基于介电谱技术的地沟油检测研究

发布时间：2018-11-04 16:31

【摘要】：食用植物油是人体重要的营养和能量来源，是重要的食品工业基础原料，“民以食为天，食以安为先”，由于我国食用植物油消费量的巨大，，劣质食用植物油不仅危害了消费者的健康利益，还关系到社会的安定。在食用植物油劣化变质过程中，会有氧化、水解、聚合等一系列的化学反应，极性小分子含量会发生变化，即表现为介电常数的变化。所以，通过检测食用植物油介电常数的变化，可以判定食用植物油品质的好坏。本文首先阐述了食用植物油的品质检测原理，依据该原理研究并设计了基于电容传感器和电容检测的食用植物油品质检测系统，用3类食用植物油进行了初步实验，分别给出了它们在特定条件下的品质关系函数。食用植物油品质检测系统设计主要有以下三个方面组成，主要采用数据前端传感器（电容和温度），分析并设计了电容信号的放大调理电路以及微控制器外围接口技术。该系统以NXP公司的Cortex-M0微处理器为控制核心，采用平板电容传感器探头测量食用植物油的介电常数；测量时将传感器探头插入样品油中，激励源正弦波信号由微控制器PWM调制产生，传感器输出电压信号经传感器模拟前端(AFE)系统LMP90100送入微控制器；由于在测量食用植物油电容时，温度会对结果有一定的干扰，系统设计了基于数字温度传感器DS18B20的温度测量电路；微控制器与上位机之间采用RS232通讯，再由计算机进行数据处理、温度的影响分析、显示和打印等。食用植物油品质检测系统有微处理器程序设计与上位机界面设计两个方面组成，微处理器程序主要有PWM的正弦调制算法和外围器件驱动，外围器件驱动有温度传感器18B20的单总线通讯，与模拟前端器件LMP90100的SPI通讯以及与上位机的串口通讯。上位机界面采用NI(美国国家仪器)的LabVIEW软件编写，实现数据记录与分析；线性回归的方法，找出待测样品的品质关系函数。课题完成了食用植物油品质检测系统的开发，并以不同品质的食用植物油为对象，进行了初步实验。实验结果表明，具有较好的数据重现性，分别建立了葵花籽油、大豆油和调和油与地沟油含量相关的数学模型。
[Abstract]:Edible vegetable oil is an important source of nutrition and energy for the human body and an important raw material for the food industry. "the people take food as the day, and the food comes first." because of the huge consumption of edible vegetable oil in China, Inferior edible vegetable oil not only endangers the health benefits of consumers, but also relates to social stability. A series of chemical reactions, such as oxidation, hydrolysis and polymerization, will occur during the deterioration of edible vegetable oil, and the content of polar small molecules will change, that is, the change of dielectric constant. Therefore, the quality of edible vegetable oil can be judged by detecting the change of dielectric constant of edible vegetable oil. In this paper, the quality detection principle of edible vegetable oil is first expounded. According to this principle, the quality detection system of edible vegetable oil based on capacitance sensor and capacitance detection is studied and designed, and the preliminary experiment is carried out with three kinds of edible vegetable oil. Their quality relation functions under certain conditions are given respectively. The design of edible vegetable oil quality detection system is mainly composed of the following three aspects: the data front-end sensor (capacitance and temperature) is used to analyze and design the amplifying and conditioning circuit of the capacitor signal and the peripheral interface technology of the microcontroller. In this system, the dielectric constant of edible vegetable oil is measured by using the panel capacitance sensor probe with the Cortex-M0 microprocessor of NXP company as the control core. When the sensor probe is inserted into the sample oil, the exciting source sinusoidal wave signal is modulated by the microcontroller PWM, and the output voltage signal of the sensor is fed into the microcontroller via the sensor analog front-end (AFE) system LMP90100. Because the temperature will interfere with the result when measuring the capacitance of edible vegetable oil, a temperature measuring circuit based on digital temperature sensor DS18B20 is designed. RS232 communication is used between the microcontroller and the host computer, and then the data is processed by the computer, the influence of temperature is analyzed, and the display and print are carried out. The edible vegetable oil quality detection system consists of two aspects: microprocessor program design and upper computer interface design. The microprocessor program mainly includes PWM sinusoidal modulation algorithm and peripheral device driver. The peripheral device drives the single bus communication with the temperature sensor 18B20, the SPI communication with the analog front-end device LMP90100 and the serial port communication with the host computer. The upper computer interface is compiled with the LabVIEW software of NI to record and analyze the data, and the linear regression method is used to find out the quality relation function of the sample to be tested. The quality detection system of edible vegetable oil was developed, and a preliminary experiment was carried out on different quality edible vegetable oil. The experimental results show that there is a good reproducibility of the data. The mathematical models of sunflower oil, soybean oil and blending oil related to the oil content in the gutter are established respectively.
【学位授予单位】：河南工业大学
【学位级别】：硕士
【学位授予年份】：2012
【分类号】：TP274;TP368.11

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