Risk of Clostridium botulinum type E toxin production in blue crab meat packaged in four commercial-type containers.

The aim of this investigation was to determine if a risk of Clostridium botulinum growth and toxin production existed in four different packaged crabmeat products. Freshly picked blue crab meat was inoculated with 10(3) to 10(4) spores per g of a mixed pool of four strains of C. botulinum type E (Beluga, Minnesota, G21-5, and 070). The lump crabmeat was packaged in four different packaging containers: (i) 12-oz copolymer polyethylene cups currently used by most crab processors; (ii) 12-oz copolymer polyethylene cups with heat-shrink, tamper-evident low-density polypropylene seals; (iii) 8-oz copolymer polyethylene cups with easy-open aluminum ends: and (iv) 8-oz copolymer polypropylene cups with integral tamper-evident pull-tabs. The packages were stored at either 4 degrees C for 21 days or 10 degrees C for 15 days. Storage at 10 degrees C was used to simulate temperature abuse. The mouse bioassay was used to detect the presence of C. botulinum toxin. Psychotrophic and anaerobic populations were enumerated and were found to increase with time regardless of packaging type. No botulinum toxin was detected in any of the four packaging types stored at 4 degrees C or 10 degrees C throughout the entire storage period.     

Detection of discoloration in thermally processed blue crab meat

This study objectively and quantifiably examined the effect of a series of factors on blue crab meat discoloration. Factors explored include heating process, animal harvest location, and position of meat within a container. A Spectrogard colorimeter was used to collect visual reflectance spectra between 380 and 720 nm. Meat degree of coloration was characterised objectively and rapidly by using lightness (L), red–green (a) and yellow–blue (b) colour values. Results showed that meat became darker with increasing heating process; crab harvest location had significant effect on the lightness of the flesh; and meat that is located in the bottom of a can was darker than that in the top. This study will serve as a baseline for the development of a coloration quality control system. © 1999 Society of Chemical Industry     

Combined effect of oregano essential oil and modified atmosphere packaging on shelf-life extension of fresh chicken breast meat, stored at 4 degrees C

The combined effect of oregano essential oil (0.1% and 1% w/w) and modified atmosphere packaging (MAP) (30% CO2/70% N2 and 70% CO2/30% N2) on shelf-life extension of fresh chicken meat stored at 4 degrees C was investigated. The parameters that were monitored were: microbiological (TVC, Pseudomonas spp., lactic acid bacteria (LAB), yeasts, Brochothrix thermosphacta and Enterobacteriaceae), physico-chemical (pH, TBA, color) and sensory (odor and taste) attributes. Microbial populations were reduced by 1-5 log cfu/g for a given sampling day, with the more pronounced effect being achieved by the combination of MAP and oregano essential oil. TBA values for all treatments remained lower than 1 mg malondialdehyde (MDA) kg(-1) throughout the 25-day storage period. pH values varied between 6.4 (day 0) and 5.9 (day 25). The values of the color parameters L*, a* and b* were not considerably affected by oregano oil or by MAP. Finally, sensory analysis showed that oregano oil at a concentration of 1% imparted a very strong taste to the product for which reason these lots of samples were not scored. On the basis of sensory evaluation a shelf-life extension of breast chicken meat by ca. 3-4 days for samples containing 0.1% oregano oil, 2-3 days for samples under MAP and 5-6 days for samples under MAP containing 0.1% of oregano oil was attained. Thus oregano oil and MAP exhibited an additive preservation effect.     

Effect of low-dose radiation on microbiological, chemical, and sensory characteristics of chicken meat stored aerobically at 4 degrees C

The effect of gamma-radiation (0.5, 1, and 2 kGy) on the shelf life of fresh skinless chicken breast fillets stored aerobically at 4 degrees C was evaluated. Microbiological, chemical, and sensorial changes occurring in chicken samples were monitored for 21 days. Irradiation reduced populations of bacteria, i.e., total viable bacteria, Brochothrix thermosphacta, lactic acid bacteria (LAB), and the effect was more pronounced at the highest dose (2 kGy). Pseudomonads, yeasts and molds, and Enterobacteriaceae were highly sensitive to gamma-radiation and were completely eliminated at all doses. Of the chemical indicators of spoilage, thiobarbituric values for nonirradiated and irradiated aerobically packaged chicken samples were in general low (<1 mg of malonaldehyde per kg of muscle) during refrigerated storage for 21 days. With regard to volatile amines, both trimethylamine nitrogen (TMA-N) and total volatile basic nitrogen (TVB-N) values for nonirradiated aerobically packaged chicken increased steeply, with final values of ca. 20.3 and 58.5 mg N/100 g of muscle, respectively. Irradiated aerobically packaged chicken samples had significantly lower TMA-N and TVB-N values (P < 0.05) of ca. 2.2 to 3.6 and 30.5 to 37.1 mg N/100 g of muscle, respectively, during refrigerated storage for 21 days. Of the biogenic amines monitored, only putrescine and cadaverine were detected in significant concentrations in both nonirradiated and irradiated chicken samples, whereas histamine formation was noted only in nonirradiated samples throughout storage. On the basis of sensorial evaluation, low-dose irradiation (0.5 and 1.0 kGy) in combination with aerobic packaging extended the shelf life of fresh chicken fillets by ca. 4 to 5 days, whereas irradiation at 2.0 kGy extended the shelf life by more than 15 days compared with that of nonirradiated chicken.     

