| The time-based food labeling system provides shelf life for foods,but the temperature changes which the food experienced during storage and transportation are unpredictable and can affect the food's shelf life and normal consumption,especially for temperature-sensitive foods.Time-Temperature-Indicator(TTI),defined as a mass recording device and designed according to time and temperature parameters.The TTI,by means of a time-temperature accumulation effect reflecting the food's temperature change course which can instrcut all or part of the food's temperature history,and through the calculation of the food's remaining shelf life to grasp the quality and status of food.In this paper,potatoes were used as the raw material of volt battery,and the factors influencing the discharge characteristics were explored.The DC voltage measurement and temperature control system based on KL25 was designed to record the battery discharging process under different temperature conditions,and finally get a stable and reliable relationship between the total discharge of the volt battery and temperature accumulation.The main research contents are as follows:(1)After a deep research on two typical TTIs,it was found that the enzyme type TTI responds to the time course of the food by matching the activation energy of the chemical reaction,and determined the food quality according to the reaction color;the electronic TTI was determined by electron equipment recording to achieve this function,and calculated the remaining shelf life according to the food TTI curve.Based on the advantages of two TTIs,this paper put forward the research ideas of time and temperature indicators based on the volt battery:using the volt battery discharge characteristics to reacte the time temperature history,which is intuitive and reliable.(2)The basic principle of the volt battery was studied,and the treated potato tissue was chosen as the battery material of the battery,when the copper and zinc used as the battery electrode.The temperature and other factors influencing the discharge characteristics of the battery were investigated,and the relationship between total discharge of the volt battery and the cumulative temperature was selected as a TTI mathematical model.(3)The KL25-based DC voltage measurement and temperature control system was designed,when it's measurement function was used to record the voltage and temperature values of the volt battery during the discharge.Considering the reliability of the model of TTI mathematics,the system's temperature control function was used to meet a wide range of different temperature test conditions.The system was verified by the actual measurement of voltage error was less than 0.2mV,temperature control error was less than 0.2?,and could meet the test requirements.(4)A test scheme was developed to explore the relationship between the total discharge of the volt battery and the cumulative temperature of time.A volt battery with heat-treated potato tissue as an electrolyte was fabricated.An external resistance discharge test was performed and the data were measured using a measuring device.After the data analysis,the relationship between the total discharge of copper-zinc-volt battery and the accumulated temperature of time under 40min's heating time and 3 cm2's effective contact area was:y=-9E-06x~2+0.339x-0.2964.In this formula,the equation correlation coefficient was 0.983176,F test of the P value of 9.92×10-8,which indicated that the equation is highly significant.The formula was with a(-1.115e-005,-7.667e-006),(0.03106,0.03681)and(-1.295,0.7017)'s confidence interval,when the each coefficient error was less than 5%,and interval prediction can be fully realized.The experimental study of time-temperature indicator based on volt battery had provided a new TTI design method.The practical results can be combined with food TTI curve,which can estimate food shelf life and reflect the quality of food. |
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