Total Aerobic Bacterial Counts Research Articles

Food borne pathogen contamination in minimally processed vegetable salads in Riyadh, Saudi Arabia

The increasing demand for fresh fruits and vegetables and for convenience foods is causing an expansion of the market share for minimally processed vegetables in different areas. Riyadh, the capital city of Saudi Arabia witness flourishing of hotel and food industry and eating green salad is a daily habit of about 50% individuals in the country. Hence microbial quality of minimally processed vegetable salads (Tabbouleh, Fattoush, Hummus, Mutabbel and Caesar) being served in restaurants and homes in Riyadh were evaluated to ascertain that they are safe for human consumption and are free from potential food borne pathogens. The samples were assessed for the presence of total aerobic bacterial plate count, total coliforms, Escherichia coli, Salmonella, and Shigella. The total aerobic plate count for salad prepared in the restaurants was around 2 – 4.5 x105 CFU/g, however, in homemade salads the count was 2-8 x 104 CFU/g. The total coliform counts in restaurants salad were around 2-8 x 104 CFU/g as compared to 2-4.8 x 103 CFU/g of homemade salads. All salads, except Caesar, recorded E. coli and Enterobacter aerogenes, whileShigella sp and Salmonella sp were present in few samples. The results of the present study warrant an urgent need to have strict control measures to eliminate food borne pathogen contamination. This is the first report on microbial quality of the said minimally processed vegetable salads in Saudi Arabia. Key words: Saudi Arabia, vegetable salads, fruits, food borne pathogen contamination.

Microbial quality of chevon and mutton sold in Tamale Metropolis of Northern Ghana

The microbial quality of 80 meat samples made up of 40 chevon and 40 mutton were collected from the Aboabo, Central-internal, Central-external, and Sakasaka meat shops in Tamale Metropolis and assessed in order to ascertain it safety. Chevon from Aboabo and mutton from the Central market-internal had the highest mean total aerobic bacterial count of 3.9 X 10 6 cfu/cm 2 and 3.7 X 10 6 cfu/cm 2 , respectively. The lowest total aerobic count in chevon was found in the Central-internal (6.0 X 10 5 cfu/cm 2 ) and that of mutton was found in Sakasaka market meat shop (6.0 X 10 5 cfu/cm 2 ). Bacteria isolated from the samples were Escherichia coli, Streptococcus species, Salmonella species , Enterococcus species, and Staphylococcus species, some of which harbor human pathogens of public health concern. The isolation of various bacteria in chevon and mutton sold in the Tamale Metropolis indicates that, lower standard of operating systems in the slaughtering, processing and sale of meats are adhered to. The Government of Ghana, Ministry of Health and Ministry of Food and Agriculture should enforce the laws that prohibit the illegal slaughtering of animals without veterinary inspection, unstandardized methods of handling animals, slaughtering and selling of meats on the open market. @JASEM J. Appl. Sci. Environ. Manage . December, 2010, Vol. 14 (4) 53 - 55

A Study of Microbiological Contamination in Cosmetics and Toiletries in Iraq. Contamination of Talcum Powder and Body Lotion

One hundred items of 60 talcum powders and 40 body lotions were examined for their total aerobic bacterial, coliform and fungal counts. We also carried out anaerobic bacterial counts for talcum powder as well as tests to detect some potentially hazardous bacteria in all tested samples. Talcum powders were more heavily contaminated with bacteria than body lotions. More than 60% of the tested body lotions contained no viable bacteria or less than 100 C.F.U./gm, while 35% of the talcum powders contained this level. Five per percent of the talcum powder were contaminated with 104 C.F.U. /gm and none of the body lotions were contaminated to that extent. No coliforms were recovered from any of the body lotions, while 3.3% of the talcum powder examined contained coliforms in the range of 250-300 C.F.U/gm.Staphylococcus Spp. were detected in one sample of both talcum powders and body lotions. Two samples of talcum powder contained E. coli. Neither talcumpowder nor body lotions showed fungal counts. Also no talcum powder showed the presence of anaerobic bacterial counts.

