迷迭香和甘草复配液对冷却肉李斯特菌抑制效果及品质的影响

对接种和不接种李斯特菌的冷却肉喷洒不同浓度的香辛料提取物复配液[V(迷迭香)∶V(甘草)=1∶1]后,采用气调包装(80%O2,20%CO2),测定其在贮存过程中微生物指标和理化指标的变化,以考察其保鲜效果。相对未经保鲜液处理的对照,喷洒不同浓度香辛料提取物复配液对冷却肉中李斯特菌和常见腐败菌都有很强的抑制作用,且提取物复配液的抑菌效果与浓度呈正比。贮存28d时喷洒2.5、5.0、10.0mg/mL提取物复配液的冷却肉中李斯特菌数与对照相比分别降低了2.9、3.1和3.6个对数循环;需氧菌数与对照相比分别降低了2.7、2.9和3.1个对数循环;假单胞菌数与对照相比分别降低1.6、2.1和2.6个对数循环;肠杆菌数与对照相比分别降低0.6、0.8和1.2个对数循环;均与对照组差异显著(P<0.05)。对不接种李斯特菌的冷却肉(气调包装)喷洒不同浓度复配液后进行理化指标测定,结果表明香辛料提取物对肉色无不良影响,对脂质氧化也起到了较好的抑制作用。     

防腐保鲜剂对牛肉火腿切片腐败菌抑制效果的研究

本文以牛肉火腿切片分离出的乳酸杆菌及肠杆菌为供试菌，采用滤纸片法对10种防腐保鲜剂：乳酸钠、双乙酸钠、山梨酸钾、EDTA二钠、Nisin、茶多酚、壳聚糖、水溶性壳聚糖、芦丁、苦荞壳提取液(黄酮)，以及部分复配剂的抑菌效果进行了筛选。结果发现Nisin对乳杆菌的作用效果明显；茶多酚、壳聚糖对肠杆菌有较强的抑制作用。实验表明可采用复合天然防腐保鲜剂-0．015％Nisin 0．5％茶多酚，对牛肉火腿切片的腐败菌进行控制，不同pH介质、热处理对其抑菌活性影响不大。最后对苦荞壳提取液的抑菌活性进行了探讨。     

ε-聚赖氨酸对牛肉火腿切片腐败菌的抑制效果

以细菌总数、乳酸菌、大肠杆菌三种菌落作为微生物生长繁殖指标,考察ε-聚赖氨酸(ε-PL)对两种贮藏条件下牛肉火腿切片的抑菌效果。结果表明:在55天的贮藏期内,ε-PL对乳酸菌和细菌的抑制作用效果明显,相比于常温贮藏,ε-PL对8℃冷藏条件下牛肉火腿切片的抑菌效果更佳。因此,ε-聚赖氨酸能够有效抑制低温贮藏环境下牛肉火腿切片的腐败微生物生长繁殖。     

不同贮藏温度西式火腿切片品质变化规律研究

为研究市场上低温火腿切片的质量和安全性,对不同贮藏温度的真空包装火腿切片的品质变化进行动态跟踪,分析产品在0～4、7～11℃条件下,其感官品质、菌落总数、大肠菌群、色泽、pH值、水分含量、保水性和质构特性的动态变化。结果表明：两种产品品质变化的规律大致相同。0～4℃贮藏比7～11℃产品的菌落总数增长相对缓慢,pH值、水分含量,保水性和质构特性的变化更加稳定。低温更有利于保持产品品质的稳定性和安全性,延长肉品的货架期。     

发酵火腿中单核细胞增生李斯特氏菌限量探讨与建议

在长期的发酵过程中,火腿表层的水分活度小于0.92;发酵火腿成品的水分活度也小于0.92。在此条件下,单核细胞增生李斯特氏菌不能生长,但仍能存活较长时间。发酵火腿成品无需冷藏即可贮存。目前的增菌培养检测法不适用于发酵火腿中单核细胞增生李斯特氏菌的检测。本文建议发酵火腿中单核细胞增生李斯特氏菌的限量为100CFU/g;或者,不将单核细胞增生李斯特氏菌列为发酵火腿中需要检测的项目。     

