Study On Separating Tea Polyphenols And Caffeine From Instant Tea By-Product With Ultrafiltration Membrane

In the production process of commercial instant tea, the tea juice was filteredby membranes and something was left in membranes. The retention was calledinstant tea by-product. There were some large particle, hardly dissolved matterand residue in it. At present, the instant tea by-product was not reutilizedeffectively as industrial waste liquid. But it contains many effective components,such as Tea Polyphenols and caffeine. So by using instant tea by-product as rawmaterial, Tea Polyphenols and caffeine had been separated with ultrafiltrationmembrane in the paper. The ultrafiltration membrane with different molecular weightcut off were selected, and then on the basis of the result, the treatment had beenoptimized.According to final yield of Tea Polyphenols and the content of caffeineof the factors, the optimum conditions for separating Tea Polyphenols andcaffeine were determined. It could be a base for researching into separating TeaPolyphenols and caffeine from instant tea by-product with ultrafiltrationmembrane in the production.The main results were as follows:1According to penetration, retention, purity, final yield of Tea Polyphenols,degree of membrane fouling of the factors, the paper investigated four kinds ofretention molecular weight ultrafiltration membrane, which were100kDa,50kDa,30kDa,10kDa.The solution was filtered with100kDa membrane, and thenconcentrated with30kDa membrane.The optimum conditions for separating Tea Polyphenols from instant teaby-product with ultrafiltration membrane were determined. The best operatingconditions of100kDa were as follows: solution concentration0.40%, temperature35℃,pressure0.138MPa. And the best operating conditions of30kDa were asfollows: temperature35℃,pressure0.138MPa.Under these conditions, the resultsof penetration, retention, content, degree of membrane fouling were13.22%、86.78%、78.51%、30.21%, respectively.2According to penetration, retention, content, degree of membrane foulingof the factors, the paper investigated four kinds of retention molecular weightultrafiltration membrane, which were100kDa,50kDa,30kDa,10kDa.Thesolution was filtered with100kDa membrane, and then filtered with30kDamembrane.The optimum conditions for separating caffeine from instant tea by-productwith ultrafiltration membrane were determined. The best operating conditions of 30kDa were as follows: solution concentration0.30%,temperature30℃,pressure0.138MPa.And the best operating conditions of10kDa were as follows:temperature35℃,pressure0.138MPa..Under these conditions, the results ofpenetration, retention, content of caffeine, degree of membrane fouling were90.89%、9.05%、10.25%、75.94%, respectively.The work would be a base for the future development of the reutilization ofwaste materials in the industry of instant tea.