真空包装烟熏火腿切片贮藏品质动态变化研究

对不同温度贮藏条件下真空包装烟熏火腿切片的品质变化进行动态跟踪,分析产品在4℃、10℃、20℃条件下贮藏,其感官、pH值、TVB-N值、TBARS值、蛋白、脂肪及水分含量的动态变化。结果表明:产品在贮藏过程中,pH值呈下降趋势,TVB-N值和蛋白含量呈上升趋势,脂肪、水分含量及TBARS值变化不明显。贮藏温度对产品质量和货架期影响显著,低温可以延长产品的货架期。根据感官品质判断产品的货架期,4～10℃贮藏货架期为21 d,20℃贮藏货架期为14d。     

Evaluation of antilisterial action of cilantro oil on vacuum packed ham

Cilantro oil is an essential oil preparation extracted from the plant Coriandrum sativium. A series of experiments were conducted to evaluate the ability of cilantro oil to control the growth of Listeria monocytogenes on vacuum-packed ham. The in vitro minimal inhibitory concentration for five strains of L. monocytogenes was found to vary from 0.074% to 0.018% depending on strain. Cilantro oil treatments were then tested on ham disks inoculated with a cocktail of the five L. monocytogenes strains. The treatments studied were 0.1%, 0.5%, and 6% cilantro oil diluted in sterile canola oil or incorporated into a gelatin gel in which lecithin was used to enhance incorporation of the cilantro oil. Gelatin gel treatments were also conducted with 1.4% monolaurin with or without 6% cilantro oil to determine if an interaction between the antimicrobials could increase inhibition of L. monocytogenes. Treated ham was then vacuum-packed and stored at 10 degrees C for up to 4 weeks. The only cilantro oil treatment which inhibited growth of L. monocytogenes on the ham samples was 6% cilantro oil gel. Samples receiving this treatment had populations of L. monocytogenes 1.3 log CFU/ml lower than controls at week 1 of storage, though there was no difference between treatments from week 2 onward. It appears that immobilization of the antimicrobial in a gel enhanced the effect of treatments. Cilantro oil does not appear to be a suitable agent for the control of L. monocytogenes on ham. The possible reasons for reduced effectiveness of cilantro oil against L. monocytogenes on ham are discussed.     

卷烟纸中钾含量的快速检测

目的：为卷烟厂车间提供一种简单、快速测定卷烟纸中钾含量的方法。方法：采用离子选择性电极法,比较卷烟纸样品的预处理方法,比较钾离子选择电极在不同缓冲溶液中的电位响应行为。结果：钾离子选择电极在醋酸锂缓冲溶液(0.1 mol/L,pH 7.0)中具有优异的响应性能,对K+的线性响应范围为1.0×10-5~1.0×10-2mol/L,线性响应斜率为55.79 mV/dec (25 ℃),检测下限可达到2.14×10-6mol/L。钾离子选择性电极对卷烟纸样品的日内测试平均相对标准偏差为0.55%,日间测试相对标准偏差为2.8%,均＜5%。电极方法与离子色谱法的测试结果一致,平均相对偏差为4.1%(n=10),回收率为95.0%~101.9%,在连续1周的测试过程中展示出良好的时效性。结论：卷烟纸样品预处理方法中,采用1%稀醋酸超声萃取30 min提取钾离子快速简单,环保易行,离子选择性电极法准确可靠,适用于卷烟纸中钾含量的快速检测。     

Feasibility of NIR interactance hyperspectral imaging for on-line measurement of crude composition in vacuum packed dry-cured ham slices

There is a growing market for packaged slices of dry-cured ham. The heterogeneity of the composition of slices between packages is an important drawback when aiming to offer consumers a product with a known and constant composition which fits individual consumer expectations. The aim of this work was to test the feasibility of NIR interactance imaging for on-line analysis of water, fat and salt and their spatial distribution in dry-cured ham slices. PLSR models for predicting water, fat and salt contents with NIR spectra were developed with a calibration set of samples (n = 82). The models were validated with an external validation set (n = 42). The predictive models were accurate enough for screening purposes. The errors of prediction were 1.34%, 1.36% and 0.71% for water, fat and salt, respectively. The spatial distribution of these components within the slice was also obtained.     

