预处理对热风干燥番茄粉理化性质的影响研究

考察预处理方法对不同温度下热风干燥番茄粉理化性质的影响。预处理方法包括醇滤、水滤和糊精助滤,并以无任何添加物直接过滤的样品作对照。样品经预处理后,置于一定温度下强制对流干燥至规定含水量,粉碎后得番茄粉,分别测定所得番茄粉的番茄红素含量、堆密度、分散时间、复水比、吸湿性和颜色。实验结果表明,番茄粉的理化性质与预处理方法有密切关系,醇滤预处理所得番茄粉的品质最好,其次是水滤,而糊精助滤与直滤相差不大。在65℃下干燥时,醇滤样品的番茄红素含量是直滤样品的1.43倍,提高了176.34μg/g;堆密度从0.44g/mL降低到0.33g/mL,分散时间由52s减小至23s,复水比由原来的7.6倍增加到10.3倍,吸湿性由1.9%增加至3.1%;粉末L*值由48.13增加至53.55。证明醇滤预处理可明显提高番茄粉中番茄红素的含量,减小其堆密度和分散时间,增大复水比和吸湿性,且番茄粉的颜色更加亮丽。

Effect of Pretreatments of Tomato Pulp on Physicochemical Properties of Forced Convective Hot-air Drying Tomato Powders

The effect of different pretreatments to tomato pulp on physicochemical properties of forced convective hot-air drying tomato powders was studied. The methods of pretreatment included ethanol filtration, dextrin-aid filtration and water filtration, Free-aid filtration sample was selected as control. Tomato pulp pretreated was dried by forced convective hot air until specified moisture was obtained. The drying samples were collected, comminuted and sieved, then tomato powders were obtained. And physicochemical properties of tomato powders were analyzed, including lycopene content, bulk density, dissolution, rehydration ratio, hygroscopicity and color. The results indicated that method of pretreatments was closely correlated with physicochemical properties of tomato powders, especially ethanol filtration pretreatment improved physicochemical properties significantly, water filtration on tomato powders was also got improved, while the effect of dextrin-aid filtration was similar to that of free-aid filtration. When drying at 65℃, lycopene content of ethanol filtration sample was 1.43 times than that of free-aid filtration sample. And ethanol filtration sample was less bulk density and dissolution time, more rehydration ratio and hygroscopicity, and bright color. Therefore, ethanol filtration pretreatment was advantageous for physicochemical properties of tomato powders produced by forced convective hot-air drying.