Key Processing Technology And Antioxidant Activities Of Asparagus Fermented Tea

As a kind of food and medicine, Asparagus is regarded as a valuable material. The foreign studies have confirmed the asparagus’ functions for nutrition and health. Our country is one of the most important asparagus producers and exporters in the world. At present, the market supply of asparagus is given priority to fresh products, and processed products mainly include frozen asparagus and canned asparagus. Poor water resistance of asparagus and the lack of processing products greatly limit the development of asparagus industry. Therefore, it is of great significance to research and develop new asparagus processing products, and thus to extend the asparagus processing industrial chain, and expand the market both at home and abroad of asparagus. This study is based on the demand of asparagus processing industry and market which exist both at home and abroad, using asparagus as raw material and fermented tea processing technology as the method to research the key processing technology of asparagus fermented tea. Meantime, antioxidant activities of Asparagus fermented tea was investigated as well. These results will contribute a theoretical basis to the development of new products of sparagus fermented tea. The main results were as follows:1. Withering technology shows that frozen wilting can better preserve asparagus’ nutritional value. By withering in door and withering by forced draft, quality of asparagus fermented tea produced is very close. However, withering by freezing, asparagus fermented tea is better than the above two processing in taste, tang and leaf base. The parameters in withering process by freezing is as follows : temperature- 20 ℃, time 12 h.2. Fermentation process test showed that the fermentation temperature has a great influence on the quality score of asparagus fermented tea, followed by the fermentation time, and fermentation humidity has minimal impact on asparagus fermented tea. The best fermentation parameters obtained is as follows: fermentation temperature, 40 ℃, fermentation time, 6 h, and 80% relative humidity. In this condition, the asparagus fermented tea scored 72 points in sensory evaluation, with asparagus fermented tea being good shape, below leaves present dark red, sweet and wild taste, bright liquor color and good quality. These suggested that processing technology of fermented tea is feasible.3. Drying process test showed that processing asparagus tea fermentation by different drying methods has significantly differences between single components. In sensory evaluation, all factors reached the optimal results by drying treatment except liquor color, then followed by steam drying, and the microwave drying is the worst; Analysis results of component contents keep in basic consistent with sensory evaluation. The evaluation score for the senses is as follows: drying, 68 points, steamed green dry, 70 points, fried dry, 76 points, microwave drying, 62 points.4. Antioxidant capacity of asparagus powder, asparagus green tea and asparagus fermented tea was studied and results show that: the hydroxyl free radical scavenging ability: asparagus powder > asparagus fermented tea > asparagus green tea. Super oxygen anion free radical scavenging ability: asparagus fermented tea, asparagus green tea > asparagus powder; Reducing power: asparagus powder > asparagus fermented tea > asparagus green tea; DPPH scavenging ability: asparagus powder > asparagus fermented tea > asparagus green tea.