy-drocolloids and flocculation were established. Mechanisms of phosphates affecting emulsions flocculation and stability were discussed.The preparation process of dairy desserts was optimized by orthogonal experimental de-sign. And the assessment criterion were hardness, elasticity and d4,3. Results showed that the optimum technical conditions were as follows: homogenization temperature and pressure was 75℃and 30MPa respectively; hydrating temperature and time was 75℃and 15 min inde-pendently. The results showed that the most effective factor of size distribution was homoge-nization pressure. However, hydrating time was the main element influenced hardness and elasticity. Furthermore, the influences of homogenization and sterilization on texture and flocculation were studied. When the homogenization pressure increased, the particle size de-creased accordingly and the taste turned better. The 121℃/15min treatment reduced hardness, elasticity and taste feeling compared with 100℃/30min and 137℃/5s. Considering efficiency and economic effectiveness, 137℃/5s sterilization had been chosen.The carrageenan and KCl had significantly effects on hardness, elasticity and d4,3. The hardness of dairy desserts increased with the amount of carrageenan and KCl. When the con-centration of carrageenan was 0.05% and 0.1%, the gel structure was poor and the hardness was low. When the carrageenan quantity was higher than 0.15%, the gel structure was fine and the hardness was high. But the system began to flocculate according to particle size and microstructure. KCl could promote gel formation and increased syneresis rate, but high con-centration of carrageenan would result in flocculation, especially when the carrageenan was also high. Overall, the dairy desserts had good quality when carrageenan was 0.15% and KCl was 0.01%. Konjac gum, gelatin, locust bean gum and xanthan gum had influence on the quality of dairy desserts. The hardness of dairy desserts increased with the amount of konjac gum, but high concentration of konjac gum was not favorable for system flocculation stability. We im-proved sensory quality and bleeding capacity by adding gelatin. When the concentration of gelatin was 0.1%, the particle size(d4,3) was big, which indicated flocculation. The low con-centration of locust bean gum and xanthan gum could improve taste and bleeding capacity, while high concentration would lead to flocculation.Phosphates were very important for the quality of dairy desserts, especially for particle size and stability. The addition of phosphates could not only increase the stability of milk protein and restrain flocculation, but also improve the taste and quality of water retention. So-dium Tripolyphosphate and Sodium Hexameta- phosphate had preferable effects. Dairy des-serts had good texture characteristic and sensory quality when Sodium Tripolyphosphate and Sodium Hexametaphosphate were 0.01% respectively.