转轮除湿冷风干燥技术是一种新型食品干燥技术,它是热泵和除湿深度独立的一种节能干燥方式。为探究不同转轮除湿冷风干燥条件下对苹果切片干燥过程的具体影响,研究了不同送风温度(10、20、30 ℃)、再生温度(90、100、110 ℃)、切片厚度(3、4、5 mm)下的苹果切片干燥特性及品质分析。利用菲克第二定律计算可得各个工况下的水分扩散系数范围为6.03E-9~3.00E-8 m2/min。提出了6种薄层干燥模型,发现Page模型可以较好地预测苹果切片的冷风干燥过程。测定了不同工况下干制品色差、质构,结果表明转轮除湿干燥相比于其他传统干燥拥有较低的色差值,冷风干燥苹果切片的硬度随着送风温度升高而降低主要因为切片软化程度会随着含水率的变化而变化,脆度会随着温度的增加而增加;随着厚度的增加硬度、脆度也会增大,再生温度对于硬度、脆度来说影响不大,咀嚼性与硬度呈正相关关系。总体而言冷风干制苹果切片相比热风而言质地更软,但脆度比热风干燥要低。
Runner dehumidification cold air-drying technology is a new type of food drying technology, which is an energy-saving drying method with an independent heat pump and dehumidification depth.To explore the specific effects of different rotor dehumidification and cold air-drying conditions on the drying process of apple slices, the drying characteristics and quality analysis of apple slices under different supply air temperatures (10, 20, 30 ℃), regeneration temperatures (90, 100, 110 ℃) and slice thickness (3, 4, 5 mm) were studied.Fick’s second law was used to calculate that the moisture diffusion coefficient under each working condition ranged from 6.03E-9-3.00E-8 m2/min.Six thin-layer drying models were proposed, and it was found that the Page model could better predict the cold air-drying process of apple slices.Results showed that the rotor dehumidification drying had a lower color difference value than other traditional drying methods, and the hardness of apple slices dried by cold air decreases with the increase of air supply temperature, mainly because the softening degree of slices would change with the change of moisture content, and the crispness would increase with the increase of temperature.With the increase in thickness, the hardness and brittleness also increased, and the regeneration temperature had little effect on the hardness and brittleness, and the chewiness was positively correlated with the hardness.Overall, cold-air-dried apple slices have a softer texture than hot air but have a lower crispness than hot-air-dried.
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