Study of the Lactobacillus sakei protective effect towards spoilage bacteria in vacuum packed cooked ham analyzed by PCR-DGGE

The effectiveness of Lactobacillus sakei B-2 inoculated as a protective culture on the inhibition of spoilage bacteria on sliced vacuum packed cooked ham was investigated by using culture-dependent and -independent approaches. Total microbial DNA was directly extracted from both control and treatment samples, and subjected to a nested PCR protocol, PCR–DGGE analysis was used to identify and monitor the dynamic changes in the microbial population, followed by partial 16S rDNA sequencing. The DGGE profile demonstrated that the protective culture effectively suppressed growth of predominant spoilage bacteria L. sakei, Lactobacillus curvatus and Leuconostoc mesenteroides in cooked ham during storage at 4 °C, however, growth of uncultured Leuconostoc was not inhibited. The shelf-life of this product inoculated with L. sakei B-2, at levels of 5.91 ± 0.04 log₁₀ CFU g⁻¹ was 35 days, compared to 15 days of control samples, when the ham was stored at 4 °C.     

Detection of Kluyveromyces marxianus and other spoilage yeasts in yoghurt using a PCR-culture technique

A combined PCR-culture technique was developed for the detection of viable yeasts in yoghurt samples. Yoghurt samples were inoculated with either viable or heat-inactivated Kluyveromyces marxianus cells, and analyzed before and after incubation for 24 h at 25 degrees C under agitation. DNA was extracted from the samples and amplified using yeast-specific primers targeted at the gene coding for the 18S rRNA. A 251-bp fragment was amplified by the Polymerase Chain Reaction from the yoghurt samples containing initial yeasts counts of 10 cfu g(-1) or higher, whereas no PCR product was generated from control uninoculated yoghurt samples. Comparison of PCR results obtained before and after the incubation step was used to assess yeast viability. Viability was also confirmed by plating on Sabouraud-Dextrose-Chloramphenicol Agar. Moreover, comparison of the results obtained using PCR-culture and plate count methods for the analysis of commercial yoghurt samples, demonstrated that the PCR-culture technique developed in this work can be very useful for the rapid detection of viable spoilage yeasts in dairy industries.     

基于高光谱成像技术的金华火腿无损分级检测研究

目的 建立金华火腿的质量等级评判模型。 方法 采用高光谱成像仪检测不同质量等级的金华火腿样本, 结合数据分析软件对得到的图像信息作主成分分析(PCA)和偏最小二乘(PLS)分析。 结果 用PCA处理, 第一主成分(PC1)和第二主成分(PC2)的贡献率分别为86%和11%, 总贡献率为97%。PLS建立的判别模型中, 训练集和验证集的总体识别吻合率分别为96.19%和89.52%。 结论 将高光谱成像技术与一定的模式识别方法相结合建立评判模型, 是一种可行的金华火腿质量等级检验新技术。     

酵母味素在低温圆火腿中的应用研究

研究了LB00型酵母味素、猪肉型酵母味素添加量对低温圆火腿品质的影响,获得LB00型酵母味素与猪肉型酵母味素的添加量范围及最佳添加量:LB00添加范围0.2%～1.2%、最佳用量0.7%;猪肉型添加范围0.2%～0.8%、最佳用量0.6%。酵母味素还可以替代部分调味、调香料(如:香精、味精、I+G等),既降低了成本又提高了品质,是一种新型的肉类制品调味料与品质改良剂。     

牛肉品质快速检测装置的设计

目的 开发基于可见/近红外光谱技术的牛肉品质快速检测系统。方法 利用波长范围为400~2600 nm的光谱仪为核心检测部件, 结合控制器、光源、光纤等辅助装置构成了检测系统的硬件部分, 对32个牛肉通脊样本进行检测, 并用肉类嫩度仪进行验证。结果 27个样本为嫩肉, 5个样本为粗糙肉, 嫩度检测正确率为100%。结论 该装置能够对牛肉的嫩度品质进行较准确的检测。     

腊肉的加工工艺

主要介绍腊肉的加工方法以及加工要点.     

