超声波对低嘌呤脱脂豆浆溶解性、保水性及黏度的影响

为了研究超声波处理对低嘌呤脱脂豆浆溶解性、保水性及黏度的影响,以脱脂豆粕为原料,采用超声波法,通过单因素及正交试验,研究最佳超声波处理条件。研究结果表明,最佳超声波处理条件为超声功率315 W、超声时间40 min、超声温度60℃,此条件下的黏度为1.4 mPa·s、保水性为81.83%、溶解性为58.15%。超声波处理的溶解性比未经超声波处理提高了22.35%。因此,超声波处理能显著提高低嘌呤脱脂豆浆的溶解性及低嘌呤脱脂豆腐的保水性,降低低嘌呤脱脂豆浆的黏度。     

超声波处理对低嘌呤脱脂豆腐粉蛋白质二级结构及功能的影响

为了探讨超声波处理对低嘌呤脱脂豆腐粉的影响,利用扫描电镜技术、红外光谱技术及动物实验分别研究超声波处理对低嘌呤脱脂豆腐粉微观结构、蛋白质二级结构及营养功能的影响。研究结果表明:超声波处理的豆腐粉颗粒大部分呈球形体,且表面布满微孔;未经超声波处理的脱脂豆浆、低嘌呤脱脂豆腐粉和经超声波处理的脱脂豆浆、低嘌呤脱脂豆腐中蛋白质的β-折叠和无规则卷曲的总含量分别是59.64%,52.49%,65.46%,56.21%;低嘌呤脱脂豆腐粉的雄性和雌性小鼠蛋白质消化率分别是79.33%,70.03%。超声波处理改变了低嘌呤脱脂豆腐粉的微观结构,蛋白质的二级结构,改善了蛋白质的营养功能。     

利用高温脱脂豆粕制备脱脂豆浆工艺的研究

实验以高温脱脂豆粕蛋白溶出率为指标,通过单因素与正交实验比较加热搅拌法与超声波法两种方法处理脱脂豆粕粉制备豆浆的工艺,得到了脱脂豆粕制备脱脂豆浆的最佳工艺参数。加热搅拌法最佳工艺参数为:提取温度60℃,提取时间60min,料液比1:18,蛋白溶出率为80.9%;超声波法最佳工艺参数为:提取温度50℃,提取时间30min,料液比1:16,蛋白溶出率为81.8%。从节能角度考虑,选取超声波法为高温脱脂豆粕制备脱脂豆浆的最佳方法。      

超声处理大豆浆体对提高蛋白质和固形物萃取率的作用

采用低频超声波处理大豆浆体以提高其蛋白质和固形物的萃取率。探讨了处理时间、温度、ｐＨ和超声振幅诸因素对超声处理效果的影响，并初步得出其最佳处理条件。结果表明，采用低频超声波处理大豆浆体及其豆渣能有效地提高蛋白质和固形物的萃取率     

超声波辅助兔骨粉脱脂工艺优化

为提高兔骨粉的脱脂率,以兔四肢骨为原料进行超声辅助溶剂脱脂工艺参数优化。以脱脂率及蛋白质保留率筛选脱脂剂,并通过单因素及Box-Behnken响应面试验优化超声波辅助脱脂参数,对比研究不同工艺条件下兔骨粉的脱脂率,再进行生产验证试验。结果表明,乙酸乙酯为最优脱脂剂;经单因素试验,超声波辅助脱脂的最佳条件为液料比5∶1(g∶g)、超声波功率360 W、超声波处理时间15 min;在单因素的基础上,用响应面法优化超声波辅助脱脂参数,建立了二次回归方程,最终优化得到兔骨超声波辅助脱脂工艺最佳参数为液料比5.3∶1(g∶g),超声波功率480 W,超声波处理时间24 min,脱脂率达到(94.63±0.20)%,与理论预测值的相对误差<5%,这将对动物骨粉的应用产生一定的指导意义。     

采用核酸酶酶解联合离子交换树脂吸附开发低嘌呤腐竹

为研究开发一种低嘌呤腐竹,将树脂吸附和核酸酶酶解核酸2种措施相结合,对豆浆中的嘌呤类物质进行吸附,通过正交试验,确定吸附效果最强的树脂结合核酸酶酶解吸附的最佳技术条件。实验结果表明,树脂NUF20是最佳嘌呤吸附树脂,对嘌呤核苷酸吸附率达98. 40%,树脂NUF20结合核酸酶酶解吸附豆浆中嘌呤的最佳技术条件为核酸酶用量26. 67 U/m L,树脂添加量0. 2 g/m L,反应温度70℃下搅拌吸附1 h。与对照组相比,经过树脂NUF20结合核酸酶酶解技术处理后的豆浆加工的腐竹产品,第1~5张腐竹的嘌呤含量分别下降89. 70%、88. 28%、76. 69%、72. 03%和65. 62%。研究将树脂吸附和核酸酶酶解2种措施结合,采用优化的工艺条件,有效降低了腐竹中的嘌呤含量。实验结果为开发针对高血尿酸症等特殊人群的低嘌呤腐竹提供了技术基础,同时也为其他降嘌呤豆制品的研究及加工提供了理论参考。     

