肉鸡胴体分割过程中污染微生物分析及不同冲淋条件对产品减菌影响

目的:为防制肉鸡屠宰分割环节产品的微生物污染。方法:调查肉鸡胴体分割车间环境的菌落总数和分割后鸡腿产品表面的菌落总数、假单胞菌、大肠菌群、肠球菌数量以及检测其金黄色葡萄球菌、沙门氏菌污染情况;通过正交实验优化淋洗条件。结果:在分割前、中、后期,分割车间的加工用水、空气中细菌数均未超过国家标准,但接触面污染较为严重,大多处于不可接受水平;分割后鸡腿产品表面污染的菌落总数、假单胞菌、大肠菌群和肠球菌数量分别为3.85~4.17、3.14~3.87、2.86~3.68、1.07~1.82lg(cfu/cm2),金黄色葡萄球菌、沙门氏菌的检出率分别为46.67%、14.17%;减菌的最适宜条件为乳酸浓度0.5%(w/v)、柠檬酸浓度1.0%(w/v)、冲淋时间30s,可减少菌落总数1.97lg(cfu/cm2),且减菌处理对其色泽、气味以及加热后肉汤滋味几乎无影响,最终鸡腿产品中菌落总数为2.20lg(cfu/cm2)。结论:肉鸡胴体分割车间环境以及分割后鸡腿细菌污染较严重,且存在致病菌污染;乳酸结合柠檬酸冲淋可明显减少分割后鸡腿表面的菌落总数。      

禽类屠宰加工过程中微生物污染及减菌措施

为了解肉鸡生鲜产品生产过程中胴体污染的发生情况以及微生物多样性和动态变化,综述了禽类商业屠宰过程中微生物污染来源、种群构成及菌相变化,并概述了相关的减菌措施,以期为在线控制工序间胴体表面细菌交叉污染和延长鲜禽产品货架期提供有用信息.     

生猪屠宰加工过程中微生物的污染及减菌措施

为确保屠宰加工肉类产品的安全和卫生,主要对生猪在屠宰加工过程中微生物污染和减菌措施进行了总结,旨在对屠宰行业在预防和减少屠宰线上胴体污染方面提供参考。     

肉鸡屠宰加工中减菌工艺及抗菌剂的研究进展

肉鸡屠宰加工过程中的微生物控制对保障食品安全和人类健康具有重要意义。肉鸡屠宰加工过程中,浸烫、洗涤、冷却是微生物污染控制的重要环节,多种措施的联合使用可有效降低肉鸡胴体中微生物载量。其中次氯酸钠、氯化十六烷基吡啶、酸化亚氯酸钠等抗菌剂可有效减少肉鸡胴体中沙门菌、大肠埃希菌和弯曲菌等致病菌污染,但不同减菌环节及抗菌剂的使用剂量、作用时间等对减菌效果影响较大。本文综述了肉鸡屠宰加工过程中各环节微生物污染的控制措施,同时也对多种抗菌剂在上述工艺环节中的减菌效果进行系统阐述,以期为国内肉鸡屠宰加过程中微生物污染防控提供数据参考,促进肉鸡生产行业健康发展,保护消费者健康。     

肉鸡屠宰加工及冷藏中的微生物污染来源及菌相分析

研究了商业屠宰及冷藏过程对肉鸡胴体天然茵落的影响,结果表明,空气、预冷水与环境中各种接触面均是禽类生鲜产品的潜在污染源.尽管加工过程能减少胴体表面各种腐败茵、致病茵污染,但某些工序也增加了特定细菌的污染程度,细菌交叉污染发生在加工过程中的所有阶段.总的说来净膛操作会导致胴体污染程度上升,冲洗、预冷过程对减菌都有很好效果.但预冷过程也可能导致嗜冷茵污染的发生,并且加工过程中存活的细菌能在冷藏阶段继续增殖进而导致产品腐败.     