Contamination of herbal medicinal products marketed in Kaduna Metropolis with selected pathogenic bacteria.

The study aimed to evaluate the bacterial contamination of powdered herbal medicinal preparations sourced from identified herbal retail outlets in different parts of Kaduna metropolis. The assessments of the contamination of the herbal products were carried out using standard procedures: total aerobic bacterial plate count, measurement of some physical parameters, isolation and characterization of selected bacterial pathogens etc. The results showed that out of a total of 150, 70 (46.67%) herbal remedies were contaminated with Salmonella typhi, twenty nine (19.33%) with Shigella spp. Eighty eight (58.67%) and 98 (65.33%) were contaminated with Escherichia coli and Staphylococcus aureus, respectively. The total aerobic plate count results showed that the highest average count of > 5x10(7) cfu/g was found in 89 (59.33%) of the preparations, while average plate count of < or = 5x10(7) cfu/g was found in 42 (28%) and no bacterial count was obtained in 19 (12.67%) of the preparations. Correlation was positive (P = 0.01; r = +0.109) between the physical parameters tested and the bacterial load. Antibacterial activities result of some common antibiotics showed that all the antibiotics had activities on the test bacterial isolates at various minimum inhibitory concentrations. Most traditionally prepared herbal medications in Kaduna state are likely to be contaminated with a wide variety of potentially pathogenic bacteria. The quality assurance of these products should be thoroughly enforced and monitored in the production and distribution of herbal preparations.

Aspects of the microbiological quality and safety of ready-to-eat foods in Sharjah supermarkets in the United Arab Emirates.

Over the last few years, ready-to-eat (RTE) foods have become popular in grocery stores all over the world. This study was conducted to evaluate the microbiological safety and shelf life of some RTE salads sold in supermarkets in Sharjah Emirate, United Arab Emirates. Samples of four RTE salads, tabbouleh, hummus, Greek salad, and coleslaw, were obtained from supermarkets and examined for aerobic bacteria, Escherichia coli, Staphylococcus aureus, Salmonella, and Listeria monocytogenes. The results indicated significant differences (P < or = 0.05) for the aerobic bacteria count among the RTE salad types. In tabbouleh, hummus, Greek salad, and coleslaw, E. coli counts of 0.9, 0.50, 0.27, and 0.25 log most probable number (MPN)/g and total aerobic bacterial plate counts of 3.57, 2.71, 2.76, and 2.52 log CFU/g, respectively, were found after preparation (day 0). At day 0, all RTE salads tested except tabbouleh contained an acceptable count of total bacteria, but the aerobic bacteria count for all the RTE salads increased rapidly during storage from day 2 to day 6, regardless of the storage temperature (5, 25, and 40 degrees C). Twenty percent of all samples contained E. coli, although the numbers were as low as 1 log MPN/g. No S. aureus, L. monocytogenes, or Salmonella serotypes were detected in any of the RTE salads tested in this study.

Effect of dietary supplementation of some antioxidants on growth performance, carcass composition and breast meat characteristics in quails reared under heat stress