超声波结合壳聚糖对龙虾虾仁保水性的影响

采用壳聚糖、蛋白酶、磷酸盐和超声波处理,研究了不同处理方式对龙虾虾仁保水性的影响,通过响应面法优化了提高龙虾虾仁保水性的工艺参数。结果表明,磷酸盐处理提高了虾仁的保水性,但不适合食品中用,蛋白酶处理对龙虾虾仁有一定的保水效果,而壳聚糖和超声波处理对提高虾仁的保水性有显著效果。响应面法优化的提高龙虾虾仁保水性的最优条件为壳聚糖浓度1.0%,超声时间6 min,超声波功率74 W,在此条件下龙虾虾仁的解冻失重率为4.31%。方差分析显示,所建的回归模型显著,能很好地预测龙虾虾仁保水性的变化。其中,壳聚糖浓度显著影响虾仁保水性,壳聚糖浓度和超声时间、超声时间和超声功率之间的交互作用均显著影响虾仁的保水性。     

超声处理大豆浆体对提高蛋白质和固形物萃取率的作用

采用低频超声波处理是大豆浆体以提高其蛋白质和固形物的萃取率。探讨了处理时间、温度、ｐＨ值和超声振幅诸因素对超声处理效果的影响。并初步得出其最佳处理条件。通过对不同浓度大豆浆体、磨前经热处理大豆浆体及其分离出的豆渣进行超声处理等一系列实验，结果表明：（１）超声处理有可能用于直接生产浓度（高蛋白）的豆奶产品；（２）超声处理磨碎前先经热烫大豆的浆体，固形物提取率比不经超声处理的提高２１％￣４６％；（３）     

超声波处理对低嘌呤脱脂豆粉巯基含量、疏水性及粒径分布的影响

为研究超声波处理对低嘌呤脱脂豆粉性质的影响,利用可见分光光度计、激光粒度分布仪、荧光分光光度计进行了检测分析。结果表明：超声波处理样品的游离巯基含量、体积平均粒径、粒径分布宽度及蛋白质表面疏水性均显著高于未经超声波处理的样品（P＜0.05）。超声波功率为405 W、超声波温度50 ℃、超声波时间30 min时,游离巯基含量达到最大值8.75 μmol/g;超声波功率为450 W、超声波温度40 ℃、超声波时间60 min时,相对表面疏水性达到3.86%。因此,超声波处理引起了低嘌呤脱脂豆粉蛋白质游离巯基含量、粒径分布和表面疏水性的变化。     

不同物理方法对啤酒糟蛋白溶解性的影响

为了提高啤酒糟蛋白的溶解性,使它更广泛的应用于食品行业,研究了水浴加热和超声波处理对啤酒糟蛋白溶解性的影响。通过单因素试验,确定了水浴加热处理和超声波处理的最佳改性条件。通过水浴和超声波的交互试验确定了各因素影响的主次顺序,最后确定了提高啤酒糟蛋白溶解性的最佳工艺条件为：水浴温度100℃,蛋白浓度7%,超声时间60s,在此条件下,啤酒糟蛋白的溶解性与对照相比可提高866%,其中水浴温度、蛋白浓度以及水浴温度与蛋白浓度的交互作用是影响啤酒糟蛋白溶解性的高度显著因素。     

Impact of transglutaminase on the textural, physicochemical, and structural properties of chicken skeletal, smooth, and cardiac muscles

This study examined the effects of microbial transglutaminase (MTG; 3.1 mg/ml) on chicken skeletal, smooth, and cardiac muscles; the meat containing the different muscle types was shaped into sausages and treated at 40 °C and/or 78 °C for 30 min. Although the three muscle types were obtained from the same bird, the effects of MTG addition were not uniform. All the muscle types showed a significant increase in the breaking strength (P < 0.01), but skeletal muscle exhibited the maximum increase. All samples showed a decrease in the fluorescence intensity and a significant reduction in the concentration of proteins that were extracted in a high ionic strength solution (P < 0.05). Scanning electron microscopy images and histological studies revealed that different muscle types had different physical structures and frameworks after MTG treatment, which is a reflection of the differences in the reaction specificity of MTG with different muscle proteins. Histological studies revealed that the reactions of MTG with meat proteins are both exogenous and endogenous. Cooking loss data suggested that MTG did not have any negative effect on water retention during cooking. MTG appears to be a functional and contributive substance since the results suggest that MTG can function on all muscle types that are mechanically processed for different industrial applications. MTG aggregates muscle proteins in different ways that improve their organoleptic properties such as texture, appearance, and water retention.     

