天然减菌剂对宰后鸡胴体表面雾化喷淋减菌效果研究

以某肉鸡屠宰加工厂的肉鸡胴体为试验对象,研究食品中常用的0. 5%混合Nisin、壳聚糖、茶多酚、ε-聚赖氨酸、姜黄素、溶菌酶和海藻酸钠等天然减菌剂对其进行雾化喷淋及复合喷淋处理后的减菌效果。结果表明:Nisin、聚赖氨酸和壳聚糖对鸡胴体表面的菌落总数、乳酸菌、葡萄球菌属、假单胞菌属、热杀索丝菌和肠杆菌科的减菌效果较好。确定0. 1%Nisin、0. 2%ε-聚赖氨酸和0. 2%壳聚糖的复合喷淋减菌效果优于Nisin、ε-聚赖氨酸和壳聚糖的单一喷淋减菌效果,且复合天然减菌剂喷淋减菌后对鸡胴体的a*、b*和L*值基本无显著性影响(p 0. 05)。在11 d的贮藏期内,复合有机酸喷淋后鸡胴体的TVB-N和TBARS等指标都明显降低,复合天然减菌剂雾化喷淋处理的肉鸡胴体具有明显的减菌效果并可延长产品的货架期。     

不同减菌剂对小型屠宰厂牛肉表面减菌效果的研究

采用乳酸、乙酸、柠檬酸、次氯酸钠、酸化亚氯酸钠、二氧化氯六种减菌剂,在不同的浓度的情况下,运用简易的手持式喷淋设备对人工接种的优势腐败菌液(假单胞菌属、大肠菌群、葡萄球菌、乳酸菌)的牛肉表面进行喷淋,通过喷淋前后牛肉表面细菌的计数,来检测减菌剂的减菌效果。结果表明,有机酸的减菌效果大于含氯化合物;2%的三种有机酸中,乳酸的减菌效果最好,三种含氯化合物中,酸化的亚氯酸钠溶液减菌效果最好;2%的乳酸对人工接种的牛肉表面喷淋减少菌落总数和腐败菌分别为5.19 lg CFU/cm2和3.37~4.71 lg CFU/cm2;由于2%乳酸较好的减菌效果,性价比高,使用方便,所以最适合在小型屠宰厂对牛胴体喷淋。     

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。     

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。     

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。     

有机酸对冷鲜猪肉气调贮藏品质的影响

基于单纯形重心设计法研究不同有机酸及其复合配比对冷鲜猪肉气调贮藏品质的影响。以5 mg/m L有机酸浸泡处理冷鲜猪肉,相较空白对照组,酒石酸、抗坏血酸、柠檬酸及其复合酸液处理均能有效抑制冷鲜猪肉气调贮藏过程中的微生物生长,同时减少挥发性盐基氮(TVB-N)生成。以复合酸液中各有机酸的质量分数为因素,以冷鲜猪肉贮藏至第6天的菌落总数和TVB-N值为响应值,分别构建回归模型优化有机酸配比。经比较验证发现,单一柠檬酸处理的保鲜效果最佳,冷鲜猪肉气调贮藏至第6天的菌落总数和TVB-N值分别为5.23 lg(CFU/g)和9.33mg/100 g,与对照组相比延长货架期约3 d。研究结果可为冷鲜猪肉的品质控制提供参考。     

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。     

不同的混合酸处理对猪胴体表面细菌作用效果的研究

采用乳酸(1%、2%、3%) 乙酸(0.5%、1%、1.5%) 柠檬酸(0.5%、1%、1.5%)9种不同浓度混合配比对冷却猪肉生产中的胴体进行在线喷淋实验,应用棉球擦拭法在胴体的槽头部位进行取样,研究微生物污染的控制效果。结果表明,9种不同浓度配比的混合酸处理对猪胴体表面的微生物有抑制作用。与未经混合酸处理的对照组相比,各处理组的细菌总数减少了0.29～0.61logcfu/cm2,大肠菌群数减少了0.31～0.84logcfu/50cm2。处理组2～9均与对照组有明显差异(P<0.05),只有处理组1(1%乳酸 0.5%乙酸 0.5%柠檬酸)差异不显著(P>0.05)。其中,3%乳酸 0.5%乙酸 1.5%柠檬酸(处理组7)混合使用对减少细菌总数和大肠菌群数效果最显著,且比单独使用乙酸效果更好。     

