交变磁场对食品体系在开路和闭路状态下的影响研究

发布时间：2018-06-29 17:26

本文选题：交变磁场 + 电磁感应　；参考：《江南大学》2017年博士论文

【摘要】：磁场对微生物作用的研究可以追溯到1938年,但是,磁场作为一种食品非热处理技术于1985年才被初次报道,这是由磁场设备开发缓慢、农作物资源短缺和食品体系成分复杂等诸多因素造成。随着工业技术的发展和人们生活的提高,人们对食品的要求不仅仅是用于满足基本生存需求,进一步追求食品的多样性、安全性和天然健康的品质,故磁场辅助加工作为非热技术被引入食品领域,因此当前对于磁场对食品组分影响的研究也逐步增多。现有研究主要集中在检测和加工两个方面:1.利用核磁共振技术对食品品质进行分析检测(多为与水分相关的品质特性);2.利用振荡脉冲磁场对食品进行杀菌和灭酶处理进而帮助食品的贮藏保鲜。为了进一步拓展磁场技术在食品工业中的应用,推动磁场辅助加工技术的发展,本论文基于电磁感应原理和霍尔效应设计了食品体系的开路检测和闭路加工系统,分别用于食品物料的理化品质分析和加工处理。主要研究内容和结论如下:基于电磁感应定律,搭建了具有单级变压器结构的食品感应电学参数的测量系统。选取不同传导性能的液态食品物料(盐渍黄瓜汁液和全蛋液)替换传统变压器的次级铜线圈,研究食品体系在交流初级电压激励下所表现出来的感应电学特性,发现:食品料液线圈可对外加交变磁通产生响应信号,具体表现为可通过电压计检测到次级线路的终端电压Us,并通过将激励电压和终端电压做比得到初次级电压降参数λ值。终端电压Us和电压降λ值会受到激励电压幅值和食品物料自身物理特性的影响,但激励电压的频率对次级食品物料的感应电学参数影响微小:即食品料液的传导性能越强,所表现出的终端电压Us越大,初次级电压降λ值越小;当激励电压恒定时,在整个测试频率范围内120~400 Hz频率范围内,食品料液次级线圈的终端电压Us基本维持在恒定水平。通过计算感应电参数与食品料液理化特性之间存在的计量关系,可实现对食品物料理化指标的表征:盐渍黄瓜汁液的盐分含量和可溶性固形物与终端电压Us呈正线性相关关系,与λ值呈负线性相关关系;全蛋液可溶性固形物和脂肪含量与终端电压呈负线性相关关系,与电压降λ值呈正线性相关关系;线性模型的R2均大于0.8。因此,可通过测试食品物料在开路状态下对交变磁通激励响应出的感应电学特性实现其理化指标的快速检测。基于霍尔效应的理论,设计了闭路的传导性流体回路体系并对固态果蔬物料进行了盐渍和钙强化研究。大蒜盐渍过程中的盐分增长和苹果钙强化过程中的钙含量增长可用负指数模型Y(t)(28)a(10)b[1-exp(-kt)]进行描述,通过求解不同处理下的溶质增长速率k和平衡含量b,验证了磁场作用结合流动处理可显著加速大蒜盐渍和苹果钙强化进程。此外,磁场强度(0~0.13 T)和浸渍温度(5~30oC)的提高可单调加快浸渍速率,而旋转磁场频率(0~10 Hz)和浸渍液流动程度(Re:0~4134)的提高则对浸渍效率具有先促进后抑制的作用。0.13 T磁感应强度和7.5 Hz旋转频率为最优的磁场条件,Re=1197为浸渍液的最佳流动状态。在此工艺参数下,若采用30oC的浸渍温度,与传统静置浸渍相比,大蒜盐渍浸渍速率提高了89.87%,苹果钙强化速率提高了202.55%。磁场参数和电解质溶液流动状态影响了浸渍动力学,而温度不仅影响浸渍速率,还可造成溶质渗透的最终平衡状态的改变。同时,设计了交变磁场激励下的流体闭路体系对粉末态的食品原副料即南瓜粉和玉米秸秆进行辅助处理。与果蔬浸渍不同的是,南瓜粉和玉米秸秆粉末溶液反应体系流动状态的增强,即雷诺数的提高可单调促进南瓜粉和玉米秸秆的水解产糖,未观察到过高流速对糖产量的负面影响;磁场旋转频率的提高对水解同样具有先促进后抑制的作用;对于南瓜多糖的提取,酸浓度越高、处理温度越高对水解越有利,最优工艺条件为f=7.5Hz旋转频率,Re=2500反应溶液流动雷诺数,pH 2酸性条件和50°C处理温度。在此条件下,南瓜多糖得率为16.88%,较传统搅拌提高了51.37%;南瓜多糖产物重均分子为1.435×105 Da,5mg/mL的多糖对DPPH·,O_2~-·,OH·的清除能力分别为52.8%,22.42%和92.13%,说明磁场闭路流体系统下提取的多糖仍具有较高的抗氧化活性。对于玉米秸秆碱预处理,适当提高磁场旋转频率和料液碱浓度可促进玉米秸秆降解糖化,但过高频率和过高碱浓度则对糖产量(五碳糖+六碳糖)提高产生了不利影响。提高料液流速对玉米秸秆降解具有积极作用。由响应面方法对关键工艺参数进行优化,得到最佳工艺条件,即6.71 Hz磁场旋转频率,0.5 L/min料液流速,和1.02%氢氧化钠浓度,此条件处理下的糖产率为429.24 mg/g干玉米秸秆,较传统搅拌处理提高了8.34%。食品物料体系的开路和闭路状态下,具有电传导性的料液均能对外加的交变磁通产生积极响应,响应效果除了取决于食品料液的理化特性外,加工参数如磁场感应强度、磁场旋转频率、料液流速、温度等外界条件也有其显著影响。本研究设计的开路磁场检测系统和磁场闭路流体系统可用于食品物料理化品质的评估检测和用于食品物料及农副产物的加工处理,为拓展磁场在食品工业领域的应用提供了理论依据。
[Abstract]:The study of the effect of magnetic field on microorganism can be traced back to 1938. However, as a non heat treatment technology for food, magnetic field was first reported in 1985. It is caused by many factors such as slow development of magnetic field equipment, shortage of crop resources and complex components of food system. With the development of industrial technology and the improvement of people's life, people are The demand for food is not only to meet the basic survival needs, and to further pursue the diversity, safety and quality of natural health of the food, so the magnetic field assisted processing is introduced as a non thermal technology into the food field, so the current research on the effects of magnetic field on food components is also increasing. The two aspects: 1. using nuclear magnetic resonance (NMR) technology to analyze the quality of food (mostly water related quality characteristics); 2. to use oscillating pulse magnetic field to sterilize food and eliminate enzyme treatment to help food storage and keep fresh. In order to further expand the application of magnetic field technology in the food industry and promote the magnetic field assisted