在惰性气体环境中热泵干燥食品

在传统的食品干燥技术中，干燥介质是空气，干燥能力由变化的温度控制。通常，干燥过程在高温下进行，空气中氧的存在影响食品的营养物质。想要在低温条件下提高干燥能力，可以通过热泵来改善干燥环境。热泵是闭环系统，冷凝器产生的热控制干燥温度，蒸发器除去干燥室的水分，干燥介质在低温低湿下运行。由于整个系统在闭路下操作，为了去除空气中氧对食品的影响，采用氮气、二氧化碳等惰性气体代替空气作为干燥介质。本文主要研究：采用氮气、二氧化碳和空气干燥一些热敏性水果，如番石榴和木瓜，探讨对食品营养物质和颜色的影响，并与冷冻干燥、真空干燥的结果进行对比。

Drying of Food Products under Inert Atmosphere Using Heat Pump

In conventional drying of food products, the drying medium is air and the drying potential is controlled with the variation temperature. Normally, the drying is carded out at high temperature and the presence of oxygen in the air affects nutrients of the food product. To improve the drying potential and also to carry out the drying under low temperature conditions, a heat pump is used to improve the drying environment. Since the heat pump is operated in a closed loop, where condenser heat controls the drying temperature and evaporator removes the moisture content released at the drying chamber, the drying medium operates at low temperature and moisture content. As the system operates under closed loop condition, to eliminate the effect of oxygen in the air, the air is replaced by inert gases such as nitrogen and carbon dioxide. This paper includes results of drying of some heat sensitive fruit materials e.g. guava and papaya using nitrogen, carbon dioxide, and air to find the impact on nutrients and color. These results were also compared with those dried by freeze and vacuum dryers.