乳酸和二氧化氯对牛胴体和分割牛肉微生物的去污染效果研究

采用不同浓度的乳酸和二氧化氯对冷却前的牛胴体进行喷洒处理,研究了喷洒后对牛胴体及成熟后脖肉中微生物的去污染效果。结果表明,浓度在2.5%以下的乳酸对胴体及其成熟后的脖肉无显著的减菌效果。浓度在100mg/kg及以上的二氧化氯能显著(p<0.05)减少牛胴体表面和成熟后脖肉的菌落总数和大肠菌群;浓度为200mg/kg的二氧化氯比100mg/kg的减菌效果更显著(p<0.05)。     

Bacteriological quality of broiler carcasses as affected by in-plant lactic acid decontamination

In an attempt to improve the bacteriological quality of broiler carcasses the bactericidal effect of treatments with 1% and 2% lactic acid was investigated. Bacterial colonisation was determined immediately after treatment, after the carcasses had been chilled and during storage at 0 degrees C. Examination included numbers of mesophilic aerobic and psychrotrophic aerobic colony-forming units (CFU), CFU of Enterobacteriaceae at 37 degrees C and CFU of Staphylococcus aureus. Immediately after treatment colonisation per gram skin was generally reduced by about 1 log. Initially 2% lactic acid was not found significantly more effective in reducing colony counts than 1%. However, treatment with 2% lactic acid suppressed post-decontamination colonisation with Enterobacteriaceae more effectively than 1% lactic acid, as determined after 15-18 days storage at about 0 degrees C. Lactic acid treatment was most effective when applied shortly before chilling. Successive treatment at three different stages during slaughtering did not increase reduction of colony counts. It is concluded that decontamination with 1-2% lactic acid at pH 2, when applied shortly before chilling, will markedly improve the bacterial safety and increase the refrigerated shelf life of broiler carcasses.     

Sub-lethal heat treatment affects the tolerance of Cronobacter sakazakii BCRC 13988 to various organic acids, simulated gastric juice and bile solution

Cronobacter spp., formerly Enterobacter sakazakii, are considered emerging opportunistic pathogens and the etiological agent of life-threatening bacterial infections in infants. In the present study, C. sakazakii BCRC 13988 was first subjected to sub-lethal heat treatment at 47 °C for 15 min. Survival rates of the heat-shocked and non-shocked C. sakazakii cells in phosphate buffer solution (PBS, pH 4.0) containing organic acids (e.g. acetic, propionic, citric, lactic or tartaric acid), simulated gastric juice (pH 2.0-4.0), and bile solution (0.5 and 2.0%) were examined. Results revealed that sub-lethal heat treatment enhanced the test organism's tolerance to organic acids, although the extent of increased acid tolerance varied with the organic acid examined. Compared with the control cells, heat-shocked C. sakazakii cells after 120-min of exposure, exhibited the largest increase in tolerance in the lactic acid-containing PBS. Furthermore, although heat shock did not affect the behavior of C. sakazakii in bile solution, it increased the test organism's survival when exposed to simulated gastric juice with a pH of 3.0-4.0.     

