果蔬气调包装内相对湿度的预测模型与试验验证

Predicting model and experimental validation of relative humidity in modified atmosphere packages for fruits and vegetables

包装内相对湿度调节控制是保证果蔬产品气调保鲜包装质量的重要技术环节。该文较完整地考虑果蔬包装内外热量交换和气体质量传输,依据质量与能量守恒定律,建立包装内质量与能量平衡关系。在此基础上,导出气调包装内产品呼吸-蒸发模型,得到包装内相对湿度变化的预测模型。以香菇产品为研究对象,测定表征香菇呼吸速率,设计3种工况(不同质量、初始气体组分),对香菇气调包装内的湿度进行预测与验证测试。结果表明,理论预测与试验结果总体上吻合,在包装的初始阶段理论结果稍有偏高;初始气体组分对包装内相对湿度影响较大,低氧高二氧化碳组分显著降低了相对湿度上升的速率,同时延长了达到饱和状态的时间。

Adjusting and controlling relative humidity（RH） in packages is crucial to ensuring the quality of modified atmosphere packaging of fresh produce. A modified respiration-transpiration model was developed. The model was based on heat exchange and gases mass transport phenomena across the package, gases heat convection inside the package, and mass and heat balances accounting for the respiration and transpiration behavior of fresh produce. And then the predicting model of the RH in modified atmosphere packages was proposed. The testing system of the gas composition and RH-temperature in modified atmosphere packages was established. Fresh Lentinula edodes were packaged in different initial gas composition and sample mass, and stored for 40h at 10℃, 80% RH. The parameters of respiration model for Lentinula edodes were estimated, and the RH and temperature in packages were measured during storage. In general, the model predictions agreed well with the experimental data, except the model predictions were slightly high in the initial period. The effect of the initial gas composition on the RH in packages was notable. In modified atmosphere packages of lower oxygen and higher carbon dioxide, the ascending rate of RH was reduced, and the packages were saturated slowly during storage.