【作者】 夏远景；

【导师】 李志义；

【作者基本信息】 大连理工大学 ， 化工过程机械， 2012， 博士

【摘要】 近年来,随着消费者对食品品质和安全性要求的日益提高,超高压技术作为一种新的食品非热加工技术引起人们的广泛关注。该技术克服了传统食品热处理破坏食品营养成分和天然风味等缺点,在食品处理,尤其是对风味要求较高的果汁和水产品的处理方面具有广阔的应用前景。为了更好地丰富和完善超高压食品处理工艺基础,为该过程的设计计算和工艺优化提供方法和依据,推进该工艺的工业化应用进程,本论文选择果汁(苹果汁/橙汁)和水产品(牡蛎/海参)为研究对象,研究超高压处理参数对食品微生物、酶和食品品质的影响规律；以大豆蛋白、牡蛎蛋白和海参蛋白为研究对象,研究超高压处理对蛋白质结构和溶液性质的影响规律；以小麦淀粉、玉米淀粉、马铃薯淀粉、红薯淀粉为研究对象,研究超高压对淀粉结构和溶液性能参数的影响规律。本论文的主要研究工作及所形成的主要结果与结论如下：以果汁和水产品中菌落总数为研究对象,通过实验研究了处理压力、保压时间、处理温度等操作参数对食品微生物的影响规律,结果表明：随处理压力、保压时间和处理温度的升高,食品中微生物灭活率增加、繁殖能力降低。压力协同温度处理可取得更好的灭菌效果。通过实验研究了处理压力、保压时间、处理温度等操作参数对果汁中多酚氧化酶/过氧化物酶和海参自溶酶活性的影响规律,结果表明：压力和温度对酶的影响均具有双重性,某一压力和温度范围内,酶活性增强,另一压力和温度范围内,酶活性降低。保压时间对酶活性的影响则以压力和温度的影响为基础,在酶活性增强的压力温度范围内,延长保压时间酶活性上升,反之,随保压时间延长酶活性降低。通过实验研究了大豆、海参和牡蛎蛋白质溶液的溶解度、粘度、乳化特性随处理压力的变化规律；通过测定蛋白质溶液的DSC曲线,确定蛋白质在压力作用下的变性程度；通过SDS聚丙烯酰胺凝胶电泳观察蛋白质亚基的变化情况,分析超高压处理对蛋白质四级结构的影响；通过测定巯基含量判断蛋白质三级结构的变化情况；通过红外图谱观察蛋白质二级结构的变化；通过肽键含量和pH值判断蛋白质一级结构的变化。结果表明：随处理压力升高蛋白质的粘度、乳化特性、表面疏水性及在水中的溶解度均增强。在一定压力下,蛋白质的二、三、四级结构发生改变,超高压处理不影响蛋白质的一级结构。通过实验研究了小麦、玉米、马铃薯和红薯淀粉溶液溶解度、粘度、透明度、糊化特性等性能参数随处理压力的变化规律,通过测定淀粉溶液DSC曲线和X-射线衍射图谱观察淀粉结构的变化。结果表明：淀粉溶液的溶解度、透明度随压力升高显著增加,随压力升高粘度、糊化温度和糊化焓降低。以牡蛎和海参为对象,通过感官、pH值变化、TVB-N含量研究超高压处理对食品保质期的影响；通过灰分含量、多糖含量研究超高压处理对食品营养成分的影响。结果表明：超高压处理可延长食品的保质期,有效保护食品的营养成分和生理活性物质。建立了超高压食品处理过程模拟的人工神经网络模型,采用大量实验数据对网络进行训练和测试,成功实施了对超高压灭菌和钝酶效果的模拟和预测。更多还原

【Abstract】 In recent years, with the increasing requirements of food quality and safety, ultra high pressure food processing technology has attracted many attentions as a new non-thermal processing technology in food manufacture. Unlike the traditional heating processes, the ultra high pressure food processing does not damage original nutrients and natural flavor of the food products. Therefore, this technology is especially suitable for processing such products as juices and seafoods which have high requirements of maintaining original flavor. The aims of this work are to develop the method of process design, optimize process operation conditions, and provide a fundation for the development and industrialization of ultra high pressure food processing technology. Fruit juices (apple juice/orange juice) and seafoods (oyster/sea cucumber) are chosen as model materials to study the effects of ultra high pressure processing parameters on food microorganisms, enzymes and food quality. Proteins of soy, oyster and sea cucumber are used to study the effects of ultra high pressure processing on protein structure and solution properties. Wheat starch, corn starch, potato starch and sweet potato starch are employed to study the effects of ultra high pressure processing on starch structure and solution properties. The main results and conclusions are summarized as follows:The effects of pressure, pressure holding time and temperature on the total amount of microorganisms in the fruit juices and seafoods are investigated during the ultra high pressure food processing. The results show that microorganism inactivation rate increases and proliferation rate decreases with the increase of pressure, pressure holding time and temperature. A better sterilization can be achieved with the combined treatment of pressure and temperature.The effects of pressure, pressure holding time and temperature on the enzyme activity (polyphenol oxidase/peroxidase in juice and autoenzyme in sea cucumber) are studied. It is found that there is an enhancement of enzyme activity within a certain range of pressure and temperature, while the enzyme activity decreases in another range of pressure and temperature. The effect of the time on the enzyme activity is affected by pressure and temperature. When the enzyme activity increases with the pressure and temperature, it is also enhanced as time increasing. Otherwise, the enzyme activity decreases when the time increases.The effects of pressure on solubility, viscosity, and emulsifying properties of soy, sea cucumber and oyster protein solutions are studied. The degree of protein denaturation under high pressure is determined by DSC curve of the protein solution. The change of protein subunits obtained by SDS-PAGE (sodium dodecyl sulfate polyacrylamide gel electrophoresis) is used to analyze the effect of high pressure treatment on protein quaternary structure. The change of protein tertiary structure is studied by sulphydryl content measurement. The change of protein secondary structure is studied by IR spectra, while the change of protein primary structure by peptide bond content and pH value. The results indicate that viscosity, emulsifying properties, surface hydrophobicity and solubility of protein increase with the increase of the pressure. The secondary, tertiary and quaternary structures of protein are changed under a certain high pressure, while the primary structure of protein is not affected.The effects of high pressure on solubility, viscosity, transparency, gelatinization properties and other performance parameters of different materials (wheat, corn, potato and sweet potato starch solutions) are studied. The change of starch structure is observed by DSC curves and X-ray diffraction patterns. The solubility and transparency of the starch solution increase with the increase of the pressure, while viscosity, gelatinization temperature and gelatinization enthalpy decrease with the increase of the pressure.The effect of high pressure on food shelf life is studied by pH value, TVB-N content, and the changes of oysters and sea cucumbers appearances. The effect of high pressure on food nutrients is determined by the ash content and polysaccharide content. The results show that ultra high pressure treatment extends the shelf life of food, and protects food nutrients and physiologically active substances effectively.A model is established based on artificial neural network to study ultra high pressure food processing. After training the model with a large volume of experimental data, the effects of high pressure on sterilization and enzyme deactivation are simulated and predicted successfully.更多还原