| Instant tea as a product of deep processing of tea,developed rapidly with its healthy and convenience properties,consumption increased year by year.Compared with the overseas,our development of instant tea started late,and there is still a huge market and development space.At present,our instant tea products exist some problems like small particle size,poor mobility,poor cold solubility and single use etc.The granulation process can improve the particle characteristics,improve the fluidity and solubility characteristics of instant tea particles,thus to enhance the overall quality of the instant tea and the international market competitiveness.This study is based on the current application of instant tea,with green tea as raw material,the extraction parameters(time,ratio of material to liquid,temperature)were optimized by single factor experiment and orthogonal method,the selection of different types and proportion of dry excipients P-CD and MD were studied,as well as the parameters(including concentration of materials,MD concentration,and CO2 concentration)which may affect the particle characteristics during the granulation process.For the first time developed a CO2 hollow granulation production process,and prepared instant tea granules with hollow shape,well solubility and better overall quality.The experimental results are as follows:(1)Through the green tea raw materials extraction optimization study,the extraction time,the ratio of material to liquid and the extraction temperature had significant effects on the content of tea polyphenols in the extract liquid.,and the order was B(the ratio of material to liquid)>C(extraction temperature)>A(extraction time).The optimal extraction conditions were as follows:the ratio of material to liquid is 1:22,the extraction temperature is 85 ? and the extraction time is 60 min.The content of tea polyphenols in this extract was 17.65%.On the basis of this,added 4.0-8.0%p-CD can largely reserves the effective components.(2)The effects of different types and different proportions of dry excipients on the main quality components,spray drying efficiency and sensory quality were investigated.The results showed that:adding a certain range of P-CD and MD drying excipient can significantly improve the rate of powder collection,WSI value and solubility of the spray-dried product,while decreasing the moisture content and WAI value.However,the content of main quality components and sensory evaluation will be affected when the amount is too large.In view of the comprehensive production efficiency and quality,the addition of 30%-90%MD in the process of spray drying has higher production efficiency and can make the finished instant tea powder have a lower moisture content,higher solubility,better transport and storage capacity,lower production costs on the basis of keeping the original flavor of the instant tea as much as possible.(3)In the process of CO2 hollow granulation,the effects of materials concentration,MD concentration and CO2 concentration on the moisture content,particle size range and average particle size,bulk density,fluidity and particle morphological of the instant tea powder changes were significant.Combined particle properties and sensory evaluation results showed that the optimum conditions of CO2 hollow granulation were as follows:the concentration of materials was 40%,the proportion of MD was 50%,and the addition ratio of CO2 is 1:1.By this condition,the instant tea powder had lower moisture content,smooth surface,uniform particle size,smaller solid density,good fluidity and good solubility,and could be used as cold soluble tea. |
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