Polyphenol oxidase from bayberry (Myrica rubra Sieb. et Zucc.) and its role in anthocyanin degradation

Polyphenol oxidase (PPO) was extracted from bayberry (Myrica rubra Sieb. et Zucc. cv. Biqi), and its partial biochemical characteristics were studied. Stable and highly active PPO extracts were obtained using insoluble polyvinylpolypyrrolidone (PVPP) in sodium phosphate, pH 7.0, buffer. The highest PPO activity was observed in the ripe fruits. Optimum pH and temperature for bayberry PPO activity were pH 6.0 and T = 30 °C with 0.1 M catechol as substrate. PPO showed activity using the substrates of catechol, gallic acid and protocatechuic acid, but no activity with the substrates (+)-catechin, p-coumaric acid or caffeic acid. K_m and V_max values were 313 mM and 3.26ΔOD/min/g FW, respectively, with catechol as the substrate. Bayberry PPO did not act directly on cyanidin 3-glucoside but the rate of anthocyanin degradation was stimulated by the addition of gallic acid.     

Nutritional composition of underutilized bayberry (Myrica rubra Sieb. et Zucc.) kernels

The kernels of five bayberry cultivars (Biqi, Zaodamei, Ding-ao, Dongkui and Wandao), grown in Zhejiang Province, China, were analyzed for their proximate composition, protein fractionation, amino acid profile, fatty acid composition and mineral contents. The antinutritive compounds, tannin and cyanide, were also quantified. These bayberry kernels possessed 25.0–27.64% DW protein. A majority of storage protein in bayberry kernels was of the globulin form. The kernel protein was rich in methionine, arginine, aspartic and glutamic acids while limiting amino acid was lysine. The most outstanding feature was the abundant fat content (62.5–68.1% DW) of kernels. Approximately 84.9–90.1% of the fatty acids were unsaturated with oleic acid (43.3–50.7%) and linoleic acid (34.1–46.8%). Bayberry kernels were good sources of magnesium, potassium and calcium. These results may offer a scientific basis for use of the under-exploited bayberry seeds.     

杨梅提取物抑制二羰基化合物活性研究

目的 分离纯化杨梅果实提取物并考察不同组分对模型及饼干中甲基乙二醛(methylglyoxal, MGO)、乙二醛(glyoxal, GO)的抑制效果。方法 乙醇浸提制备杨梅果实粗提物(crude extract, CE),采用AB-8大孔吸附树脂,以不同体积分数的乙醇(20%、40%、60%)洗脱,得到三种杨梅提取物;采用NaNO₂- Al(NO₃)₃-NaOH比色法、pH示差法、液相色谱-质谱法测定提取物中花色苷、总黄酮含量和主要成分,并用气相色谱法考察其对模型和曲奇中MGO/GO的抑制活性。结果 40%乙醇组分F₁得率最高,活性最好,主要成分为矢车菊素-3-O-葡萄糖苷(cyanidin-3-O-glucoside, C-3-Glu)和杨梅素-3-O-鼠李糖苷(myricetin-3-O-rhamnoside, M-3-Rha);60%乙醇洗脱组分F₂成分主要为槲皮素-3-O-鼠李糖苷(quercetin-3-O-rhamnoside, Q-3-Rha);当曲奇中提取物添加量为0.4%时,F_1、F₂对MGO和GO均有抑制活性,其中F₁效果最佳,分别为61.5%和40.4%。结论 杨梅果实提取物具有良好清除MGO/GO的能力,为其作为添加剂应用于抑制食品加工中的MGO和GO提供了一定的理论基础。     

Identification and characterisation of low-molecular-weight phenolic compounds in bayberry (Myrica rubra Sieb. et Zucc.) leaves by HPLC-DAD and HPLC-UV-ESIMS

Leaves of each of two bayberry cultivars, Biqi and Dongkui, were divided into three categories by age, namely immature, intermediate, and mature. Phenolic compounds were analysed by the methods of HPLC-DAD and HPLC-UV-ESIMS. Gallic acid and EGCG were identified positively, and 13 other compounds (flavan-3-ol monomers, prodelphinidin oligomers, and flavonol glycosides) were partially identified. Gallic acid (7.5–87.8 mg/100 g) was the only phenolic acid detected and flavan-3-ols were abundant. Myricetin deoxyhexoside (535.4–853.0 mg/100 g) was the major flavonol glycoside. Among the three categories, immature leaves of both cultivars recorded the highest level of total phenolics, irrespective of whether they were measured by the Folin–Ciocalteu method (19404.0 mg/100 g in Biqi and 19626.0 mg/100 g in Dongkui) or as the sum of individual phenolic compounds (2255.9 mg/100 g in Biqi and 1797.1 mg/100 g in Dongkui). The results showed that bayberry leaves are a potentially rich source of beneficial phenolics.     