This research investigates the effects of adding vitamin E, vitamin C, vitamin E+C, and alpha lipoic acid to feed rations for Japanese quails (Coturnix coturnix japonica) exposed to heat stress. The aspects studied were growth performance, carcass composition and breast meat characteristics. Five groups of quails, containing 50 birds each (250 Japanese quails: 150 female and 100 male) were used. The 21-days-old birds were fed for a period of 21 days, and they were kept in a controlled environment with a temperature of 34˚C between 08:00 and 17:00 and a temperature of 24˚C for the remaining part of the day. The five groups under study included: a control group without any additive (BS), a group fed diets with vitamin E (BSE), with vitamin C (BSC), with vitamin E+C (BSEC) and with lipoic acid (BSLA). The supplement additions to the diets did not affect the growth performance and carcass composition of the birds. The TBA (malonaldehyde) value of the BS group was significantly higher (P &amp;lt; 0.001) than in the other groups. L*, a*, and b* values in muscle samples, superficialis pectoralis muscle (SPM) and deep pectoralis muscle (DPM), were determined. In the samples from the SPM, the L* value of the BS group was higher than in the BSC group; the a* value of the BSE group was higher than in the BS group; and the b* value of the BSC group was higher than in the BS group (P &amp;lt; 0.05). In the samples from the DPM, the L* value of the BS group was higher than in the BSEC group (P &amp;lt; 0.05); the a* values of the BSE and BSEC groups were higher than in the BS group (P &amp;lt; 0.05); and the b* values of the BSC, BSEC and BSLA groups were higher than in the BS group (P &amp;lt; 0.01). In the microbiological analysis of meat, total aerobic mesophilic bacterial counts of the BS and BSE groups were higher than the counts in the BSC, BSEC, and BSLA groups (P &amp;lt; 0.01); coliform bacterial counts were higher in the BSE group than in the BSC group (P &amp;lt; 0.05); and lactic acid was higher in the BSE and BSEC groups than in the BSC and BSLA groups (P &amp;lt; 0.01). In conclusion, the supplemented antioxidants did not exhibit any significant effect on growth performance, but they significantly decreased lipid oxidation in the meat. &amp;nbsp;

Emulsifying bacteria in produce water from Niger-Delta, Nigeria.

The study reports the diversity of emulsifying bacteria in produce water obtained from Bonny Oil Terminal, Niger Delta, Nigeria. Physico–chemical analysis of produce water showed a high chloride ion content of 650.0 mg/L. Total aerobic mesophilic bacterial count was 8.6 x 106 CFU/mL while the oil utilizing bacterial count was 1.32 x 106 CFU/mL. The predominant bacteria genera were Bacillus, Pseudomonas, Serratia and Klebsiella. The ratio of the surface active agent producers in the mesophilic bacteria was 0.34%, while 2.2% was recorded among the oil utilizing bacteria. The highest emulsification and de-emulsification indices of 65 and 50% recorded respectively were for Pseudomonas mallei. The result obtained was discussed in relation to the use of the emulsifying bacteria in microbial enhanced oil recovery (MEOR) in the Niger Delta, Nigeria. Key words: Emulsifying bacteria, emulsification-index, surface-active agents, biosurfactants, MEOR, crude oil, Niger-Delta.

레토르트 및 감마선 조사에 의한 화닭 덮밥 소스의 미생물 제어 효과 비교

극한 환경에서 취식이 가능하도록 안전성 및 기호성이 확보된 덮밥 소스류 개발을 위한 기초연구로 많이 소비되고 있는 화닭 덮밥소스의 위생화를 위해 감마선 조사 기술을 적용하고 레토르트 살균과의 비교연구를 진행하였다. 화닭 덮밥 소스의 미생물 오염도 평가 결과 레토르트 비처리군은 총세균수가 4.5 log CFU/g 검출되었고 레토르트 처리군은 2.1 log CFU/g의 총 세균이 검출되었다. 반면 3 kGy의 감마선 처리군 에서는 검출한계 이하의 세균이 검출되었다. 검출된 미생물을 동정한 결과 Bacillus spp.로 확인되었으며, B. cereus 및 B. subtilis에 대한 방사선 감수성 측정 결과 각각 0.39 및 0.28 kGy로 확인되었다. SOS chromotest를 이용한 유전독성학적 안전성 평가 결과 감마선 조사에 의한 돌연변이원성은 관찰되지 않았다. 이상의 결과를 종합하여 볼 때, 화닭 덮밥 소스의 효과적인 위생화를 위하여 3 kGy의 감마선 조사처리가 레토르트 처리보다 효과적으로 미생물을 사멸하는 것으로 확인되었다. This study evaluated the antimicrobial effects of retort process and gamma irradiation on reduction of total bacterial populations in spicy chicken sauce, which is served on top of the steamed rice. Commercial spicy chicken sauce was treated with retort and gamma ray at 0, 1, 3, 5, and 10 kGy. Total aerobic bacterial populations were then enumerated on plate count agar and isolated bacteria from the test samples were identified using PCR analysis. Moreover, gamma ray sensitivity of identified bacteria was evaluated by <TEX>$D_{10}$</TEX> values, and genotoxicity of gamma-irradiated samples was examined. Gamma irradiation at 3 kGy reduced total aerobic bacterial cell counts in spicy chicken sauce below detection limit, but total aerobic bacterial cell counts in test samples treated with retort were 2.1 log CFU/g. Identified bacteria from the samples were Bacillus subtilis, B. amyloiquefaciense, and B. pumils, and the <TEX>$D_{10}$</TEX> values for B. subtilis and B. cereus were 0.39 (<TEX>$R^2\;=\;0.921$</TEX>) and 0.28 log CFU/g (<TEX>$R^2\;=\;0.904$</TEX>), respectively. The SOS chromotest showed that the gamma-irradiated spicy chicken sauce did not cause mutagenicity. These results indicate that gamma irradiation of spicy chicken sauce could be useful in ensuring microbial safety.