复配抑菌剂对单增李斯特菌的抑制作用及其保鲜效果

研究溶菌酶、甘氨酸和乙酸钠对单增李斯特菌的抑制效果,通过单因素抑菌率的结果,运用响应面法优化三种抑菌剂复配后对单增李斯特菌的抑制效果,并且将得到的最优浓度复配抑菌剂用来保鲜感染了单增李斯特菌的三文鱼,以细菌总数、单增李斯特菌数、pH、TBA值和TVB-N值为指标,研究复配抑菌剂的保鲜效果。结果表明:溶菌酶0.6 g/L、甘氨酸浓度为6.4 g/L、乙酸钠浓度为4.9 g/L为复合保鲜剂的最佳配比,此条件下对单增李斯特菌的抑菌率为80%±0.23%。冷藏条件下,经复配抑菌剂处理后的三文鱼品质优于未经处理的空白组,第7 d时,实验组细菌总数、单增李斯特菌数、pH、TBA值和TVB-N值分别为5.56 lg CFU/g、4.65 lg CFU/g、6.78、1.048 mg MDA/kg、18.03 mg N/100 g,相比空白组,能延长2 d的货架期。      

乳酸链球菌素和迷迭香提取物对调理切片羊肉保鲜效果研究

为研究乳酸链球菌素（Nisin）和迷迭香提取物（rosemary extract,RE）对调理切片羊肉保鲜效果的影响,本实验设置了对照组、真空包装组、Nisin(0.1、0.3、0.5 g/kg Nisin)、RE(0.1、0.2、0.3g/kg RE)8种处理方式,分析不同处理的调理切片羊肉在冷藏过程中感官评价、色差值、pH、TVB-N含量、TBARS值和羰基含量等品质指标变化。结果表明：不同处理方式对调理切片羊肉的色差值影响较小;0.3g/kg RE处理组相较于其他处理组（除真空包装处理组外）有较高的感官评分（P <0.05）和较低TBARS值（P <0.05）及羰基含量（P <0.05）;0.5 g/kg Nisin处理组的TVB-N含量最低（P <0.05）,0.3 g/kg Nisin和0.3 g/kg RE处理组次之。综上,0.3 g/kg RE处理组调理切片羊肉能够在冷藏过程中保持较高的氧化稳定性和较好的新鲜度。     

金华火腿中单增李斯特菌的风险评估

本文拟研究月桂酰精氨酸乙酯（lauroyl arginate ethyl,LAE）对单增李斯特菌（Listeria monocytogenes）的失活机制。采用二倍稀释法测定LAE对L. monocytogenes的最小抑菌浓度（minimum antibacterial concentration,MIC）。通过测定细胞形态、细胞膜完整性、胞内ATP水平、细胞膜电位、细胞表面疏水性及胞内活性氧（reactive oxygen species,ROS）水平等指标,揭示LAE失活L. monocytogenes的作用机制。结果表明,LAE对L. monocytogenes的MIC值为10 μg/mL。与未处理组相比,经终浓度为40 μg/mL的LAE处理10 min后,L. monocytogenes细胞形态发生明显皱缩,胞外核酸和蛋白质水平分别升高了1.64和15.39倍（P<0.05）,表明细胞膜通透性显著增强（P<0.05）,且细胞膜发生去极化,细胞表面疏水性显著增强（P<0.05）;胞内ATP水平降低了92.40%（P<0.05）;胞内活性氧水平升高了77.27%（P<0.05）。此外,添加抗氧化剂谷胱甘肽和N-乙酰-L-半胱氨酸均能显著降低LAE的抑菌活性（P<0.05）。综上表明,LAE能够有效失活L. monocytogenes,这可能与其损伤细胞膜和诱导氧化应激等有关。该研究为LAE在食品保鲜中的实际应用提供了理论依据。

     

