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。     

黄羽肉鸡屠宰过程中胴体表面腐败菌的变化

为了分析黄羽肉鸡屠宰加工环节的肉鸡胴体污染菌的菌群组成,本试验利用平板倾注法及Illumina MiSeq高通量测序高效地测定黄羽肉鸡屠宰过程中加工环境和胴体表面腐败菌的多样性。结果表明,净膛、预冷及分级是黄羽肉鸡菌落总数增长的主要污染来源工序,分级秤、分级车间工人手套、预冷槽及净膛工人手套为以上三个工序中污染来源接触面,且分级秤及分级车间工人手套所污染菌群是黄羽鸡胴体菌群的主要来源,使黄羽鸡胴体表面菌落总数及假单胞菌增长率高达24.13%、41.27%,经过分级秤及分级车间工人手后黄羽鸡菌落总数显著（P<0.05）增加至4.63 lg(CFU/g)。打毛后（DM）、净膛后（JH）、净膛消毒后（CH）黄羽鸡胴体优势菌主要为链球菌属（Streptococcus）,大肠杆菌属（Escherichia）和气单胞菌属（Aeromonas）。黄羽鸡经预冷槽预冷后气单胞菌属丰度大幅增加,链球菌属次之。经过分级秤分级后黄羽鸡胴体菌群中不动杆菌属（Acinetobacter）为主要优势菌,巨球菌属（Macrococcus）次之。添加次氯酸电解水减菌后,黄羽肉鸡胴体表明气单胞菌属和链球菌属丰度大幅...     

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。     

冰鲜鸡预冷过程中微生物菌群多样性动态分析

为了对肉鸡屠宰预冷过程中预冷水、鸡胴体的微生物群落结构进行动态分析,研究二者优势菌群的消长规律。本文对第一批屠宰鸡通过预冷水0、2、4、6、8 h时预冷池中一阶、二阶预冷水以及鸡胴体进行菌落总数(TVC)检测,然后采用高通量测序的方法对二者的群落结构进行动态分析。菌落总数测定结果表明:在预冷过程中,一阶预冷水菌落总数由103 CFU/mL增长到105 CFU/mL,二阶预冷水菌落总数由102 CFU/mL增长到104 CFU/mL,在预冷前,鸡胴体的菌落总数为4.53 lg CFU/g,经预冷后在6~8 h内,鸡胴体表面菌落总数高于预冷前,说明预冷水已经失去了清洗减菌的作用,还可能会对鸡胴体造成交叉污染。高通量测序发现:在预冷过程中,一阶预冷水中气单胞菌属减少,假单胞菌属、链球菌属增加;二阶预冷水的不动杆菌属减少,假单胞菌属增加;与预冷前相比,预冷过程中鸡胴体的魏斯氏菌和漫球菌属减少,金黄杆菌属和假单胞菌属增加。本研究表明预冷后期预冷水失去减菌作用,对鸡胴体造成污染,预冷工艺主要对气单胞菌属、魏斯氏菌和漫球菌属有较好的减菌效果,对金黄杆菌和假单胞菌属减菌效果不佳。这为宰后胴体预冷工艺的优化提供参考依据,同时为冰鲜鸡产品的质量安全提供保障。     

冰鲜鸭加工冷藏过程中主要腐败菌来源及菌相分析

研究工业屠宰加工过程对冰鲜鸭胴体表面菌相形成的影响。采用传统微生物培养方法,对车间环境接触面、胴体表面、预冷水以及贮藏期产品的微生物数量进行测定。结果表明：车间空气、预冷水、环境接触面是构成加工过程胴体表面菌相的主要污染源;总体来讲,环境及胴体表面菌量延生产线进程而呈下降趋势,但由于脱毛前鸭子表面的菌量对环境菌量有补充作用,而经脱毛后的胴体表面受环境中菌量的补充作用,导致部分加工工序微生物数量有阶段性上升,如脱毛、净膛工序;预冷工序的抑菌作用由于存在过程性变化,因此对终产品品质有决定性影响。     

肉牛屠宰工序微生物污染状况分析和喷淋减菌技术

以减少冷却后牛胴体表面的微生物数量为目标,在企业实际生产条件下,以菌落总数为指标分析屠宰过程中各工序胴体表面的微生物变化状况,探讨不同喷淋方式的减菌效果。结果表明,屠宰工序中初始剥皮操作对胴体造成的污染最严重,其次为去脏工序。高压清水清洗对全胴体的减菌量为0.62(log10CFU/cm2);2%的乳酸喷淋对胸口部位菌落总数的减少量为1.06(log10CFU/cm2)。采用2%的乳酸喷淋可以有效减少肉牛屠宰过程中的胴体污染。     