Comparison study between Iraqi beef meat and other sources of imported frozen meat

Many kind of market – available frozen meats were selected. These involves Iraqi meat, Emirate meat as well as four types of Indian meats ( Amarona, Alana, Al – Mubark and Al – Halal ) The chemical, Physical and Microbial characteristics of these types were investigated. All studies types were identical with [1] in protein percentage. Excluding data of fat percentage of Emirale meat, all types were identical with [1] in fat percentage. Significant differences in free fatty acid percentage were observed in studied types, however it still in accordance with [1]. Highly significant (P&gt;0.05) differences were noticed among meat types in total volatile nitrogen values. On the other hand, all meat types were not identical with Iraqi standards in thaw loss percentage; all sensory characters were decline in all frozen meat studied. Greater total aerobic and total bacterial count were noticed in all meat types. These exceeded that of [1]. On the same manar, Higher count of Psychotropic bacteria (5.12 x 104 ) were observed in Indian meat (Halal).

New challenges in professional cleaning: hygiene quality and monitoring of surfaces in private domestic homes

AbstractIn many countries, changes in the pattern of working lives and ageing of the population increases the need for professional cleaning in private domestic homes. The objective of this study was to obtain basic knowledge concerning professional home cleaning. The study consisted of two parts. First, cleanability of surfaces contaminated with microbiological and organic soils was examined in the laboratory using cleaning cloths, detergents and rapid detection methods with potential for use in conjunction with professional cleaning in private homes. Second, hygienic conditions in three households were screened using the same rapid detection methods as in the laboratory experiments. According to the laboratory study, the cleaning efficiency of the non‐woven cloth was clearly poorer than that of the cleaning cloths containing microfibers. There were differences between the efficacy of the cleaning agents in removal of protein and microbiological soils. Despite the differences between surface topography observed with scanning electron microscopy, differences between the cleanability of the three examined surface materials (steel and two plastic surfaces) were small. In hygiene monitoring, the highest levels of total aerobic bacterial counts were detected in the plughole of the sink, on the eating table in kitchens and along the edge of the toilet washbowl and the cover of toilet seats. Low amounts of Enterobacteriaceae indicating faecal contamination were detected in the toilet and bathroom after cleaning. Moulds were not detected in any of the three households, and the amounts of yeasts were low. Detection methods, microbiological dipslides and the protein test, were well suited to the laboratory study. Furthermore, they complemented each other in the hygiene monitoring. The information obtained will be used for development of better practices in professional home cleaning. Good quality management in professional home cleaning and the cleanliness of surfaces in homes are important factors affecting comfort and safety.

Effects of selected washing treatments and drying temperatures on biochemical and microbiological quality of dagaa (Rastrineobola argentea).

