苹果浑汁贮藏过程中浑浊稳定性的研究

Studies on the Cloud Stability of Cloudy Apple Juice during Storage

为了探讨贮藏对苹果浑汁浑浊稳定性的影响,将苹果浑汁产品分别贮藏在4、22和40℃下120d。采用HPLC技术测定了果汁沉淀物中的酚类物质;用SDS-PAGE测定了沉淀物中蛋白质的分子质量;用粒径仪测定了果汁贮藏过程中的粒径分布变化,同时测定了苹果浑汁的浊度和黏度变化。结果表明:随着贮藏温度的升高和贮藏时间的延长,果汁浊度增大,并产生了一些新的小颗粒;果汁瓶底沉淀物以蛋白质为主,还含有碳水化合物、酚类、5-羟甲基糠醛(5-HMF)等VC降解产物,其成分很复杂;沉淀物中蛋白质的分子质量为25507Da和40443Da;该沉淀物主要是由果汁中原有的颗粒聚集、长大、下沉产生;低温贮藏有助于果汁浑浊稳定性的保持。

In order to study the effect of storage on the cloud stability, a 120 days storage experiment of cloudy apple juice was conducted at 4. 22 and 40 ℃ respectively. Phenols and molecular weight of proteins in the sediment of juice were analyzed both using HPLC and SDS-PAGE and size distribution of particles in juice was analyzed using Mastersizer. The turbidity and viscosity changes of juice during storage were also assayed. Results showed that the turbidity was affected by the storage temperature and time and the turbidity of cloudy apple juice became acutely along with increased temperature and prolonged storage time. Some new particles formed during the storage of juice. The sediment of juice was complicated and consisted mainly of proteins, carbohydrate, phenols, 5-hydroxymethyl-furfural （5-HMF） . Molecular weight of protein in the sediment was 25 507 Da and 40 443 Da and the sediment mainly formed by the assembling and settling of original particles in juice. The cloud stability of juice could be retained by storing at lower temperature.