牛肉火腿切片的腐败微生物鉴定及贮藏过程中的品质变化

对牛肉火腿切片的腐败微生物进行了鉴定。结果表明,腐败产品中的细菌主要是乳杆菌属兼性异型发酵菌——干酪乳杆菌(Lactobacillus casei)。干酪乳杆菌发酵产酸、产气是牛肉火腿切片胀袋、出水的根本原因。并研究了贮藏过程中不同包装、温度、光照条件对品质变化的影响。光照对真空包装的牛肉火腿切片的脂肪氧化及色泽变化影响都较小,但对气调包装的a值影响较大,造成褪色明显。保持低温环境对于抑制乳杆菌的生长繁殖,延长产品货架期具有重要作用。     

不同加工条件对茶黄素抑制单增李斯特菌稳定性的影响

目的 探讨不同加工条件对茶黄素(theaflavins, TFs)抑制单增李斯特菌(Listeria monocytogenes, LM)稳定性的影响。方法 以LM为指示菌, 采用二倍稀释法测定了TFs的最小抑菌浓度(minimum inhibitory concentration, MIC), 并在此基础上通过牛津杯法进一步探讨不同加工条件(环境因素: 加工温度、pH、NaCl浓度; 食品基质: 脱脂奶粉、卵磷脂、蔗糖)对TFs抑菌稳定性的影响。结果 TFs对LM的MIC为2 mg/mL, 此时的抑菌效果为中敏水平, LM的正常生长被明显抑制; 加工温度在25~121℃时, TFs对LM的抑菌圈直径无显著性差异; pH在2~10时, 其抑菌圈直径从12.74 mm显著降低至9.86 mm; NaCl摩尔浓度在0.2~0.8 mol/L时, 其抑菌圈直径有所增加; 脱脂奶粉质量浓度在60~120 g/L时, 其抑菌圈直径显著降低; 卵磷脂质量浓度在2~12 g/L和蔗糖质量浓度在10~60 g/L时, 其抑菌圈直径无显著性变化。结论 TFs对LM具有较好的抑菌活性且在不同加工条件下能保持良好的抑菌稳定性。本研究为TFs作为一种新型抗菌产品在食品加工和贮藏中的应用提供了理论依据。     

Antimicrobial activity of lauric arginate-coated polylactic acid films against Listeria monocytogenes and Salmonella typhimurium on cooked sliced ham

A novel type of environmentally friendly packaging with antibacterial activity was developed from lauric arginate (LAE)-coating of polylactic acid (PLA) films after surface activation using a corona discharge. Scanning electron microscopy (SEM)-based analysis of the LAE/PLA films confirmed the successful coating of LAE on the PLA surface. The mechanical properties of the LAE/PLA films with different levels of LAE-coating (0% to 2.6%[w/w]) were essentially the same as those of the neat PLA film. The antibacterial activity of the LAE/PLA films against Listeria monocytogenes and Salmonella enterica Serovar Typhimurium (S. Typhimurium) was confirmed by a qualitative modified agar diffusion assay and quantitative JIS Z 2801:2000 method. Using the LAE/PLA film as a food-contact antimicrobial packaging for cooked cured ham, as a model system, suggested a potential application to inhibit L. monocytogenes and S. Typhimurium on ham with a 0.07% (w/w) LAE coating on the PLA when high transparency is required, as evidenced from the 2 to 3 log CFU/tested film lower pathogen growth after 7 d storage but even greater antibacterial activity is obtained with a LAE coating level of 2.6% (w/w) but at the cost of a reduced transparency of the finished product. This article shows how we can simply develop functional green packaging of PLA for food with effective and efficient antimicrobial activity by use of LAE coating on the surface via corona discharge. PRACTICAL APPLICATION: The effectiveness of an innovative antimicrobial LAE-coated PLA film against foodborne pathogens was demonstrated. Importantly, the application of the LAE to form the LAE-coated PLA film can be customized within current film manufacturing lines.     

