HYGIENIZATION OF INDIAN CHICKEN MEAT BY IONIZING RADIATION

Both fresh and frozen chicken meat were evaluated for microbiological status by screening for total bacterial counts and for the presence of pathogens like Enterobacteria , Bacillus cereus, coagulase positive Staphylococci and Salmonella spp. Most of the samples exhibited heavy bacterial contamination (1.2 × 10⁵ - 2.6 × 10⁶/g), mainly with Staphylococcus spp. (1.5 × 10⁴ - 2.8 × 10⁵/g). All the chicken samples also showed the presence of Salmonellae (3 × 10¹ - 2.1 × 10²/g). Among the different serotypes observed in chickens . S. typhimurium was common in fresh as well as frozen chicken. Radicidation at 2 kGy at cryogenic conditions (−40°C) was efficient in eliminating the natural pathogenic contamination of the poultry . Salmonella spp. viz. S. seftenberg and S. typhimurium differed in radiation sensitivity, the D₁₀ values in phosphate buffer (pH 7.2) being 0.25 kGy and 0.12 kGy, respectively. Chicken homogenate (10%) offered approximately 2-fold protection to these cells. Chicken samples artificially inoculated with a heavy inoculum (10⁸ cells/g) of these 2 serotypes required higher gamma radiation doses of 4–5 kGy. The findings suggested that a dose of 2 kGy is adequate for normally contaminated chicken samples, but for the heavily contaminated chicken a dose of 4–5 kGy, depending upon the predominating Salmonella serotype present, is required .     

Microbiological quality of ice creams commercialized in some cities in the state of Rio de Janeiro, Brazil

The microbiological quality of 60 ice cream samples of three commercial brands (A, B and C) of various flavours, commercialized in some towns in the State of Rio de Janeiro, Brazil, was evaluated. Total bacteria count (TCB), coliforms at 35°C (CT), coliforms at 44°C (CF) and presence of Staphylococcus aureus were performed on all samples. TCB ranged from 2.0 × 10 ² to 6.9 × 10 ⁵ cfu/mL, CT from < 3–≥ 2400 MPN/mL, CF from < 3–1100 MPN/mL and S. aureus from < 10–1.4 × 10 ⁶ cfu/mL. The level of bacterial contamination found in this study reflects the unhygienic conditions prevalent in manufacturing and storage of ice creams. Actions are thus necessary by the Brazilian regulatory agencies to require the ice cream processing plants to adopt quality guarantee systems, such as good manufacturing practices and hazard analysis and critical control points system.     

MICROBIOLOGICAL QUALITY OF TRADITIONAL MARKET CURED FISH IN TANZANIA

The microbiological quality of six varieties of retail market traditionally cured fish in Morogoro, Tanzania was investigated over a five-month period. The fish were contaminated with bacteria and molds at levels of: total aerobes, 10⁶ - 1.7 × 10⁷ c.f.u/g; faecal coliforms, 1.1 × 10¹ - 2.5 × 10³ MPN/g; faecal streptococci, 1.4 × 10¹ - 1.3 × 10³ MPN/g; Staphylococcus aureus, 1.3 × 10³ - 8.6 × 10³ c.f.u/g; Aspergillus flavus group, 2.1 × 10¹ - 2 × 10² c.f.u/g of fish. Of faecal coliform, 45% of the isolates were Escherichia coli. Twenty-five percent of the S. aureus isolates were coagulase positive. Sixteen percent of A. flavus isolates were aflatoxigenic. Aflatoxin contamination ranged from O to 18.5 μg/kg of fish. Insect infestation by Dermestes spp. and mites was observed. The results of this preliminary study emphasize the importance of proper processing and handling offish in the tropics in order to safeguard public health .     

