Effects of Different Drying Methods on Quality Characteristics of Lettuce
In order to determine the most suitable drying method of lettuce,the effects of five common drying methods on the quality characteristics of lettuce were compared.Taking fresh lettuce as raw material,the effects of hot air drying,heat pump drying,short-wave infrared drying,infrared combined heat pump drying and vacuum freeze-drying technology on the appearance quality(chromaticity),sensory quality(taste value,texture,sensory score,rehydration ratio),nutritional quality(vitamin C,chlorophyll,reducing sugar,amino acid),drying time and equipment energy consumption of dried lettuce were studied.The best drying method of lettuce was evaluated by the weight method of variation coefficient,and correlation analysis and cluster analysis were carried out finally.The results showed that the color difference value(68.71)of hot air drying was the smallest and the richness value was the largest.The contents of essential amino acids and total amino acids in heat pump drying were the highest,which were 1.95 mg/g and 8.77 mg/g respectively.The vitamin C content of medium-short-wave infrared drying were the highest,which was 7.18 mg/100 g.The adhesiveness and chewiness of infrared combined heat pump were the highest,which were 24.56 N and 13.53 mm,and the shortest drying time and the lowest energy consumption,which was 1 h and 1.20 kW h respectively.Vacuum freeze-drying had the maximum brightness value(58.47),the minimum hardness was 30.41 g,the maximum elasticity was 0.83 mm,the maximum rehydration ratio was 10.64,and the maximum chlorophyll content was 0.28 mg/g FW.The comprehensive score of coefficient of variation method showed that the quality of medium-short-wave infrared drying was the best,followed by infrared combined with heat pump drying,and vacuum freeze-drying scored the lowest.So medium-short-wave infrared drying was a more suitable drying method for lettuce.
lettucedryingcoefficient of variation methodcluster analysisquality
万方数据
维普
