Mean Total Aerobic Plate Count Research Articles

Occurrence of Listeria monocytogenes in Camel Milk Cheese from two township markets of Borno and Kano States, Nigeria

Introduction: Camel milk cheese is one of the major camel milk products consumed in Northern Nige-ria. The conditions in which the cheese is sold in markets pose a risk of cross-contamination with foodborne pathogens such as Listeria monocytogenes. The study was carried out to evaluate the microbial quality of raw camel milk cheese sold in two different markets. Methods: A total of 200 cheese samples, (100 samples from each market) of Kano and Borno States, of Northern Nigeria were analysed for total aerobic plate count (TAPC) and total coliform count (TCC). Listeria species were isolated from the samples and the isolates were subjected for antimicrobial susceptibility test with commonly used antibiotics. Results: The results of the study show that mean TAPC of the sampled cheese was 5.90 log10 cfu/g and 5.70 log10 cfu/g for the Kano and Borno markets, respectively. While the mean for TCC per gram sampled was 3.75 log10 cfu/g and 3.81 log10 cfu/g for Kano and Borno, respectively. The occurrence rate of Listeria monocytogenes was 1(0.5%) in Kano and none in Borno market. However other Listeria species were isolated in both markets with overall occurrence rate of L. ivanovii 6(3%), L. welshimeri 1(0.5%) and L. grayi 2 (1%). The results of antimicrobial susceptibility test of the isolates show resistance of 77.7%, 66.7% and 55.6% to penicillin, gentamicin and tetracycline, respectively while 66.7% of the isolates were susceptible to erythromycin. Significance: This study has demonstrated the need for food regulatory agency to carry out routine investigation of ready to eat foods sold in the market to ascertain safety of such food for human consumption.

Microbial Quality of Chhoyla and Kachela: Traditional Newari Meat Products

Chhoyla and Kachela are indigenous and popular meat dishes in the Newar community that are widely consumed in Kathmandu valley. The present study was carried out to investigate the microbial quality of Chhoyla and Kachela from different parts of the valley. The mean total aerobic plate count of Chhoyla and Kachela ranged up to 6.38 and 6.54 log10 cfu/g respectively. The mean total coliform count of Chhoyla and Kachela ranged up to 5.25 and 5.82 log10 cfu/g respectively. Coliform (93%), Staphylococcus aureus (75%), Salmonella Typhi (12%), Salmonella Paratyphi A (5%) and Shigella spp (3%) were isolated from Chhoyla. Likewise, bacteria isolated from Kachela were coliforms (97%), Staphylococcus aureus (86.66%), Salmonella Typhi (15%), Salmonella Paratyphi A (8%) and Shigella spp (7%). High microbial load and the potent human pathogens isolated from these meat products indicate potential risk of food borne diseases.

Coliform count and isolation of <i>Escherichia coli</i> in fresh fruits and vegetables sold at retail outlets in Samaru, Kaduna State, Nigeria

Vegetables and fruits are commonly viewed as potential risk factors for infection with enteropathogens. One hundred and eight vegetables and fruits sold within Samaru, Zaria were cultured for coliforms and Escherichia coli using total aerobic plate and coliform counts on Nutrient and MacConkey agar plates respectively, and Eosin Methylene Blue for Escherichia coli isolation. The mean total aerobic plate count (TAPC) ranged between 1.05 ×10 11 to 1. 64 ×10 11 . The highest TAPC (1.64 ×10 11 ) was in pineapple while the lowest count (1.05 ×10 11 ) was in water melon. There was no much difference between the TAPC of lettuce (1.44 ×10 11 ) and cabbage (1.42 ×10 11 ) as well as carrot (1.37 ×10 11 ) and cucumber (1.39 ×10 11 ). Samaru market had the highest (1.56 ×10 11 ) TAPC while Suleiman market had the least (1.30 ×10 11 ). The mean coliform count (TCC) ranged from 1.28×10 9 to 3.55 ×10 9 CFU/ml. Carrot (1.28×10 9 ) had the lowest TCC while cucumber (3.55 ×10 9 ) had the highest. Others were pineapple (2.02 ×10 9 ), water melon (3.05 ×10 9 ), lettuce (3.17 ×10 9 ) and cabbage (2.72 ×10 9 ) CFU/ml. Out of 108 samples obtained, 50 (46.3%) were suspected to be E. coli with 23 (46%) yielding reactions typical of E. coli , with an overall prevalence of 21.3%. Cucumber had the highest isolation of 5 (27.8%) while the least was water melon 1 (5.6%). Other coliforms isolated were Klebsiella (8.3%), Enterobacter (7.4%), Citrobacter (5.5%), Proteus (2.7%) and Serratia (0.93%) spp. This study has demonstrated the public health significance of consuming fresh fruits and vegetables sold in the study area as they may be sources of infection to consumers especially if the produces are not properly washed or cooked. Keywords: Coliform, E.coli , Fruits, Vegetables