EXAMINATION OF THE MICROBIAL STATUS OF SELECTED INDIGENOUS FERMENTED FOODS IN NIGERIA

Four Nigerian traditionally fermented foods (wara, nono, ogi and kununzaki) were evaluated for the presence of some microorganisms of public health concern. Among the dairy foods , Staphylococcus aureus and Klebsiella sp. were isolated from wara while Escherichia coli, Salmonella sp. and Klebsiella sp. were isolated from nono. The cereal-based fermented foods (ogi and kunu-zaki) contained Bacillus subtilis, E. coli, S. aureus, Klebsiella sp. and Enterococcus faecalis. The mesophilic aerobic counts were: 5 × 10⁵ for wara; nono, 1.53 × 10⁷; ogi, 3.6 × 10⁶ and kunu-zaki, 2.6 × 10⁶ cfu/mL. The enterobacteriaceae counts on nono, wara, ogi and kunu-zaki were 1.79 × 10⁷, 4.5 × 10⁵, 4.0 × 10⁵ and 1.2 × 10⁶ cfu/mL, respectively. No Vibrio count (detection limit: <10 cfu/mL) was recorded in all the food samples considered. The yeast and mold counts ranged from 1.0 × 10⁵– 3.31 × 10⁷ among the food products. The antimicrobial susceptibility patterns of the organisms isolated from dairy products (nono and wara) revealed that they were resistant to ampicillin (100%) and sensitive to gentamicin (100%) and nalidixic acid (100%). Most isolates from cereal based products (ogi and kunu-zaki) were 100% resistant to penicillin, ampicillin and chloramphenicol. This work highlights the need to maintain hygienic standards in the preparation of our locally fermented cereal and dairy foods.     

SHELF-LIFE OF FRESH FILLED PASTA. HAZARD ANALYSIS AND CRITICAL CONTROL POINTS OF THE MANUFACTURING PROCESS AND HOUSEHOLD PRACTICES

Hazard Analysis and Critical Control Point (HACCP) approach was used to assess the safety of a fresh filling pasta (ricotta-filled ravioli) manufacturing plant in La Plata region, Argentina. Household practices like cooking and holding meals before serving were also evaluated. Samples of ricotta, main raw material of the filling, showed colony counts of Enterobacteriaceae total microorganisms, molds and yeasts of (5 × 10³-1 × 10⁵), (1x10⁵−1x10⁸) and 1 × 10⁵ CFU/g, respectively. E. coli was also detected in one out of five samples, suggesting a hazardous condition of this raw material. Salmonella spp. was not isolated from any of the dough samples tested. Ricotta filling showed high colony counts of mesophilic microorganisms (6 × 10⁶ CFU/g), Enterobacteriaceae (1 × 10⁵ - 1 × 10⁶ CFU/g), while E. Coli was detected in 20% of the samples. Counts of B. cereus, S. aureus were less than 1 × 10² CFU/g in the analyzed materials. In the finished product (ricotta-filled ravioli), the colony counts of mesophilic microorganisms and Enterobacteriaceae were 3 × 10⁸ and 8 × 10⁵ CFU/g, respectively. Critical Control Points found were cooking and holding time before serving. The implementation of suggested corrections allowed the microbial quality of the final product (ricotta-filled ravioli) to be improved considerably. The growth of total microbial counts during refrigerated storage (0, 4, 8 and 10C) were measured and the shelf-life of ricotta and ricotta-filled ravioli was calculated.     

Effect of irradiation and modified atmosphere packaging on the microbiological safety of minced pork stored under temperature abuse conditions

The safety of irradiated pork packed in 25% CO₂:75% N₂ and stored at abuse temperature (10 or 15°C) was assessed by inoculation studies involving Salmonella typhimurium, Listeria monocytogenes, Escherichia coli, Yersinia enterocolitica and Clostridium perfringens . Irradiation to a dose of 1.75 kGy reduced pathogen numbers to below the detection limit of 10² cells g^-1. When higher inoculum levels were used (10⁶ cells g^-1) irradiation at 1.75 kGy reduced pathogen numbers by 1 –>5 log₁₀ cycles depending on strain. Clostridium perfringens was the most resistant, and Y. enterocolitica the most sensitive of the pathogens studied.
In all cases when high numbers (10⁶ to 10⁷g^-1) of spoilage and/or pathogenic bacteria were present initially on the pork the meat appeared spoiled, and although irradiation reduced the number of microorganisms, the meat was still unacceptable from a sensory viewpoint after treatment.
It was concluded that the microbiological safety of irradiated, modified atmosphere packaged (MAP) pork is better than that of unirradiated MAP pork.     

