【作者】 刘英；

【导师】 陈健初；

【作者基本信息】 浙江大学 ， 农产品加工与贮藏， 2007， 硕士

【摘要】 四季柚(Citrus grandis Osbeck cv．Siji you)是浙江省苍南县的特色水果，目前主要用于鲜食，产品附加值低，柚果实中的功能性成分得不到充分利用，所以本试验以四季柚为研究对象，对不同时期果实各个组织部位的主要功能成分进行了初步研究，并对柚皮苷的超声波提取工艺进行了优化，为四季柚的综合开发利用提供了理论依据。试验结果如下：1．果实各组织部位在不同时期所占比例不同，以贮藏9周为转折点，可食率先上升后下降，果皮的变化则与之相反。未成熟果汁的基本营养指标都低于成熟期，酸度高于成熟期的果汁。贮藏5周后，可溶性固形物、总糖和还原糖含量达到峰值，随着贮藏期的延长，呈下降趋势。糖酸比和固酸比都在贮藏13周后达到最高。蛋白质在贮藏过程中较稳定，仅在贮藏13周时出现峰值。果汁的水分含量与可溶性固形物含量、总糖、还原糖呈显著负相关(p＜0.05)，出汁率与糖酸比和固酸比成显著负相关(p＜0.05)。2．对不同时期果汁中功能成分进行分析，得出总酚含量在贮藏5周后达到最高(45.71mg/100mL)，成熟期的果汁中总酚含量最低。黄酮类成分中，新橙皮苷仅在未成熟果汁中检出(3.94 mg/L)；橙皮苷在成熟果实的汁液中含量最高(25.03 mg/L)，随着贮藏时间的增加而降低，贮藏13周后检测不到；柚皮素在果汁中未能检出；柚皮苷在未成熟果汁中含量最高(28.46mg/L)。柠檬苦素类物质中，诺米林在未成熟果汁中的含量最高(46.30mg/L)，柠檬苦素在贮藏13周后达到最高(109.74mg/L)。3．对不同时期四季柚果皮不同组织部位主要黄酮成分的分析得出，果皮的各个组织中均含有柚皮苷，柚皮苷在各个皮层分布量为：中果皮＞囊衣＞外果皮，未成熟囊衣中柚皮苷含量最高，为40.68 mg/g。柚皮素仅存在于未成熟果皮中，且在外果皮中的含量最高(137.1μg/g)，而橙皮苷和新橙皮苷均未检出。柠檬苦素和诺米林在囊衣中含量最高，其次是外果皮、中果皮。未成熟果实囊衣中柠檬苦素和诺米林含量，分别高达515.9和346.1mg/100g干样。总酚在中果皮中含量最高，囊衣中最低，都在贮藏9周后，柚皮苷含量升高。而囊衣中柚皮苷含量的升高则在贮藏13周后。4．通过FRAE DPPH，ABTS三个抗氧化体系，对四季柚果皮不同组织部位提取物进行抗氧化能力体外评价，得出FRAP和DPPH体系测定的抗氧化能力为：外果皮＞中果皮＞囊衣，而ABTS体系测定的结果为：中果皮＞外果皮＞囊衣。不同皮层提取物在三个不同抗氧化体系中所表现出的抗氧化能力也不同，FRAP体系和DPPH体系对抗氧化效果的评价上具有一致性，而ABTS体系抗氧化能力的评价则与柚皮苷含量显著相关(p＜0.05)。5．探讨了Vc和总酚对果汁提取液抗氧化能力的贡献，得出在不同抗氧化体系中，Vc对抗氧化的贡献率也不同，在DPPH体系中，Vc对抗氧化的贡献率达到50.38％。四季柚贮藏5周后其果汁抗氧化能力最高。在ABTS体系中，总酚与其抗氧化能力成正相关(p＜0.05)。在去除Vc影响后，成熟期的果汁抗氧化能力最低。总酚含量与ABTS体系和FRAP体系测定的抗氧化能力都呈正相关(p＜0.05)。6．通过单因素试验考察超声温度、超声时间、超声功率、料液比和乙醇浓度对柚皮苷提取率的影响，在此基础上用正交试验进行工艺参数的优化，结果为：当提取时间为1h时，超声波辅助提取柚皮苷的较优工艺条件为超声温度50℃，料液比1∶30，乙醇浓度50％，超声功率25W。在此工艺条件下所得的柚皮苷提取率为5.437％。更多还原

