食品通电加热速率控制系统设计与实验

Design of an Ohmic Heating Rate Control System for Food Processing

加热速率对食品品质影响很大。通电加热为食品加工提供了一种全新的加热方法,但由于当前通电加热系统多采用恒压电源供电,因而加热速率控制一直是业界的难点。本研究设计了一个基于单片机的食品通电加热速率控制系统,该系统主要由单片机、调压电路、数据采集电路、功能按键、液晶显示屏、加热槽构成,可以设定加热速率,能实时监控加热过程中的温度变化。在加热过程中采用复合控制方法,根据温度变化实时调节加热槽两端电压,使加热速率保持在设定值。用该系统对牛奶进行了加热实验,结果表明,在设定加热速率分别为6℃/min、8℃/min、10℃/min、12℃/min时,通电加热过程中牛奶的温度与时间均保持良好的线性关系,实际加热速率与设定值之间的相对误差为0.5～3.83%。该研究为食品通电加热过程中加热速率的控制提供了参考。

Heating rate has a great influence on food quality,ohmic heating provides a new heating method for food processing.However,the control of the heating rate has been considered as the difficulty in food industry for the constant voltage control applied in current ohmic heating systems.In this study,an ohmic heating rate control system was designed based on single chip microcomputer（SCM）,including a single chip microcomputer,a voltage regulator circuit,a data acquisition circuit,function keys,a LCD screen and a heating cell.The system could not only set the heating rate,but also give a real-time monitoring to the temperature change during the heating process.Compound control method was adopted to maintain the heating rate at the setting value during heating.Afterwards,the system was tested by heating milk.The result showed a good linear relationship between the temperature of milk and time when setting the heating rate of 6 ℃/min,8 ℃/min,10 ℃/min and 12 ℃/min respectively,and the relative error between actual heating rate and setting value was 0.50～3.83%.The study can provide a reference for the control of heating rate in the ohmic heating process.