冷却猪肉分割过程中微生物污染状况的研究

对冷却猪肉在分割过程中的主要接触物、分割肉本身的微生物污染和增殖情况进行研究。结果表明:分割过程中分割线上主要接触物的微生物数量随生产时间的延长而增加,传送带的微生物数量1h内达到1.89～2.48 lg(CFU/cm2),4h达到2.63～3.18lg(CFU/cm2);工人手、刀具、电锯和案板0.5h内微生物数量达到1.42～2.36 lg(CFU/cm2),2h达到1.84～3.08lg(CFU/cm2);初始冷却猪肉的微生物主要集中在胴体表层,在分割和精修过程中,冷却猪肉与污染物的接触,造成二次污染,不同部位分割冷却猪肉的微生物数量也不同,表面微生物数量在2.56～3.68 lg(CFU/cm2)之间,肉中微生物数量在3.18～3.97 lg(CFU/g)之间。     

鸡肉调理制品生产过程中污染微生物的调查研究

针对目前鸡肉调理制品货架期短的问题,对鸡肉调理制品在生产过程中的微生物污染状况进行调研。以菌落总数为测定指标探讨肉鸡屠宰分割生产线和鸡肉调理制品生产线及各车间生产环境的微生物污染状况。结果表明：屠宰车间环境污染严重,分割车间环境较好,屠宰结束后的鸡胴体和其分割产品菌落总数在2.12～3.95(lg(CFU/cm2))范围内,处在国标规定范围内,属于合格产品;肉鸡副产品(内脏)菌落总数达到3.87～4.31(lg(CFU/cm2)),显著高于分割产品;鸡肉调理制品生产环境存在严重微生物污染问题,处在不可接受水平内;鸡肉调理制品生产存在严重的微生物污染问题,鸡肉丸生产过程中菌落总数高达4.27～5.55(lg(CFU/g)),而鸡柳菌落总数则达到4.32～5.78(lg(CFU/g)),终产品属于超标产品。     

卤豆干生产过程微生物检测及安全控制

目的：确定卤豆干车间、设备及重要工序菌落总数污染情况,为保证卤豆干品质和安全控制提供理论依据。方法：根据GB4789.2-2010《食品微生物学检验 菌落总数测定》和大气微生物评级标准,对卤豆干车间空气、设备及重要工序进行菌落总数测定并评级。结果：豆腐制作车间空气菌落总数（3.98±0.14）（lg（CFU/m3））,生产设备接触面及操作人员的手菌落总数均高于4.50（lg（CFU/m2））;原料、泡豆、干豆腐和调味菌落总数分别为（6.21±0.49）、（7.28±1.30）、（5.54±0.28）、（7.32±0.30）（lg（CFU/g））,评级为污染至严重污染;熟浆、豆腐脑、卤前清洗和灭菌后的豆腐菌落总数为（2.48±0.07）、（2.47±0.16）、（3.01±0.15）、（2.11±0.30）（lg（CFU/g））,评级为清洁;Duncan’s新复极差法分析结果表明不同生产工序间菌落总数差异显著。结论：车间环境、生产设备及操作人员易对卤豆干造成二次污染;微生物分布与生产工序密切相关;原料、泡豆、烘烤和调味是影响卤豆干食品安全的关键工序;煮浆、豆腐脑、卤前清洗和灭菌是减少微生物污染的关键工序。     

基于高通量测序分析冷冻熟制小龙虾加工过程中微生物的消长规律

为揭示冷冻熟制小龙虾加工过程中微生物的消长规律并确定加工过程关键控制点,用微生物传统培养法结合高通量测序手段分析了小龙虾在原料、吐沙、清洗、蒸煮及成品等加工环节中的微生物变化情况。结果表明：吐沙环节可使虾鳃微生物数量显著下降,减菌率达98.9%,肠道中菌落总数变化不显著。蒸煮环节可使小龙虾虾鳃和肠道中的菌落总数分别降低4.22(lg(CFU/g))和4.64(lg(CFU/g)),使虾肉中的微生物含量低于检测限,并且能够完全杀灭大肠菌群和假单胞菌。高通量测序结果显示原料虾鳃及肠道中的物种丰度和多样性与虾肉相比较低,虾鳃中主要是变形菌门（Proteobacteria）,肠道中以厚壁菌门（Firmicutes）为主。吐沙环节会降低小龙虾物种丰度及多样性,虾肠道中变形菌门相对丰度显著降低,蒸煮后虾肉和虾鳃中的黄杆菌属（Flavobacterium）较清洗环节显著下降。研究确定了加工过程微生物的关键控制点为吐沙和蒸煮环节,为提升小龙虾制品质量安全和防腐保鲜提供理论依据。     

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.     