Bayberry (Myrica rubra Sieb. et Zucc.) kernel: A new protein source

Bayberry (Myrica rubra Sieb. et Zucc.) kernel protein isolate (BKPI) was isolated from bayberry kernel defatted flour (BKDF) by isoelectric precipitation. BKPI was evaluated for chemical composition and selected functional properties with defatted kernel flour as reference. BKPI contained over 90% dry weight (DW) of protein versus 60.5% DW of protein in BKDF. It possessed a well-balanced amino acid composition according to the FAO/WHO reference except for a low content of lysine. BKPI had a solubility profile similar to that of BKDF, with minimum solubility observed at pH 4.0 and maximum solubility at pH 12.0. BKPI exhibited minimum foaming capacity (FC) (31.1%) and maximum foaming stability (FS) (72.7%) at pH 4.0. Minimum emulsifying capacity (EC) and emulsifying stability (ES) of BKPI and BKDF were observed at pH 4.0. BKPI had a least gelation concentration of (LGC) of 6% (w/v) at pH 4.0. Results indicated that bayberry kernel has potential to be exploited as a new protein source in China.     

Phenolics and antioxidant properties of bayberry (Myrica rubra Sieb. et Zucc.) pomace

Five cultivars of Myrica rubra, Biqi, Wandao, Dongkui, Dingao, and Zaodamei, were collected to analyze the phenolic compounds and evaluate the antioxidant properties of bayberry pomaces. The main anthocyanin was cyanidin-3-o-glucoside (3073.3–6219.2 mg/kg dry weight (DW)) and the main flavonol was quercetin-3-o-glucoside (296.2–907.9 mg/kg dry weight). Quercetin and myricetin were also found in the bayberry pomaces, and quercetin deoxyhexoside and myricetin deoxyhexoside were tentatively identified. The dominant phenolic acids were gallic acid (102.9–241.7 mg/kg dry weight) and protocatechuic acid (29.5–57.2 mg/kg dry weight). Other phenolic acids such as p-hydroxybenzoic, vanillic, caffeic, p-coumaric, and ferulic acids were also present in the bayberry pomaces, whereas, chlorogenic acid was only detected in Dongkui (1.58 mg/kg dry weight). The antioxidant activity of Wandao was the strongest of the five cultivars, whereas the activity of Dongkui was the weakest, and a significant positive relationship was observed between antioxidant activity and total phenolic content or total anthocyanins.     

山茱萸保健果汁饮料的研制

以营养丰富,兼具酸、涩、苦味的山茱萸为原料,探讨既能够保留有效成分,又能够加强营养成分并改善其尖锐的酸、涩感的方法,研制出能够使大众接受和喜欢的山茱萸保健果汁饮料。结果表明制作山茱萸保健果汁饮料宜选择霜降后成熟的山茱萸,山茱萸果汁最佳的澄清方法为离心澄清法,关键技术参数为离心转速3 000 r/min、时间15 min。通过正交优化最终得出2种较好的配制方法:(1)7.5%山茱萸果汁,5.0%苹果汁,2.5%白砂糖。果汁饮料橙红透明,具有山茱萸和苹果汁浓郁的混香,清爽可口,酸甜适中,口感层次丰富。(2)10.0%山茱萸果汁,8.0%番茄汁,5.0%白砂糖。果汁饮料粉红透明,具有山茱萸和番茄汁的混合清香,酸甜清爽,口感层次丰富。     