Fate of Escherichia coli O157:H7, Salmonella typhimurium DT 104, and Listeria monocytogenes in fresh meat decontamination fluids at 4 and 10 degrees C.

Bacterial pathogens may colonize meat plants and increase food safety risks following survival, stress hardening, or proliferation in meat decontamination fluids (washings). The objective of this study was to evaluate the ability of Escherichia coli O157:H7, Salmonella Typhimurium DT 104, and Listeria monocytogenes to survive or grow in spray-washing fluids from fresh beef top rounds sprayed with water (10 or 85 degrees C) or acid solutions (2% lactic or acetic acid, 55 degrees C) during storage of the washings at 4 or 10 degrees C in air to simulate plant conditions. Inoculated Salmonella Typhimurium DT 104 (5.4 +/- 0.1 log CFU/ml) died off in lactate (pH 2.4 +/- 0.1) and acetate (pH 3.1 +/- 0.2) washings by 2 days at either storage temperature. In contrast, inoculated E. coli O157:H7 (5.2 +/- 0.1 log CFU/ml) and L. monocytogenes (5.4 +/- 0.1 log CFU/ml) survived in lactate washings for at least 2 days and in acetate washings for at least 7 and 4 days, respectively; their survival was better in acidic washings stored at 4 degrees C than at 10 degrees C. All inoculated pathogens survived in nonacid (pH > 6.0) washings, but their fate was different. E. coli O157:H7 did not grow at either temperature in water washings, whereas Salmonella Typhimurium DT 104 failed to multiply at 4 degrees C but increased by approximately 2 logs at 10 degrees C. L. monocytogenes multiplied (0.6 to 1.3 logs) at both temperatures in water washings. These results indicated that bacterial pathogens may survive for several days in acidic, and proliferate in water, washings of meat, serving as potential cross-contamination sources, if pathogen niches are established in the plant. The responses of surviving pathogens in meat decontamination waste fluids to acid or other stresses need to be addressed to better evaluate potential food safety risks.     

Prevalence, characterization and sources of Listeria monocytogenes in blue crab (Callinectus sapidus) meat and blue crab processing plants

Seven blue crab processing plants were sampled to determine the prevalence and sources of Listeria spp. and Listeria monocytogenes for two years (2006–2007). A total of 488 raw crabs, 624 cooked crab meat (crab meat) and 624 environmental samples were tested by standard methods. Presumptive Listeria spp. were isolated from 19.5% of raw crabs, 10.8% of crab meat, and 69.5% of environmental samples. L. monocytogenes was isolated from 4.5% of raw crabs, 0.2% of crab meat, and 2.1% of environmental samples. Ninety-seven percent of the isolates were resistant to at least one of the ten antibiotics tested. Eight different serotypes were found among 76 L. monocytogenes isolates tested with the most common being 4b, 1/2b and 1/2a. Automated EcoRI ribotyping differentiated 11 ribotypes among the 106 L. monocytogenes isolates. Based on ribotyping analysis, the distribution of the ribotypes in each processing plant had a unique contamination pattern. A total of 92 ApaI and 88 AscI pulsotypes among the 106 L. monocytogenes isolates were found and distinct pulsotypes were observed in raw crab, crab meat and environmental samples. Ribotypes and serotypes recovered from crab processing plants included subtypes that have been associated with listeriosis cases in other food outbreaks. Our findings suggest that molecular methods may provide critical information about sources of L. monocytogenes in crab processing plants and will augment efforts to improve food safety control strategies such as targeting specific sources of contamination and use of aggressive detergents prior to sanitizing.     