离子色谱法同时测定蛋白胨中葡萄糖、果糖、蔗糖、麦芽糖、乳糖含量

目的建立离子色谱法同时检测蛋白胨中葡萄糖、果糖、蔗糖、麦芽糖、乳糖的分析方法。方法样品用水作为提取剂,用OnGuard Ⅱ RP柱和OnGuard Ⅱ H柱净化,50mmol/LNaOH溶液作为流动相,用Carbopac PA20柱进行离子色谱分析。结果在该条件下5种糖都能得到较好分离,线性良好,葡萄糖、果糖、蔗糖、乳糖和麦芽糖的检出限为0.002、0.004、0.011、0.007、0.018 mg/L,平均回收率为90.59%～97.68%(n=9)。结论该方法操作简便、灵敏度高,可用于作为蛋白胨中葡萄糖、果糖、蔗糖、麦芽糖、乳糖的检测。     

拟穴青蟹新型过敏原肌质钙结合蛋白的纯化、鉴定及分子克隆

为进一步认识蟹类的过敏原,采用免疫印迹方法,分析发现甲壳类过敏患者血清能与拟穴青蟹肌浆蛋白中分子质量约为21 kD的蛋白质产生特异的IgE结合反应,结果显示该蛋白可能是蟹类新型过敏原。通过硫酸铵盐析、阴离子交换和凝胶过滤柱层析等方法对21 kD-蛋白进行分离纯化,采用Western blotting和基质辅助激光解析电离飞行时间质谱（matrix assisted laser desorption ionization-time of flight-mass spectrometry,MALDI-TOF-MS）确认纯化的21 kD-蛋白为肌质钙结合蛋白（sarcoplasmic calcium binding protein,SCP）。采用SMART-RACE（SwitchingMechanism At RNA Termini-Rapid Amplification of cDNA Ends）的方法获得SCP的cDNA序列,该序列全长986 bp,开放阅读框为579 bp,编码193 个氨基酸,其理论分子质量21.94 kD,等电点4.44。拟穴青蟹SCP与甲壳类动物SCP具有较高的同源性,与昆虫SCP的同源性较差;三级结构模拟分析显示,SCP含有5 个螺旋-转角-螺旋结构区,即EF-手型结构区,并在其中两个手型结构区形成2 个钙离子结合位点;进一步预测得到SCP的4 个线性抗原表位和3 个构象性抗原表位。     

Pilot survey of commercial pasteurized milk consumed in the metropolitan area of Rio de Janeiro,Brazil, for tetracyclines residues,including the 4-epimers of oxytetracycline,tetracycline and chlortetracycline

This pilot survey aimed to assess the occurrence of tetracyclines and the 4-epimers of oxytetracycline, tetracycline and chlortetracycline in commercial pasteurized milks sold in the metropolitan area of Rio de Janeiro, Brazil, between October 2009 and March 2010. A liquid chromatography–tandem mass spectrometry (LC–MS/MS) method, developed and validated in our laboratory, was used. All 100 analyzed samples were compliant, but 14 contained oxytetracycline in concentrations ranging from the method limit of detection (3.7?µg?l^–1) to the method limit of quantification (12.2?µg?l^–1). One sample contained oxytetracycline and tetracycline simultaneously (at a concentration slightly higher than method limit of quantification, 7.0?µg?l^–1). The presence of 4-epioxytetracycline and 4-epitetracycline in contaminated samples with the parent drugs could not be confirmed as traces were detected only in the quantification MRM transition. No other tetracyclines were detected.     

Determination of Zn,Cu, Cd,Pb, Ni and Cr in some Slovenian foodstuffs

An acid-assisted microwave digestion procedure was optimised for the determination of trace elements in foodstuffs by the use of flame and electrothermal atomic absorption spectrometric (FAAS, ETAAS) techniques. Zn, Cu, Cd, Pb, Ni and Cr were determined in cabbage, wheat, potato, instant milk, fish, eggs and baby foodstuffs. The repeatability of measurements was tested in the cabbage sample and was found to be ±3.3% for Zn, 4.6% for Cd, ±6.8% for Cu and ±15.5% for Cr. The worse value obtained for Cr was probably due to its inhomogeneous distribution and very low concentration in the cabbage. Concentrations of Ni and Pb in the cabbage sample were below the limit of detection (0.2 mg kg^–1). The accuracy of the analytical procedure was checked by the analysis of the standard reference material CRM 1570 Trace and minor elements in spinach leaves and IAEA 336 Trace and minor elements in lichen. Good agreement between the certified or indicative and determined values was obtained. The results indicate that the concentrations of Zn, Cu, Cd, Pb, Ni and Cr found in cabbage, wheat and potato are comparable to the literature data. Cd, Pb and Ni were not found to be the contaminants in the foodstuffs analysed. Higher concentrations of Ni were found only in baby food "okolenik", arising from the cocoa that "okolenik" contained. It was demonstrated that the Cr content is very low in baby food, yolk and white of egg and in fish (<0.05 mg kg^–1 Cr). Elevated concentrations of trace elements were found only in mussels that accumulate heavy metals from the marine environment.     

