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基于层次分析法的红枣切片热风真空及组合干燥试验与品质评价

Experiment and Quality Evaluation of Hot-Air Vacuum Combined Drying for Red Jujube Slices Based on Analytic Hierarchy Process

  • 摘要: 红枣富含维生素和糖分,营养价值高,干燥是红枣加工的主要方式之一,通过降低红枣的水分含量来延长货架期。但传统的红枣干燥方法存在品质差、效率低等问题,同时目前关于红枣干燥的分析难以对多个品质指标进行综合评价,为此,文章以陕西特产狗头枣为试验材料,研究了热风干燥、真空干燥、热风真空组合干燥、真空冷冻干燥(参照组)四种干燥方式下红枣切片的干燥品质,比较了不同干燥方式下的干燥特性,以干燥时间、复水比、色泽、Vc含量、质构特性为评价指标,采用层次分析法(AHP)对热风干燥、真空干燥、热风真空干燥进行了综合评价。试验结果表明:红枣切片干燥由外部水分蒸发和内部水分扩散共同控制,热风干燥有效水分扩散系数Deff最大,其次是热风真空组合干燥,真空干燥的有效水分扩散系数最小;在干燥品质方面,虽然真空冷冻干燥(参照组)Vc含量、色差、复水比等品质最佳,但其过高的干燥耗时使其能耗增加,干燥成本增加,因此对于热风干燥、真空干燥、热风真空干燥采用层次分析法进行了综合评分排序,最终综合评分最高的为热风真空组合干燥。

     

    Abstract: Red jujubes are rich in vitamins and sugar and have high nutritional value, and drying is one of the main ways to process jujubes, extending the shelf life by reducing the moisture content of red jujubes. However, the traditional jujube drying method has problems such as poor quality and low efficiency, and it is difficult to comprehensively evaluate multiple quality indicators in the current analysis of jujube drying, so this paper used the special product of Shaanxi jujube as the test material to study the drying quality of red jujube slices under four drying methods: hot-air drying, vacuum drying, hot-air vacuum combined drying and vacuum freeze drying (reference group), and compared the drying characteristics of them. Drying time, rehydration ratio, color difference, Vc content and texture characteristics were used as evaluation indexes, and the analytic hierarchy process (AHP) was used to comprehensively score hot air drying, vacuum drying and hot air vacuum drying. The experimental results showed that the drying of red jujube slices was controlled by both external water evaporation and internal water diffusion. The effective moisture diffusion coefficient Deff of hot air drying was the largest, followed by hot air vacuum combined drying, and the effective moisture diffusion coefficient of vacuum drying was the smallest. In terms of drying quality, vacuum freeze drying (reference group) has the best quality in terms of Vc content, color difference, and rehydration ratio, but its high drying time increases its energy consumption and drying cost. However, we used the AHP to rank the overall scoring of hot air drying, vacuum drying and hot air vacuum drying, and the highest overall scoring was hot air vacuum combination drying.

     

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