Use of organic acids to inactivate Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on organic fresh apples and lettuce

Abstract: This study was undertaken to investigate the antimicrobial effect of organic acids against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on whole red organic apples and lettuce. Several studies have been conducted to evaluate organic acids as sanitizers. However, no studies have compared antimicrobial effects of various organic acids on organic fresh produce, including evaluation of color changes of produce. Apples and lettuce were inoculated with a cocktail of 3 strains each of 3 foodborne pathogens provided above and treated with 1% and 2% organic acids (propionic, acetic, lactic, malic, and citric acid) for 0, 0.5, 1, 5, and 10 min. With increasing treatment time and acid concentration, organic acid treatments showed significant reduction compared to the control treatment (distilled water), and differences in antimicrobial effects between organic acids were observed. After 10 min of treatment with 1% and 2% organic acids in apples, propionic (0.92 to 2.75 log reduction), acetic (0.52 to 2.78 log reduction), lactic (1.69 to >3.42 log reduction), malic (1.48 to >3.42 log reduction), and citric acid (1.52 to >3.42 log reduction) exhibited significant (P < 0.05) antibacterial effects against 3 foodborne pathogens compared to the control treatment. In lettuce, propionic (0.93 to 1.52 log reduction), acetic (1.13 to 1.74 log reduction), lactic (1.87 to 2.54 log reduction), malic (2.32 to 2.98 log reduction), and citric acid (1.85 to 2.86 log reduction) showed significant (P < 0.05) effects compared to the control treatment. Changes in sample color subjected to organic acids treatment were not significant during storage. Practical Application: It is suggested that organic acids have a potential as sanitizers for organic fresh produce. These data may help the organic produce industry provide safe fresh produce for consumers.     

Integrating microbial decontamination with organic acids in HACCP programmes for muscle foods: prospects and controversies

A considerable literature reports the antibacterial efficacy of dilute solutions of organic acids (lactic, acetic). With carcasses an overall reduction in surface contaminants of 1.5 log cycles can be expected. Carcass decontamination may not improve the safety of the resultant meat, but laboratory trials confirm that acid decontamination of subprimal and retail cuts is more efficacious. An advantage over many other intervention strategies is that residual antimicrobial activity is demonstrable over extended periods of storage. These studies have also shown that some meatborne pathogens are particularly sensitive to organic acids (i.e., Yersinia enterocolitica) while others are resistant (i.e., E. coli 0157:H7). Dilute solutions of organic acids (1 to 3%) are generally without effect on the desirable sensory properties of meat when used as a carcass decontaminant. However, dependent on treatment conditions, lactic and acetic acid can produce adverse sensory changes when applied directly to meat cuts, with irreversible changes in appearance being a frequent occurrence. It is speculated that organic acid decontamination will be implemented in American abattoirs in an effort to meet specified performance standards for pathogen reduction as part of an overall HACCP program. In contrast, the EU advocates that strictly controlled processing hygiene is sufficient to ensure the safety of the product. Additional research is necessary to establish a set of treatment conditions that may permit a practicable reduction in bacterial contamination throughout the processing chain with a measurable effect on safety and storage life, without imposing any change in sensory properties. It will also be necessary to develop standard, objective measures to assess HACCP and the efficacy of decontamination procedures. Without such commercial studies controversy on the practicality of acid decontamination will persist.     

Treatments using hot water instead of lactic acid reduce levels of aerobic bacteria and Enterobacteriaceae and reduce the prevalence of Escherichia coil O157:H7 on preevisceration beef carcasses

Lactic acid has become the most commonly used organic acid for treatment of postevisceration beef carcasses. Many processors have also implemented 2% lactic acid washes on preevisceration carcasses. We previously demonstrated that hot water washing and steam vacuuming are effective carcass interventions. Because of the effectiveness of hot water, we compared its use with that of lactic acid as a preevisceration wash in a commercial setting. A commercial hot water carcass wash cabinet applying 74 degrees C (165 degrees F) water for 5.5 s reduced both aerobic plate counts and Enterobacteriaceae counts by 2.7 log CFU/100 cm2 on preevisceration carcasses. A commercial lactic acid spray cabinet that applied 2% L-lactic acid at approximately 42 degrees C (105 to 110 degrees F) to preevisceration carcasses reduced aerobic plate counts by 1.6 log CFU/100 cm2 and Enterobacteriaceae counts by 1.0 log CFU/100 cm2. When the two cabinets were in use sequentially, i.e., hot water followed by lactic acid, aerobic plate counts were reduced by 2.2 log CFU/100 cm2 and Enterobacteriaceae counts were reduced by 2.5 log CFU/100 cm2. Hot water treatments reduced Escherichia coli O157:H7 prevalence by 81%, and lactic acid treatments reduced E. coli O157:H7 prevalence by 35%, but the two treatments in combination produced a 79% reduction in E. coli O157:H7, a result that was no better than that achieved with hot water alone. These results suggest that hot water would be more beneficial than lactic acid for decontamination of preevisceration beef carcasses.     