Dagaa (Rastrineobola argentea) is one of the most important fish foods for the lowincome households in the Nyanza Province, Kenya. However, the off-flavour and offodour that results from the traditional sun-drying process of sun-dried dagaa is a major disincentive to the use of the fish for human consumption, hence leading to utilization in animal feed. Chemical analyses for pH, Thiobarbituric reactive substances (TBARS), Total volatile bases-nitrogen (TVBN) and aerobic bacterial counts were carried out on dagaa sampled from various process steps within the openfield sun-drying and market conditions. Dagaa was also oven-dried at 30oC, 40oC and 50oC after washing with selected solutions namely salted (3% sodium chloride), chlorinated solutions (100ppm) and potable tap water (control). Results indicated that TBARS values increased significantly (p

HYGIENIC CRITERIA OF SMOKED HERRING FISH MARKETED IN KAFR EL- SHEIKH CITY

A total number of one hundred samples from each packed and unpacked locally produced smoked herring fish (50 of each) were collected randomly from different shops and supermarkets of different sanitation levels at Kafr El-sheikh city. The collected samples were directly transferred to the laboratory under complete aseptic conditions with a minimum of delay where they were subjected to sensory, chemical and microbiological evaluation. The obtained results revealed that, regarding the sensory evaluation only 2% of packed smoked herring fish samples were rejected due to macerated skin, friable consistency and musty flesh odor. Meanwhile unpacked examined samples contained 14% rejected due to macerated skin, very macerated skin and friableconsistency, and 10 % rejected due to musty flesh odor and salty flesh taste. Concerning the chemical examination, 4% of packed smoked herring fish samples were rejected due to their over pH, value while16 %, 12%, 8 % and 10 % of unpacked smoked herring fish samples were rejected due to their pH value, TVN content, salt content and thiobarbituric acid number respectively. On the other hand, microbiologically, all the samples of packed smoked herring fish lied within the limits of Egyptian standard of smoked fish number 228/2005, concerning unpacked samples 10%, 12%, 20% and 12% were rejected due to contamination with total aerobic bacterial count, total anaerobic bacterial count, total coliforms count and Staphylococcus aureuscoagulase positive respectively, more than the accepted limits of the previous standard. The recommended points to safety and quality of smoked herring fish were discussed .

Bacterial loads and microbial composition in high pressure treated oysters during storage

Analysis of bacterial communities present in high-pressure (HP)-treated, quick-frozen (QF), and raw oysters was carried out during three different seasons. Bacterial numbers and species diversity in each sample were determined at 0, 7, 14, and 21 days of storage. Results showed that numbers of total aerobic bacterial counts (TABC) in treated oysters were significantly lower than in untreated oysters at day 0 by 10 to 10 5 colony forming units per gram of oyster meat (CFU/g) in all samplings. However, an increase in TABC in HP-treated oysters was observed at days 7, 14, and 21 indicating that some bacteria survived the treatment and were able to proliferate during refrigeration conditions. Surprisingly, TABC in HP-treated oysters reached 10 8 CFU/g at 14 days of storage in all samplings (higher than TABC from raw oysters in two of the samplings performed). Analysis of the bacterial flora by 16S rDNA sequencing, revealed six different classes within the bacterial communities. The majority were Gram-negative bacteria, with the Gammaproteobacteria class representing between 56% and 92%. The most common bacterial genera found in this study were Shewanella, Vibrio and Psychrobacter. Four species of human pathogenic bacteria were also identified: V. vulnificus, V. parahaemolyticus, V. alginolyticus, and A. hydrophila although V. vulnificus was detected only in raw oysters.

Effect of Selected Washing Treatments and Drying Temperatures on bacterial Quality and Safety of Dagaa (&lt;i&gt;Rastrineobola argentea&lt;/i&gt;)

Microbiological analyses for aerobic bacteria counts and pathogens (coliforms, E. coli, S. aureus, Salmonella spp and V. cholerae) were carried out on small pelagic fish specie commonly found in Lake Victoria, dagaa (Rastrineobola argentea). The samples were obtained from various process steps within the field sun-drying and market conditions in Kisumu, Kenya. Dagaa was also oven-dried at 30oC, 40oC and 50oC after washing with selected solutions i.e. salted (3% sodium chloride), chlorinated solutions (100ppm) and potable tap water, which was used as control. Results obtained indicated that total aerobic bacterial counts in the freshly caught dagaa increased significantly (p

Influence of nutrients addition and bioaugmentation on the hydrocarbon biodegradation of a chronically contaminated Antarctic soil