INHIBITION OF STAPHYLOCOCCUS AUREUS AND BACILLUS CEREUS ON A VEGETARIAN FOOD TREATED WITH NISIN COMBINED WITH EITHER POTASSIUM SORBATE OR SODIUM BENZOATE

Various amounts of nisin (0, 10³ and 5 × 10³ IU/g) in combination with either potassium sorbate (0, 2, and 3%) or sodium benzoate (0, 0.06 and 0.12%) were tested for effectiveness in inhibiting growth of Staphylococcus aureus C10 and Bacillus cereus B7 inoculated on a vegetarian food. The strains used were isolated from vegetarian foods obtained commercially in Taiwan, and the test food, spice and dried bean curd, was selected for the study based on ability to support the growth of these organisms. After treatment with a preservative combination, the surfaces of sterilized food samples were inoculated, samples were stored in vacuum or nonvacuum packages at either 4C or 30C, and at appropriate times, tested for microbial growth. Growth of both isolates was unaffected by vacuum-packaging treatment; however, a bacteriostatic effect was found at 4C. Data indicated that during the 14-day storage at 4C, vacuum-packaged samples treated with 5 × 10³ IU/g nisin and 0.12% sodium benzoate significantly (p < 0.05) decreased the counts of S. aureus C10 and B. cereus B7 by 2.61 and 3.02 log₁₀ CFU/g, respectively. In the vacuum-packaged samples treated with 5 × 10³ IU/g nisin and 3% potassium sorbate, counts for C10 and B7 were decreased by 2.35 and 2.64 log₁₀ CFU/g, respectively. Thus, the combined treatment extended the shelf-life of the vegetarian food .     

MICROBIOLOGICAL STATUS OF EGYPTIAN SALTED MEAT (BASTERMA) AND FRESH SAUSAGE

The microbiological quality of 125 samples of the most popular Egyptian meat products (75 Egyptian fresh sausage "EPS" and 50 basterma) was determined. The aerobic plate count (APC) and Lactobacillaceae count of basterma ranged from 1 × 10⁴ to 9 × 10⁶ CFU/g, respectively . Enterobacteriaceae, mold and yeast counts for basterma were similar (<1 × 10² CFU/g). Artificially contaminated slices of meat and garlic paste of basterma showed that the paste inhibited growth of Salmonella typhimurium. APC and Enterobacteriaceae counts of EFS ranged from 1.1 × 10⁴ to 1 × 10⁸ and from 1 × 10² to 1 × 10⁷ CFU/g, respectively. Nearly 26% and 29% of EFS were positive for Clostridium perfringens and coagulase-positive Staphylococcus aureus, respectively . Salmonella could not be detected in any examined samples. Bacteriologically, EFS might pose a potential health hazard, making it imperative to institute sanitary measures during its production and sale .; Accepted for Publication July 2, 1997     

EVALUATION OF BACTERIOLOGICAL QUALITY IN SELECTED COMMERCIAL INFANT FORMULAS AVAILABLE IN POLAND AND EGYPT

One hundred samples of commercial infant formula bought in shops in the Poznan region (Poland) and Cairo region (Egypt) were investigated. Samples were analyzed for aerobic plate counts (APC), total Bacillus cereus (TBC), and incidences of Bacillus spp. and coliforms. The mean APC and TBC did not show any important variation with country, being practically the same in products bought in Poland and Egypt. All commercial infant formula analyzed immediately after opening were of satisfactory bacteriological quality, exhibiting APC lower than 10⁴ CFU g⁻¹ (mean 4.9 × 10²) and TBC lower than 10³ CFU g⁻¹ (mean 1.1 × 10²). However, 60% of the examined fruit juice and ready-to-feed infant formula presented TBC above the recommendation safety limit after storage at 22C for 72 h and at 35C for 48 h. In most cases the mean log APC and TBC were highest (P > 0.05) for fruit juice and ready-to-feed infant formula stored at elevated temperature (35 ± 1C).     

