| Stems and leaves of sweet potato are main by-product during production of sweet potato crop, are the farm by-product in many provinces where sweet potato is widely planted. Stems and leaves of sweet potato are very abundant. General output per year is over 100 million tons. But stems and leaves of sweet potato are used as livestock feed or abandoned at present, so they lost their economic value. Stems and leaves of sweet potato contain large number of useful chemical component, in which, the biological active component is flavonoid. Flavonoid has the function of regulating immunity system, anti-cancer, anti-inflammation, and so on. The functional beverage that produced with extraction juice of stems and leaves of sweet potato, has medical and healthy action, the process of sweet potato stems and leaves will possess significant economic value and realistic significance, including making full useful of abandoned resource, improving economic value of sweet potato stems and leaves, promoting the economy development of the regions where sweet potato is widely planted, and enlarging the beverage market. In this study, stems and leaves of sweet potato are used as material and the functional component is extracted. Flavonoid, solid matter content and anti-oxidation ability in the extraction matter, are analyzed, biological activity of extraction matter is researched, and healthy beverage is prepared.Stems and leaves of sweet potato are used as raw material, is extracted with 95% ethanol and water, the extraction ratio of flavone in the sweet potato stems and leaves is 0.83% and 0.33% separately. Extraction matter of sweet potato stems and leaves possesses biological activity. Considering the source, actual produce cost and maneuverability, finally determine to extract stems and leaves of sweet potato with water.The single-factor test result of beverage quality shows granulated sugar content, citric acid content and extraction juice content of sweet potato have influence on beverage quality of sweet potato stems and leaves. Granulated sugar content is larger, sense grade of beverage trends to increase. Citric acid content increases, color and luster of beverage becomes dark gradually, acidity increases, and transparence lowers. Extraction juice content increases, color of beverage changes from snuff color to brown, transparence lowers, and sense grade lowers.0.05%β-cyclodextrin can conceal acerbity taste of beverage of sweet potato stems and leaves; 0.09% Chinese date essence can well improve the flavor of beverage; 0.06% xanthan can advance the stability of beverage.Based on single-factor test, beverage formula of sweet potato stems and leaves is optimized. The result shows, solid matter content of extraction juice has more influence on sense grade of beverage, the second one is granulated sugar content,β-cyclodextrin content has less influence. When extraction juice content is 13.8%, granulated sugar content is 6%,β-cyclodextrin content is 0.10%, citric acid content is 0.078%, xanthan content is 0.06%, maltol content is 0.002% and Chinese date essence content is 0.09%, sense grade of beverage is the highest, i.e. 79.Clearing free radical activity of beverage of sweet potato stems and leaves is analyzed, the result indicates, granulated sugar content has more influence on the activity of clearing free radical of beverage, the second one isβ-cyclodextrin content, solid matter content of extraction juice has less influence.To reduce the damage of active matter in the producing process, the influence of clearing free radical in the conditions of different producing process and acidity is studied, determine to adopt the treatment method, i.e. twain homogenization, pressure is 20 to 25MPa, sterilization condition is 100℃10min, pH value is 3.96, here, active matter in the beverage can keep well. More longer sterilization interval is, higher sterilization temperature is, the clearing free radical activity of beverage is much lower. Sterilization temperature has more influence on the activity of clearing free radical than sterilization interval. |
