香菇热泵–真空联合干燥工艺优化

    Optimization of drying process for Lentinus edodes by combing heat pump with vacuum

    • 摘要:
      目的  降低加工成本、保证干制香菇的品质。
      方法  在单因素试验基础上运用Box-Behnken Design(BBD)方法设计优化试验,研究热泵温度(A)、真空度(B)和转换点含水率(C)对单位能耗、感官评分、复水比和硬度的影响,推导多项式回归模型,优化联合干燥工艺条件,并与单一热泵干燥,单一真空干燥相比较。
      结果  确定了最佳联合干燥工艺:热泵温度49 ℃,真空度110 Pa,转换点含水率(w)56%。在此条件下实测得单位能耗345.01 kJ·g–1、感官评分8.3、复水比2.72、硬度3.61 N;与预测值相近,相对误差分别为0.19%、3.61%、1.47%和1.66%。联合干燥的单位能耗比真空干燥减少37.69%,但高于热泵干燥;其感官评分和复水比与真空干燥相近,高于热泵干燥;其硬度略大于真空干燥,小于热泵干燥。
      结论  热泵干燥和真空干燥相结合,得到能耗低、质量好的干制香菇,解决了热泵干燥品质不佳、真空干燥能耗高等问题,可为香菇的热泵–真空联合干燥提供理论依据。

       

      Abstract:
      Objective  To reduce the cost of processing, and obtain high quality dried Lentinus edodes.
      Method  On the basis of single-factor experiment, Box-Behnken Design (BBD) was used to study the effects of heat pump temperature(A), vacuum degree(B) and conversion point moisture content(C) on unit energy consumption, sense judgment, rehydration ratio and hardness. We deduced a multinomial regression model, optimized the combined drying technology and compared with single heat pump drying and single vacuum drying.
      Result  The optimal parameters were obtained as follows: The heat pump temperature was 49 ℃, the vacuum degree was 110 Pa, and the conversion point moisture content was 56%. Under these conditions, the tested unit energy consumption was 345.01 kJ·g–1, the sense judgment was 8.3, the rehydration ratio was 2.72, and the hardness was 3.61 N, which were close to the predicted values. The relative errors were 0.19%, 3.61%, 1.47% and 1.66% respectively. The unit energy consumption of combined drying was 37.69% less than that of vacuum drying and higher than that of heat pump drying. The sense judgment and rehydration ratio of combined drying were close to those of single vacuum drying and higher than those of heat pump drying. The hardness was slightly larger than that of vacuum drying and less than that of heat pump drying.
      Conclusion  The method combining heat pump drying and vacuum drying obtained dried L. edodes with low energy consumption and good quality. It solves the poor quality in heat pump drying and high energy consumption in vacuum drying. This study can provide a theoretical basis for heat pump-vacuum combined drying of L. edodes.

       

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