毛细管电泳测定乳酸发酵液中有机酸

运用毛细管区带电泳模式,在磷酸缓冲液中成功地分离了苹果酸、甲酸、乙酸、丙酸、琥珀酸、酒石酸、柠檬酸、乳酸、草酸9种有机酸。研究了缓冲液浓度、pH值、电泳电压、检测波长等因素对分离的影响,并对实际发酵液进行分析测定,加标回收率为97.5%～107.1%。该方法简便、快速、准确,适于整个发酵过程条件的优化及发酵产物的监控工作。     

四川不同地区的熟醋及其固态发酵过程中有机酸含量变化分析

为了解不同地区的四川麸醋中有机酸含量差异及其固态发酵过程中有机酸含量变化,采用高效液相色谱对其7种主要的有机酸含量进行测定。结果表明,在四川麸醋固态发酵过程中,乙酸由1.2712 mg/mL升高至3.1214 mg/mL,是含量最高的酸,占总有机酸58.12%。而含量次之的是乳酸,由0.8858 mg/mL升高至1.3216 mg/mL,占总有机酸32.67%,其中乙酸和乳酸变化最为显著,草酸、柠檬酸、酒石酸、柠檬酸和酒石酸变化不明显。对结果进行主成分分析发现,在熟醋中,乳酸对四川麸醋显示了较高的相关性,四川麸醋中乳酸的含量明显高于其它地区熟醋中乳酸的含量,这表明乳酸可以将四川麸醋与其它地域的食醋有效的区分开。在四川麸醋固态发酵过程中,发酵前期3d^10d与乳酸体现了较高的关联性,后期12 d^23 d与乙酸具有较高的相关性。     

高盐腌雪菜坯低盐化前后有机酸的对比研究

采用高效液相色谱法(HPLC)对高盐腌雪菜坯低盐化前后样品中有机酸进行了研究,并将其与市场上销售腌雪菜和传统腌雪菜两个样品进行了对比检测.结果表明,低盐化前样品中有机酸检出种类有酒石酸、苹果酸、乳酸、柠檬酸、琥珀酸;低盐化后样品中有机酸检出种类仅有苹果酸及柠檬酸.就有机酸总量而言,腌雪菜由低盐化前的0.445%下降到低盐化后的0.133%,市场和传统腌雪菜样品分别为0.565%和0.228%.     

Microbial and Quality Characteristics of Pork Cuts from Carcasses Treated with Sanitizing Sprays

Pork carcasses were sprayed with 1.5% acetic, citric, or lactic acid. Loins were vacuum packed and stored at 0–2°, chops were cut periodically from loins and stored at 2–4°. Acetic and citric acids decreased (P<0.05) aerobic plate counts (APC) and total coliforms in loins for 14 days. Species of Salmonella, Yersinia, and Campylobacter were found on 0, 6, and 5% of samples. Lisreria spp were detected on 69% of loins and on 33% of chops. The sanitizing treatments were of relatively limited effectiveness for long term storage. No pH, TBA or sensory quality differences were observed.     

有机酸复合护色液对猕猴桃果脯PPO活性的影响

研究了柠檬酸、酒石酸、植酸3种有机酸复合护色液对猕猴桃果脯PPO(多酚氧化酶)活性的影响。运用混料回归设计试验,得出复合护色液中3种有机酸的最佳配比,并确定复合护色液总浓度及护色浸泡时间。结果表明,最佳护色工艺为:柠檬酸、酒石酸、植酸配比(质量分数)为1∶0.51∶0.51,复合护色液总浓度为0.5%.护色时间为2h。