Assessment of microbiological and chemical qualities of selected cocoa, tea and coffee brands in Nigerian markets

Background: Cocoa, Tea, and Coffee products are consumed worldwide; they are rich in nutrient and, thus, prone to microbial contaminations that could cause food infections and intoxication.Objective: the objectives of the paper are: To evaluate the microbial and chemical qualities of some popular brands of cocoa, coffee and tea products in Nigerian market and benchmark it with standard specifications, to determine the products safety for human consumption and proffer solutions on ways to prevent possible food borne hazards associated with these products.Materials and Methods: This study examined the microbiological and chemical qualities of some brands of these products at the consumer level using standard analytical methods. Results: Five (50%) of the cocoa products had coliform counts (cfu/g) significantly (p<0.05) higher than acceptable limits and range from 2.6×101±0.01 to 4.6×101±0.01. The mean total aerobic plate count and fungal counts (cfu/g) cocoa, coffee, and tea were not significantly (p<0.05) different from standard specifications. The microbial isolates include species of Bacillus (59.2%), Staphylococcus(12.0%), Enterobacter(1.6%), Aspergillus(20.0%), Penicillium(14.4%) and Saccharomyces (12.0%). Moisture contents higher than 6% and 3% standard specifications in tea and cocoa products was detected in 7(70%) of tea and 2(20%) of cocoa products respectively. The samples are rich in phenol contents (mg/ml) and contain varying concentrations of manganese, calcium, iron, and copper. Free Radical Scavenging (DPPH) activity of 6.2±0.01 to 16.3±0.02μg/ml was detected in the samples. Conclusion: Some cocoa products contain unacceptable levels of coliforms, the high moisture contents above 3 and 6% standard specifications in some cocoa and tea products could encourage the proliferation of mycotoxigenic moulds and pathogenic bacteria to hazardous levels. The use of good raw materials, compliance to good manufacturing practices (GMP) and apt storage are advocated.Keywords: Chemical qualities, Cocoa, Coffee, Microbial qualities, Mycotoxigenic moulds, Tea

Effect of Black Cumin and Arjuna Fruit Extract on Lipid Oxidation in Pork Nuggets during Refrigerated Storage

In this study, the efficacy of arjuna fruit extract (AFE, 1.0%) and black cumin extract (BCE, 1.5%) in retarding lipid oxidation of pork nuggets was investigated and compared with a synthetic antioxidant, butylated hydroxytoluene (BHT, 100 ppm) and control sample during refrigerated storage at 4±1oC for 20 days under aerobic packaging. The total phenolics content of AFE treated cooked pork nuggets was significantly (p 0.05) less in all treated samples as compared to control. The pork nuggets with AFE had significantly (p<0.05) lower mean total aerobic plate count than control. In samples incorporated with AFE and BCE, thiobarbituric acid reactive substances (TBARS) value, peroxide formation, free fatty acids were significantly (p<0.05) lower than control even on 20th day of storage. Sensory evaluation revealed that incorporation of AFE and BCE improved the flavour and overall acceptability scores of pork nuggets than control and prolonged the shelf-life of the product up to 20 days by inhibiting lipid oxidation and microbial growth. From the above findings, it is concluded that AFE at 1% and BCE at 1.5% were effective and could be used as natural antioxidant in retarding lipid oxidation of processed muscle foods.