青花椒保鲜技术研究现状

综述了贮藏过程中与鲜青花椒品质劣变相关的主要成分(如叶绿素、挥发油及麻味物质酰胺类物质)的变化,并对青花椒活体保鲜技术(如高温蒸汽瞬时处理、气调冷藏及化学试剂处理)进行了分析,指出后续可对多种保鲜方法相结合的综合保鲜技术进行研究。     

山茱萸中马钱素的提取工艺研究

为探讨山茱萸中马钱素含量及超声波提取效率优劣,通过溶剂回流法和超声波法对山茱萸中马钱素的提取工艺进行了研究。采用单因素法确定提取溶剂种类等参数后,以提取温度、提取时间、95%乙醇用量等为因素,选用L16(43×26)和L9(34)正交表进行工艺优化设计,马钱素含量以高效液相色谱法外标定量。结果表明,超声波法的提取效率高于溶剂提取,其最佳工艺条件是:提取温度为75℃,提取时间为240min,95%乙醇用量为50mL。用此提取工艺,马钱素的提取效率较高,可达14.05mg/g。     

山茱萸有效成分和药理作用的研究进展及其在食品工业中的应用

山茱萸是一种重要的野生植物资源，也是我国传统的中药材。山茱萸中含有多种具有药用价值的物质，从果肉中分离得到的主要成分可分为有机酸及其酯类，五环三萜及其酯类，环烯醚萜类，鞣质类，维生素，氨基酸和矿物质等。山茱萸的药理作用主要包括免疫作用，降血糖作用，抗炎作用和抗休克，强心作用等。目前国内和国外山茱萸产品并不多，大体上可以分为以下四类：补酒，口服液，饮料和果脯蜜饯，果酱，罐头等。     

青花椒的热稳定性研究

研究了加热对青花椒的影响.用差热-热重分析(TG-DTA)对青花椒进行了热分析研究.青花椒果皮和青花椒籽的热分解分为几个阶段,其分解特征峰明显.青花椒果皮的特征峰可作为青花椒的辅助鉴别;青花椒的保存使用温度不宜过高.     

超声波和溶剂法提取山茱萸中总皂甙的工艺研究

本文通过溶剂法和超声法对山茱萸中总皂甙的提取工艺进行了研究,以提取温度、提取时间、95%乙醇用量等为因素,选用L16(43×26)和L9(34)正交表进行试验。结果表明,超声波的提取效率高于溶剂提取,大大缩短提取时间,优化工艺条件是:提取温度为85℃,提取时间为120min,95%乙醇用量为50ml。在此条件下,总皂甙的提取效率较高,其水解产物人参二醇含量可达5.16mg/g。     

辅色素对杨梅汁色泽短期稳定性的影响

研究了多种辅色素对杨梅汁贮藏中色泽稳定性的影响．将辅色素添加于杨梅汁中并贮藏7d后发现，乙二胺四乙酸(EDTA)、吐温-80、L-脯氨酸、L-赖氨酸、乙酸和丙二酸对杨梅汁色泽的稳定性作用不明显．L-谷氨酸、紫甘薯色素和紫玉米色素有一定的护色作用，十二烷基硫酸钠(SDS)、乙醛和桑椹红色素对杨梅汁贮藏中的色泽有明显的保护作用．     

从虎杖中同时提取分离白藜芦醇和蒽醌类工艺研究

以自然发酵后的虎杖为原料,采用甲醇热回流同时提取虎杖中的白藜芦醇和蒽醌类化合物,选择甲醇浓度、料液比、提取次数和提取时间作为考察因素,以白藜芦醇和蒽醌类化合物的含量为指标,通过正交试验,得到白藜芦醇和蒽醌类化合物同时提取的适宜条件为:体积分数98%甲醇,料液比1∶6,提取3次,每次1 h,白藜芦醇的含量1.912%,提取率达90%,蒽醌类化合物的含量为1.504%,提取率达91.15%;粗提物经V(丙酮)∶V(乙醚)=1∶3的混合溶剂纯化,体积分数50%乙醇溶解分离后,分别得到了白藜芦醇和蒽醌粗品,粗品中白藜芦醇的含量达63.72%,蒽醌含量达50.82%。     