processing technology In this paper, based on the principle of electromagnetic induction and the Holzer effect, the open circuit detection and closed circuit processing system of food system are designed for the physical and chemical quality analysis and processing of food materials. The main contents and conclusions are as follows: Based on the law of electromagnetic induction, the food induction electrical parameters with the structure of a single stage transformer are set up. The liquid food materials of different conductive properties (salted cucumber juice and all egg liquid) are replaced by the secondary copper wire ring of the traditional transformer, and the inductive electrical characteristics of the food system under the AC primary voltage excitation are studied. The terminal voltage Us of the secondary line can be detected by the voltmeter and the initial voltage drop parameter is obtained by comparing the excitation voltage to the terminal voltage. The value of terminal voltage Us and voltage drop will be affected by the amplitude of the excitation voltage and the physical properties of the food material, but the frequency of the excitation voltage is induced by the induction of the secondary food materials. The influence of the parameters is small: the greater the conductivity of the food material is, the greater the terminal voltage Us is, the smaller the initial voltage drop, the lower the value of the voltage drop. When the excitation voltage is constant, the terminal electrical pressure of the secondary coil of the food and liquid secondary coil is basically maintained at a constant level in the 120~400 Hz frequency range of the whole test frequency range. The quantitative relationship between the physical and chemical properties of food material and the physical and chemical properties of food can realize the characterization of food physical and chemical indexes: the salt content and soluble solids of the salted cucumber juice have a positive linear correlation with the terminal voltage Us, and a negative linear correlation with the value of lambda; the soluble solids and fat content in the whole egg liquid and the terminal voltage are negative lines. The relationship between the sexual correlation and the voltage drop is a positive linear correlation; the R2 of the linear model is greater than 0.8., so it can be used to test the rapid detection of the physical and chemical properties of the food materials in response to the response of the alternating magnetic flux excitation in the open state. Based on the Holzer effect theory, a closed circuit fluid circuit is designed. The growth of salt and calcium in the process of garlic salting can be described by the negative exponential model Y (T) (28) a (10) b[1-exp (-kt)) in the process of salt salting and the growth rate K and the equilibrium content B under different treatments are solved to verify the magnetic field binding flow. In addition, the increase of the magnetic field intensity (0~0.13 T) and the impregnation temperature (5~30oC) can accelerate the impregnation rate monotonically, while the rotational magnetic field frequency (0~10 Hz) and the impregnation fluid (Re:0~4134) increase in the impregnation fluid (Re:0~4134) have the first promoting post inhibition effect of.0.13 T magnetic induction intensity on the soaking efficiency. And the optimum flow condition of the 7.5 Hz rotation