Bioactive compound content,antioxidant activity,deoxynivalenol and heavy metal contamination of pearled wheat fractions

Wheat kernels are rich in antioxidant compounds, that are mainly present in the outer bran layers and which are removed during milling. Unfortunately, several contaminants, e.g., mycotoxins and heavy metals, are also concentrated in the external layers. Pearling of 3 wheat varieties gave five fractions (each 5% of the original grain weight), starting from the outer layer until the inner kernel, designated as 0–5%, 5–10%, 10–15%, 15–20%, 20–25%, respectively. The remaining 75% of the inner kernel was also collected. Dietary fibre, free phenolic acids and total antioxidant activity decreased progressively from the external to the internal layers. However, the 5–10% fraction was richer in β-glucan content than the external one (0–5%). Heavy metals were only found in the most external fraction. Deoxynivalenol contamination decreased from the external to the internal layers: 64% of total contamination of kernel was found in the 0–5% and 5–10% fractions. The 10–15% kernel fraction offered the best compromise between high nutritional value and low contamination risk.     

动物源弯曲菌分离纯化鉴定方法优化

【目的】弯曲菌是重要的食源性人畜共患病原菌,通常难以诊断,而动物源方向缺少系统的检测分析方法及相应的优化。为了获得更适宜分离动物来源的空肠弯曲菌和结肠弯曲菌,提高分离效率,降低分离成本,特开展方法优化,填补动物源弯曲菌分离方法建设的空白,为耐药菌株的有效追踪溯源和风险评估提供依据。【方法】对已有的空肠弯曲菌和结肠弯曲菌分离纯化鉴定方法Preston肉汤和Bolton肉汤增菌;CCDA选择性培养分离、弯曲菌显色培养分离、Skirrow选择性培养分离;生化鉴定和分子生物学鉴定做了筛选优化,针对目前存在的分离纯化和鉴定方法进行了调查比较,得到了更适合于健康动物来源的粪便和盲肠中的分离方法。【结果】牛血清预增菌、CCDA选择性分离、弯曲菌显色培养基纯化、哥伦比亚血琼脂进行扩增及分子学方法鉴定,同时建议采用厌氧条件进行培养。该流程简单易行,成本较低,适合于绝大多数实验环境条件,是获取弯曲菌的首选流程,便于推广实施。【结论】通过将现研究阶段存在的大多数检测方法进行了综合分析,整理出一套针对于动物来源的粪便及肠道内容物的检测分析方法,对健康动物中弯曲菌的分离效率能够提高30%,同时空肠弯曲菌和结肠弯曲菌的分离效率无明显差异。     

红发夫酵母中3R,3’R-虾青素的分离纯化和结构鉴定

研究红发夫酵母中3R,3’R-虾青素的分离纯化工艺条件,并利用高效液相色谱串联大气压化学电离源质谱(high performance liquid chromatography-atmospheric pressure chemical ionization-mass spectrometry,HPLCAPCI-MS)、核磁共振(nuclear magnetic resonance,NMR)和高效液相色谱-紫外光谱(high performance liquid chromatography-ultra violet,HPLC-UV)对纯化得到的虾青素结构进行鉴定。结果表明:利用细胞玻璃研磨器进行研磨提取、硅胶柱层析分离和结晶提纯相结合的方法,能够有效减少反式虾青素的异构化,得到的虾青素纯度高于95%。采用高效液相色谱-质谱仪(high performance liquid chromatography-mass spectrometry,HPLC-MS)、超导核磁共振谱仪(1H和13C NMR)以及Chiralpak IC手性固定化纤维柱分析,显示制备的反式虾青素几乎都以3R,3’R结构组成。     

重组水稻 α-半乳糖苷酶的分离纯化及酶学性质研究

对重组水稻α- 半乳糖苷酶的分离纯化及其酶学性质进行研究。结果表明：该重组酶分子质量约为59kD;最适酶反应温度为45℃,最适pH 值为5.0;酶活力在0～20℃,pH4.0～7.0 最为稳定;酶学动力学常数Km 为0.78mmol/L,Vmax 为10.16mmol/(mg·min)。多数的金属离子和有机离子对酶催化作用没有影响,Hg2+、Ag+及－ SH 基团抑制剂p-chloromercuribenzoic acid(pCMB)对酶活性有强烈抑制作用。