不同预处理方法对马铃薯片热泵干燥速率及其干片品质的影响

Effects of different pretreatment methods on heat pump drying rate of potato slices and quality of dried products

采用烫漂、汽蒸、冷冻、汽蒸+冷冻和烫漂+冷冻5种方法对马铃薯片进行预处理,比较其热泵干燥速率及干片复水比,并使用测色仪、物性分析仪、凯氏定氮法和扫描电镜分别测定干片的色泽、质构、蛋白质含量和微观结构。结果表明,汽蒸预处理效果最好,即在一定条件下,干燥2h后干片的水分含量达到14.80%,比对照组干燥时间缩短了25.9%;L^*值(亮度)和b^*值(黄度)分别为87.44和31.77;硬度居中(1546.35g),脆度较小(17.24mm);复水比(4.65)和蛋白质含量(9.90%)均最高;且干片表面呈“结壳硬化”的膜结构,内部呈“砖块堆砌”结构,干片平整无蜷曲,呈明亮的淡黄色,综合品质最佳。说明汽蒸预处理能显著提高马铃薯片的干燥速率,改善干片品质,适合推广应用。

The potato slices were pretreated by blanching,steaming,freezing,steaming+freezing,and blanching+freezing. The heat pump drying rate and rehydration ratio of dried slices were compared,and their color,texture,protein content and microstructure were further determined. The results showed that steaming pretreatment had the best effects,as the moisture content of dried potato products reached 14.80% after drying for 2 h,which was 25.9% shorter than the control group. Moreover,the values of L^* and b^* of steaming-pretreated dried potato products were 87.44 and 31.77,respectively. Their hardness was moderate (1 546.35 g) with smaller brittleness (17.24 mm),and their rehydration ratio and protein content reached the highest,which were 4.65 and 9.90%,respectively. Besides,the surface of the dried products formed a ‘shell hardening’ membrane structure,and the interior had a ‘brick building’ structure. The surface of the dried slice was flat with no distortions and had the best comprehensive quality. Overall,steaming pretreatment can significantly improve the drying rate of potato slices and improve the quality of dried potato chips,which is suitable for popularized application.