Preliminary Studies on Processed Garri as a Source of Bacterial Hazards to Students

Microbial contamination is considered the most significant hazard associated with food. Data on pathogens present in foods are needed to provide valuable information on the exposure of consumers to certain food borne pathogens. Also, consumption habits among consumers may increase the risk of health hazards. This study aimed to assess some practices, signs and symptoms associated with consumption of soaked garri among university students, to also determine the presence and virulence characteristics of some bacteria in garri on sale in the market. A questionnaire was designed and distributed to a hundred university students to ascertain their perception on safety of garri and handling practices. Fifty samples of garri were randomly collected from the market and assessed for presence of bacteria. Isolates of selected genera were then screened for some virulence-associated properties. The results showed that majority of the students (91%) affirmed they do consume soaked garri at least once in a while, even though almost 70% think garri is nutritious. The students (54%) reported to have experienced at least a symptom of ill health after consuming garri soaked in water. The most commonly reported signs and symptoms were: stomach upset > malaise > fever > nausea > vomitting. There was a direct relationship between the number of students that suspect garri could be a source of illness (57.1%) and those that have actually experienced at least a symptom after consuming garri (54%). Results of bacteriological analysis of garri samples from the market indicated mean total aerobic plate count to be 5.42 log cfu/g. Staphylococcus aureus and Klebsiella were found in 60% of the samples collected. Most isolates of Staphylococcus aureus, Klebsiella and Pseudomonas were found to be positive for haemolysin and biofilm formation tests which indicate their pathogenic potential. The conclusion is that bacteria with pathogenic potential are common in processed garri being sold in the market and that university students in the habit of consuming soaked garri are probably at risk of health hazards associated with pathogens in garri. Therefore, new food safety regulations should be formulated to incorporate food safety management systems during processing of garri in order to reduce the prevalence of food borne pathogens.

English

This study was conducted to determine the bacteriological quality of retail raw meat. Twenty one raw meat samples were randomly collected from four administrative towns: Bure, Debre-Markos, Dejen and Fenoteselam meat-stalls of Gojjam area. Samples were collected and transported kept in cold sterile screw cap bottles with ice contained icebox. It was cultured on plate count agar and mannitol salt agar plates for enumeration of aerobic and pathogenic staphylococci bacteria respectively. Bacterial isolation was identified by culturing on selective medium and biochemical test. The mean total aerobic plate count (APC) ranged 6.325 to 6.477 log cfu/g was not significantly different (P&lt;0.05); but enumeration of pathogenic Staphylococci ranged 3.588 to 4.251 log cfu/g was significantly different (P&lt;0.05) between places. According to international standards microbial quality acceptability of ready-to-eat food and raw meat aerobic plate and pathogenic staphylococci count of almost all samples were categorized in borderline and unsatisfactory quality. A total of 65 gram positive cocci isolates were identified. The dominant bacterial pathogens isolates were Staphylococcus epidermidis, Staphylococcus aureus and Streptococcus pyogenes in a ratio of 0.86, 0.71 and 0.71 respectively. The high bacteria count and isolates of aerobic plate count and pathogenic Staphylococci is an indication of higher risk for retail raw meat consumption. Hence needs improved hygienic practice at all levels in the raw meat production industry. Key words: Raw meat, aerobic plate count, pathogenic Staphylococci, Gojjama.

Microbiological Quality and Safety of pre-cut fruit retailed in Ilorin, Kwara State, Nigeria

The microbiological quality of pre-cut fruits retailed in three local markets in Ilorin, Kwara state, Nigeria was assessed. Pre-cut fruit samples comprising watermelon, pineapple and pawpaw were obtained from vendors at different retail outlets in the markets and the physicochemical and microbiological characteristics were examined. Mean total aerobic plate count ranged from 1.20 x 104 to 2.0 x 104cfu/g while fungal count ranged from 0.5 x 102 to1.6 x 102 cfu/g. Eight bacterial and six fungal species were isolated: Proteus vulgaris, Staphylococcus aureus, Bacillus subtilis, Pseudomonas aeruginosa, Campylobacter jejuni, Klebsiella aerogenes, Escherichia coli, Salmonella spp. Aspergillus niger, Aspergillus flavus, Mucor mucedo, Rhizopus stolonifer , Aspergillus fumigatus and Saccharomyces cerevisiae. The physicochemical parameters studies varies as follows: pH ranged from 3.5 to 4.1, moisture content 60.20 to 90.73%, titratable acidity 0.42 to 0.80g/100ml, ash 0.50 to 1.11% and total sugar 2.01 to 2.53g/100ml. The findings from this study showed that the fruits contained microorganisms that are potentially pathogenic. Under favourable conditions, they may multiply and thus render the fruits unsafe for consumption as they could become means of food poisoning.

