The Effects of Biological Activities in Ukogi Leaves on the Quality of Cut Vegetables.

我们研究了利用Ukogi叶片的抗氧化和抗菌活性来提高鲜切蔬菜品质的可能性。枸杞子叶10%水溶性提取物对4种食物中毒细菌、E..大肠杆菌，蜡状芽孢杆菌，金黄色葡萄球菌，Sa。typhimurlum。用甲醇、丁醇和乙酸乙酯对水溶提取物进行进一步的分馏。含有皂苷的丁醇组分对四种细菌均有较高的抑菌活性。而含绿原酸的乙酸乙酯部分对大肠杆菌具有抑菌活性。1 .大肠杆菌和金黄色葡萄球菌；枸杞子提取物处理对切菜中维生素C含量的影响切菜中维生素C总含量约为未切鲜甘蓝的76%。研究了2%水浸提液、蒸馏水、1% NaCl、1%醋酸、1%柠檬酸和0.1%次氯酸浸泡30 min对白菜中总维生素C含量的影响。切白菜中总维生素C的含量不受枸杞提取物浸泡的影响。醋酸和柠檬酸溶液浸泡后，切白菜总维生素C含量由1/3显著降低至1/2.3。牛蒡提取物对切块蔬菜褐变的影响。牛蒡提取物分别用2%水溶性提取物、蒸馏水、1% NaCl、1%抗坏血酸、1%乙酸和1%柠檬酸浸泡10 min，观察切块后的外观色调随时间的推移。牛蒡提取物浸泡后的褐变程度与1% NaCl和1%柠檬酸浸泡后的褐变程度相同。这些结果表明，Ukogi提取物可用于切块蔬菜的保鲜。

We examined the possibility of utilization of antioxidative and antibacterial activities in Ukogi leaves for quality of fresh cut vegetables.1. Quantitative analysis of antibacterial activity in Ukogi leaves10% water-soluble extract of Ukogi leaves has the antibacterial activity against four food poisoning bactera, E.. coli, B. Cereus, St. aureus, Sa. typhimurlum. The water-soluble extract of Ukogi was further fractionated by methanol, butanol and ethyl acetate. The butanol fraction containing saponin has high antibacterial activity against all four bactera. While, the ethyl acetate fraction containing chlorogenic acid has the antibacterial activity against E.. coli and St. aureus.2. Effects of Ukogi extract treatment on vitamin C content in cut vegetableThe total vitamin C content in cut cabbege was about 76% of that in non-cut fresh cabbege. The effect of the 30 min soaking in 2% water-soluble extract of Ukogi, distiled water, 1% NaCl, 1% acetic acid, 1% citric acid and 0.1% hypochlorous acid on the total vitamin C content in cut cabbege was examined. The total vitamin C content in cut cabbege did not changed by the soaking in Ukogi extract. However, the total vitamin C content in cut cabbege soaked in acetic acid and citric acid solution were markedly reduced from 1/3 to1/2.3. Effects of Ukogi extract treatment on browning of cut vegetableThe color tone of appearance of cut burdock after the 10 min soaking in 2% water-soluble Ukogi extract, distiled water, 1% NaCl, 1% ascorbic acid, 1% acetic acid and 1% citric acid was observed with elapse of time. The degree of browning of cut burdock soaked in Ukogi extract was same that in 1% NaCl andl% citric acid.These results suggest that Ukogi extract is useful for freshness preservation of cut vegetable.