Effect of kafirin protein coating on sensory quality and shelf-life of 'Packham's Triumph' pears during ripening

BACKGROUND: Pears are exported in large quantities from South Africa, resulting in large revenues. Minimisation of quality losses once the fruit has reached the export destination is as important as following strict export and distribution protocols. Kafirin can form edible films. In this study an edible coating made from 20 g kg^?1 kafirin coating solution was applied as a postharvest treatment to retard quality deterioration of ‘Packham's Triumph’ pears during storage at the typical ripening temperature (20 °C). Changes in physicochemical and sensory quality were monitored over a period of 24 days. RESULTS: The kafirin coating was unable to retard the onset of ripening but decreased the respiration rate and retarded the progression of senescence. However, moisture loss was exacerbated in the kafirin‐coated fruit during ripening at 20 °C, especially towards the end of the shelf‐life. CONCLUSION: The kafirin coating extended the eat‐ripe quality of the pears by 1–2 weeks. However, the appearance of the fruit was unacceptable after 14 days of storage in terms of wrinkled skin. Further work is needed to improve the water barrier properties of the kafirin coating by incorporating a wax or triglyceride into the coating formulation or more simply by applying a kafirin coating to waxed fruit. Copyright © 2011 Society of Chemical Industry     

Structural characterization and antioxidant activities of 2 water-soluble polysaccharide fractions purified from tea (Camellia sinensis) flower

Abstract: The water‐soluble crude polysaccharide tea flower polysaccharide (TFP), obtained from tea (Camellia sinensis) flower by boiling‐water extraction and ethanol precipitation, was fractionated by Sephadex G‐100 column chromatography, giving 2 polysaccharide fractions termed TFP‐1 and TFP‐2. The structural features of TFP‐1 and TFP‐2 were investigated by high‐performance liquid chromatography (HPLC), gel‐permeation chromatography (GPC), rheometer, infrared (IR) spectra, nuclear magnetic resonance (NMR) spectroscopy, atomic force microscope (AFM), and scanning electron microscope (SEM). Results indicated that TFP‐1 was composed of glucose: xylose: rhamnose: galactose = 1.0:1.2:0.81:0.98 with a molecular weight of 167.5 KDa, while TFP‐2 comprised glucose: xylose: rhamnose: arabinose = 1.0:0.76:2.3:2.3 with a molecular weight of 10.1 KDa. The ¹H NMR revealed that TFP‐1 contained α‐L‐Rhap, α‐D‐Galp, α‐D‐GalpNAc, α‐D‐Xylp, α‐D‐Glcp, and β‐D‐Glcp residues, while TFP‐2 was illustrated to have α‐L‐Rhap, α‐L‐Arap, α‐D‐Xylp, α‐D‐Glcp, and α‐D‐GlcpNAc residues. Antioxidant activities of these fractions were investigated using various in vitro assay systems compared with ascorbic acid. In conclusion, TFP‐2 exhibited the higher antioxidant activities and could be explored as a novel potential antioxidant. Practical Application: At present, commonly low‐grade tea is preferred to extract the tea polysaccharide, to take full advantage of tea flower resource to extract polysaccharides can greatly reduce the cost of tea products. Thus, the search for plant‐derived biomaterials from this study could generate natural value‐added products from underutilized tea plant waste and used as a medicinal agent against chronic health problems, such as cancers, aging, and atherosclerosis caused by reactive free radicals that produced from oxidation.     

超声波辅助提取石榴花色素工艺研究

该文研究了石榴花中色素的超声波辅助提取技术,研究了超声波功率、提取时间、频率、料液比和提取次数对石榴花色素提取效率的影响.结果表明,石榴花色素超声波辅助提取最佳条件为功率80W,提取时间50min,频率80kHz,液料比1∶15,提取次数2次.在该最佳条件下,石榴花色素提取效率为95％.     

茶树花对大鼠肥胖病和高脂血症预防作用研究

目的:研究茶树花对大鼠肥胖病和高脂血症的预防作用.方法:将40只大鼠分为5组,即:基础饲料组、高脂饲料组、茶树花2.5％、5％、7.5％3个剂量组.每两天测量体重和摄食量1次,24d后断头取血,测定总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDL-C)、高密度脂蛋白胆固醇(HDL-C).取体脂(肾及睾丸周围脂肪)称重.结果:与基础饲料组相比,高脂饲料组大鼠体重、脂肪系数、TC、TG、LDL-C、动脉粥样硬化指数(AI)显著增加;3个剂量茶树花添加组大鼠体重、脂肪系数、TC、TG、LDL-C、AI均低于高脂饲料组,且呈显著或极显著差异;中、高剂量组大鼠体重、脂肪系数、TC、TG、LDL-C、HDL-C、AI与基础饲料组无明显差异.结论:茶树花对大鼠肥胖病和高脂血症有一定的预防作用,3个剂量组中添加5％茶树花效果最好,可开发为降脂减肥的纯天然保健食品.     

