复合蛋白酶在卤鹅类潮式卤水生产中的应用

针对蛋白酶在潮式卤鹅传统熟肉食品生产中的应用,以剪切力的变化来研究木瓜蛋白酶、胰蛋白酶和复合蛋白酶对卤鹅肉质的影响。通过单因素试验和正交试验确定了最佳的工艺生产条件为：复合酶液的胰蛋白酶用量为2000U／kg原料、木瓜蛋白酶用量为1000U/kg唱原料,温度为20℃,处理时间为30min,所得到的卤鹅颜色酱红有光泽、肉质细嫩有弹性,滋味浓郁。     

菥蓂提取物体外抗氧化活性研究

研究了菥蓂提取物的体外抗氧化活性,筛选有效活性部位。通过对菥蓂水提物的有机溶剂萃取、D101大孔树脂分离纯化,制备得到8个部位样品。以抗坏血酸作为阳性对照,通过考查各部位还原Fe3+的能力、清除二苯基苦基苯肼自由基(DPPH.)和羟基自由基(.OH)的能力、抑制油脂氧化的能力,来评价菥蓂水提物不同部位的抗氧化能力。结果表明:菥蓂的各部位均具有一定的抗氧化能力,但抗氧化活性总体上弱于抗坏血酸和BHT。大孔树脂分离得到的30%乙醇洗脱部位(VII)和乙酸乙酯萃取部位(II)抗氧化能力明显强于菥蓂水提物,稍弱于抗坏血酸。得到结论为萃取、大孔树脂分离纯化等步骤能富集更多的抗氧化成分。     

Concentrations and composition profiles of benzotriazole UV stabilizers in municipal sewage sludge in China

The environmental contamination and fate of benzotriazole UV stabilizers (BZTs) have received increasing attention due to their large production volume and wide usage in various consumer and industrial products. In the present work, 60 municipal sewage sludge samples from wastewater treatment plants (WWTPs) in 33 cities in China were collected to investigate the occurrence and distribution of 9 frequently used BZTs. The most dominant analogue was 2-[3,5-bis(1-methyl-1-phenylethyl)-2-hydroxyphenyl]benzotriazole (UV-234) at a median concentration of 116 ng/g (dry weight) and accounted on average for 27.2% of total BZTs. The abundance was successively followed by 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole (UV-329, average 24.3%), 2-(2-hydroxy-3-tert-butyl-5-methylphenyl)-5-chlorobenzotriazole (UV-326, average 22.2%), 2-(3,5-di-tert-amyl-2-hydroxyphenyl)benzotriazole (UV-328, average 17.7%), and 2-(2-hydroxy-5-methylphenyl)benzotriazole (UV-P, average 6.6%), with median concentrations of 66.8, 67.8, 57.3, and 20.6 ng/g, respectively. 5-Chloro-2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole (UV-327) and 2-(3-sec-butyl-5-tert-butyl-2-hydroxyphenyl)benzotriazole (UV-350) had low detection frequency, while 2-(3,5-di-tert-butyl-2-hydroxyphenyl)benzotriazole (UV-320) and 2-(5-tert-butyl-2-hydroxyphenyl)benzotriazole (UV-PS) were not detectable in any sample. To our knowledge, this is the first study reporting the occurrence of UV-234, UV-329, and UV-350 in sewage sludge in China. Significant correlations were found among the BZT concentrations and also with a WWTP characteristic (daily treatment volume). Furthermore, results from degradation prediction and multimedia fate simulation based on a quantitative structure-property relationship (QSPR) model at screening level also implied that the commercial BZT chemicals and their plausible transformation products might be persistent in the environment.     

The production of surfactin during the fermentation of cheonggukjang by potential probiotic Bacillus subtilis CSY191 and the resultant growth suppression of MCF-7 human breast cancer cells

Bacillus subtilis CSY191, the potential probiotics and surfactin-like compound producer, was isolated from doenjang (Korean traditional fermented soybean paste).The survival rate of this strain appeared to be the 58.3% under artificial gastric conditions after 3 h at pH 3.0. Surfactin was purified from the strain CSY191. Three potential surfactin isoforms were detected, with protonated masses of m/z 1030.7, 1044.7, and 1058.71. These different structures were detected in combination with Na⁺, K⁺ and Ca²⁺ ions by MALDI-TOF mass spectrometry. Upon 500 MHz ¹H NMR analysis, the surfactin isoforms had identical amino acids (GLLVDLL) and hydroxy fatty acids (of 13-15 carbons in length). The MTT assay showed that surfactin inhibited growth of MCF-7 human breast cancer cells in a dose-dependent manner, with an IC₅₀ of approximately 10 μg/ml at 24 h. Additionally, the surfactin contents, during cheonggukjang fermentation with strain CSY191, increased from 0.3 to 48.2 mg/kg over 48 h of fermentation, while the level of anticancer activity increased from 2.6- to 5.1-fold.     