肉鸡屠宰加工中减菌处理前后细菌菌相分析

基于16S rDNA V6～V8可变区的聚合酶链式反应-变性梯度凝胶电泳（polymerase chain reaction-denaturinggradient gel electrophoresis,PCR-DGGE）技术分析肉鸡屠宰加工过程中减菌处理前后胴体或产品细菌多样性。在预冷环节前采用50 ℃、1.5%乳酸溶液对肉鸡胴体冲淋15 s进行减菌处理,采集屠宰加工环节中减菌处理前后的胴体或分割产品表面样品,提取样品中的细菌总DNA,通过16S rDNA V6～V8可变区的PCR扩增,变性梯度凝胶电泳,对PCR扩增片段割胶回收、克隆测序分析减菌前后细菌菌相变化。结果表明,减菌前,胴体清洗环节DGGE条带的数量最多、亮度最强,细菌污染最严重,其次是分割环节,而预冷环节细菌种类及数量最少,污染程度最低;减菌后,各屠宰加工环节细菌种类与数量较减菌前均有所减少,其中胴体清洗环节与分割环节细菌的种类与数量减少量最多,预冷环节细菌的种类及数量最少,不同屠宰加工环节细菌种类并不完全一致;乳杆菌属细菌在整个肉鸡屠宰加工过程中均有出现,与肠杆菌科和假单胞菌属细菌为肉鸡屠宰加工过程中的优势腐败菌。     

不同有机酸雾化喷淋处理对鸡胴体表面减菌效果的影响

以某屠宰加工厂的鸡胴体为实验对象,研究食品中常见的乳酸、丙酸、酒石酸、柠檬酸、葡萄糖酸、山梨酸钾和焦磷酸钠（质量分数均为2%）对鸡胴体雾化喷淋处理后的减菌效果及复合有机酸雾化喷淋处理后对鸡胴体在贮藏期间品质的影响。结果表明：柠檬酸、丙酸和酒石酸对鸡胴体表面的菌落总数和乳酸菌、葡萄球菌属、假单胞菌属、热杀索丝菌、肠杆菌科的减菌效果较好;对柠檬酸、丙酸和酒石酸进行复合喷淋减菌效果研究,确定1%（质量分数,下同）柠檬酸、0.5%丙酸和0.5%酒石酸的复合喷淋减菌效果优于单一有机酸喷淋处理,且复合有机酸喷淋处理后对鸡胴体的红度、黄度和亮度值基本无影响;在11 d的贮藏期内,复合有机酸喷淋处理后鸡胴体的菌落总数、挥发性盐基氮和硫代巴比妥酸反应产物含量都明显降低。因此,复合有机酸雾化喷淋处理对鸡胴体具有明显的减菌效果,并可延长产品的货架期。     

热水结合乳酸喷淋处理对屠宰生产链中肉鸡胴体微生物、理化及感官指标的影响

以某肉鸡加工厂屠宰生产链的肉鸡胴体作为试材,采用热水(50℃)结合乳酸(1.5%)喷淋(15s)的减菌方法对其进行喷淋处理,采集处理前后的肉鸡胴体表面样品或产品进行微生物、理化及感官指标的测定。减菌处理后肉鸡胴体表面菌落总数、大肠菌群及肠球菌的数量在不同的加工环节均有一定程度的降低;鸡肉产品金黄色葡萄球菌检出率(从37.5%降至9.76%)和沙门氏菌(从12.75%降至1.22%)检出率明显降低;在两个月贮藏期内,处理前后鸡肉的p H、挥发性盐基氮及解冻后失水率无明显变化;处理前后鸡肉产品的组织状态、色泽无明显差异,且处理组鲜味更浓,加热煮沸后肉汤较对照组澄清。采用热水(50℃)结合乳酸(1.5%)喷淋(15s)的减菌方法处理肉鸡胴体能有效降低微生物污染数量,且处理前后胴体分割后速冻产品的部分理化指标、感官指标无明显变化。      

肉牛屠宰过程中的减菌技术研究进展

为了减少冷却肉的初始菌落数,延长其货架期并提高其安全性,众多学者对畜禽胴体及冷却肉减菌技术进行了研究。因此,本文对近年来肉牛屠宰过程及冷却牛肉生产过程中应用的减菌技术研究进展进行概述,总结基于物理方法减菌的胴体修整及清水冲洗、热除菌、紫外线杀菌和低温等离子体杀菌等措施,以及基于化学方法减菌的有机酸喷淋、过氧乙酸喷淋等措施。通过比较分析每种方法的减菌效果及优缺点,初步得出清水冲洗与乳酸喷淋的复合减菌方法是既有效又经济的牛胴体减菌措施的结论。通过本文的总结和概述,期望可以为肉牛屠宰企业合理地选择减菌措施提供参考。     

