The Research Of The Influence Of Two Different Processing Ways On The Quality Of Concentrated Citrus Juice

The citrus, with sweet taste, alluring color and balmy scent, wins the great popularity of the global consumers and becomes the fruits with the largest trade volume. At present, the domestic research about the citrus processing mainly focuses on the optimization of the processing technique condition, while the research on the quality of the citrus juice is little. How to reduce the loss of aromatic substance and nutrient substance and to prevent producing the bitter substance in the citrus juice are the key points that should be concerned when adjusting and optimizing the technological operation in the citrus juice processing. Comparing the different effects on the quality of three kinds of common citrus juice caused by the unit operations on FMC medium-sized concentrated citrus juice production line and laboratory simulation concentrated citrus juice production line, this paper aims to select a mode of operation to improve the quality of concentrated citrus juice. This paper also studies the limonin production dynamics during the preservation of concentrated citrus juice processed and produced by the above two different processing ways, and estimate the shelf life of the concentrated citrus juice at a certain temperature (25℃) according to the ASLT. After these experiments, we can conclude that:1,Comparison of the effects among the two different processing ways on the nutrient component and chromaticity of the citrus juice. Taking 3 kinds of citrus (Beibei447^ Wuhexuegan,Zhongyu7hao) as the experimental raw material, this experiment makes a research on the effects of total sugar, total acid, Vc, total reducing sugar and chromaticity in the citrus juice caused by the unit operations on FMC medium-sized concentrated citrus juice production line and lab-simulation concentrated citrus juice production line. The result indicates that the different juicing, homogeneity, sterilization and concentration operation of two different processing ways actually affect the nutrient component and color of the citrus juice, and among those factors the different methods of sterilization and concentration affect more. Compared with that from the production line in the factory, the nutrient component and color of the concentrated citrus juice produced from the production line in the laboratory are closer to the fresh fruit juice.2,Comparison of the effects among the two different processing ways on the fragrance component of the citrus juice. For Beibei447, Wuhexuegan, Zhongyu7hao after processing on these two different processing ways, the changes of every tiny fragrance component lead to the change of the citrus juice intrinsic flavor. The juicing and homogeneity operation have a smaller impact while the sterilization and concentration operation have a greater one. After the sterilization operation, both processing ways produce some extra material, which would have a negative influence on the flavor, but this influence need the collective judge with GC-O. For both processing ways, after the concentration operation the fragrance component in the citrus juice reduces greatly. After the concentration operation, the production line in the factory produces some material that could have a negative influence on the flavor, while the line in the laboratory does not produce any new volatile material.3,Comparison of the effects among the two different processing ways on the fragrance component of the citrus juice. Taking Beibei447 as the experimental material first, the experiment optimize limonin extraction technology from the citrus juice according to the response surface methods. The best condition to extract the limonin from the citrus juice is 17 mL methylene chloride,26.4 min vortex oscillation extraction and pH 6.2. At this time, the extract content of limonin is 2.723 mg/L, which is obviously better than 2.286 mg/L without any optimization. And then under the optimizing conditions, the experiment studies the effects on the content of limonin and limonoids in the citrus juice caused by the unit operation of the above two different processing ways. The results show that after the homogeneity and sterilization by two processing ways and concentration operation by the production line in the factory, the content of limonin increases obviously. Except the content of limonoids of Wuhexuegan changes little by every unit operation of lab-simulation production line, the content of Limonoids of other kinds of citrus juice in t two processing ways changes obviously, but the regularity of change is not obvious.4,the research on the generation of the limonin during the preservation of concentrated citrus juice. This experiment studies the limonin production dynamics model in concentrated citrus juice under different preservation temporatures, and estimates the shelf life of the concentrated citrus juice at 25℃according to the ASLT.It shows that the content of limonin in the concentrated citrus juice increases with the increase of preservation temperature and time. Under 28℃,35℃and 45℃, the change of the content of limonin in concentrated citrus juice is in conformity with the 0 degree dynamics model. The shelf life (25℃) of the concentrated citrus juice produced by the production lines in the laboratory ang factory are 122d and 98d,98d and 72d,120d and 98d separately.