| Summary: | 碩士 === 國立中興大學 === 食品科學系 === 91 === Pudding is one of the favorite and popular desserts in Taiwan. It is made up of egg, milk and sugar. Heat induced gelling properties of egg proteins constitute the texture of pudding. This study was to research into the effect of different whole egg concentrations and heating conditions (heating temperature and time) on the gelling properties and qualities of heat-induced whole egg gel. Besides, the effect of compositions of pudding on gelling properties was studied by different ratios of whole egg / milk and the model system of ovalbumin / casein combination. On the other hand, response surface methodology experiment design was used to determine optimum produce conditions for preparation of pudding. Results were as follows:
Whole egg (protein) concentrations and heating conditions were important factors that would influence the gelling properties and qualities of egg gel products (pudding). With whole egg concentration, heating temperature, and heating time increased, the gel strength and breaking force of whole egg gel increased (r2＞0.90). But high temperature and long time treatment might cause the protein excessinely denatured and make the syneresis of the gel occured. At the same time, it might led to a porous texture in the gel. With heating times increased, Hunter-L value of gel increased and both of a value and b value decreased.
Addition of milk to pudding could improve the water-holding capacity and increase the softness of pudding. In ovalbumin / casein model system, heating treatment increased the surface sulfhydryl group content and turbidity. It might improve the formation of double sulfide bond and increase the value of gel strength and breaking force of ovalbumin / casein gel. High temperature and long heating time treatment might cause the protein excessinely denatured and result in a pourous texture in the gel. On the aspect of microstructure of gel, with the adding ratio of casein and heating temperature increased, pores in the network structure of gel uniformly distributed and the texture of gel became more delicate. Therefore, addition of milk to pudding not only could improve the outer surface of pudding but also increase water-holding capacity.
Response surface methodology experiment design was applied to determine optimum production conditions for the preparation of pudding in this study. Results showed that the optimum produce conditions of pudding were whole egg concentration 40 %, milk 50 %, sugar 10 %, heating temperature 145℃, and heating time 40 min.
|
|---|
