樱桃番茄渗透预处理热风干燥特性研究

为了提高干制品的营养保留率和品质,进行了渗透预处理联合热风干燥的工艺路线的实验研究。以樱桃番茄为例,分别对不同浓度(50%,70%)蔗糖溶液常压渗透以及真空渗透处理后热风干燥的干燥时间、干燥速率、样品体积比、Vc保留率、硬度、颜色等参数分别进行测定和比较。结果表明:渗透预处理可以除去新鲜樱桃番茄中的大部分自由水,从而减少其热风干燥时间,使产品在高温中的暴露时间减少,从而缩短整体干制时间、提高干制效率及营养品质。经渗透预处理的樱桃番茄干制产品的体积比和Vc保留率要比直接热风干燥的产品增加,而硬度大大下降;其中经浓度为50蔗糖溶液真空渗透预处理后干燥产品的体积比、Vc保留率以及硬度是直接70℃热风干燥的1.72、2.26和0.12倍;而且产品的色泽更加接近新鲜原料,使产品的口感和感官品质更好。研究表明,渗透预处理联合热风干燥是1种很有发展前景的制干工艺。

Properties of cherry tomatoes in osmotic dehydration followed by hot-air drying

In order to improve the nutritional preservation and quality of dried products,an experimentation of osmotic dehydration followed by hot air drying was investigated.By taking cherry tomato as an example,the technology parameters and product quality indices,such as drying duration,drying rate,volume ratio,Vc content,hardness and color,were detected and compared.The results indicated that,osmotic pretreatment can remove from the samples a majority of free water,reducing the drying duration in the process of hot air drying,and thus shortening the whole process time of dried product,increasing the process efficiency and nutritional quality.As compared with hot air dying alone,osmotic pretreatment followed by hot air drying increased the volume ratio and Vc content of dried products,and greatly decreased the hardness.For example,the volume ratio,Vc content and hardness of dried products produced by vacuum osmotic dehydration in 50% sugar solution followed by hot air drying at 70 ℃ were 1.72,2.26 and 0.12 times those directly by hot air drying alone;and the dried products were closer to the fresh fruit in color,and softer in taste,and better in sensory quality.The investigation indicated that,the osmotic pretreatment followed by hot air drying is a promising drying technology.