Studies On The Process Of Low Oil Content Potato Chips

Potato chips have the unique texture-flavor combination that makes them so desirable. However, there are existing problems during manufacturing procedure, such as high oil content and oil on surface. In this study, a new method of vacuum microwave drying (VMD) and vacuum frying combination was used to control dehydration and oil absorption. Lower oil content (below 20% wb) potato chips were obtained by studying the characteristics of VMD, investigating the law of dehydration and oil absorption during vacuum frying, optimizing VMD-Vacuum frying-VMD combination conditions and finding out optimum transition points of VMD-Vacuum frying-VMD combination, revealing mechanism of reducing oil absorption during vacuum frying.In order to reduce the fat content of potato chips and improve the quality of potato chips, vacuum microwave pre-drying and post-drying were employed .The effects of vacuum microwave pre-drying and post-drying on the quality of potato chips were investigated systemically, and the law of affecting oil content by vacuum microwave pre-drying and post-drying was obtained. Furthermore, in order to predict the moisture content accurately during VMD, The characteristics of vacuum microwave pre-drying and post-drying was investigated. Nonlinear regression and multiple linear regression procedures were used to estimate the parameters associated with the drying kinetics models, from which a semi-empirical mathematical model was developed for predicting the thin layer vacuum microwave drying kinetics of potato chips during vacuum microwave pre-drying. A semi-empirical mathematical model was proposed for describing the emersion of moisture and oil combination during vacuum microwave post-drying, and empirical models were also developed for estimating the rate constants as a function of the microwave power and vacuum level.For the purpose of revealing the law of dehydration and oil absorption, the influence of vacuum frying on the quality of potato chips were investigated systemically, and the heat and mass transfer of potato chips during vacuum frying was studied. The foundational characteristics were also studies during vacuum frying, including a first order kinetic equation was used to analyze the moisture and fat content and found the empirical equation of moisture, fat content and drying rate as a function of frying time. A one-dimensional heat transfer model was developed to obtain the convective heat transfer coefficient during vacuum frying. A first order kinetic equation combined with series of empirical models was used to predict the moisture and fat content as a function of initial moisture content, frying temperature and vacuum level.In order to obtain lower oil content products that still retain the desirable texture and flavor, VMD-vacuum frying-VMD combination process was employed. The optimum transition points of three stages combination process were obtained by optimizing the process conditions. For discuss the mechanism of reducing oil absorption by vacuum microwave pre-drying, the high-speed oil absorption period was analyzed and the micro-structure was studied using lights and scanning electron microscopy. The results showed that the vacuum microwave pre-drying lower the high-speed oil absorption period and porosity, which probable reducing the oil absorption during vacuum frying.