橘皮类黄酮的分离、纯化及结构鉴定研究

柑橘皮内含丰富的类黄酮化合物,具有多种生物学活性,受到医药、食品等行业的关注。本文通过硅胶、聚酰胺及Sephadex HL-20柱对温州蜜桔皮中类黄酮化合物进行反复分离纯化,得到5种类黄酮单体。采用LC-ESI-MS、1H-NMR和13C-NMR及红外光谱等技术对其结构进行鉴定。鉴定结果:化合物A,3,5,6,7,8,3’,4’-七甲氧基黄酮;化合物B,5,6,7,8,4’-五甲氧基黄酮;化合物C,3-羟基-5,6,7,8,3’,4’-六甲氧基黄酮;化合物D,5,6,7,8,3’,4’-六甲氧基黄酮;化合物E,橙皮素芸香糖苷。其中,化合物C是从温州蜜桔皮中首次发现的。     

Molecular Mass and Solubility Changes in Pectins during Storage of Satsuma Mandarin Fruits (Citrus unshiu Marc.)

Soluble pectins in satsuma mandarin fruits stored at 5°C were investigated by High Performance Gel Filtration chromatography. Pectins isolated from the flavedo, albedo, membranes and juice sacs were separated into four fractions. The hydrochloric acid soluble pectin fraction in each part was the highest and decreased slightly while the water-soluble pectin increased slightly. The avergae molecular weights of the fractionated soluble pectins in juice sacs were nearly constant but those in flavedo, albedo and membranes decreased as storage time increased. The ratios of higher molecular weight of water soluble and ammonium oxalate-soluble pectins in all the four parts and those of hydrochloric acid soluble pectin in flavedo and membranes decreased as ratios of lower molecular weight fractions increased.     

Purification and characterisation of basic ascorbate oxidase from satsuma mandarin (Citrus unshiu Marc)

Basic ascorbate oxidase of the multiple enzyme forms existing in young fruit of satsuma mandarin (Citrus unshiu Marc) has been separated and subsequently purified to electrophoretic homogeneity through (NH₄)₂SO₄ fractionation and chromatographies on DEAE-Toyopearl 650M, CM-Sephadex C-50 and Sephadex G-100. The native molecular weight was estimated to be 141 kDa by gel filtration and composed of two non-identical subunits with an apparent mass of 74 kDa and 62 kDa. The optimum pH was found to be 5.5 with reasonable stability between pH 5 and 8. The enzyme had an optimum temperature at 45°C and was stable up to 50°C upon heat treatment for 5 min. The presence of sodium diethyldithiocarbamate, metabisulphite and potassium cyanide completely inhibited the enzyme activity. Fluoride also inhibited the activity substantially at higher concentrations. Other tnonovalent and divalent metal ions did not have inhibitory effects.     

蜜橘酸腐病病原菌的分离鉴定以及不同抑菌剂处理对其控制效果

为确定蜜橘果实酸腐病的致病菌及膜醭毕赤酵母、水杨酸和壳寡糖对蜜橘果实采后酸腐病的控制效果,从自然发病的蜜橘果实上分离出一株致病真菌,通过形态学特征、rDNA-ITS分析以及致病性检测,发现该真菌为蜜橘白地霉(Geotrichum candidum)。离体实验发现2.5 mmol/L水杨酸、质量分数1.5%壳寡糖处理能够抑制白地霉孢子萌发和菌丝的生长,膜醭毕赤酵母产生的挥发性物质能够抑制白地霉菌丝的生长。果实上的实验结果表明,1×10~8 CFU/m L膜醭毕赤酵母、2.5 mmol/L水杨酸、1.5%壳寡糖同孔接种和异孔接种处理均能够有效抑制蜜橘果实酸腐病的发病率和病斑直径的上升,其中同孔处理膜醭毕赤酵母效果最好,异孔处理水杨酸效果最好。     

温州蜜柑皮中氨基酸及脂肪酸的组成分析研究

柑橘是我国大宗水果,皮中富含精油、果胶和类黄酮等生物活性成分,是一种具有较高开发价值的资源。应用氨基酸全自动技术分析温州蜜柑皮中的蛋白质,结果表明蛋白质含量为3.446%(干物质),其中必需氨基酸含量1.239%,比重35.956%,略小于大豆分离蛋白的39.4%;蛋氨酸、胱氨酸为限制性氨基酸。采用索氏法对果皮进行萃取,以GC-MS技术对萃取物中的脂肪酸进行分析鉴定,确定含有11种脂肪酸:6种饱和脂肪酸,占总量的26.06%,主要是十六烷酸19.75%;5种不饱和脂肪酸,占总量的66.20%,主要是9,12-十八碳二烯酸(亚油酸)37.14%和亚麻酸19.06%。     

Neutral and acidic ascorbate oxidases from satsuma mandarin (Citrus unshiu Marc): Isolation and properties

The neutral and acidic forms of ascorbate oxidase (AAO) were isolated and purified from young fruits of satsuma mandarin by a combination of (NH₄)₂SO₄ fractionation, ion-exchange and hydrophobic chromatography, and gel filtration. The neutral and acidic AAO were both diamers of two subunits with native molecular weights of 133 and 136 kDa, respectively. Neutral AAO was stable in the range of pH 5 and 8 and exhibited optimal activity at pH 5.5 and 45°C. In contrast, acidic AAO was stable between pH 5 and 10 and exhibited optimal activity at pH 5.5 and 50°C. When L-ascorbate and D-isoascorbate were used as substrates, K_m values of neutral AAO were 2.98 × 10^?4 M and 3.36 × 10^?4 M and those of acidic AAO were 1.99 × 10^?4 M and 1.86 × 10^?3 M, respectively. The activities of the two forms of AAO were totally inhibited by metabisulphite and cyanide, substantially suppressed by higher concentrations of diethyldithiocarbamate and fluoride, and not inhibited at all by monovalent and divalent metal ions tested.     

橘瓣酶解脱囊衣工艺及其罐头品质的研究

研究利用酶制剂脱除温州蜜柑橘瓣囊衣的方法。通过试验筛选最佳的酶及酶解工艺,结果表明使用和氏璧果胶酶,在酶液质量分数1.0%、pH 3.5、酶解温度45℃、酶解时间45 min条件下,可以得到较佳的脱囊衣效果;酶解过程中使用超声波辅助酶解,可以提高酶解效果。通过感官分析、理化指标检测,对比酶解脱囊衣和传统酸碱脱囊衣的橘瓣罐头的品质,结果显示酶解工艺提高橘瓣破碎率5.5%,降低维生素C含量20.4%,而不影响橘瓣的硬度、色差、滋味和气味。温州蜜柑橘瓣的酶解脱囊衣工艺可用于工业化生产橘瓣罐头。