Preparation And Application Of Microcapsuled Sulphite As Preservative

The objective of this study was to develop the sulphite microcapsules with stability and two-phase (quick and slow) release characteristics. Sulphite microcapsules were prepared by using phase separation method and dissolve dispersion condensing method. Characterization of microencapsulation containing sulphite including particle size distribution, morphology, and release profiles, inhibition property and stability have been investigated and its application on the storage of Muscat Hamburg Grape was also investigated. The results indicated that,It was obtained that sulphite microencapsule prepared by phase separation method using follow process conditions: 4.0 wt% ethylcellulose with the viscosity of 200 mPa·s, 0.6 wt% polyethylene wax with the molecular weight of 2000, the wall-core ratio of 1:5, stirring speed of 900 r/min, phase separation time of 75 min. It was also drawn that sulphite microencapsule prepared by dissolve dispersion condensing method using follow conditions: the wall-core ratio of 1:2, stirring speed of 600 r/min, phase separation time of 120 min. Moreover, it was also obtained that sulphite microencapsule with double wall coating prepared by dissolve dispersion condensing method using follow conditions: the wall-core ratio of 1:1, stirring speed of 450 r/min, phase separation time of 120 min.For particle size of microencapsulation, it was different with different coating material. The morphology of microencapsulation was irregular. Many small holes exist in ethylcellulose but can't be seen in paraffin and polyethylene, which indicated that the compactness of paraffin was higher than that of ethylcellulose. On the other hand, release profiles and inhibition ability of microencapsulation were also affected by the structure of coating material. Compared to sulphite particle, microcapsules with different coating material provided protection for sulphite particles against the sunlight, heating and different relative humidity.For table grape treated by two-phase preservative composed with microencapsulation coated with different wall material, rot indexes decreased 80% compared to CK. Bleaching rates decreased 35% and rot indexes decreased 10%, respectively, sulfur dioxide residue decreased 20% in comparison with table grape with the treatment by marketed preservative.The results in this study indicates that microencapsulation technology improve the stability and environment adaptability of sulphite. It also shows better ability of control release. The sulphite microencapsule has a good potential to be used on the storage of table grape.