野生黄刺玫花总黄酮的提取工艺优化

目的:优化野生黄刺玫花总黄酮提取工艺条件。方法:以野生黄刺玫花为原料、总黄酮得率为评价指标,采用L9(34)正交试验设计,考察乙醇体积分数、料液比、提取时间和提取温度对黄刺玫花总黄酮提取效果的影响。结果:野生黄刺玫花总黄酮的最佳提取工艺条件为75%乙醇、料液比1:30(g/mL)、提取1h、提取温度75℃,总黄酮得率32.77mg/g。结论:优选得到了野生黄刺玫花总黄酮提取工艺,稳定性良好。     

七种日韩梨果泥贮藏稳定性研究

以丰水、华山、南水、大果水晶、圆黄、黄金、新高梨为原料,通过检测梨泥的pH值、还原糖、氨基态氮、5-羟甲基糠醛(5-HMF)、可溶性酚和总色差的含量,对7种日韩梨果泥贮藏稳定性进行研究。结果表明：在贮藏过程中,7种梨泥贮藏稳定性由高到低依次为圆黄、华山、大果水晶、丰水、南水、新高和黄金。圆黄梨泥的还原糖(9.6%～7.2%)和氨基态氮(4.2～3.5mg/100mL)含量较高,5-HMF(0.6～1.1mg/100g)和可溶性酚(3.3～2.1mg/g)含量较少,pH值(3.3～3.4)和色差值(22.7～39.9)较低,贮藏稳定性优于其他品种。     

杜鹃花色素的分离与鉴定分析

运用特征性颜色反应、高效液相色谱(HPLC)和质谱(MS)等技术对浅红色毛叶杜鹃(R. championae Hook)花瓣花色素提取液进行初步鉴定和含量测定。结果表明：该杜鹃品种的花色素含有非红色的黄酮类化合物,主要有黄酮、黄酮醇、二氢黄酮等色素,其中还有部分酚类色素。高效液相色谱(HPLC)显示杜鹃花色素提取液至少包括39种物质,其中有7种可以确定,分别为杨梅黄素3-半乳糖苷、槲皮素3-半乳糖苷、槲皮素-鼠李糖苷、槲皮素3-葡萄糖苷、锦葵素3-阿拉伯糖苷-5葡萄糖苷、杨梅黄素3-鼠李糖苷、绿原酸。利用紫外分光光度法测得杜鹃花瓣中花色苷的含量为131.025mg/100g,总黄酮含量为10.68mg/g。     

抗坏血酸处理对鲜切水晶梨营养成分及褐变的影响

采用0.025、0.05、0.075 mol/L3种不同浓度的抗坏血酸处理鲜切梨果实,研究其在10℃贮藏过程中的褐变及其营养物质的变化。结果表明,抗坏血酸处理能抑制鲜切梨果实PPO活性.减轻果蔬表面褐变程度,延缓果实的硬度和Vc含量的下降速度,提高鲜切梨果实的营养价值和外观品质。     

HPLC-ELSD analysis of 18 platycosides from balloon flower roots (Platycodi Radix) sourced from various regions in Korea and geographical clustering of the cultivation areas

An effective HPLC method to analyse platycosides from the balloon flower root was developed using ELSD. The optimum resolution of the platycosides was achieved on an ODS column with gradient elution of eluent A, 30 mM ammonium acetate buffer (pH 4.81): methanol: acetonitrile = 75:5:20 (v/v/v), and B, 69:5:26 (v/v/v). Amongst 18 platycosides, platycoside E showed the highest content, followed by polygalacin D₂ and 3″-O-acetylplatyconic acid A. The sum of these three compounds was recommended for quality control of balloon flower root for medicinal purposes. The samples could be clustered into groups based on platycoside content. Group I, characterised by a high concentration of platycosides, was located near the west coast of Korea, whereas group II, characterised by a low concentration of platycosides, was located inland or in mountainous area. The method could be used to control the quality of balloon flower root.     

顶空固相微萃取- 气相色谱/质谱法分析霸王花挥发性成分

目的：探索分析霸王花挥发油化学成分的方法。方法：采用聚二甲基硅氧烷萃取头室温顶空微萃取20min、初始柱温60℃、程序升温至250℃、进样口温度250℃的气相色谱条件,EI 离子源、电子能量70eV 的质谱条件进行气相色谱/ 质谱法分析。结果表明：共鉴定出49 种化合物,主要挥发性成分及其含量为倍半萜及其含氧衍生物(27.78%)、脂肪族化合物(25.14%)、酯(14.40%)、2,6- 二叔丁基对甲酚(10.08%)和硅氧烷类化合物(6.27%)。结论：无溶剂的顶空萃取- 气相色谱/ 质谱联用技术可作为霸王花挥发性成分分析的有效方法。