危害分析关键控制点体系(HACCP)原理在罐装巴氏杀菌保鲜蟹肉生产中的运用

目的 在罐装巴氏杀菌保鲜蟹肉的生产管理中提高安全卫生水平。 方法 根据危害分析关键控制点体系(HACCP)的质量管理原理, 通过对其生产流程的每道工序进行危害分析, 确定相关措施。结果 确定了冷却、添加食品添加剂、封口、巴氏杀菌、冰水冷却、冷藏6个关键控制点, 制定了HACCP工作计划表, 确定了关键限值和纠偏措施, 构建了罐装巴氏杀菌保鲜蟹肉的HACCP管理体系模式。结论 将该管理体系运用于罐装蟹肉的生产实践, 结果表明其显著提高了该产品质量安全卫生水平, 取得良好的效果。     

Phospholipid changes in the course of beef meat storing at 4 °C

The mean molecular weight of beef meat phospholipids (738) and the recalculating factor (23.8), making possible to determine the total phospholipid content from lipid phosphorus, were estimated experimentally. The total amount of phospholipids decreases from 569 to 486 mg per 100 g of meat during 14 days of meat storing at 4 °C. The content of phosphatidylcholine, sphingomyelin, phosphatidylserine and phosphatidylinositol decreases, too. In contrast to this the content of lyso-phosphatides and temporarily also phosphatidylethanolamine is increasing. This temporary increase of phosphatidyiethanolamine (PE) concentration is due to enzymatic demethylation of phosphatidylcholine (PC). The course of this conversion has been followed by PE PC ratio changes in the course of meat storing.     

Quality characteristics of imitation crab sticks made from Alaska Pollack and spent laying hen meat

Imitation crab stick (ICS) samples were divided into four treatments, a control (C) prepared with Alaska Pollack as a commercial ICS, T1, which consisted of Alaska Pollack with spent laying hen surimi collected by the pH adjust method, T2, which was composed of Alaska Pollack with spent laying hen surimi collected by the filter cake method, and T3, which consisted of Alaska Pollack with whole spent laying hen meat batter collected by the cutting method. The moisture content was significantly higher in T3 than in the other ICS samples; but, there was no significant difference in the crude protein, fat and ash content, regardless of the spent laying hen substitution methods. The lightness (L∗) and whiteness (W) was higher in the control than in the other ICS samples at 0 days of storage, whereas the yellowness (b∗) was significantly higher in T3 than in the other ICS samples. The level of polyunsaturated fatty acids was significantly higher in the control group than in the other ICS samples. Additionally, the pH increased with storage time in the spent laying hen substituted samples (T1, T2 and T3), with T1 showing a significantly higher pH during storage. The TBARS value increased with storage time in all ICS samples, with T2 showing a significantly lower TBARS value than the other ICS samples at the beginning and end of the storage periods. There was no significant difference in any sensory evaluation items among the ICS samples during storage. Thus, we assumed that T3 was better than other ICS samples, because T3 method (cutting) is much easier to collect spent laying hen surimi than T1 (pH adjust) and T2 (filter cake).     

Biogenic amines in vacuum-packaged and carbon dioxide-controlled atmosphere-packaged fresh pork stored at -1.50 degrees C

Biogenic amines are formed in foods as a result of amino acid decarboxylation catalyzed by bacterial enzymes. When consumed in sufficient quantities, these compounds will cause headache, hypertension, fever, and heart failure. Technologies such as vacuum packaging and carbon dioxide-modified atmosphere packaging (CO2-MAP), when combined with low-temperature storage (-1.5 degrees C), allow fresh pork to have a storage life long enough for export to overseas markets. During low-temperature storage of pork in these packaging systems, the lactic acid bacteria (LAB), which possess the enzymes for biogenic amine formation, dominate the microflora. The objectives of this study were to determine the quantities of biogenic amines in packaged fresh pork, to monitor LAB growth, and to determine the storage life by sensory evaluation. Vacuum-packaged and CO2-MAP pork were stored at -1.5+/-0.5 degrees C for 9 and 13 weeks, respectively. Phenylethylamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine concentrations were determined weekly by high-performance liquid chromatography and capillary gel electrophoresis. LAB and carnobacteria were enumerated weekly. Samples were evaluated for odor and appearance. The CO2-MAP was successful in delaying bacterial growth and the development of unacceptable off-odors compared with the vacuum packaging. The storage lives of the vacuum-packaged and CO2-MAP pork were 5 and 13 weeks, respectively. High-performance liquid chromatography was the superior method for biogenic amine quantification. Tyramine and phenylethylamine in pork of both packaging treatments approached levels considered to be potentially toxic. Given Canada's increasing role in the export of fresh meat to foreign markets, it is recommended that the formation of biogenic amines in vacuum-packaged and CO2-MAP pork be further investigated.     