肉牛屠宰过程中胴体表面及接触环境污染情况分析

为研究肉牛屠宰场屠宰过程中牛胴体表面污染及接触环境污染变化情况,选取某牛屠宰场采集样品共计322 份,分别在剥皮扯皮、去内脏、修整称质量、冲洗及排酸环节对牛胴体后腿、背部、胸部、前腿及颈部以及屠宰前后的工人手部及刀具进行采样,测定菌落总数、乳酸菌、大肠菌群、金黄色葡萄球菌及假单胞菌的污染情况。结果表明：胴体表面污染情况总体呈现先上升后下降的趋势,修整称质量环节污染最为严重,菌落总数可达到2.82（lg（CFU/cm2））;胸部为屠宰过程中污染最严重的部位,平均菌落总数可达到2.10（lg（CFU/cm2））;屠宰空气在冲洗时污染最为严重,空气沉降菌落总数高达271.33 CFU/皿;屠宰工人的手部及刀具也是胴体污染的主要来源。     

肉鸡胴体分割过程中污染微生物分析及不同冲淋条件对产品减菌影响

目的:为防制肉鸡屠宰分割环节产品的微生物污染。方法:调查肉鸡胴体分割车间环境的菌落总数和分割后鸡腿产品表面的菌落总数、假单胞菌、大肠菌群、肠球菌数量以及检测其金黄色葡萄球菌、沙门氏菌污染情况;通过正交实验优化淋洗条件。结果:在分割前、中、后期,分割车间的加工用水、空气中细菌数均未超过国家标准,但接触面污染较为严重,大多处于不可接受水平;分割后鸡腿产品表面污染的菌落总数、假单胞菌、大肠菌群和肠球菌数量分别为3.85~4.17、3.14~3.87、2.86~3.68、1.07~1.82lg(cfu/cm2),金黄色葡萄球菌、沙门氏菌的检出率分别为46.67%、14.17%;减菌的最适宜条件为乳酸浓度0.5%(w/v)、柠檬酸浓度1.0%(w/v)、冲淋时间30s,可减少菌落总数1.97lg(cfu/cm2),且减菌处理对其色泽、气味以及加热后肉汤滋味几乎无影响,最终鸡腿产品中菌落总数为2.20lg(cfu/cm2)。结论:肉鸡胴体分割车间环境以及分割后鸡腿细菌污染较严重,且存在致病菌污染;乳酸结合柠檬酸冲淋可明显减少分割后鸡腿表面的菌落总数。     

The effect of slaughter operations on the contamination of chicken carcasses with thermotolerant Campylobacter

To evaluate the effect of specific slaughter operations on the contamination of broiler carcasses with naturally occurring thermotolerant Campylobacter, experiments were carried out in two Danish commercial slaughter plants (Plant I and Plant II). Six broiler flocks determined Campylobacter positive prior to slaughter were investigated at four sampling locations within each slaughter plant. Quantification of thermotolerant Campylobacter in 30 neck skin samples per flock per sampling location showed that the evisceration operation in Plant I led to a significant increase in the Campylobacter concentration of 0.5 log(10) cfu/g in average, whereas no significant changes were observed during this operation in Plant II. Air chilling (Plant I) and water chilling (Plant II), both including a carcass wash prior to the chilling operation, caused similar, but significant reductions of 0.83 and 0.97 log(10) cfu/g, respectively. In packed frozen chickens (Plant II) an additional reduction of 1.38 log(10) cfu/g in average was obtained due to the freezing operation. In packed chilled chickens (Plant I), however, the number of thermotolerant Campylobacter per gram remained at the same level as after air chilling. Enumeration of thermotolerant Campylobacter in 30 intestinal samples per flock showed that in two of the six flocks examined the within flock colonization was very low (<3% and 27% positive samples). The remaining four flocks were colonized at percentages of 100 (three flocks) and 97 (one flock) and had intestinal mean counts ranging from 6.65 to 8.20 log(10) cfu/g. A correlation between Campylobacter concentrations in intestinal content and on chicken carcasses after the defeathering operation was documented. This finding indicates that a reduction in the Campylobacter concentration on chicken carcasses may also be obtained by interventions aimed at reducing the concentration of Campylobacter in the intestines of the living birds.     

Campylobacter spp. contamination of chicken carcasses during processing in relation to flock colonisation