RADIATION STERILIZATION OF SPICES FOR HOSPITAL FOOD SERVICES AND PATIENT CARE

A survey of the commercial spices used by food services in a typical hospital environment revealed high contamination with microorganisms, i.e., 10⁴ to 10⁷ counts per gram. The predominant microorganisms were as followed (in colony counts/gram): (1) heat-resistant bacterial spores in black pepper, 1 × 10⁷; thyme, 2 × 10⁶; anise, 7 × 10⁴; curry powder, 4 × 10⁵; poultry seasoning, 8 × 10⁴; pickling spice, cardamom, and cumin, 1.5–3 × 10⁴; (2) mixed populations of vegetative cells and bacterial spores in cumin, 1 × 10⁶; (3) molds in cream of tartar, 2 × 10⁴. Sterility of food may be important in a hospital setting, especially in the care of immunocompromised patients. To eliminate the organisms, we recommend radiation treatment, accompanied by appropriate microbiological quality control. On the basis of radiation survival data, the composite natural flora would be reduced to the level of "commercial sterility" (defined as less than 10 organisms per gram((Kiss 1982) by the following minimum radiation doses (in kGy): black pepper, 13; thyme, 13; cumin, 12; anise, 10; curry, 7.3; pickling spice, 7; poultry seasoning, 6; cardamom, 9.4; cream of tartar, 4. For practical purposes, two dose levels can be recommended for treatment of spices in the hospital environment, low = 6–10 kGy and high = 10–15 kGy.     

Postharvest Microbiology of Farm-reared, Tropical Freshwater Prawn (Macrobrachium Rosenbergii)

ABSTRACT: The microbiological quality of farm-reared, tropical freshwater prawn ( Macrobrachium rosenbergii ) stored at 2 different temperatures was studied. The prawn muscle was found to have the initial bacterial load of 10⁴ cfu/g. The lactics and vibrios were in the range of 10² cfu/g, while the E. coli , aeromonads, staphylococci, anaerobes, and molds were in the level of 10¹ cfu/g. Salmonella and Vibrio cholerae were present in the prawn muscle. The prawn muscle held at room temperature (28 ± 2 °C) was organoleptically acceptable up to 8 h, when the bacterial load was more than 10⁶ cfu/g. However, the prawn muscle stored at freezer temperatures (−10 to −15 °C) was found to be in acceptable condition even after 30 d of storage and the bacterial load was fluctuating in the range of 10³ to 10⁴ cfu/g.     

HYGIENIC PARAMETERS, TOXINS AND PATHOGEN OCCURRENCE IN RAW MILK CHEESES

In total, 71 samples of retail raw milk cheeses produced or imported in Belgium and samples of Belgian farmhouse cheeses were examined for cotiforms, β-glucuronidase positive Escherichia coli, Escherichia coli O157 , Staphylococcus aureus, Salmonella spp. , Listeria spp. and Listeria monocytogenes. The presence of staphylococcal enterotoxins was investigated on samples with S. aureus counts higher than 10³ cfu/g. The incidence of coliforms, β-glucuronidase positive E. coli and S. aureus was higher in soft than in blue veined, semi-hard, hard and fresh cheeses. Four mold-ripened soft cheeses were positive for E. coli O157. One of the 4 cheeses was positive for verotoxin VT2. Staphylococcal enterotoxins were detected in 1 soft redsmear cheese, which was positive for L. monocytogenes. L. monocytogenes was also detected in one fresh cheese . Salmonella was not detected in any of the 71 raw milk cheeses.     

