A Study On Products And Characteristics Of Stevia Lactic Acid Fermentation

Stevia redaudianaBertohi origins in northeastern South America Paraguay border with Brazil joining with the mountains of Oman, and it has been introduced around the world by now. It contains14kinds of trace elements and32kinds of nutrients, so it is not only an excellent source of sugar but also a good source of nutrition. Its leaves has plenty of functions,such as regulating blood pressure, soften blood vessels, lowering blood fat, lowering blood sugar, urine, antibacterial bleeding, ease pain, weight loss, beauty, nourishing yin and promoting the secretion of body fluid, help digestion, promote pancreas, developing the functions of spleen and stomach and the efficacy of detoxification. But now the main research for stevia are focusing on the Stevioside’s extraction, research and application, and the application of the stevia plant were rarely reported. In this paper, the use of stevia fermented by lactic acid bacteria fermented stevia juice and fermented stevia leaf tea. This approach improves the utilization and has a broad application prospects, which has a great significance to promote the development of China’s food industry. Then the main results are as follows:Firstly is the research for condition of fermented stevia juice. Key Technology of fermented stevia juice process to pH and stevioside content as an indicator,extraction process using orthogonal experiment, response surface methodology optimize the fermentation conditions of Stevia leaf juice and the selection of enrichment process and pH. Finally identified the optimum extraction conditions of Stevia leaf juice are:extraction time is35min, extraction temperature is80℃, feed water ratio is1:8. Fermentation conditions for diammonium phosphate dosage added is0.2%, inoculation is4%and fermentation time is2d. Conditions are concentrated concentration temperature is60℃, vacuum degree-0.1mpa, concentrated in vacuo and evaporation under conditions of a concentrated percentage of40%. The results show that under this condition, pH of4.55and stevioside content of18.06mg/ml.The fermented juice is20-50times the relative sweetness of sucrose, which is directly used in the beverage industry sweeteners.Secondly is the research for fermented Stevia leaf tea’s processing conditions.The experimentselects Lactobacillus, Streptococcus thermophilus and Lactobacillus bulgaricus as fermentation bacteria, using orthogonal experiment with combining sensory evaluation methods, optimizingthe fermentation time, bacteria inoculation and fermentation materials. The results showed that:the strains was Lactobacillus, fermentation time was2d, inoculation amount was10%.Determined the conditions for the fermentation materials are:water added is0.1%, sucrose added is3%, potassium dihydrogen phosphate added is0.1%, yeast extract added is0.2%.This kind of tea does not have abnormal odor that stevia has, but has normal smell of tea and sweet taste.Thirdly is Comparative research for unfermented stevia leaves Products and fermented stevia leaves Products. Isolation and identification of the volatile flavor compounds in unfermented stevia leaves Products and fermented stevia leaves Products by SPME-GC-MS. It was identified that the total contents and the main substances of volatile components of unfermented stevia products were significantly higher than fermented stevia products. Compared with unfermented Stevia products, fermented Stevia products can eliminate the grassy smell which comes from itself and increase refreshing flavor.