Preliminary study on hazards and critical control points of kokoro, a Nigerian indigenous fermented maize snack.

The microbial and proximate composition of an indigenous snack from fermented maize was investigated. Critical control points of milling the raw materials, fermentation pH, processing temperature and time intervals during holdings in processing and storage were evaluated with a view to optimizing the product. The mean total aerobic plate count (TAPC) log10 values for samples of the finished products range from 2.07 ± 0.50 to 4.36 ± 0.10 cfu/g. Mean fungi count log10 was 2.00 ± 0.00 to 3.50 ± 0.50 while mean coliform count 1.04 ± 0.10 log10 cfu/g was detected in one of the sales outlets investigated. Bacterial and fungal species were isolated belonging to the genera Aspergillus, Rhizopus, Penicillium, Fusarium, Cephalosporium, Alternaria, Bacillus, Klebsiella, Staphylococcus, Lactobacillus, Pseudomonas, Proteus and Enterobacter. The moisture content of the samples ranged from 3.41 to 6.75%; fat content was 19.68 to 32.59%; fiber content was 1.84 to 2.78% while protein ranged from 6.76 to 9.23%. The ash and carbohydrate contents ranged from 1.97 to 2.31% and 49.21 to 61.96%, respectively. Based on the specifications by International Commission for Microbiological Specification for Foods (ICMSF), the TAPC counts of the finished products remained at low levels. However, presence of coliforms could prejudice the hygienic quality of these types of products hence, the need for quality control.

Study on the microbial status of unseasoned ground turkey meat from an EU producer–a new product with risk potential?

1. The aim of this study was to point out potential risks associated with a product new to the market in the European Union: unseasoned minced turkey meat. 2. On 6 d of sampling, minced turkey meat from a large-scale EU producer was analysed at 4 processing stages. 3. The packaged minced meat was examined during 10 d of storage, once using the legally recommended conditions (<+2°C), and then under simulated consumer handling; one batch was stored for 3 d at +2°C then kept for 45 min at 25°C and then stored at +7°C. Microbiological and physical variables were tested on 5 d. 4. Results showed that the mean total aerobic plate count (APC) of the unprocessed material was 3.8 log CfU/g and did not rise significantly, although the temperature rose briefly after the material left the meat chopper. Listeria monocytogenes was the pathogen detected most often, in 7 (14.6%) of 48 samples, followed by Salmonella in one (2.1%). No Campylobacter were found. 5. Initial contamination (APC) of about 4.5 log CfU/g was common in stored minced meat, conforming to European Union Regulations EC 2073/2005 and 1441/2007. Brochothrix thermosphacta and Pseudomonas spp. were the bacteria found most frequently. Under strict maintenance at a storage temperature of +2°C, the maximum microbiological stability of the material was 7 d. Under simulated consumer handling, the microbial counts increased significantly, immediately after transport. 6. Our findings indicate that unseasoned minced turkey meat is a risky, perishable product, especially if the raw material does not have a low APC, is not pathogen-free and is kept under typical consumer handling and storage conditions.

Porcine Blood Cell Concentrates for Food Products: Hygiene, Composition, and Preservation

The objective of this study was to determine whether porcine blood cell concentrates (BCC) can be produced and stored using hygienic measures independent of the temperature acting upon the substrate. A number of additives widely accepted by the consumer (NaCl, sugars, food-grade acids) were used to form so-called hurdles (water activity [aw], pH) to spoilage, and their impact was tested on microbiological and sensory parameters of the BCC. BCC, whole blood, plasma, and the anticoagulant were collected on 23 days in a slaughterhouse. The BCC with the additives were stored for 27 days at +3°C and at +20°C. Microbiological and chemical tests were carried out on the raw materials, and aw and the pH values of the stored BCC combinations were determined; the combinations were also submitted to sensory testing. The amounts of protein (33.4%) and hemoglobin (29.5 g/dl) in the BCC were significantly higher than in whole blood (19.4%; 13.8 g/dl). The mean total aerobic plate count was similar in all three substrates. However, the highest count (4.83 log CFU/g) was found in BCC; the count was lower in whole blood (4.62 log CFU/g) and lowest in plasma (4.22 log CFU/g). Storability (defined as a count of <5 log CFU/g) for 27 days at +20°C was achieved only with two additive types: 15% NaCl and 10% NaCl plus 10% glucose plus 1% of a food-grade acid. Spoilage of the BCC was inhibited by an aw of 0.824 (with 15% NaCl) and by the combination of aw 0.87 and a pH of 5 (with 10% NaCl, 10% sugar, 1% acid). Both substrates retained their red color and fresh odor over the entire storage time.