膜分离技术在食品精深加工中的应用

膜分离技术已在食品加工业中得到广泛应用,并推动食品精深加工业的快速发展。膜分离技术的理化稳定性、分离高效性、环境友好性以及经济实用性决定了其广阔的应用前景。本文按照食品生产种类,综述膜分离技术在食品精深加工中的应用。     

甘草纤维在烟草薄片纸基中的应用研究

以不同来源、不同品种、不同生产方式的甘草渣为原料,利用造纸法生产烟草薄片的方法探索生产甘草渣薄片的最佳工艺条件,得出最佳的浸渍条件为:温度70℃、时间30 min、液比1:12;通过磨浆、抄片后,测定其物理性能并进行对比及感官分析;得出如下结论:7号甘草渣感官评价综合得分为91分,抗张强度为0.582 KN/m,远高于其他甘草渣薄片,其松厚度为4.46 cm3/g,紧度为0.22 g/cm3,与其它薄片相差不大且均符合YC/T16-2003的要求,为最佳的甘草渣品种来源。     

膜盘联轴器-燃气轮机发电机组转子系统动力学分析

通过MATLAB对燃气轮机发电机组耦联转子系统进行了数值仿真,采用Newmark-β方法求解运动微分方程,在考虑膜盘联轴器由于大变形引起的刚度非线性下,分析了耦联转子系统临界转速、模态振型、不平衡响应和联轴器刚度对耦联转子系统动力学特性的影响,仿真结果表明:采用非线性刚度和线性刚度模型描述膜盘联轴器相差16.77%;耦联转子系统的临界转速和不平衡振动响应较单转子系统有所增加;联轴器刚度的增加会提高耦联转子系统的临界转速同时不平衡振动响应也会增大。     

抗赭曲霉毒素A单克隆抗体的制备及免疫学鉴定

通过碳化二亚胺法(EDC法)制备免疫原OTA-BSA,并免疫小鼠,经杂交瘤技术建立产抗赭曲霉毒素A(OTA)单克隆抗体的杂交瘤细胞株1株。通过体内诱生腹水法制备腹水,纯化后对其亚型、效价、灵敏性、亲和性、特异性等免疫学特性进行鉴定;单抗亚类为IgG1型,间接ELISA效价1:6.4×105,IC50为112.8pg/mL,亲和常数为9.74×1011L/mol,与赭曲霉毒素B交叉反应率为5.6%,与其他常见真菌产物交叉小于0.003%;本实验制备的抗OTA单克隆抗体具有高效、敏感、特异等特点,适合OTA的免疫学快速检测。     

The pathways for the removal of acrylamide in model systems using glycine based on the identification of reaction products

The reaction between acrylamide and glycine was studied in the aqueous model system heated at 150 °C. The main reaction products were identified as C₅H₁₀N₂O₃, C₈H₁₅N₃O₄, C₇H₁₂N₂O₅ and C₁₀H₁₇N₃O₆ using HPLC-MS/MS, IT-TOF and NMR. Both of the critical intermediates were identified as glyoxylic acid and iminodiacetic acid. The pathways for the removal of acrylamide by glycine were proposed as the Michael addition between acrylamide and glycine with or without the initial oxidation of glycine. The changes in the contents of reactants and products provided quantitative evidence for the above pathways. The addition products between acrylamide and other 14 amino acids were identified by HPLC-MS/MS also.     

Preparation and characterisation of water-soluble phytosterol nanodispersions

The purpose of this study was to prepare and characterise water-soluble phytosterol nanodispersions for food formulation. The effects of several factors were examined: four different types of organic phases (hexane, isopropyl alcohol, ethanol and acetone), the organic to aqueous phase ratio and conventional homogenisation vs. high-pressure homogenisation. We demonstrated the feasibility of phytosterol nanodispersions production using an emulsification–evaporation technique. The results showed that hexane was able to produce the smallest particle size at a mean diameter of approximately 50 nm at monomodal distribution. Phytosterol nanodispersions prepared with a higher homogenisation pressure and a higher organic to aqueous phase ratio resulted in significantly larger phytosterol nanoparticles (P < 0.05). Phytosterol loss after high-pressure homogenisation ranged from 3% to 28%, and losses increased with increasing homogenisation pressure. Elimination of the organic phase by evaporation resulted in a phytosterol loss of 0.5–9%.