Research On Extraction And Purification Of Edible Theanine And Quality Control

Theanine is a unique amino acid in tea. Beside its graceful taste, theanine is beneficial to human health with its physiological effects. As food additives or functional food, theanine will be have greater development prospects in the field of food. Currently, industrial production of theanine technology is relatively week, especially the domestic preparation of edible theanine is shortfall. And it has become a limit to further promote the theanine application of the most important factor. So it has important economic and sociological significance to establish preparation of edible theanine with indepentent intellectual property rights. This discussion group is dedicated to research and develop on an technology of edible preparation theanine to suit the industrialized production. In preliminary studies, we have successfully established an edible theanine synthesis by microbial transformation and prepared theanine transformation solution with high concerntrations of natural L-theanine. This study will research these contents: 1.To establish a technology of extraction and purification of edible theanine which is suitable to purification theanine of microbial transformation, in order to complete the production of edible theanine by microbial transformation. 2.To draft the quality standards(to try out) about edible theanine in order to provid evidence for quality control. 3. To analyse the product quality, and sum up product quality-related critical contron points in the process of microbial transformation and extraction & purification. The main results were follows: 1 .To establish the extraction and purification technology of edible theanine.This process is divided into five parts: theanine transformation solution pretreatment, ion exchange process, concentration eluent process, crystallization process and lyophilization.Theanine transformation solution pretreatment: to selecte theanine transformation solutionⅠas raw in production, and adding acid/heating to pretreat. The specific conditions are to add acid in Theanine transformation solution in order to adjuste to pH about 3.0, and to heat to 80℃. And adding 0.2% activated carbon for decolorization with stirring for 30min. After pretreatment the OD650 of transformation solution reduced around 0.02 (under this conditions the extracted yield of theanine generally higher than 90%), the expenses of theanine less than 1%.Ion exchange process: determine the optimal conditions of ion exchange is to choose H+-type 732 cation exchange resin, the resin volume and Theanine ratio of 25mg:3mL, the sample solution pH of 3.0, the column flow rate 4.0BV/h, elution liquid of ammonia solution(1.5mol/L), elution flow rate 2.0BV/h. The extraction yield of theanine in ion exchange is more than 95%.Concentration eluent process: the theanine concentration is about 20mg/mL in the collecting eluent and obtained 600mL to boil at 100℃for 30min. Then the theanine eluent was concentrated to concentration 200mg/mL.Crystallization process: to select the concentration of 200mg/mL theanine eluate concentrated and adding four times the volume of 95% ethanol at 4℃refrigerator for crystallization overnight. This process can get the recovery rate of 75%. To dissolve the crude theanine to concentration 250mg/mL with distilled water, filtering and removeing insoluble impurities in order to get the higher purity of theanine solution.Lyophilization: to select the concentration of 250mg/mL theanine solution after filtering, and pre-freeze which under -40℃for 4h and control the vacuum in 1.1Pa. After sublimation and drying, to get theanine products with white powder, and product purity of 99%.2 .To draft the quality standards(to try out) about edible theanine;To determin product quality-related critical contron points in the process. Having drafted the quality standards of edible theanine(to try out), in which contain four main substances such as Character test, identification test, chloride, heavy metals, arsenic salt inspection, microbial limit test. And Introducing 4 product quality-related critical contron points in the process, and making clear requirements.This study established the technology of extraction and purification of edible theanine, and clear the process from theanine transformation solution pretreatment→ion exchange→concentration eluent→crystallization→lyophilization. And this technology is the downstream process of microbial transformation. The production of theanine prepared has high purity, generally about 99%, the extraction yield of theanine is generally more than 95%, and the crystallization yield of theanine is about 75%, so the theanine yield in the whole process of extraction and purification is more than 71%. This production operation is simple, economic, in short production cycle, and production of high efficiency, is suitable for industrial preparation of edible theanine. The standard about the edible theanine quality (to try out) is more comprehensive and clear. The product quality-related critical contron points in the process lead standard production process.