Bacteriological quality of raw oysters in Trinidad and the attitudes, knowledge and perceptions of the public about its consumption

In Trinidad and Tobago, raw oyster cocktails are a delicacy, but they are generally believed to be responsible for illness in the consumer. The microbial loads of raw oysters, condiments/spices and ready-to-consume oyster cocktails were determined in four sampling areas. Questionnaires were also administered to 72 oyster vendors to determine practices that affect the bacteriological quality of the products. Three hundred members of the public were interviewed to determine the attitudes, knowledge and perceptions of the public about raw oyster consumption. The mean total aerobic plate count (TAPC) per g of 50 samples each, of raw oysters, condiments/spices and ready-to-consume raw oyster cocktails averaged from 1.0×10 7±4.3×10 7 to 1.4×10 8±6.4×10 8, 2.0×10 5±1.0×10 6 to 2.0×10 7±1.4×10 8, and 4.3×10 5±1.0×10 6 to 2.2×10 6±1.0×10 7, respectively. The difference for each product among the four areas was statistically significant ( P≤0.05; χ 2). Using a recommended maximum standard of TAPC per g of 5.0×10 5, 115 (57.5%), 27 (13.5%) and 51 (25.5%) of 200 samples each, of raw oysters, condiments/spices and oyster cocktails, respectively, were considered unfit for human consumption. Amongst vendor practices, source of oyster harvest and length of time between separation of oyster meat from shell and sale, significantly affected the mean TAPC per g and the prevalence of unfit oyster cocktail samples. Consumption of raw oyster cocktails was more prevalent amongst males (73.6%) than females (26.4%) ( P<0.002), East Indians (63.2%) as compared with other respondents (36.8%) ( P<0.001), individuals ≤40 years old (82.1%) than in individuals >40 years of age (17.9%) ( P<0.01), and in individuals who were aware that raw oysters are considered to be a sexual enhancer (86.8%) as compared to those who did not have this perception (11.3%) ( P<0.03). Fear of falling ill prevented 44 (37.9%) of 116 non-consumers from eating oyster cocktails, while 13 of 106 consumers (12.3%) reported having experienced an oyster-borne illness. The rather high prevalence of raw oyster cocktails found to be unfit for human consumption, coupled with the perceptions and attitudes of the consumers about the product, pose a significant health risk to the public.

Microbiological analysis of ‘black pudding’, a Trinidadian delicacy and health risk to consumers

The prevalences of Salmonella, Escherichia coli and Staphylococcus aureus in black pudding which originated from local vendors and supermarkets in Trinidad were determined. The enterotoxigenicity of S. aureus strains and occurrence of 0157:H7 strains amongst E. coli isolates were also investigated. For the 100 black puddings each sampled from supermarkets and vendors, the mean total aerobic plate count (TAPC) per g was 1.8 × 10 7 ± 1.5 × 10 7 and 1.5 × 10 8 ± 2.3 × 10 8, respectively. E. coli was isolated from 56 (56.0%) black pudding samples from supermarkets with a mean count per g of 09.2 × 10 6 ± 7.9 × 10 6 compared to a prevalence of 79% (79 of 100) and mean count per g of 3.2 × 10 7 ± 4.7 × 10 7 for samples from local vendors. The difference between prevalences was statistically significant (P <- 0.001; χ 2). Only 1 (2.2%) of 45 strains of E. coli from supermarket-purchased pudding tested, was an 0157:H7 strain compared to 9 (13.6%) of 66 strains of E. coli from vendor-sold black pudding. The difference was not statistically significant (P ≥ 0.05; χ 2). Five (5.0%) of 100 black pudding samples from supermarkets yielded Salmonella, with S. ohio being the predominant serotype. For vendor-sold black pudding however, 11 (11.0%) samples were positive for Salmonella with a new serotype, S. unnamed (4,12:d —) being responsible for 50% (6 of 12) of isolates from this source. Forty samples each of black pudding from supermarkets and vendors were all (100.0%) positive for S. aureus with mean counts per g being 3.1 × 10 5 ± 8.8 × 10 5 and 3.3 × 10 6 ± 7.7 × 10 6, respectively. Overall, 27 (33.8%) of 80 strains of S. aureus tested were enterotoxigenic producing staphylococcal enterotoxins A(SEA), SEB, SEC, SED or a combination. It was concluded that black pudding poses a high risk to consumers based on the prevalence, microbial load and toxigenicity of the pathogens detected.

