【作者】 宋贤聚；

【导师】 张慜；

【作者基本信息】 江南大学 ， 食品科学， 2008， 博士

【摘要】 马铃薯脆片因具有特殊的质构和香味而深受人们喜爱,但是,马铃薯脆片加工过程中存在产品含油率和表面带油量高的难题。本文采用真空微波干燥结合真空油炸的联合脱水、控油新方法,通过研究真空微波预干燥和后干燥规律、真空油炸脱水和吸油规律,优化低含油率马铃薯脆片的三阶段联合脱水的工艺并找出最佳转换点,揭示低含油率产品的阻油机理,获得了含油率低于20%(wb)而且具有令人满意的品质的低含油率马铃薯脆片。为降低油炸产品的脂肪含量和改善其品质,采用了真空微波预干燥和真空微波后干燥工艺,研究了真空微波预干燥和真空微波后干燥工艺对马铃薯脆片品质的影响,得出真空微波预干燥和真空微波后干燥工艺对产品含油率的影响规律。在此基础上,为更好预测产品在真空微波干燥过程的水分含量,对马铃薯片在真空微波预干燥和后干燥条件下的干燥特性进行研究,并采用非线性回归及多元线性回归等数理统计方法对其干燥曲线进行数学模拟,得出了真空微波预干燥和后干燥规律的脱水规律,建立了马铃薯片的真空微波预干燥传质方程,并得出了带油马铃薯脆片真空微波后干燥过程中油脂和水分联合脱出的动力学模型及其模型参数。为了了解真空油炸脱水和吸油规律,本论文较系统地研究了真空油炸工艺对马铃薯脆片品质的影响规律,以及传热传质模型。运用一级动力学模型研究油炸过程中马铃薯片水分与脂肪含量的变化,得出了水分、脂肪含量及其干燥速率的经验方程;根据一维热量传递模型,通过对样品表面温度和质量的测定,确定了真空油炸过程中的对流传热系数。通过一级反应动力学结合系列经验模型分析了真空油炸过程中水分与脂肪含量随油炸参数及初始含水率的变化规律,确定了模型系数。为得到低含油率并具有令人满意的品质的马铃薯脆片,采用真空微波-真空油炸-真空微波三阶段联合脱水工艺。对三阶段联合脱水工艺进行优化,得出三阶段联合脱水工艺的最佳转换点。通过对真空油炸过程中吸油高峰的分析和马铃薯片微观结构的观察,探讨了真空微波预干燥降低马铃薯脆片含油率的机理。更多还原

【Abstract】 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.更多还原