frequency is that Re=1197 is the best flow state of the impregnated liquid. Under the parameters of this process, the soaking rate of garlic is increased by 89.87% compared with the traditional impregnation temperature, compared with the traditional static impregnation, the apple calcium strengthening rate improves the 202.55%. magnetic field parameters and the electrolyte solution flow state. And the temperature not only affects the impregnation rate, but also causes the change of the final equilibrium state of the solute permeation. At the same time, the fluid closed system under the excitation of alternating magnetic field is designed to assist the food raw materials of the last state of the powder, pumpkin powder and corn straw. The increase of the flow state of the liquid reaction system, that is, the increase of the Reynolds number can promote the hydrolysis of pumpkin powder and corn straw, and the negative effect of high velocity on sugar yield is not observed. The increase of magnetic rotation frequency also promotes the hydrolysis of sugar, and the extraction of pumpkin polysaccharide is higher, the treatment temperature is higher. The better the higher the hydrolysis is, the optimum conditions are f=7.5Hz rotation frequency, Re=2500 reaction solution flow Reynolds number, pH 2 acid condition and 50 degree C treatment temperature. Under this condition, the yield of pumpkin polysaccharide is 16.88%, it is 51.37% higher than that of traditional stirring; the weight average of pumpkin polysaccharide product is 1.435 * 105 Da, and 5mg/mL polysaccharide has DPPH, O_2~-, OH. The scavenging capacity was 52.8%, 22.42% and 92.13% respectively, indicating that the polysaccharides extracted from the magnetic closed circuit fluid system still had high antioxidant activity. For corn straw alkali pretreatment, the proper increase of magnetic field rotation frequency and the concentration of liquid alkali could promote the degradation of corn straw, but the high frequency and high alkali concentration of sugar yield (five carbon sugar). The increase of six carbohydrate has a negative effect. Improving the flow velocity of the material has a positive effect on the degradation of corn straw. The optimum process parameters are optimized by the response surface method, and the optimum technological conditions are obtained, that is, the rotation frequency of the 6.71 Hz magnetic field, the flow velocity of 0.5 L/min, and the concentration of 1.02% sodium hydroxide. The yield of sugar under this condition is 429.24 mg/g dry. Under the open and closed state of the 8.34%. food material system, the corn straw has a positive response to the applied alternating magnetic flux. The response effect is not only dependent on the physical and chemical properties of the food material, but also the processing parameters such as magnetic field induction intensity, magnetic field rotation frequency, liquid flow velocity and temperature. The open circuit magnetic field detection system and the closed circuit fluid system designed in this study can be used to evaluate the quality of food material and use the food materials and the processing of agricultural and sideline products, and provide a theoretical basis for expanding the field in the food industry.
【学位授予单位】：江南大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TS205;TS207.3

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