MICROBIAL ENUMERATION IN READY-TO-EAT FOODS AND THEIR RELATIONSHIP TO GOOD MANUFACTURING PRACTICE

As a contribution to Good Manufacturing Practice (GMP) programs, we have analyzed products produced and offered by ready-to-eat food stores. Two hundred and seventy four samples of a wide variety of foods from 19 different shops were analyzed. Aerobic counts, total coliforms and yeast and molds were enumerated in each sample. Food stores were evaluated using a GMP check-list. They were grouped in three classes: Class III, nonsatisfactory GMP; Class II, partially satisfactory GMP; and Class I, satisfactory GMP. From the results of microorganism counts in the Class I food shops the following maximum counts are proposed for cooked ready-to-eat foods: aerobic colony count: 10⁵ cfu g⁻¹. It is coincident with satisfactory microbiological quality of many category 3 foods drawn up by Public Health Laboratory Service (PHLS).     

EFFECT OF HIGH HYDROSTATIC PRESSURE, GAMMA-IRRADIATION AND COMBINATION TREATMENTS ON THE MICROBIOLOGICAL QUALITY OF LAMB MEAT DURING CHILLED STORAGE

The effect of gamma irradiation (1.0 kGy) and high hydrostatic pressure (200 MPa for 30 min), either alone or in combination on the shelf-life of lamb mince meat at 0–3C was studied. Untreated control samples initially had total microbial counts of 10⁵ CFU/g, 10² CFU/g of coliforms and 10⁴ CFU/g of Staphylococcus spp. Coliforms were eliminated by all the treatments . Staphylococcus spp. however, were reduced only by 1 log cycle when treated with irradiation alone and high pressure alone. These species were a mixture of mannitol-fermenting and mannitol-nonfermenting strains. In samples subjected to the combination treatment , Staphylococcus spp. appeared only after 3 weeks of storage and all were mannitol-nonfermenting. On the basis of microbiological and sensory quality, the shelf-life of the control sample was less than 1 week. All treated meat samples had a shelf-life of 3 weeks, but only combination treated samples were free from potentially pathogenic Staphylococcus spp .     

Elimination of Listeria monocytogenes in soft and red smear cheeses by irradiation with low energy electrons

Soft and red smear cheeses are frequently contaminated by Listeria monocytogenes , sometimes at relatively high concentration (< 10⁵ CFUg^-1). This bacterium is radiosensitive (D₁₀ value of approximately 0.45 kGy) but irradiation of the whole cheese by X-rays induced off-flavours when the dose exceeded 1.0 kGy. Irradiation could be effective in eliminating L. monocytogenes only from lightly contaminated cheeses (> 10²CFU g^-1).
L. monocytogenes appears only in the rind (where the pH is greater than 6.3) and never grows in the core of the cheese. Under these conditions, a specific irradiation of the rind after ripening, with a low-energy electron beam at relatively high doses (up to 3.0 kGy), allows the total elimination of L. monocytogenes in heavily contaminated samples (10⁵-10⁶ CFU g^-1) without noticeable modifications of the organoleptic properties of the cheese.     

Recipes for antimicrobial wine marinades against Bacillus cereus, Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica

ABSTRACT:  We have evaluated bactericidal activities against Bacillus cereus , Escherichia coli O157:H7, Listeria monocytogenes , and Salmonella enterica of several antimicrobial wine recipes, each consisting of red or white wine extracts of oregano leaves with added garlic juice and oregano oil. Dose-response plots were used to determine the percentage of the recipes that resulted in a 50% decrease in colony-forming units (CFU) at 60 min (BA₅₀). Studies designed to optimize antibacterial activities of the recipes demonstrated that several combinations of the naturally occurring plant-derived ingredients rapidly inactivated the above mentioned 4 foodborne pathogens. We also showed that (a) incubation temperature affected activities in the following order: 37 °C > 21 °C > 4 °C; (b) varying the initial bacterial concentrations from 10³ to 10⁴ to 10⁵ CFU/well did not significantly affect BA₅₀ values; (c) storage of 3 marinades up to 2 mo did not change their effectiveness against Salmonella enterica ; and (d) polyphenolic compounds isolated by chromatography from red wine exhibited exceptional activity at nanogram levels against 2 strains of Bacillus cereus . These observations suggest that antimicrobial wine formulations have the potential to improve the microbiological safety of foods.     