Non-invasive and non-destructive ultrasonic technique for the detection of microbial contamination in packed UHT milk

An eight-channel ultrasonic device was developed to detect microorganism growth in UHT milk contained in carton-like packages without opening the packs. The system analyses automatically the amplitude and the delay of an ultrasonic pulse passing through packed UHT processed milk, being the coupling between the transducers and the packs accomplished in dry conditions. Changes in these parameters produced by different microbes are detected even when other physical–chemical parameters still remain within the sterility margins. Three different strains (Bacillus cereus, Proteus vulgaris and Bacillus pumilus) were inoculated at different concentrations in UHT milk packs. Variations in the velocity and amplitude of the ultrasonic wave show the growth signature of these microorganisms. Growth detection was achieved between 7 and 48 h depending on the number and type of bacteria inoculated. The experiments show that conventional analysis like pH or acidity measurements could be substituted by this non-invasive technique.     

傅立叶变换中红外光谱在食品快速分析与检测中应用

近年,傅立叶变换中红外光谱作为一种快速、无损检测技术在食品质量评价体系中得到广泛应用,并积累相当丰富研究资料。该文在前人研究基础上,重点对傅立叶变换中红外光谱原理、化学计量学数据处理方法及在食品质量安全检测中应用等方面进行综述,并就其在应用上存在缺陷及研究中亟待解决问题进行讨论。     

食品中动物源性成分的多重PCR快速检测

目的利用多重PCR技术对市售的多种食品进行检测,确定动物源性成分的种类,进行掺假及真伪鉴别。方法对鸡、猪、牛、兔、绵羊、山羊、马、鹿8种动物源性产品进行DNA提取,根据不同动物线粒体DNA设计特异性引物,根据脊椎动物细胞色素b基因mt DNA序列设计通用引物作为内源参照,对8种动物源性产品的DNA进行多重PCR扩增,同时对多种成分进行鉴定。结果琼脂糖凝胶电泳表明,此方法能同时扩增出8种动物的特异性条带,检测灵敏度达到0.01%。结论所建立的鉴定多种动物源性成分的新方法,操作简便、快速准确,可为各检验机构对食品进行检测提供方法指导。     

PCR-based fingerprinting techniques for rapid detection of animal species in meat products

A reproducible, rapid, and simple method for simultaneous identification of multiple meat species in a single step DNA-based test has been developed based on the generation of species-specific fingerprintings by two different arbitrary DNA amplification approaches (RAPD- and AP-PCR). Samples representative of various species and meat products submitted to different processing conditions were selected to verify the applicability of the techniques. RAPD-PCR fingerprintings allowed the discrimination amongst pork, beef, lamb, chicken and turkey in all cases. Samples corresponding to each species were clustered together at similarity levels ?75%. The DNA profiles consisted of a discrete but reproducible number of bands, which made possible the interpretation of the results by simple visual inspection. AP-PCR also allowed identification of the five tested species in every sample although more complex patterns were generated, including some low intensity bands. In both cases, a ramp time between annealing and extension temperatures was introduced to achieve good reproducibility. Overall, the simplicity of RAPD-PCR patterns could make this technique suitable for meat authentication in routine analysis.     

Development of a rapid response biosensor for detection of Salmonella typhimurium.

An integrated optic interferometer for detecting foodborne pathogens was developed. The interferometer is a planar waveguide with two thin antibody-coated channels of immunochemically selective agents that interact with antigen molecules. One channel is coated with antibody to Salmonella as a sample, and the other is coated with human immunoglobulin G as a reference channel by using reductive amination. Salmonella was introduced onto the sensing channels through the flow cell on the channels. Phase shift (pi) generated by refractive index variation, as determined by interfering the perturbed sample channel with an unperturbed reference channel and observing the fringe shift, was used for detection. Salmonella Typhimurium (heat-treated or boiled) was detected by binding to antibody against Salmonella common structural antigen immobilized on a silane-derived sensor surface at concentrations in the range of 1x10(5) to 1x10(7) CFU/ml. Salmonella (1x10(7) CFU/ml) mixed with Escherichia coli (1x10(7) CFU/ml) were readily detected without any decrease in sensitivity by the direct assay. Application of a sandwich assay with a second antibody or a gold-conjugated antibody increased the detection limit to 1x10(5) CFU/ml within a 10-min reaction time. Various methods for the immobilization of the capture antibody to the biosensor channels were compared. The greatest binding response was observed in a direct reductive amination method with a long reaction period and increased the detection limit of direct binding of Salmonella antigen to 1x10(4) CFU/ml. The biosensor was able to detect Salmonella Typhimurium in chicken carcass wash fluid originally inoculated at a level of 20 CFU/ml after 12 h of nonselective enrichment. The planar optic biosensor shows promise as a fast, sensitive, reliable, and economical means of detecting food pathogens in the future.     

