【作者】 高佳；

【导师】 汤浩茹； 冯晓元；

【作者基本信息】 四川农业大学 ， 果树学， 2011， 博士

【摘要】 樱桃是落叶果树中成熟较早的水果,果实色泽艳丽,营养丰富均衡,尤其富含花色苷、褪黑激素、芥子醇、鞣花酸等化合物,具有调节睡眠、清除自由基、抗氧化、抗癌等多种功效。近年来,我国樱桃引种栽培面积不断扩大,已突破50万亩,鲜樱桃出现供过于求的局面。樱桃通常以鲜食为主,但因采收、贮藏和运输困难,造成大量鲜果腐烂损失。因此,发展樱桃加工产业是缓解产量过剩和减少鲜果损失的重要途径。本课题从15个甜樱桃和酸樱桃品种中筛选出适宜加工的酸樱桃品种CAB为试材,研究酶法制备酸樱桃清汁的工艺条件及影响果汁褐变的重要因素。主要研究内容和结果如下：对15个甜樱桃和酸樱桃品种果实形态性状、内在品质和内含物含量等指标进行差异显著性检验和相关性分析,并选出适宜加工的酸樱桃品种‘CAB’。结果表明,15个樱桃品种间各项指标均表现为不同程度的差异,其中以单果均重、总酸、还原糖、可溶性固形物、花色苷、总酚和Vc含量差异明显,表明樱桃果实大小、风味和内含物含量受品种影响显著。相关性检验显示,总酚与总酸含量(r=0.661,P<0.01)呈显著正相关；花色苷与还原糖(r=0.701,P<0.01)和可溶性固形物含量(r=0.584,P<0.05)呈显著正相关；果形指数与总酸(r=-0.589,P<0.05)呈显著负相关,与pH值(r=-0.619,P<0.05)呈显著正相关；单果均重与单核均重(r=0.869,P<0.01)呈显著正相关；果实汁液色泽与糖酸、可溶性固形物、花色苷和总酚呈显著相关。红色品种酸度、花色苷和总酚含量较高；黄色品种糖度较高,花色苷和总酚含量低。15个测试样品红色品种中果形较大,花色苷、总酚和Vc含量较高的品种有：‘早红宝石’、‘早大果’、‘早丹’、‘红灯’和‘美早’；黄色品种中糖酸比高,口感较好的品种有：‘红蜜’、‘佳红’、‘雷尼’、‘巨红’。酸樱桃‘CAB’总酸、总酚和Vc含量较高,适合用于加工。对酸樱桃品种‘CAB’冷冻鲜果果实成分分析表明,酸樱桃果实含有丰富的抗氧化活性物质花色苷和总酚,含有丰富的有机酸、果胶及营养元素K、Ca。对酸樱桃果实PPO酶学特性研究得出,邻苯二酚和焦性没食子酸均能作为酸樱桃PPO活性测定底物。酸樱桃PPO最适底物为邻苯二酚；最适反应pH值为7.5；最适底物浓度为0.1 mo1/L;测定时最适粗酶液体积为1.2 ml；最适温度为20℃；沸水热烫处理80 s该酶全部钝化。L-半胱氨酸、抗坏血酸、柠檬酸和亚硫酸钠四种抑制剂对酸樱桃PPO均表现出不同程度的抑制效果,以L-半胱氨酸和抗坏血酸用量最少,效果最好。当L-半胱氨酸添加浓度达到0.4 mmo1/L可将PPO活性降低97.4%。对酸樱桃果浆热烫灭酶效果,热烫后制汁品质变化进行研究得出,采用85℃水浴热烫处理,热烫时间3～4 min,中心温度大于50℃,可灭活酸樱桃果浆95%以上PPO和POD酶活力,并可增加榨汁后可溶性固形物、花色苷和总酚含量,提高制汁品质。酸樱桃较甜樱桃、苹果和桃PPO热稳定性差,酶活力低,更利于通过热烫处理抑制加工中酶促褐变的产生。初步研究了酸樱桃汁花色苷热稳定性。结果表明,酸樱桃汁的花色苷在高温下加热发生降解反应符合一级动力学方程。酸樱桃汁在45℃加热160 min后,花色苷损失13.1%,在90℃加热时花色苷损失47.5%,损失率明显增加。因此,酸樱桃汁在加工中应尽量采用低温和短时热处理。从7种商品果胶酶制剂中筛选出对酸樱桃果浆酶解效果较好的Ultra AFP果胶酶。在单因素实验的基础上,通过响应面分析确定了酸樱桃果浆酶解工艺条件：加酶量1.73 mL/kg,酶解温度46℃,酶解时间2.3 h。此条件下酸樱桃果浆酶解后出汁率为86.2%,透光率90.5%,浊度2.67 NTU。各因素对出汁率和浊度影响的大小顺序为果胶酶添加量>酶解温度>酶解时间,对透光率影响的大小顺序为果胶酶添加量>酶解时间>酶解温度。经回归分析和验证性实验表明,响应面法能较好的对酸樱桃果浆酶解工艺进行分析和参数优化,所得酶解工艺条件可行。酸樱桃清汁经95℃高温灭菌10 min并贮藏3个月后,检测果汁内菌落总数、霉菌、酵母和大肠菌群数均低于GB19297-2003《果蔬汁饮料卫生标准》中对果汁饮料相关要求,表明果汁灭菌效果好。对酸樱桃清汁贮藏稳定性进行研究,表明不同处理果汁在4℃下随着贮藏时间的延长,果汁亮度L*值均下降,颜色变暗,且贮藏初期的变化率大。将酸樱桃清汁在4℃贮藏3个月后,观察到酸樱桃清汁变得混浊,底部产生少量二次沉淀,包装瓶上粘附部分红褐色物质。单宁和单宁-蛋白质定性实验表明,混浊物主要是由单宁或单宁-蛋白质组成。经反复洗涤和冷冻干燥,得到二次沉淀含量为32.81 mg/L。通过对二次沉淀化学成分进行检测表明,酸樱桃清汁在贮存期间产生的二次沉淀主要成分是多酚类化合物、糖和蛋白质等。二次沉淀中含量最多的是酚类物质。更多还原

