【作者】 颜治；

【导师】 刘勤晋；

【作者基本信息】 西南农业大学 ， 农产品加工及贮藏工程， 2004， 硕士

【摘要】 本实验以乌龙茶为原料，研究了高浓度无沉淀浓缩茶汁的工艺流程及工艺参数。通过正交实验确定了茶叶浸提的工艺和参数、以及包埋剂和抗氧化剂的添加量，探讨了在不同条件下超滤、纳滤、反渗透对茶汁过滤(浓缩)膜通量及主要生化成分的影响，获得了茶汁超滤和浓缩的工艺及参数。最后得到了高浓度无沉淀浓缩茶汁的主要生产工艺流程，为中试及扩大生产提供了可靠的实验数据。其具体结论如下： 1．采用低温酶法萃取的茶叶浸提工艺，工艺参数为浸提温度60℃，浸提时间60min，茶水比1∶140，纤维素酶添加量0.4％，此时茶多酚、咖啡碱、游离氨基酸的相对浸出率分别为89.36％，75.44％，95.72％，其浸提效果与传统的热水浸提工艺(浸提温度90℃，浸提时间12.5min，茶水比1∶100)接近，游离氨基酸浸出率甚至更高； 2．超滤的工艺参数为料液温度35～40℃，操作压力0.1～0.12Mpa，既可提高膜通量，又可使茶多酚、咖啡碱、游离氨基酸的保留率较高，茶多酚、咖啡碱、游离氨基酸的保留率分别为80.17％、80.98％、90.77％。超滤后的茶汁清澈明亮，澄清度大大提高； 3．纳滤的工艺参数为料液温度20℃，操作压力0.6～0.7Mpa；反渗透的工艺参数为料液温度35～45℃，操作压力0.5～0.6Mpa，可根据不同的要求选择浓缩工艺是单独使用反渗透还是反渗透+纳滤的工艺组合。反渗透+纳滤的浓缩工艺对茶多酚、咖啡碱、游离氨基酸的截留率分别为98.23％、87.45％、85.28％； 4．包埋剂选择β-环糊精，其添加量为1.5％；抗氧化剂选择抗坏血酸，其添加量为0.04％； 5．高浓度无沉淀浓缩茶汁的主要生产工艺流程为：茶叫→粉碎，过筛(40～60目)→低温酶法萃取→抽滤→超滤→一次浓缩(反渗透)→二次浓缩(纳滤或反渗透)→添加包埋剂及抗氧化剂→超高温瞬时灭菌→无菌灌装→产品； 6．所得产品固形物含量达20％(Brix)，无沉淀，保持了乌龙茶原有的滋味和香气。更多还原

【Abstract】 In this paper, by using oolong tea as experimental material, we studied the technological process and technological parameters of producing concentrated tea juice, which was of high concentration and no sediment. We studied the technology and parameters of extracting tea and the adding quantities of entrapment agent and antioxidant by way of orthogonal experiments, and we researched the effects of different conditions of ultra-filtration, nano-filtration and reverse-osmosis on flux and main ingredients in tea juice, by which we acquired the technologies and parameters of ultra-filtrating and concentrating tea juice. The technological process of producing concentrated tea juice with high concentration and no sediment was made sure, which provided the reliable data and can be applied expand production after test successfully. The detailed conclusions as follows:1. The relative extracting rate of tea polyphenol. caffeine and amino acid respectively was 89.36%, 75.44%, 95.72% at 60℃ for 60 minutes with 0.04% cellulase and 140 times weight water. There was no obvious difference between the extracting effect with cellulase at low temperature and that with conditional extracting technology at high temperature (90℃, 12.5min, 1:100), the extracting rate of amino acid even higher;2. Not only high flux could be obtained, but also high retainable rate of tea polyphenol, caffeine and amino acid by ultra-filtration with working pressure of ultra-filtration membrane ranging from 0.1Mpa to 0.12Mpa and suitable temperature for tea juice ranging from 35℃ to 40℃. The retainable rate of tea polyphenol. caffeine and amino acid respectively was 80.17%, 80.98% and 90.77%. The tea juice was much clearer and,brighter than that before ultra-filtration;3. The working pressure of nano-filtration membrane is 0.6 ~0.7Mpa, suitable temperature for tea juice is 20℃. The working pressure of reverse-osmosis membrane is 0.5 ~ 0.6Mpa, suitable temperature for tea juice is 35 ~ 45 ℃. We could choose reverse-osmosis alone or connecting reverse-osmosis with nano-filtration as concentrating technology according to different demand.The retainable rate of tea polyphenol. caffeine and ammo acid respectively was 98.23%, 87.45% and 85.28% by concentrating connecting reverse-osmosis with nano-filtration;4.β -cyclodextrin was chosen as entrapment agent with 1.5%. Ascorbic acid was chosen as antioxidant with 0.04%;5. The technological process of producing concentrated tea juice with high concentration and no sediment was: tea → crushed and through sieve (size in the range of 40-60 mesh) → extracting with cellulase at low temperature - filtering at low pressure → ultra-filtration → the first concentrating (reverse-osmosis) → the second concentrating (nano-filtration or reverse-osmosis)→ adding entrapment agent and antioxidant → UTH sterilization - aseptic filling→ products;6.The concentration of concentrated tea juice could reach 20% (Brix) with no sediment, and it kept the original flavor of oolong tea.更多还原