食品中柠檬酸快速检测试剂盒的研制

建立了一种酶法检测食品中柠檬酸含量的快速检测方法。将6 U L-苹果酸脱氢酶、9.13 U L-乳酸脱氢酶、0.5 mg烟酰胺腺嘌呤二核苷酸、2 mg硫酸镁、3.783 mg海藻糖、5 mg聚乙二醇6000在0.2 mL 0.082 g/mL双甘肽质量浓度下-60 ℃冷冻5 h,室温条件下抽真空18 h得到试剂Ⅰ,0.468 U柠檬酸裂解酶在0.2 mL水体系冷冻干燥得到试剂Ⅱ。结果表明,该方法标准曲线线性关系良好,相关系数R2=0.995,线性范围1～80 μg/L;灵敏度0.25 mg/L;检测限0.5 mg/L;各样品回收率均在90%～110%。该试剂盒方法可以在20 min实现样品中柠檬酸的快速检测,方法灵敏度高、特异性高、快速简便,适合于食品生产企业对食品中的柠檬酸进行快速检测及对食品的质量和品质进行评价。     

食品农药残留快速检测技术研究进展

随着安全健康意识提高,食品中农药残留问题更加受到重视,快速检测技术的应用和研究备受关注。综述活体检测法、化学检测法、酶抑制法、免疫分析法、仪器分析法等目前研究和应用较为广泛的农药残留快速检测技术,并分析各种技术的优缺点及其应用前景。     

金华火腿香肠的生产工艺

研制开发具有金华火腿风味的中式香肠,丰富中式香肠的花式品种,提高中式香肠的档次。通过单因素试验、正交试验对配方和生产工艺进行了甄选,确定了最佳参数:金华火腿添加量8%、金华火腿瘦肥比40%、腌制时间20h。     

免疫学技术在食品安全快速检测中的应用研究进展

随着人们对于食品安全问题的关注程度不断增加,食品安全快速检测方法得到了广泛应用。目前常用的食品安全快速检测技术包括免疫学技术、酶抑制技术、传感器技术、生物芯片技术等。免疫学检测技术具有灵敏度高、特异性强、方便、快速和经济等优点,在食品安全快速检测中发挥了重要的作用。免疫学技术在食品安全领域广泛应用的主要有免疫吸附法和免疫层析法两大体系,其中免疫吸附法以酶联免疫吸附检测法(enzyme-linked immunosorbent assay,ELISA)最常用,而免疫层析法则以胶体金免疫层析技术(colloidal gold immunochromatographic assay,GICA)为代表。本文介绍了免疫学技术在食品安全快速检测中应用的原理及特点,并对酶联免疫吸附检测技术和胶体金免疫层析技术近几年来在食品安全快速检测中的应用进展进行了综述。     

食品中沙门氏菌快速检测技术研究进展

沙门氏菌的检验在食品微生物检验中具有十分重要的意义。本文主要针对基于免疫学的快速检测方法-酶联免疫吸附法(enzyme-linked immunosorbent assay,ELISA)、基于分子生物学的聚合酶链反应(polymerase chain reaction,PCR)、环介导等温扩增(loop-mediated isothermal amplification,LAMP)和基于蛋白质的基质辅助激光解析电离飞行时间质谱法(matrix assisted laser desorption/ionization time of flight mass spectrometry,MALDI-TOF MS)在食品中沙门氏菌快速检测的应用进行了分析与比较。基于3种不同原理的检测方法各有其优缺点,ELISA方法成本低,操作简单但检出限高;PCR方法成本较高,但检测快速、灵敏度高且检出限低;MALDI-TOF MS检出限低但需要完善的细菌库进行比对。因此建议将含内控的荧光定量PCR与LAMP法作为食品中检测沙门氏菌的主要方法。