【作者】 韩玉杰；

【导师】 李志西；

【作者基本信息】 西北农林科技大学 ， 粮食、油脂及植物蛋白工程， 2003， 硕士

【摘要】 本研究采用酶解法提取枣汁，并与传统的热水浸提法进行了比较。对影响提汁和枣汁澄清的诸多因素进行了系统试验分析，并对提汁工艺和澄清工艺条件进行了试验优化。 研究结果表明：用热水浸提法制取的枣汁，其总糖提取量为原料重量的35.16％，Vc含量为13.12mg／100ml，可溶性固形物含量为7％；优化工艺条件为：浸提温度75℃，浸提时间8h，红枣：水=1:5。用酶解法提取枣汁时，单独使用果胶酶的理想工艺条件是：酶添量0.25％，温度50℃，酶解时间4h，pH值为3.5，5倍加水量，糖的提取量为原料重量的43.62％；在正交试验的基础上，采用三因素二次回归通用旋转组合设计试验结果表明，使用混合酶酶解提取枣汁的优化工艺条件为：果胶酶用量0.25％，纤维素酶用量0.03％，蛋白酶用量0.01％，酶解温度50℃，酶解时间4h，pH=4，5倍加水量；混合酶解法提取枣汁的总糖含量47.12％，可溶性固形物含量11％，总酸含量0.2438％，Vc含量19.34mg／100ml，枣汁颜色为枣红色，枣香浓郁，无苦味。与传统热水法相比，枣汁营养成分得到明显提高。 试验表明，澄清枣汁的最大透光率波长为620nm。枣汁在澄清试验中，低温澄清法对红枣原汁营养成分保存率较好，总糖保存率为97.35％，Vc保存率94.51％，透光率达到91.1％。明胶澄清枣汁，清汁透光率可达93.8％，但红枣汁营养成分损失较多，总糖损失率为9.02％，可溶性固形物损失率为11.96％，Vc含量损失3.82mg／100ml，总酸损失率为2.22％，明胶澄清枣汁的适宜工艺条件为：明胶用量4％(1％明胶水溶液)，澄清时间4h。蜂蜜澄清枣汁效果较差，清汁透光率只能达到90.4％，但蜂蜜澄清枣汁营养成分保存较好，可溶性固形物保存率为90.58％，Vc保存率为87.05％，总糖含量变化不明显。果胶酶澄清枣汁，其清汁透光率可达97.6％，清汁与原汁相比较，其营养成分含量有所减小。其澄清优化工艺条件是果胶酶用量0.1％，pH3.5，温度50℃。壳聚糖澄清枣汁透光率可达98.8％，清汁与原汁相比，Vc含量，可溶性固形物含量稍有下降，总糖含量变化不明显，其澄清优化工艺条件是壳聚糖用量3％(1％壳聚糖醋酸溶液)，温度45℃，pH3.5。 红枣清汁贮藏过程中，在低温条件下(0℃左右)，红枣汁透光率基本保持不变；常温下，有明显的下降趋势。红枣汁中Vc含量在低温下比常温下下降的幅度小。利用不同澄清方法澄清的红枣汁在低温或常温条件下贮藏一段时间后，均有少量沉淀出现。用壳聚糖澄清的枣汁在低温下贮藏6个月后出现少量沉淀。更多还原

【Abstract】 In this paper, the measures for extracting jujube juice with enzymes were studied, and the comparisons between the enzyme methods and hot water method have been made. Some factors influencing the extraction efficiency and the clarification results were analyzed systematically. The extraction and clarification conditions were optimized.The experiments results showed that the optimal extraction conditions with hot water were that the rate added water to jujube pulp was 5 to 1, the incubation temperature and time was 75* and 8h separately, the jujube sugar extraction efficiency was35.16% account for jujube pulp weight, the vitamin C content in extracted juice was 13.12mg/100ml, the solid material was 7%. The optimal extraction conditions with pectinase were that the added pectinase should be 0.25% account for jujube pulp, and the water used in extraction should be 5 times of jujube pulp, the extraction should be performed at 50* of incubation temperature for 4h, the extraction efficiency of jujube sugar was 43.62% account for the weight of jujube pulp.The effects of incubation temperature, time and pH value on the extraction efficiency of mixed enzyme methods were studied by means of the methods of orthogonal experiments, after that, a current, rotational and combination design of quadratic regression method was used and the results showed that the optimized conditions should be performed at 50℃ of incubation temperature for 4h at pH 4, the sugar extraction efficiency was 47.12% account for the weight of jujube pulp, vitamin C content was 19.34 mg/100ml, solid materials was 11%. The extracts was bright and possessed strong jujube smell and good taste. The extraction efficiency under the enzyme treatments was higher than that under the hot water treatment.The experiment results also showed that clarified juice had the maximal transmittance at 620nm , and the low temperature method for clarification was better for nutrients preservation, the total sugar remains was 97.35%, Vc remains was 94.51%, and its transmittance was 91.1%. Adding 4% of gelatin and treated for 4h, the nutrients in jujube juice were destroyed at large extent, and the transmittance of the jujube juicereached 93.8%, the total sugar lost 9.02%, the solid materials lost 11.96%, Vc lost 3.82mg/100ml and the total acids lost 2.22%. Although the transmittance of the clarified jujube juice with honey can only reach 90.4%, the preservation of juice nutrients were very good. When the clarification was done with 0.1% of pectinase at 50℃ and pH 3.5, the transmittance of the jujube juice was higher. The results indicated that the effect of chitosan for clarification was the best, the transmittance of the jujube juice reached 98.8%, the total sugar content was similar to that of untreated juice , the solid materials and Vc lost little more than that of untreated juice, the optimal conditions for chitosan clarification were adding 3% chitosan at 45℃ and pH 3.5 .The transmittance of the clarified juice keeped the same after storing for 7 months at low temperature, but a remarkable decreasing trend was appeared after 3 months’ storage at ambient temperature. The destructing degree of Vc was much smaller at low temperature than at ambient temperature. The clarified juice treated with chitosan has little sediment at low temperature during the storage period.更多还原