Process Study And Quality Control For Low Temperature Vacuum Fried Potato Chips

In recent years,people have drawn more attention to the vacuum frying technology featured the excellent qualities and extensive adaptability to material. The chips made of vacuum fried vegetables and fruits were developed rapidly because of their natural color,crispness and crude components. However, because of the complexity at vacuum frying mechanism,its developments mainly rely on practice time after time,thus there are some defects in higher fat content and poorer qualities. The objective of this paper was to study the role of water dryness, characteristics effect and quality change, investigate its storage stability and isothermal moisture absorption law.In order to improve its quality and the drying rate, the effects of pre-treatment methods such as blanching, soaking, freezing on quality were studied based on the determination of the optimum solution. The result show that the drying rate and quality of sweet potato have relation to pre-treatment methods, the network structure, the size and distribution of void left by moisture evaporation.To effects of parameters of frying and defattng on fat content and quality of sweet potato were studied in this paper. A three-factor five-level Response Surface Methodology(RSM)based on the single-factor experiment, was chosen to evaluate independent variables affecting the moisture, fat content and breaking force. The independent variables selected for this study were frying temperature, vacuum degree and frying time. The results showed the optimum frying conditions were:vacuum frying temperature of 95℃, vacuum degree of 0.090MPa, and frying time of 9min; Whereas the optimum defatting conditions were:vacuum degree of 0.090MPa, rotation speed of 400r/min, defatting time of 7min, and skim the defatting rate was related to the frying time.Aim at to resolve the procreative technical problem of high fat content of fruits and vegetables crisps at home and abroad, In this paper, water mass transfer was quantitatively investigated during dehydration of potato over a range of concentration and temperate of osmotic solution. Effective diffusion coefficients of water were estimated using the solution of Fick unstable state second law. The diffusion coefficients of water has been correlated with the concentration and temperature of the osmotic solution in addition to a parameter indicating the interaction between these two variables by an equation similar to that of Arrhenius relational expression,as well as the models of water and fat content..The changes of potato chip's quality at different storage conditions during 6 months were investigated, and included water content, fat content, texture value, vitamin C. Comparison with six models commonly used about absorption isotherm, the data of water sorption isotherm at three temperatures were studied. Sorption characteristics based on the GAB model were analyzed and the monolayer moisture content,△HC and△HK were determined.