Complexity involved in the transport of soils and the restrictive legislation for the area makes on-site bioremediation the strategy of choice to reduce hydrocarbons contamination in Antarctica. The effect of biostimulation (with N and P) and bioaugmentation (with two bacterial consortia and a mix of bacterial strains) was analysed by using microcosms set up on metal trays containing 2.5 kg of contaminated soil from Marambio Station. At the end of the assay (45 days), all biostimulated systems showed significant increases in total heterotrophic aerobic and hydrocarbon-degrading bacterial counts. However, no differences were detected between bioaugmented and nonbioaugmented systems, except for J13 system which seemed to exert a negative effect on the natural bacterial flora. Hydrocarbons removal efficiencies agreed with changes in bacterial counts reaching 86 and 81% in M10 (bioaugmented) and CC (biostimulated only) systems. Results confirmed the feasibility of the application of bioremediation strategies to reduce hydrocarbon contamination in Antarctic soils and showed that, when soils are chronically contaminated, biostimulation is the best option. Bioaugmentation with hydrocarbon-degrading bacteria at numbers comparable to the total heterotrophic aerobic counts showed by the natural microflora did not improve the process and showed that they would turn the procedure unnecessarily more complex.

501. BACTERIOSPERMIA AND ITS CONTROL IN BUBALINE SEMEN

The present study was designed to investigate the bacterial species incriminated in bubaline semen and to find out the effectiveness of antibiotics (GTLS; gentamycin, tylosin and linco-spectin or SP; streptomycin and penicillin) in cryodiluent on bacterial control and quality of buffalo bull spermatozoa. For this purpose four experiments were conducted. In experiment 1, a total of 11 bacterial species were identified from buffalo ejaculates. The predominant bacteria were Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa in the ejaculates. In experiment 2, total aerobic bacterial counts in post-thaw samples were lower (P&lt;0.05) in GTLS than in SP or NC (negative control). Fewer bacterial genera were identified in semen samples having GTLS than SP. Majority of the bacterial isolates from ejaculates showed more sensitivity towards GTLS than SP. In experiment 3, motilities (visual and computer-assisted), velocities (straight-line, average path and curvilinear), amplitude of lateral head displacement and plasma membrane integrity in post-thaw semen samples did not differ (P&gt;0.05) due to antibiotics. Spermatozoal abnormalities (acrosome, head, mid-piece and tail) were lower (P&lt;0.05) in GTLS and SP than in NC. In experiment 4, the fertility rates for SP-based vs. GTLS-containing frozen semen of buffalo bull were 42.8 and 55.2%, respectively. The results for GTLS were significantly higher than SP. The fertility rates also differed significantly in the first and second batch of inseminations performed with SP or GTLS-based cryopreserved semen of buffalo bull. In conclusion, a number of bacterial species are isolated from bubaline semen. Bacterial and seminal quality measured by standard laboratory tests and field fertility trials indicate that GTLS is more suitable in extender for cryopreservation of buffalo bull spermatozoa.

Hygienic quality of head lettuce: Effects of organic and mineral fertilizers

The hygienic quality of head lettuce ( Lactuca sativa L.) was investigated after different fertilizer treatments (fresh farmyard manure, composted farmyard manure, stinging nettle extract and calcium ammonium nitrate) in a 2-year field experiment with two trials per year, respectively. For assessment of the hygienic quality the total aerobic bacterial counts, Enterobacteriaceae, coliform bacteria, Escherichia coli and Salmonella were investigated in soil, fertilizer and lettuce samples. Plants were washed with running tap water before analysis. The total aerobic bacterial count, as well as the levels of Enterobacteriaceae and coliform bacteria tended to be slightly higher (not significant) after organic compared to mineral fertilization. No Salmonella was detected in any soil, fertilizer or lettuce sample, while E. coli was randomly detected in low concentrations independent from fertilizer treatment. No higher risk of bacterial contamination due to the use of organic fertilizers was indicated.