Fate of Staphylococcus aureus on vacuum-packaged ready-to-eat meat products stored at 21 degrees C

The U.S. Department of Agriculture has established standards for the composition and shelf stability of various ready-to-eat meat products. These standards may include product pH, moisture:protein ratio, and water activity (aw) values. It is unclear how closely these standards are based on the potential for pathogen growth or toxin production. Because the vacuum packaging used on most ready-to-eat meat products inhibits mold, Staphylococcus aureus is the pathogen most likely to grow on products with reduced aw and increased percentage of water-phase salt. In this study, 34 samples of various ready-to-eat meat products were inoculated with a three-strain mixture of S. aureus, vacuum packaged, and stored at 21 degrees C for 4 weeks. S. aureus numbers decreased by 1.1 to 5.6 log CFU on fermented products (pH < or = 5.1) with a wide range of salt concentrations and moisture content. Similarly, S. aureus numbers decreased by 3.2 to 4.5 log CFU on dried nonacidified jerky (aw < or = 0.82; moisture:protein ratio of < or =0.8). Products that were not fermented or dried clearly supported S. aureus growth and cannot be considered shelf stable. The product pH and moisture:protein ratio were the two compositional factors most highly correlated (R2 = 0.84) with S. aureus survival and growth for the types of products tested, but pH and aw or pH and percentage of water-phase salt also may provide useful predictive guidance (R2 = 0.81 and 0.77, respectively).     

Survival of Helicobacter pylori in ready-to-eat foods at 4 degrees C

The survival of Helicobacter pylori (NCTC 11638) in various semiprocessed and fresh, ready-to-eat foods, and one raw chicken was studied at 4 degrees C and under aerobic conditions by experimentally inoculating these with 10(4) CFU. Cells were concentrated by two centrifugation cycles followed by plating onto selective blood agar medium made from Wilkins-Chalgren agar supplemented with 5% whole horse blood, and 30 mg/l colistin methanesulfonate, 100 mg/l cycloheximide, 30 mg/l nalidixic acid, 30 mg/l trimethoprim, and 10 mg/l vancomycin. H. pylori was recovered from spiked pasteurized milk and tofu samples up to 5 days and from spiked leaf lettuce and raw chicken up to 2 days. H. pylori could not be recovered from yogurt after any length of storage time. H. pylori is unlikely to grow in foods; however, it may survive in low acid-high moisture environments under refrigeration and pose a possible risk for transmission of infection via foods.     

Proximate composition and mineral contents of the blue crab (Callinectes sapidus) breast meat, claw meat and hepatopancreas

The objective of this study was to determine the nutritional composition of the breast, claw meat and hepatopancreas of the blue crab (Callinectes sapidus). Samples were subjected to proximate (protein, fat, ash and moisture) and calcium, magnesium, phosphorus, potassium and sodium (Ca, Mg, P, K and Na) analyses. Protein, fat, ash and moisture of the breast, claw meat and hepatopancreas of the blue crab averaged 19.05, 0.59, 2.10 and 76.85 g/100 g, respectively. The results have revealed that this species is a rich source of protein, Ca, Mg, P and Na. Claw meat had higher protein concentrations (19.55 g/100 g) than both breast meat and hepatopancreas (18.81 g/100 g). Na was predominant element among minerals analysed. There were significant differences between Ca, Mg, P, K and Na contents of claw, breast meat and hepatopancreas of the blue crab. Information on the nutrient composition is needed to facilitate the processing, utilisation and marketing of blue crab products. Blue crab could balance human nutrition and could be used as an alternative dietary supplement of proteins and mineral matter.     

Fate of Salmonella Tennessee in peanut butter at 4 and 22 degrees C

ABSTRACT:  This study was undertaken to determine survival characteristics of inocula of a 3-strain mixture of Salmonella Tennessee in 5 commercial brands of peanut butter (A, B, C, D, and E). Inoculated peanut butter was stored at 4 (refrigerator temperature) and 22 °C (room temperature) for up to 14 d. After 1, 3, 5, 7, and 14 d, surviving cells, including injured cells, were enumerated on appropriate selective agar, including use of the agar overlay method. Populations in samples inoculated with 10^6–7 CFU/g and stored for 14 d at 4 and 22 °C decreased by 0.15 to 0.65 and 0.34 to 1.29 log CFU/g, respectively, depending on the formulation. Peanut butter A showed a significantly lower number of S . Tennessee cells when stored at 22 °C for 14 d, compared to 4 °C ( P < 0.05). However, there was no significant difference between the levels of S. Tennessee at 4 and 22 °C in products B, C, D, and E ( P > 0.05).     