大孔吸附树脂对虎杖中白藜芦醇吸附性能的研究

本文研究了多种大孔吸附树脂对白藜芦醇的吸附与脱附性能，从中选出H103树脂具有较大吸附量和解吸率。动态吸附实验研究了提取液浓度、pH、流速对H103树脂吸附量的影响，适合的上柱浓度为0．7157mg／ml，上柱液的pH为4．10，上柱液流速为2BV／h。4倍树脂床体积的80％乙醇以1BV／h的流速进行洗脱即可基本将白藜芦醇完全从H103树脂上解吸下来。     

软枣猕猴桃果实香气成分分析

用固相微萃取装置(SPME)提取软枣猕猴桃果实香气成分,用GC-MS 法从中分离并确认化学成分,用峰面积归一法通过G1701BA化学工作站数据处理系统得出各化学成分在香气成分中的百分含量。结果从软枣猕猴桃果实中共检测鉴定出21 种化学成分,其中主要成分为1- 甲基-4-(1- 甲基亚乙基)环乙烯、丁酸乙酯、乙醇、己酸乙酯、苯甲酸乙酯、β- 月桂烯、D- 柠檬烯、β- 蒎烯。     

不同产地青花椒主要营养成分的比较研究

实验主要以四川汉源、峨眉、洪雅、金阳和重庆江津五个产地的青花椒为原料,采用蒸馏法、有机溶剂萃取法、凯氏定氮法、原子吸收分光光度法、氨基酸分析等测定方法测定青花椒挥发油、醇溶抽提物、不挥发性乙醚抽提物、蛋白质、矿质元素以及氨基酸等几个营养特征指标.实验结果表明:不同产地的青花椒其营养成分的含量存在一定的差异,金阳青花椒醇溶提取物和不挥发性乙醚抽提物含量、汉源青花椒挥发油含量都显著高于其他几个产地,洪雅青花椒蛋白质含量最高;在青花椒中共检出10种必需矿质元素,含量较高的有钠、锰、铁等;青花椒中氨基酸种类齐全,其中含量较高的有天门冬氨酸、谷氨酸、赖氨酸等,汉源青花椒中总氨基酸、必需氨基酸、甜味氨基酸、酸味氨基酸含量都显著高于其他几个产地,其苦味氨基酸含量也最高,但和金阳产地无显著差异.     

野生软枣猕猴桃中脂肪酸成分分析

采用索氏提取法提取辽南地区的野生软枣猕猴桃全果及其籽中脂肪酸。甲酯化处理后,采用气相色谱- 质谱联用(GC-MS)方法分离和鉴定。结果表明：在野生软枣猕猴桃全果中分离鉴定出7 种脂肪酸,分别是棕榈酸(6.66%)、亚油酸(10.57%)、亚麻酸(77.78%)、硬脂酸(3.09%)、10,13- 十八碳二烯酸(0.2%)、11- 二十碳烯酸 (0.8%)、花生酸(0.14%);在野生软枣猕猴桃籽中分离鉴定出4 种脂肪酸,分别是棕榈酸(3.24%)、亚油酸(5.40%)、亚麻酸(42.49%)、硬脂酸(2.39%)。其中亚麻酸的含量最高,分别占77.78% 和42.49%。     

响应面法优化青花椒微波干燥工艺

利用响应面法优化青花椒微波干燥的工艺条件.在单因素实验的基础上,选取干燥温度、微波功率和铺料密度为影响因子,应用Box-Benhnken中心组合设计建立数学模型,以干燥后的叶绿素含量为响应值进行响应面分析.结果表明,微波干燥青花椒的最佳工艺条件为:干燥温度58℃,微波功率778 W,铺料密度2.7 kg/m2.此条件下,干燥后的青花椒叶绿素含量的预测值为0.5890mg/g,验证实际值为0.6005mg/g.     

响应面法优化软枣猕猴桃蛋白提取工艺

通过对软枣猕猴桃蛋白提取,考察提取时间、提取液pH值和液料比三因素对软枣猕猴桃蛋白提取率的影响。用RAS软件程序对试验数据进行响应面分析,对以上影响因素进行优化,得出软枣猕猴桃蛋白提取的二次回归方程;通过分析得出软枣猕猴桃蛋白提取的最佳条件为:提取时间2.3h,提取液pH值为7.9,液料比19∶1mL/g。在此条件下测得的蛋白提取率为53.23%。