The presence and numbers of campylobacters on chicken carcasses from 26 slaughter groups, originating from 22 single-house flocks and processed in four UK plants, were studied in relation to the level of flock colonisation determined by examining the caecal contents of at least ten birds per group. The prevalence of campylobacters on carcasses from five campylobacter-negative flocks processed just after other negative flocks was low (8.0 log(10) cfu) than carcasses originating from low prevalence flocks (average of 2.3 log(10) cfu; range: <1.1 to 4.1 log(10) cfu). There was a reduction in the numbers of campylobacters on carcasses between plucking and chilling in eight of ten fully colonised flocks. In another eight flocks, a significant (P<0.001) decrease (0.8 log(10) cfu) in the number of campylobacters on carcasses from just before to after chilling was detected. Campylobacter spp. could be isolated from aerosols, particles and droplets in considerable numbers in the hanging-on, defeathering and evisceration areas but not in the chillers. This was the case even when campylobacters were not isolated from the target flock. Campylobacters on carcasses from two partly colonised flocks were either the same subtype, as determined by speciation, Multi-Locus Sequence Typing (MLST) and flaA Restricted Fragment Length Polymorphism (RFLP) typing, as those in the fully colonised flocks processed previously, although not necessarily the most prevalent ones; or were the same subtypes as those found in the caeca of the flock itself. The prevalences of the different campylobacter subtypes found on carcasses from two fully colonised flocks did not closely reflect those found in the caeca. MLST combined with flaA RFLP provided a good method for ascertaining the relatedness of strains isolated from carcasses and caecal contents. This study showed that carcass contamination is related to the within-flock prevalence of campylobacter colonisation, but that contamination from previously processed flocks was also significant, especially on carcasses from low prevalence flocks. Forced dry air cooling of carcasses reduced contamination levels.     

Effect of logistic slaughter on Salmonella contamination on pig carcasses

Previous studies have shown that infected pigs are the source of carcass and slaughterhouse environment contamination by Salmonella. The present study tried to evaluate the effect of a logistic slaughter, organised according to Salmonella seroprevalence, on Salmonella contamination on carcasses. The study was performed at the beginning of slaughtering during three consecutive days. Low risk herds (8 batches) were slaughtered on day I, high risk herds (6 batches) on day II, and finally, moderate risk herds (5 batches) were slaughtered on day III. Each slaughtering day, holding pens, five points of the slaughter line, and 80 carcasses were sampled. The number of positive carcasses on days I, II and III was 7 (8.8%), 5 (6.3%) and 19 (24.4%) respectively. The results evidenced no clear effect of the logistic slaughter on carcass contamination, with a three times higher risk of finding a positive carcass when moderate Salmonella risk batches were slaughtered. Carcass contamination in low risk herds was linked to the contamination of holding pens and the slaughter line activities. On the other hand, Salmonella was not detected in any of the sampled carcasses in three out of six high risk Salmonella batches, showing that proper slaughtering practices can prevent carcass contamination. The experience reported here, demonstrates that apart from an accurate batch separation according to their seroprevalence levels, strict measures for cleaning and disinfection in the lairage and the slaughterhouse facilities are needed when logistic slaughter is performed.     

Quantitative investigation of the effects of chemical decontamination procedures on the microbiological status of broiler carcasses during processing

The effects of elevated chlorine concentrations (25 ppm) added to water in the final carcass washing equipment on total viable counts (TVCs 22 degrees C) and Escherichia coli and Enterobacteriaceae levels on poultry carcasses were investigated. Mean TVC counts on neck skin samples were significantly reduced when pre-evisceration and postwash samples were compared with log10 4.98 to 4.52 CFU/g recovered, respectively (P < or = 0.05). No significant reductions in TVC counts were observed in control samples at corresponding sampling points subjected to wash water containing 1 to 2 ppm chlorine. E. coli and Enterobacteriaceae counts were not significantly altered following final carcass washing in the processing plant. A second trial assessed the microbial decontamination capabilities of sodium triphosphate (TSP) on broiler carcasses. Neck skin samples from carcasses were obtained before final washing (control), following a 15-s dip in potable water and after dipping in a 10% TSP solution (pH 12) for 15 s. Reductions in E. coli and Enterobacteriaceae counts were all statistically significant for both water and TSP-treated samples when compared with corresponding controls (P < or = 0.01). The TSP treatment resulted in higher reductions of log10 1.95 and 1.86/g for E. coli and Enterobacteriaceae, respectively. In contrast, reductions of log10 0.37 and 0.3 l/g were observed for E. coli and Enterobacteriaceae counts when water-dipped carcasses were compared with corresponding controls. Significantly, Salmonella was not detected in any of the TSP-treated carcasses, while log10 1.92 and 1.04/g were found in control and water-dipped samples, respectively. Thermophilic Campylobacter counts were significantly lower in both treatment groups when compared with corresponding controlsresulting in log10 0.55 and 1.71/g reductions for water- and TSP-dipped carcasses, respectively (P < or = 0.01).     