【Abstract】 Siji pummelo (Citrus grandis Osbeck) is considered to be a characteristic Fruit inCang Nan which lies in Zhe Jiang province. Nowadays it is mainly for eating and itsfunctional components has not been explored, so we studied on the main functionalcomponents of different tissues in different periods. In addition, the optimum ultrasonicextracting conditions of naringin from Siji pummelo peel were studied. The main resultswere as follows:1. Different pummelo tissues in different periods were in different porportion. Theedible rate increased at storing for 9 week and then declined, while the change ofpeel was opposite. Nutrition indexes of pummelo juices in immature period werelower than in mature period, on the contrary, titrable acidity was higher. The solublesolid, soluble total suger and reducing suger reached the summit after storing 5weeks, and declined with storage time increasing. The suger acid ratio and solid acidratio were the highest after storing 13 weeks. Protein changed little during thestoring, only reached the summit at 13th week. Water content of pummelo juiceswere signifiant negative correlation (p＜0.05) with soluble solid content, total sugerand reduced suger. Juice yield had signifiant negative correlation (p＜0.05) with thesuger acid ratio and solid acid ratio.2. After analysing the functional components in pummelo juice for different periods, wefound that total phenols content reached 45.71mg/100mL after storing 5 weeks, andlowest in the matured pummelo juice. Neohesperidin of 3.94 mg/L was only foundin immature pummelo juice. Naringin content was 25.03 mg/L in matured pummelojuice, declined as the storing time going and can’t be detected after storing 13 weeks.Naringenin hadn’t been found in pummelo juice. Naringin reached the summit28.46mg/L in immature pummelo juice. Nomilin reached the summit 40.30mg/L inimmature pummelo juice. While limonin reached 109.74mg/L after storing 13weeks.3. After analysing the main flavonoids in different tissues of Siji pummelo peel in different periods, we found naringin existed in each tissues, the distributing contentwere mesocarp＞pericarp＞epicarp, it reached the summit 40.68 mg/g in immaturepericarp. Naringenin only existed in immatured peel and as high as 137.1μg/g inepicarp, but both hesperidin and neohesperidin weren’t detected. Limonin andnomilin had a high content in pericarp, next is epicarp and mesocarp. The content ofLimonin and nomilin reached 515.9 mg/100g and 346.1mg/100g respectively inimmature fruit’s pericarp. The content of total phenols reached the summit inmesocarp and the lowest in pericarp but both’s naringin content increased afterstoring 9 weeks. For naringin in pericarp, its increasing happened after storing 13weeks.4. To evaluate the antioxidant activities of different extracts, we used DPPH, FRAP andABTS assays. The antioxidant results of DPPH and FRAP showed that, mesocarp＞epicarp＞pericarp. And the results of ABTS showed that, epicarp＞mesocarp＞pericarp. The different extracts of tissues from pummelo peels showed differentantioxidant activities under three systems, the antioxidant capability of FRAP andDPPH were consistent, whereas the antioxidant effect of ABTS had a significantcorrelation with the content of naringin (p＜0.05).5. We also discuss Vc and the total phenols’ contribution to the antioxidant activities ofpummelo juice extract, we found Vc’s contribution rate to antioxidant capability wasdifferent in different assay. In DPPH assay, Vc’s contribution rate reached 50.38%.The antioxidant effect of pummelo juice reached the summit after storing 5 weeks.In ABTS assay, total phenols had a significant correlation with antioxidantcapability (p＜0.05). After the content of Vc deducted from pummelo juice,antioxidant capability declined to the minimum of the mature juice. Total phenolshad a significant correlation with antioxidant capability determined by ABTS andFRAP assays.6. The effects of ultrasonic temperature, time, power, solid-liquid ratio and ethanolconcentration factors on the naringin extraction rate had been investigated bysingle-factor experiments. Based on above works, the orthogonal layout method was used in the optimization of technological parameters. The result showed that whenextraction time was 1 hour, the optimum conditions of ultrasound extraction onnaringin were as follows: ultrasonic temperature was 50℃, solid-liquid ratio was1:30, ethanol concentration was 50% and ultrasonic power was 25w. By the aboveconditions, the extraction rate of naringin was 5.437g in 100g dry pummelo peels.更多还原