肉类微生物学(九) 肉类微生物的控制

肉类的腐败变质主要是由微生物引起的,本文主要介绍了肉类微生物控制的三个基本策略,即防止微生物的生长、杀死微生物、促进有益微生物的生长,使其抑制有害微生物的生长,并重点介绍了各种不同的控制措施。     

Elimination of Listeria monocytogenes on hotdogs by infrared surface treatment

ABSTRACT:  The objective of this research was to develop an infrared pasteurization process with automatic temperature control for inactivation of surface-contaminated Listeria monocytogenes on ready-to-eat meats such as hotdogs. The pasteurization system contained 4 basic elements: an infrared emitter, a hotdog roller, an infrared sensor, and a temperature controller. The infrared sensor was used to monitor the surface temperature of hotdogs while the infrared emitter, modulated by a power controller, was used as a heating source. The surface temperature of hotdogs was increased to set points (70, 75, 80, or 85 °C), and maintained for bacterial kill. The infrared surface pasteurization was evaluated using hotdogs that were surface-inoculated with a 4-strain L. monocytogenes cocktail to an average initial inoculum of 7.32 log (CFU/g). On the average 1.0, 2.1, 3.0, or 5.3 log-reduction in L . monocytogenes was observed after the surface temperature of hotdogs was increased to 70, 75, 80, or 85 °C, respectively. Holding the sample temperature led to additional bacterial inactivation. With a 3 min holding at 80 °C or 2 min at 85 °C, a total of 6.4 or 6.7 logs of L. monocytogenes were inactivated. This study demonstrated that the infrared surface pasteurization was effective in inactivating L. monocytogenes in RTE meats.     

Functionality of Wheat Germ Protein in Comminuted Meat Products as Compared with Corn Germ and Soy Proteins

Wheat germ protein flour (WGPF), corn germ protein flour (CGPF), and soy flour (SF) were used as additives at a level of 3.5% in comminuted meat products (CMP). Frankfurters with protein additives showed increased water-holding capacity and batter stability and decreased cooking loss. Improved viscosity and adhesiveness were observed with protein additives when the level of added water was constant. Protein additives also influenced textural and sensory properties of frankfurters. WGPF at a level of 3.5% was found similar to effects of SF and CGPF. WGPF is a potential nonmeat protein additive that can be utilized as an extender in CMP such as frankfurters and bologna.     

A review of nitrite and chloride chemistry: Interactions and implications for cured meats

Concerns for the health-related implications of sodium nitrite and sodium chloride in cured meats have lead to reductions in use of both ingredients and there is evidence of chemical interaction between nitrite and chloride in food systems which have implications for cured meats. This review considers the role of chloride in nitrite chemistry and extends this consideration to evaluation of potential changes in cured meat products. Microbiological control depends on nitrite reactivity and a chloride effect has been demonstrated in Clostridium botulinum spore outgrowth and toxin formation. Changes in flavour of cured meats or in development of cured colour are of lesser concern but may take place. More information on specific inhibitory mechanisms by nitrite is needed.     

Use of visible spectroscopy to assess colour development during ageing of fresh pork from different quality classes

The objective of this research was to study the entire visible spectra evolution during meat ageing in different pork meat quality classes (PSE, DFD and RFN). The potential use of the visible spectra for discriminating low meat quality classes during the 24 hours postmortem (hpm) was also analysed. For these purposes, 26 pork loins were used: 3 PSE (pale, soft and exudative), 3 DFD (dark, firm and dry) and 20 RFN (red, firm and non‐exudative). At 12, 24, 48 h and 7 days postmortem, reflectance spectra (400–700 nm) were obtained by a spectrocolorimeter Minolta CM‐3600D after one and a half hour of blooming time. It was demonstrated that the ageing time has an influence in colour parameters and in blooming ability of RFN loins. The evolution of visible spectra was influenced by ageing time in PSE and RFN loins, while the visible spectra of DFD loins showed no variation with postmortem time. The results showed the possibility of separating PSE meats from the other classes by using visible reflectance spectra at 24 hpm.     