The Use of Bacterial Alkaline Phosphatase Assay for Rapid Monitoring of Bacterial Counts on Spinach

This study was undertaken to evaluate the applicability of bacterial alkaline phosphatase (ALP) activity for rapid monitoring of total mesophilic bacteria counts in spinach. A set of fresh and decayed spinach mixtures were tested to rapidly (10 min) monitor spinach bacterial counts. To assay ALP activity, Lumigen APS-5 was used as a substrate. Bovine ALP was reduced after heat treatment at 75 degrees C for 1 min; in contrast, bacterial ALP activity increased. To differentiate bacterial ALP from other ALP, heat treatment (75 degrees C, 1 min) was applied before measurement. As a result, a regression equation was established between the actual mesophilic aerobic bacteria count and ALP activity of spinach mixtures (r= 0.90). The predicted total mesophilic aerobic bacterial count calculated from the fitted regression line (predicted log(10) CFU/g = 0.00056 x ALP values + 1.4002) showed a high correlation with the actual observed total bacterial count (r= 0.93). The ALP assay is a simple and rapid method to utilize for estimation of existing or contaminating microorganism levels on spinach.

Effect of Different Concentrations of Carbon Dioxide and Oxygen on the Growth of Pathogenic Yersinia enterocolitica 4/O:3 in Ground Pork Packaged under Modified Atmospheres

The influence on Yersinia enterocolitica counts of a gradual increase of carbon dioxide concentrations (percentage by volume in air) during packaging and storage of ground pork meat artificially contaminated with this pathogen was evaluated. Ground meat was packaged under customary conditions using modified atmospheres with various carbon dioxide percentages (0, 30, 50, 70, and 100% CO2 by volume; for atmospheres of less than 100% CO2, the rest of the gas was O2). The packs were stored at 2°C for 12 days. During the entire storage time, counts of Y. enterocolitica were determined by the spread plate method for direct plate counts (DPCs). Microbiological shelf life of the stored ground pork also was assessed by total mesophilic aerobic bacterial plate counts (APCs). Y. enterocolitica counts were not significantly different (P ≥ 0.05) in the ground pork packaged under the various CO2-enriched atmospheres. The growth of Y. enterocolitica was nearly entirely inhibited in all tested modified atmospheres containing the protective CO2. However, in ground pork packaged with 100% oxygen, there was a significant decrease (P ≤ 0.05) in the DPC for Y. enterocolitica from 4.30 log CFU/g (day 0) to 3.09 log CFU/g at the end of the storage time (day 12). The decrease was presumably due to the marked increase in APC seen only in those packages stored under 100% O2. Packaging with high CO2 concentrations had significant inhibitory effect (P ≤ 0.05) on the growth of mesophilic aerobic bacteria.

Quantitative assessment of total and Gram-positive aerobic bacteria in fresh and ambient-temperature-stored sub-tropical marine fish

The current study was undertaken to enumerate Gram-positive bacteria in fresh sub-tropical marine fish and determine the effect of ambient storage (25°C) on the Gram-positive bacterial count. Total and Gram-positive bacteria were enumerated in the muscles, gills and gut of fresh and stored Pseudocaranx dentex, Pagrus auratus and Mugil cephalus on tryptone soya agar (TSA) and TSA with 0.25% phenylethyl alcohol (PEA), respectively. Initial studies indicated that PEA significantly reduced total aerobic bacterial count (TABC) whereas control Gram-positive bacteria were not affected by 0.25% PEA. TABC significantly increased in all fish body parts, whereas Gram-positive aerobic bacterial count (GABC) significantly increased only in the muscles and gills during ambient storage for 15 h. The TABC of the fish species increased from 4.00, 6.13 and 4.58 log cfu g−1, respectively in the muscles, gills, and gut to 6.31, 7.31 and 7.23 log cfu g−1 by the end of storage. GABC increased from 2.00, 3.52 and 2.20 log cfu g−1 to 4.70, 5.85 and 3.36 log cfu g−1. Within each species, TABC were significantly higher in the gills compared to that of muscles and gut; however, no significant differences were found in GABC between muscles and gills. This study demonstrated the potential importance of Gram-positive bacteria in sub-tropical marine fish and their spoilage.