Antimicrobial activity of Ginkgo biloba leaf extract on Listeria monocytogenes

ABSTRACT: The antimicrobial activities of Ginkgo biloba leaf extract (GBE) and the combined effects of GBE and sodium EDTA (sodium Ethylenediaminetetraacetic acid) against Listeria monocytogenes were determined at 4 °C, 25 °C, and 37 °C. Listeria monocytogenes grown at 37 °C for 24 h was inoculated (6 to 7 log CFU/mL) into BHI broth containing either GBE or GBE and EDTA (1.6 mg/mL) with various GBE concentrations of 0.1, 0.25, 0.5, 1, 2.5, 5.0, 7.5, 10.0, 15.0, or 20.0% vol/vol and stored at 4 °C, 25 °C, and 37 °C. The inhibitory effect of the GBE was more pronounced at low temperature of 4 °C. GBE was effective in inhibiting microbial growth. Addition of EDTA enhanced antimicrobial activity of GBE.     

Inactivation of Listeria monocytogenes on ham and bologna using pectin-based apple, carrot, and hibiscus edible films containing carvacrol and cinnamaldehyde

Edible films can be used as wrapping material on food products to reduce surface contamination. The incorporation of antimicrobials into edible films could serve as an additional barrier against pathogenic and spoilage microorganisms that contaminate food surfaces. The objective of this study was to investigate the antimicrobial effects of carvacrol and cinnamaldehyde, incorporated into apple, carrot, and hibiscus-based edible films against Listeria monocytogenes on contaminated ham and bologna. Ham or bologna samples were inoculated with L. monocytogenes and dried for 30 min, then surface wrapped with edible films containing the antimicrobials at various concentrations. The inoculated, film-wrapped samples were stored at 4 °C. Samples were taken at day 0, 3, and 7 for enumeration of surviving L. monocytogenes by plating on appropriate media. Carvacrol films showed better antimicrobial activity than cinnamaldehyde films. Compared to control films without antimicrobials, films with 3% carvacrol induced 1 to 3, 2 to 3, and 2 to 3 log CFU/g reductions on ham and bologna at day 0, 3, and 7, respectively. Corresponding reductions with 1.5% carvacrol were 0.5 to 1, 1 to 1.5, and 1 to 2 logs, respectively. At day 7, films with 3% cinnamaldehyde reduced L. monocytogenes population by 0.5 to 1.5 and 0.5 to 1.0 logs on ham and bologna, respectively. Inactivation by apple films was greater than that by carrot or hibiscus films. Apple films containing 3% carvacrol reduced L. monocytogenes population on ham by 3 logs CFU/g on day 0 which was 1 to 2 logs greater than that by carrot and hibiscus films. Films were more effective on ham than on bologna. The food industry and consumers could use these films to control surface contamination by pathogenic microorganisms. PRACTICAL APPLICATION: Antimicrobial edible, food-compatible film wraps prepared from apples, carrots, and hibiscus calyces can be used by the food industry to inactivate Listeria monocytogenes on widely consumed ready to eat meat products such as bologna and ham. This study provides a scientific basis for large-scale application of edible fruit- and vegetable-based antimicrobial films on foods to improve microbial food safety.     

Combined washing effect of noni extract and oregano essential oil on the decontamination of Listeria monocytogenes on romaine lettuce

Combined washing effect of noni extract (NE) and oregano essential oil (OE) on the decontamination of Listeria monocytogenes on romaine lettuce was examined. The fractional inhibitory concentration index (FICI) between NE and three different essential oils (cinnamon leaf, thyme and OE) was determined. Fractional inhibitory concentration index results indicated that OE only had an additive effect (FICI = 1). Noni extract/oregano essential oil combined washing resulted in the greatest reduction in viable cell numbers (3.42 log CFU g⁻¹) relative to non-washed samples. Furthermore, the combined washing was more effective than sodium hypochlorite washing in terms of reducing the microbial load (>1.44-log reduction). Washing treatment did not change the surface colour or total phenolic content in lettuce samples. These results suggest that NE/OE combined washing is applicable as a novel decontamination treatment to ensure the microbial safety of romaine lettuce without changing the quality.     