【Abstract】 Cherry is a deciduous tree in the first mature fruit, fruit colorful, nutritious balanced, especially rich in a variety of anthocyanins, melatonin, flavonoids, can regulate sleep, free radical scavenging, antioxidant, anti-cancer and other effects. In recent years, introduction and cultivation of cherry growing area, has exceeded 50 million mu, the situation of oversupply of fresh cherries. Cherry usually fresh mainly because of the harvesting, storage and transportation difficulties, causing heavy loss of fruit rot. Therefore, the development yield of cherry processing industry is to ease the loss of excess and an important way to reduce the fruit. The topics to sour cherry varieties CAB is used to study the process conditions of preparation clarification sour cherry juices for enzymic method and the influence of the important factors of fruit browning. The main contents and results are as follows:Differences in morphological trait, internal quality and main inclusions contents among fourteen main production cultivars of Prunus avium L. were invertigated. And all the indexes related were inspected. The result showed that:fifteen cherry cultivars for each indexes performance were significant for each other, average weight of simple fruit, total acid, reducing sugar, soluble solids, anthocyanins, total phenol and Vc contents contrast obviously. So the fruit size, palatability and inclusions contents significant with cultivars. By varieties correlation with tests showed that, the total phenol content of total acid is a significant positive correlation. Anthocyanins and reducing sugars and soluble solids content positively correlated. Shape index and total acid is a significant negative correlation, with pH value is a significant positive correlation. Both are heavy and mononuclear fruit weight is a significant positive correlation. Fruit juice colour and reducing sugar, total acid, soluble solids, anthocyanins and total phenolic significant correlation. Red varieties acidity, anthocyanins and total phenol content is higher; Yellow varieties, sugar higher, anthocyanins and total phenols content is low. Sour cherry CAB total acid, total phenol and Vc content is higher, can be used for processing.The sour cherry varieties CAB frozen fruit component analysis showed that it contains rich in antioxidant activity material anthocyanins and total polyphenol, contains, rich in organic acids, pectin and nutrition elements K, Ca.The activitiy of polyphenol oxidase (PPO) in sour cherry fruit were determined. The results showed that the optimum conditions were pH7.5,0.1 M substrate and 20℃for PPO assay. However, the PPO was inactivated in boiling water for 80s. Of the inhibitors tested, L-cysteine and ascorbic acid were the most effective.To explore the effect of blanching on PPO, POD enzyme activity, juice quality of sour cherry. Results showed that, using 85℃water bath, blanching time of 3-4 min, center temperature above 50℃, sour cherry pulp 95% PPO and POD inactivated, the soluble solid, juice anthocyanins, total polyphenol and Vc content is higer, protect color is obvious; Sour cherry than sweet cherry, apple and peach with lower PPO enzymatic activity and PPO thermal stability, be helpful for processing of enzymaticPreliminary studies sour cherry juice anthocyanins thermal stability. The results show that the sour cherry juice anthocyanins in hightemperatures will degradation, it conforms to the level 1 dynamic equation. Sour cherry juice in 45℃heating 160 min, anthocyanins loss of 13.1%, in 90℃heating loss of 47.5% anthocyanins, loss increased significantly. Therefore, sour cherry juice should as far as possible in the processing of low-temperature and short-term heat treatment.Sour cherry was treated with 7 different commercial pectinase on physical characteristics such as juice yield, transmittance, turbidity, soluble solid content, pH, pectin content and anthocyanin content. Ultra AFP was the best one. The optimization condition was determined by single factor experiments and Box-Behnken response surface methodology. It was indicated that all of the conditions significantly influenced juice yield, transmittance and turbidity. The optimum values were determined as follows:enzyme concentration 1.73 mL/kg, hydrolysis temperature 46℃and hydrolysis duration 2.3 h. Under these conditions, the experimental values of juice yield, transmittance and turbidity were 86.2%,90.5% and 2.67 NTU, respectively.Sour cherry clear juice high temperature sterilization by 95℃10 min and storage after 3 months, total numbers of colony, mould, barm and coli group were lower than that of the number of GB19297-2003 for fruit juice related requirement. Indicate that juice sterilization effect is good.Sour cherry juice on storage stability were studied, indicating that different treatment juice at 4℃with storage time, the brightness L* value of fruit decreased, the color darkens, and the initial rate of change of storage large. Sour cherry juice will be stored at 4℃after 3 months, sour cherry juice were observed to become turbid, the bottom of the second produced a small amount of precipitation, some bottles of red-brown material on the adhesion. Tannin and tannin-protein characterization experiments showed that the turbidity is mainly tannin or tannin-protein. After repeated washing and drying, are secondary precipitation content 32.81 mg/L. By testing the chemical constituents of secondary precipitation that sour cherry juice produced in the secondary precipitation during storage is the main component of polyphenols, sugar and protein. Secondary precipitation is the most abundant phenolic compounds.更多还原