Rapid dye reduction tests for the determination of microbiological quality of meat

Rapid dye reduction tests have been developed to determine the quality of meat. Three chemical indicators, resazurin and two tetrazolium compounds, were used to correlate the microbial numbers and reduction times in meat samples. Twenty-five surface samples from sheep carcasses were subjected to each reduction test. Total viable counts given were obtained at 37°C. Resazurin reduction time was 90–120 min when the bacterial counts ranged from 1.5×10⁶ to 7.7×10⁶/cm². Samples showing bacterial counts between 1.5×10⁶ and 6.0×10⁶/cm² reduced tetrazolium (NBT) in 360–390 min whereas samples containing bacterial counts of 2.1×10⁶/cm² took 420–450 min to reduce iodophenyl nitrophenyl tetrazolium (INT) dye. Regression equations relating the number of organisms per cm² and reduction time were applied to predict the microbiological quality of meat samples from reduction time data. Among the three dyes, resazurin gave the lowest reduction time.     

Thermal Inactivation of Salmonella Senftenberg and Listeria innocua in Beef/Turkey Blended Patties Cooked via Fryer and/or Air Convection Oven

ABSTRACT: Beef/turkey blended patties, containing 10⁷ to 10⁸ cfu/g of Salmonella Senftenberg or Listeria innocua , were battered and breaded. The effect of frying (177 °C) and air convection cooking (288 °C) on thermal inactivation of S. Senftenberg and L. innocua was evaluated. A model was obtained to correlate product internal temperature with frying and oven cooking time. Cooking method significantly affected thermal history and subsequently the thermal inactivation of S. Senftenberg and L. innocua. The effect of frying time interacted with oven cooking time. Increasing frying time reduced the oven cooking time. Mathematical models were developed to correlate the survival rate of S. Senftenberg or L. innocua with frying and oven cooking time.     

DETECTION OF STAPHYLOCOCCUS AUREUS PRODUCTS IN FOODS USING ENZYME LINKED IMMUNOSORBENT ASSAY AND SPECTROPHOTOMETRIC THERMONUCLEASE ASSAY

The comparative sensitivity of an enzyme linked immunosorbent assay (ELISA) using four different antistaphylococcal antisera and a spectrophotometric assay for thermonuclease were determined using cheese and ravioli samples seeded with strains of Staphylococcus aureus and S. epidermidis. The ELISA used antisera to enterotoxin A, enterotoxin B, S. aureus strains 14609 (human), and UNH-570 (bovine). The 570 ELISA and spectrophotometric thermonuclease assay were of comparable sensitivity and detected seeded culture in concentrations as low as 2 × 10⁷ CFU/g of cheese. A simple two hour method for extracting thermonuclease from foods was 50% efficient when as little as 50 ng of purified enzyme was seeded per g of cheese. Analyses of 43 commercial cheeses for viable S. aureus found five (12%) positive with 3 × 10⁴ CFU/g of cheese being the highest counts detected. All samples were negative by ELISA and thermonuclease assay. A simple screening procedure for demonstration of S. aureus contamination of foods is discussed.     

The distribution of Enterobacteriaceae and some pathogenic micro-organisms in nonbranded white cheese samples sold in Ankara city

In this research, 75 samples of nonbranded white cheese, presented for sale in small markets from various regions and bazaars in Ankara, were studied. Eighty-six isolates, 71 of which are Gram-negative isolates and 15 of which are Gram-positive isolates, were obtained. These isolates were identified by using bioMérieux API20E and classical methods. Total mesophilic bacteria counts and total coliform bacteria counts were carried out for each white cheese sample. The total average mesophilic bacteria of 75 white cheese samples was 15.5 × 10⁵ cfu/g and the total average coliform bacteria were 13.6 × 10⁵ cfu/g.