超高压协同温度处理对烟熏火腿中单增李斯特菌生长预测模型的建立

为了建立超高压协同温度处理烟熏火腿中单增李斯特菌生长预测模型。本研究分别以20、30、40、50℃结合600MPa对接种106cfu/g单增李斯特菌烟熏切片火腿进行5min的超高压处理,4℃贮藏条件下,每10d测定处理后样品中单增李斯特菌的数量。结果表明:当超高压协同处理的温度高于40℃时显著延长了单增李斯特菌在烟熏火腿修复生长的延滞期,所得生长曲线用修正的Gompertz模型进行了拟合,在35、45d进行验证,建立了烟熏火腿中单增李斯特菌在超高压协同温度处理后的生长预测模型,经验证其精确因子(Af)、偏差因子(Bf)、根平均方差(RMSE)和决定系数(R2)均在较好范围内,能较好的模拟单增李斯特菌的生长情况,为低温肉制品中单增李斯特菌的控制提供理论参考。     

复合香辛料精油对冷却猪肉中单核增生性李斯特菌的抑制作用

利用超临界CO2萃取丁香、肉桂及黑胡椒精油,研究三种精油对单核细胞增生性李斯特菌的抑制作用,并将复合精油应用于冷却猪肉保鲜。结果表明:三种精油对单增李斯特菌都有较强的抑制作用,黑胡椒精油的抑菌能力最强,最低抑菌浓度为48 mg/L,肉桂和丁香分别为72 mg/L和96 mg/L;通过正交实验确定最优复合精油菌比例,即丁香精油∶肉桂精油∶黑胡椒精油为3∶2∶2;复合精油MIC值为16 mg/L,精油复配产生相加作用,使复合精油的抑菌效果增强;复合精油对冷却肉中的单增李斯特菌具有抑制作用,可以延长冷却猪肉的保鲜期。     

单核细胞增生李斯特氏菌的PCR检测方法

研究比较了裂解法、热煮沸法、试验盒法提取单增李斯特氏菌DNA的效果 ,认为Promega试剂盒法提取的DNA ,得率高、纯度好。同时根据单增李斯特氏菌的毒力相关基因的 5对引物 ,进行了引物的特异性研究 ,结果发现inlA引物、inlB引物、plcA引物特异性好 ,可以用于食品中单增李斯特氏菌的检测     

Modeling the lag phase and growth rate of Listeria monocytogenes in ground ham containing sodium lactate and sodium diacetate at various storage temperatures

ABSTRACT:  Refrigerated ready-to-eat (RTE) meats contaminated with Listeria monocytogenes were implicated in several listeriosis outbreaks. Lactate and diacetate have been shown to control L. monocytogenes in RTE meats. The objective of this study was to examine and model the effect of lactate (1.0% to 4.2%) and diacetate (0.05% to 0.2%) in ground ham on the lag phase duration (LPD, h) and growth rate (GR, log CFU/h) of L. monocytogenes at a range of temperatures (0 to 45 °C). A 6-strain mixture of L. monocytogenes was inoculated into ground ham containing lactate and diacetate, and stored at various temperatures. The LPD and GR of L. monocytogenes in ham as affected by lactate, diacetate, and storage temperature were analyzed and accurately represented with mathematical equations. Resulting LPD and GR equations for storage temperatures within the range of 0 to 36 °C significantly represented the experimental data with a regression coefficient of 0.97 and 0.96, respectively. Significant factors ( P < 0.05) that affected the LPD were temperature, lactate, diacetate, and the interactions of all three, whereas only temperature and the interactions between temperature and lactate and diacetate had a significant effect on GR. At suboptimal growth temperatures (≤12 °C) the increase of lactate and diacetate concentrations, individually or in combination, extended the LPD. The effect of higher concentrations of both additives on reducing the GR was observed only at temperatures that were more suitable for growth of L. monocytogenes , that is, 15 to 35 °C. These data may be used to assist in determining concentrations of lactate and diacetate in cooked ham products to control the growth of L. monocytogenes over a wide range of temperatures during manufacturing, distribution, and storage.