Health Drinks Product Development Of The Leaves From Sweet Potato

Sweet potato(Ipomoea batatas LAM.),is one of the four primary crops in China.As a vegetable,its leaves have abundant nutritional value and have enjoyed the"vegetable empress" reputation in the world.Studies have shown that sweet potato leaves hold a lot of biologically active ingredients,which have antioxidant,anti-tumor and other antibacterial activities.However,there is little research pay attention to sweet potato leaves.In this thesis,the sweet potato leaves after sweet potato harvest were chosen as the material.In order to solve some problems in sweet potato leaves juice processing,metal ions and pectinase were used to improve the quality of sweet potato leaves juice.The functional active components of sweet potato leaves juice were also discussed.The main contents and conclusions were as follows:1.The result from single factor and orthogonal analysis of variance showed that the order of effect of factors on sweet potato leaves color-preserving was:zinc acetate concentration)blanching temperature and ascorbic acid concentration)blanching time>NaCl concentration.The optimal process for sweet potato leaves color-preserving was blanching temperature 80 ?,blanching time 2min,zinc acetate concentration 0.04%,ascorbic acid concentration 0.07%,NaCl concentration 1.5%.The E value of sweet potato leaves juice was lower at this processing condition and the color-preserving effect was significantly.The PPO activity of at different blanching time was also studied,the result displayed that the PPO activity reached a lower level after blanching time more than 2 min,which can control sweet potato leaf browning effectively.2.The pectinase was used to improve juice yield of sweet potato leaves,three single factors experiment-water addition,dosage of pectin enzyme and pectin enzyme time-was carried out respectively,which revealed the effect of each factor on sweet potato leaves juice yield.By orthogonal test,the optimum conditions for the extract of sweet potato leaves juice were found:water addition 9 double,dosage of pectin enzyme 100mg/g,pectin enzyme time 2h.The juice yield of sweet potato leaves was 75%at the optimum conditions.3.By single-factor and orthogonal test,the optimum conditions for the sweet potato leaves juice process were found:the dosage of sweet potato leaves normal juice 12%,sugar dosage 10%,citric acid dosage 0.06%.The taste and flavor sweet potato leaves juice beverage were wonderful,which popular in consumers.In the view of color and stability,gelatin was added as a stabilizer and the optimum additive dosage was 0.4%.Owning to sweet potato leaves juice beverage belonged to low acidity beverage,the sterilization for the process was 121 ? for 20 min.The result of bacteriological examination showed that total bacterial count was 200 per 1 mL and coliform bacteria was not detection,which mean beverage was in good health condition.4.Accurate quantitative functional ingredients for Sweet potato leaf juice by HPLC:Quercetin content is 15.63 mg/100 g;Kaempferol content was 7.92 mg/100 g;Myricetin content was 4.69 mg/100 g.