Studies to determine the critical control points in pork slaughter hazard analysis and critical control point systems

Aerobic mesophilic counts (AMC), coliform (CC) and coliform resuscitation counts (CRCs) were obtained by swabbing 50 cm² areas at three sites (ham, belly and neck) on pig carcasses, after each of seven stages of the slaughter/dressing process (bleeding, scalding, dehairing, singeing, polishing, evisceration and chilling). In most cases, there were no statistical differences (P>0.05) among the counts derived by these three methods. Reductions in counts at individual sites were observed after scalding (3.5 log₁₀ cfu cm⁻²), and singeing (2.5 log₁₀ cfu cm⁻²). Increases in counts at individual sites were observed after dehairing (2.0 log₁₀ cfu cm⁻²) and polishing (1.5 log₁₀ cfu cm⁻²). The incidence of Salmonella on pig carcasses was also obtained by swabbing the outside surfaces of 100 half carcasses. Information on the incidence of Salmonella in scald tank water (108 samples) was also investigated. Carcass swabs and scald tank water were examined for the presence of Salmonella using standard enrichment methods. Salmonella were detected on 31% of carcasses immediately after bleeding, 7% of carcasses immediately after dehairing and evisceration, and 1% of carcasses immediately after scalding. Serovars included Salmonella Typhimurium, Salmonella Hadar, Salmonella Infantis and Salmonella Derby. No Salmonella were recovered from samples of scald tank water. The impact of pig slaughter/dressing processes on carcass microbiology and their potential use as critical control points (CCPs) during pork production are discussed.     

拉萨地区牦牛屠宰过程中的微生物污染

为探明拉萨地区牦牛胴体屠宰过程中的微生物污染程度,明确微生物关键控制点,对拉萨地区某具有代表 性的规范屠宰企业屠宰前车间空气中的微生物、各屠宰工艺环节牦牛胴体表面以及人员用具的菌落总数和大肠菌群 数量进行测定。结果表明：屠宰前车间微生物污染严重;随着剥皮和去内脏工艺的进行,牦牛胴体的菌落总数和大 肠菌群数量显著增加;斧劈四分体后胴体的菌落总数和大肠菌群数量均显著高于剥皮和去内脏后;牦牛屠宰过程中 微生物的主要来源是垫板和斧头。     

Effectson carcass weight and meat quality of pigs dehaired by scalding or singering post-mortem

Two experiments were designed to compare the effects of two pig dehairing techniques. In the first experiment, 120 pigs were slaughtered in the same abattoir in five weekly sereis. One half of each series was dehaired by singeing (the usual technique in this abattoir), while the other half was dehaired in a scalding-dehairing combination. In the second experiment, 48 pigs were slaughtered in two series, one-half of each series in an abattoir practising singeing, the other half in an abattoir practising scalding. Temperature and pH were measured 30 min after slaughter in the longissimus lumborum. Meat quality was assessed the day after slaughter in various muscles. One ham was cured and cooked, while the other one was processed by dry-curing. In both experiments, carcass weights and yields were noticeably higher after singeing. Hams were heavier in singed carcasses, but their proportions in the carcasses were little or not at all affected by the dehairing technique. Proportions of loins, shoulders and bellies were similar with both dehairing techniques. The dehairing technique affected neither temperature nor rate of post-mortem pH fall. Meat quality as assessed on fresh meat was slightly better in singed carcasses. Weights of cooked ham and dry ham per side were higher in singed carcasses, due to the higher initial ham weight, but processing yields were not affected by the dehairing technique.     

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。     

Bacteriological Safety of Swine Carcasses Treated with Reconditioned Water

Swine carcass microflora were evaluated for selected foodborne pathogens after exposure to reconditioned water during scalding, dehairing, and polishing operations. Reused water had been reconditioned and chlorinated. Rodac plates applied to hams were used to assess carcass microflora. Water samples were enumerated using membrane filtration or spiral plating. Sampling was at mid-week throughout the year. Total aerobic plate counts on hams were unaffected by treating with potable or reconditioned waters. No differences were observed for staphylococci, enterics, fecal streptococci, Listeria monocytogenes, coliforms, and Aeromonas levels. A preevisceration potable water carcass wash reduced the bacterial load, regardless of initial treatment. Bacterial counts on carcasses paralleled those in water. Reuse is an alternative to potable water for initial slaughter operations without diminishing bacteriologic safety.     