Cryoprotectants improve physical and chemical properties of frozen blue crab meat (Callinectes sapidus)

The storage stability of cryogenically frozen crab meat treated with cryoprotectants was compared with pasteurised and water-treated frozen samples to determine changes in physical and chemical properties. Commercially processed, hand-picked blue crab meat was treated with solutions of polydextrose, sucrose + sorbitol/sodium tripolyphosphate or water, vacuum packaged, and cryogenically frozen prior to storage at ?29°C. All treatments were compared with an untreated reference control stored at ?65°C and a pasteurised sample stored at 1.1°C. Samples were evaluated for physical and chemical changes at 4-week intervals over 32 weeks of storage. Cryoprotectants improved oxidative stability, drip loss, expressible moisture, texture, and colour compared to untreated reference and pasteurised samples.     

Microbiological and physicochemical properties of fresh retail cuts of beef packaged under an advanced vacuum skin system and stored at 4 degrees C

The effect of an advanced vacuum skin packaging system on the microbiological and physicochemical properties of fresh retail cuts of beef (including meat portions from six different anatomical regions) stored at 4 degrees C was compared with the effect of traditional vacuum packaging. The vacuum skin packaging system whose effect on meat quality was evaluated in this work displayed two remarkable features: (i) the instantaneous heating of the lower surface of the upper film of the package before the film descended over the meat surface and (ii) the tight disposition of the plastic film on the meat surface, which avoided wrinkles and purges. Throughout storage at 4 degrees C, rates of bacterial growth were statistically significantly slower in beef portions processed with the vacuum skin packaging system than in those processed with traditional vacuum packaging, with average differences of 2.07, 1.60, and 1.25 log CFU/g in counts of aerobic mesophiles, anaerobes, and lactic acid bacteria, respectively. pH values were statistically significantly lower for beef portions packaged with the vacuum skin system than for those that were vacuum packaged in the traditional manner, probably because of the relative predominance of lactic acid bacteria observed in such samples, which coincided with both higher meat firmness values and a slower meat tenderization process. The vacuum skin system prevented the appearance of undesirable coloration on the meat surface and also significantly improved the commercial color of the meat as determined on the basis of luminosity (L*) and the redness (a*). Overall, the quality (as determined by microbiological and physicochemical analyses and by visual examination) of fresh retail cuts of beef packaged with the vacuum skin system and stored at 4 degrees C was higher than that of meat samples processed with the traditional vacuum-packaging system.     

Quality of donkey meat and carcass characteristics

A study based on 15 entire donkey males was carried out to evaluate carcass quality and nutritional characteristics of meat obtained by these animals slaughtered at 15 months of age and a mean final body weight of 181 kg. The meat had a low (2.02 g/100 g) fat content, an appreciable (22.8 g/100 g) protein content, and cholesterol content was 68.7 mg/100 g. Glycogen was also determined (0.45 g/100 g) within 12 h of sampling. Potassium was the mineral with the highest content (343 mg/100 g), followed by phosphorus (212 mg/100 g), sodium (52 mg/100 g) and magnesium (24 mg/100 g). Donkey meat obtained from young animals can be considered a good alternative to other red meats and not only for the production salami, or other fermented meat products.     

中华绒螯蟹鲜活及死后品质变化规律初探

为了探究中华绒螯蟹新鲜、垂死及死亡初期品质变化规律,选取鲜活、垂死、死后0、2、5、10、15和24 h共8个状态下的中华绒螯蟹进行研究,对此八种状态下的中华绒螯蟹进行感官评价,并测定失重率以及可食部位得率,结合滋味指标游离氨基酸(FAA)、非蛋白氮(NPN)、鲜度指标K值、p H、腐败指标挥发性盐基氮(TVBN)、生物胺进行品质研究。结果表明:中华绒螯蟹的感官评分随死后时间的延长而下降,中华绒螯蟹在死后10 h出现明显的腐败臭味,死后24 h打开蟹壳,里面的气味达到可接受极限;新鲜和垂死两个状态下,蟹的品质指标几乎无显著性差异(p<0.05);中华绒螯蟹在死亡10 h检测出生物胺,且直到15 h其体内有毒生物胺的含量较低,不足以引起中毒。多数指标均在D5和D10时发生较大改变,表明此时中华绒螯蟹品质有较大变化,中华绒螯蟹在死后10 h进入腐败阶段。