Analysis of heterocyclic amines and β-carbolines by liquid chromatography–mass spectrometry in cooked meats commonly consumed in Korea

Heterocyclic amines (HAs), which form in meats during heating and cooking, are recognized as mutagenic and carcinogenic compounds. In this study, 13 HAs and 2 β-carbolines (BCs) were analyzed in cooked Korean meat products, including griddled bacon, griddled pork loin, boiled pork loin, boiled chicken meat, chicken meat stock, chicken breast for salad and chicken patty. The samples were either cooked in the laboratory or purchased from local fast-food restaurants. The HAs and BCs in the samples were separated using solid-phase extraction and were analyzed by high performance liquid chromatography–mass spectrometry (HPLC–MS). The most frequently detected HAs and BCs in the cooked meats were harman (1-methyl-9H pyrido[4,3-b]indole; 990.9 ng g^?1), norharman (9H-pyrido[4,3-b]indole; 412.7 ng g^?1) and PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine; 258.2 ng g^?1). The griddled pork loin and bacon contained higher levels of norharman, harman and PhIP than the other cooked meats. PhIP, which is classified as a Group 2B carcinogen by the International Agency for Research on Cancer, had levels of 258.2 and 168.2 ng g^?1 in the griddled pork loin and griddled bacon, respectively. The griddled bacon was the only sample containing TriMeIQx (2-amino-3,4,7,8-tetramethylimidazo[4,5-f]quinoxaline; 79.9 ng g^?1). IQ (2-amino-3-methyl imidazo[4,5-f]quinoline), 7,8-DiMeIQx (2-amino-3,7,8-trimethylimidazo[4,5-f]quinoxaline), 4,8-DiMeIQx (2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline) and AαC (2-amino-9H-pyrido[2,3-b]indole) were detected at trace levels in all samples.     

Yield, USDA Grade Factors and Time Requirements for a Beef Partial Hot Fabrication Procedure

No major differences were noted for lean yield or development of USDA grade factors between control (CS) or partial hot fabricated (AS) beef sides. Less time (25%) was necessary for removal of the thin cuts from the AS vs CS sides. Also, AS sides required 67% less energy to chill than did CS sides. Fat removed hot contained more moisture, which could increase rendering costs.     

高氧气调包装肉类研究进展

肉类高氧气调包装通常是用含有70%~80%的氧和20%~30%的二氧化碳的混合气体对新鲜肉类进行包装的技术,其中的氧气可使肉类呈现稳定的红色,二氧化碳主要是抑制细菌的生长而延长贮藏期限。本文对近年来该技术在新鲜肉类中应用的研究情况进行了总结,从高氧包装对肉类颜色的影响、高氧环境下的微生物生长、高氧对肉类的脂类氧化和蛋白质氧化的影响以及提高高氧气调包装肉类品质的措施等方面进行了评述。肉类的颜色稳定性与肌肉类型有关,随O2浓度的增加而增大,随CO2浓度的增加而降低。另外,肉类颜色稳定性受肉类氧化特别是脂类氧化的影响。高氧气调包装肉类中的微生物受到CO2的抑制作用表现出比生长速率降低及生长的迟滞期延长。高氧气调包装会引起脂类和肌红蛋白的氧化以及蛋白质的交联,导致肉的嫩度和多汁性下降。高氧气调包装会导致肉类煮制时出现过早熟褐现象。添加某些防腐剂和抗氧化剂可以有效改善高氧气调包装肉类质量,延长肉类贮藏期限。     

肉类掺杂掺假的高光谱成像检测研究进展

肉类的掺杂掺假是国内外普遍关注的公共安全问题,对社会经济、健康、环境等方面具有潜在影响。近年来,不法商家为牟取暴利导致肉类掺杂掺假现象层出不穷、多种多样,针对此类问题研究行之有效的检测技术与方法以保障肉品真实性具有重要意义。高光谱成像技术以快速、非侵入、图谱合一等优势在食品农产品检测领域发展迅速,不仅可同时提取图像及光谱特征信息,还具备让肉类掺杂掺假"快速现形"的能力,具有较好的未来市场应用前景。该文介绍了肉类掺杂掺假现状,简述了高光谱成像原理及相关研究中数据解析方法,在探讨现有肉类掺杂掺假定性判别及定量预测研究进展基础上展望进一步研究突破方向,以期为相关肉品市场监管办法提供参考,也为其他类农产品掺假检测研究提供方法和思路借鉴。     

肉类保藏技术(三) 干燥脱水法在肉类保藏中的应用

本文介绍了肉类保藏中常用的一种方法即干燥脱水法,其中包括干燥脱水法的原理、常用方式以及此法目前的应用现状,并在此基础上对干燥脱水法在肉类保藏中的应用前景进行了预测。