山楂切片冷冻干燥动力学与品质特性研究

Study on Freeze Drying Kinetics and Quality Characteristics of Hawthorn Slice

为了解山楂切片冷冻干燥特性,采用新鲜的山楂为原料,设置山楂切片厚度分别为2、3、4、5、6 mm,得到山楂干基含水率随干燥时间的变化曲线。将曲线与3种常见的果蔬干燥模型进行拟合。对真空冷冻干燥后的不同厚度的山楂切片进行复水率、收缩率、褐变度、抗坏血酸、总酚等指标测定。结果表明:山楂冷冻干燥过程与Lewis与Page模型拟合程度较好(0.9829<R2<0.9913)。切片厚度为6 mm时山楂片干燥效果最佳,含水率1.66%、复水率2.17 g/g、收缩率13.67%、总酚含量高达40.43 mg/100 g;切片厚度为3 mm的山楂切片褐变度最小(OD420 nm=0.645),硬度、咀嚼性、弹性和黏附性相对较好,抗坏血酸的含量163.6 mg/100 g。研究结果可为山楂冷冻干燥技术提供理论依据和指导。

The dry hawthorn slices was used to study the change curves of the drying rate with the moisture content of the dry hawthorn and the different thickness(2,3,4,5,6 mm)of the hawthorn slices was prepared.Besides,the curve was utilized to fit with another three common drying models.Then,a series of analysis were carried out such as rehydration rate,shrinkage rate,browning degree,ascorbic acid,total phenol,etc.The results showed that the freeze-drying process of hawthorn were well-matched with the Lewis and Page models(0.9829<R2<0.9913).The hawthorn slices with 6 mm had the best drying effect(moisture content 1.66%,rehydration rate 2.17 g/g,shrink rate 13.67%)and the total phenol content(40.43 mg/100 g).Furthermore,the hawthorn slices with 3 mm possessed the smallest browning degree(OD420 nm=0.645)and a good texture.Compared with other samples,ascorbic acid(163.6 mg/100 g)were fewer for the slices with 3 mm.This could be introduced as a guidance for freeze-drying technology of hawthorn.