ENUMERATION OF AEROMONAS FOR VERIFICATION OF THE HYGIENIC ADEQUACY OF SWINE CARCASS DRESSING PROCESSES1

Populations of Aeromonas spp. and aerobic bacteria from dehairing equipment and from carcasses passing through different processing steps in a swine slaughtering plant were evaluated to identify the hygienic risks of each operation. Sponge samples were taken from the scraper flails in dehairing machines and the surface of the shackling table at pre‐ and post‐operation times, with 20 samples from each location being collected at each time. Increased post‐operation levels of Aeromonas spp. indicated a buildup and possible spread of these bacteria to carcasses. The belly skins of 40 dehaired carcasses were each sampled at five points along the process line which were after the shackling, after the final singeing, after the final polishing, after the final wash and after chilling. The levels of microbial contaminants on carcasses varied at each processing step. The heaviest contamination of carcasses with Aeromonas (1.88 log CFU/cm²) and aerobic bacteria (2.66 log CFU/cm²) occurred after shackling. Counts were reduced at other steps as a result of singeing, washing and chilling operations. However, singed carcasses were recontaminated with Aeromonas and aerobic bacteria during the polishing operation. Aeromonas hydrophila were the most prominent motile aeromonads (74.1%) recovered at the plant. The findings for Aeromonas spp. were similar to those for aerobic bacteria (r²= 0.9995) which suggested that Aeromonas spp. are appropriate indicators for assessing carcass dressing processes.     

宰后冷却工艺对白条鸡肉品质的影响

采用L9(34)正交试验探讨宰后预冷温度、预冷时间、分割车间停留时间对白条鸡肉保水性的影响,采用L9(34)正交试验探讨预冷温度、预冷时间、次氯酸钠加入量对白条鸡胴体表面菌落总数以及大肠菌群的影响。结果表明：通过控制预冷温度、预冷时间及分割车间停留时间,可以提高白条鸡肉的保水性、减少血冰的生成量;通过控制预冷温度、预冷时间及次氯酸钠加入量,可以有效减少白条鸡胴体表面的菌落总数,抑制大肠菌群的生长繁殖。各因素对保水率、失水率的影响程度均为预冷温度＞预冷时间＞分割车间停留时间;提高保水性的最佳工艺条件为预冷温度(15℃,8℃)、预冷时间35min、分割车间停留时间30min;控制失水率的最佳工艺条件为预冷温度(10℃,4℃)、预冷时间30min、分割车间停留时间40min。各因素对感官质量(血冰)的影响程度为预冷温度＞分割车间停留时间＞预冷时间,控制血冰的最佳工艺条件为预冷温度(10℃,4℃)、预冷时间30min、分割车间停留时间25min。各因素对菌落总数、大肠菌群的影响程度为预冷温度＞次氯酸钠加入量＞预冷时间,最佳工艺条件为预冷温度(10℃,4℃)、次氯酸钠加入量80mg/kg、预冷时间30min。     

Incidence of coagulase positive Staphylococcus on beef carcasses in three Australian abattoirs.

The contamination of beef carcasses with coagulase-positive staphylococci (CPS) was studied at three beef abattoirs (A, B and C). The incidence and the number of CPS were determined on cattle hides immediately after slaughter and on three carcass sites (brisket, flank and round) at different points during processing along the slaughter line. The incidence of CPS on cattle hides ranged from 20 to 68.6%. At abattoir A, 6.5% of the carcasses sampled before evisceration were contaminated with CPS, compared to 40% of the carcasses after evisceration. The incidence on carcasses changed little during further processing; however, after chilling for 72 h, the incidence increased to 83%. After evisceration, the brisket and flank areas were more often contaminated than the round. A similar pattern of contamination was observed at abattoir B. At abattoir C, 26.7% of the samples collected before evisceration were contaminated and this fell to 16.7% after evisceration. After chilling for 72 h, the incidence of carcass contamination with CPS increased to 46.7%. The average number of CPS on contaminated carcasses prior to and after overnight chilling was less than 50 colony-forming units (cfu)/cm2 and, after weekend chilling, increased to 64 and 112 cfu/cm2 in abattoirs A and B, respectively. Of the isolates tested, 71.4% produced staphylococcal enterotoxin and 21% could not be classified phenotypically. The hands of workers and environmental sites associated with the evisceration process were examined for CPS at abattoir A. Hands were heavily contaminated and were the likely source of CPS contamination at this abattoir.