Identification of microbial hazards, methods for their control and critical control points for black pudding (‘boudin noir’)

Hazard analyses of black pudding (`boudin noir') preparation practices were conducted in four operations at an abattoir in Trinidad. The analyses consisted of watching all steps of preparation of the product on three occasions by each of the four processors, taking samples of ingredients and mixtures used during the steps to culture for common food pathogens, taking swab samples of chopping boards used for celery, pepper, onions and garlic, recording the sequential temperatures of water used for heating the stuffed intestine and the internal temperature of the stuffed intestine. A general build up of aerobic mesophilic bacteria was observed on addition of various ingredients like spices, celery, pepper, onions, garlic, fat, bread and blood before stuffing the intestine with a semi-solid mixture. The mean total aerobic plate count was 8.8×10 8±2.7×10 9and 8.5×10 5±1.3×10 6g −1for pre-heated and post-heated stuffed intestine, respectively. Preheated samples yielded Escherichia coli(89.0%), Staphylococcus aureus(99.0%) and Salmonella(14.6%). The mean temperatures of water used in heat processing ranged from 81.0±3.5 to 87.0±8.0°C, the mean internal temperature of stuffed intestine during processing ranged from 63.2±2.8 to 72.6±2.5°C and the mean processing time ranged from 17.3±10.2 to 26.7±4.2min between processors. The temperature treatments employed by the processors were lower than the 85°C for 10–15min recommended for the product. Consequently, the temperature exposure achieved between a 1–4log decrease in the counts aerobic mesophilic bacteria per gram. Of the 22 ready-to-consume black pudding samples tested, 15 (68.2%), 19 (86.4%) and 3 (13.6%) were positive for E. coli, S. aureusand Salmonella, respectively. Hazards were primarily associated with the keeping of blood at ambient temperature for several hours before use, insanitary practices and keeping processed black pudding at ambient temperature. Critical control points were cooking or heat processing, handling of the product after cooking and holding processed black pudding.

Contamination of infant powdered milk in use with enterotoxigenic Staphylococcus aureus

One-hundred and ten of the 114 samples of infant milk formulae collected from nursing mothers contained viable staphylococci, with the highest mean count of 1·0 × 10 2 cfu g −1, from samples collected the day the tin was opened. The highest mean total aerobic plate count was 2·6 × 10 3 cfu g −1. Titratable acidity and pH of the reconstituted milk ranged from 0·06 to 0·8 and 6·40 to 6·52 respectively. 52·0% of the 123 isolates were S. aureus, 49·6% produced β-hemolysin and 17·1% produced α-hemolysin. Enterotoxin A was produced by 6·5%, B by 1·6%, C by 2·4%, D by 1·6% and E by 0·8% of the isolates. The total staphylococcal and aerobic plate counts were not affected by either the period elapsed from the opening of tin to sampling or the brand of milk.

Bacteriological Analysis of Ground Beef

A survey on the bacteriological quality of ground beef in Maryland was conducted to provide information relating to establishment of bacterial standards on fresh meats. One hundred forty samples were obtained at the retail, processor, and slaughter-processor levels. Retail samples yielded the highest bacterial numbers. The mean coliform, fecal coliform, and Escherichia coli count per gram, for all samples, was 200, 10, and 5, respectively. The mean total aerobic plate count per gram was 7.9 × 106 (28 C) and 2.0 × 106 (35 C). Forty-three percent of all the samples analyzed exceeded 50 fecal coliform per gram, while 18% exceeded a total aerobic plate count of 1.0 × 107 per gram.