Location of bung bagging during beef slaughter influences the potential for spreading pathogen contamination on beef carcasses

Preevisceration carcass washing prior to bung bagging during beef slaughter may allow pooling of wash water in the rectal area and consequent spread of potential pathogens. The objective of this study was to compare protocols for bung bagging after preevisceration washing with an alternative method for bung bagging before preevisceration washing for the potential to spread enterohemorrhagic Escherichia coli, E. coli O157:H7, and Salmonella on carcass surfaces. The study evaluated incidence rates of pathogens in preevisceration wash water (10 ml) samples (n = 120) and on surface (100 cm2) sponge samples (n = 120) in the immediate bung region when bagging occurred before (prewash bagging) and after (postwash bagging) preevisceration washing. Surface sampling from postwash bagging yielded incidence rates of 58.3, 5, and 8.3%, whereas wash water sampling yielded 28.3, 1.7, and 5% for enterohemorrhagic Escherichia coli, E. coli O157:H7, and Salmonella, respectively. Surface sampling from prewash bagging yielded incidence rates of 35, 1.7, and 0%, whereas wash water sampling yielded 18.3, 0, and 8.3% for enterohemorrhagic Escherichia coli, E. coli O157:H7, and Salmonella, respectively. Results of this research indicate that the rectal area is a significant source of pathogen contamination on carcasses and that wash water is an important mechanism for potential transfer of pathogen contamination from the rectal area. Results from this study suggest that bung bagging, as proposed in this study, before (prewash bagging) rather than after (postwash bagging) preevisceration washing was generally more effective in controlling pathogen contamination and potential spread from the rectal area of carcasses.     

Microbiological contamination of pig carcasses at different stages of slaughter in two European Union-approved abattoirs

At sequential steps of slaughter (scalding, dehairing, singeing, polishing, trimming, washing, and chilling), 200 pig carcasses from two abattoirs were examined for total viable bacteria count (TVC) and the presence of Enterobacteriaceae and coagulase-positive Staphylococcus (CPS) by the wet-dry double-swab technique at the neck, belly, back, and ham. Before scalding, mean TVCs ranged from 5.0 to 6.0 log CFU cm(-2), and Enterobacteriaceae and CPS were detected on all carcasses. At abattoir A, mean TVCs and the percentage of Enterobacteriaceae-positive carcasses were reduced (P < 0.05) after scalding (1.9 log CFU cm(-2) and 12%, respectively), singeing (1.9 log CFU cm(-2) and 66%, respectively), and blast chilling (2.3 log CFU cm(-2) and 17%, respectively) and increased (P < 0.05) after dehairing (3.4 log CFU cm(-2) and 100%, respectively) and polishing (2.9 log CFU cm(-2)). The proportion of CPS-positive samples decreased to < or = 10% after scalding and remained at this level. At abattoir B, mean TVCs and the percentages of Enterobacteriaceae- and CPS-positive carcasses were reduced (P < 0.05) after scalding (2.4 log CFU cm(-2) and 29 and 20%, respectively), polishing (3.7 log CFU cm(-2)), and chilling (2.6 log CFU cm(-2) and 55 and 77%, respectively) and increased (P < 0.05) after the combined dehairing-singeing (4.7 log CFU cm(-2) and 97 and 100%, respectively). Among sites, the neck tended to yield higher levels of contamination from trimming to chilling at both abattoirs (P < 0.05). Consequently, scalding, singeing, and chilling may be integrated in a hazard analysis critical control point (HACCP) system for pig slaughter. As indicated by the higher levels of contamination on carcasses after dehairing-singeing and the following stages at abattoir B, each abattoir should develop its own baseline data and should customize HACCP systems to match process- and site-specific circumstances.     

Microbiological effects of acid decontamination of pork carcasses at various locations in processing

The microbiological effect of hot (55° C), 1% (v/v) lactic acid sprayed on the surface of pork carcasses (n = 36) immediately after dehairing, after evisceration (immediately before chilling) or at both locations in slaughter/ processing was determined. Mean aerobic plate counts (APCs) of all acid-treated carcass surfaces were numerically lower than those of control carcasses: however, in most cases these reductions were not statistically significant (P>0·05). All samples tested for the presence of Salmonella and Listeria were negative. No significant differences in sensory characteristics or microbiological counts were evident for acid-treated and control carcass loins that were vacuum packaged and stored 0–14 days post-fabrication. Mean pH value and scores of sensory attributes such as lean color, surface discoloration, fat color, overall appearance and off-odor of chops from acid-treated carcasses were not significantly and/or consistently different from chops of comparable control carcasses. The role of bacterial attachment to pork skin and its effect on the decontaminating efficiency of lactic acid are discussed.