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1.
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.  相似文献   

2.
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.  相似文献   

3.
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.  相似文献   

4.
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 .  相似文献   

5.
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  相似文献   

6.
Fresh pink salmon (Oncorhynchus gorbuscha) fillets and whole Pacific herring (Clupea harengus pallasi) were stored for two weeks at 10C to determine if significant amounts of histamine were produced before the fish spoiled. Spoilage odors in salmon were moderate by day 4 and intense by day 7, while herring had detectable spoilage by day 4 and became potent by day 6. Aerobic bacterial counts increased from 4.0 × 102/g initially to 3.6 × 108/g in salmon fillets by day 14 and from 2.3 × 103/g initially to 2.7 × 107/g in whole herring by day 14. Total volatile nitrogen increased from 1.8 to 78.5 mg N/100 g in salmon and 2.2 to 23.6 mg N/100 g in herring. Histamine was not detected in salmon, while concentrations reached 54.9 ppm in herring at day 14. However, herring were considered spoiled by day 6.  相似文献   

7.
Eighteen pedha samples procured from A and B grade retail shops were examined for their overall microbiological quality and for the presence of foodborne pathogens viz. Staphylococcus aureus, Salmonella sp., Coliforms , Listeria monocytogenes, Yersinia enterocolitica and Bacillus cereus. The microbiological quality of pedha samples from B grade shops was very poor as compared to pedha from A grade shop as evidenced by the very high total bacterial counts (6 × 107 cfu/g), high counts of S. aureus (as high as 7 × 106 cfu/g) and presence of coliforms and Listeria and Yersinia sp. in 33% of the samples. All the samples from A grade shops were also positive for S. aureus though negative for coliforms , Yersinia, Salmonella, Listeria and B. cereus. Gamma irradiation of pedha at a dose of 3kGy at 0C reduced overall bacterial load by five log cycles and S. aureus and coliforms could be totally eliminated. However, 5 kGy dose was necessary to eliminate S. aureus if the initial number exceed 1 × 105 cfu/g. Inoculated pack studies confirmed that 3 kGy dose was sufficient for the complete elimination of up to 1 × 105 cfu/g of S. aureus. A dose of 3 kGy had minimal effect on the sensory quality of pedha and even pedha samples irradiated at 5 kGy dose were acceptable. Treatment with 3 kGy dose of gamma radiation totally eliminated S. aureus and coliforms in pedha, thereby ensuring their microbial safety.  相似文献   

8.
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 .  相似文献   

9.
The effect of gamma radiation on aflatoxin production by Aspergillus flavus EA-81 in maize with different initial moisture levels was determined over a 15-day period. The viability of A. flavus on maize decreased over time with increasing moisture contents and storage at 8C. After 45 days at 28C, levels of viable conidiospores of A. flavus increased from 4.5 × 107 to about 3.0 × 108 per gram of maize. Levels of aflatoxin B1 produced by A. flavus were 10 μg kg-1 in the maize stored at 8C after 45 days. Production of aflatoxin was highest at 40% moisture and 28C. Irradiation of 1.0 or 2.0 kGy greatly reduced the level of mold growth relative to unirradiated controls. A dose of 4.0 kGy eliminated all viable fungi. Aflatoxin B1 production decreased with increased levels of irradiation and was negligible at 4.0 kGy. When maize was inoculated after irradiation and stored, the spore counts and aflatoxin levels were higher than in unirradiated and inoculated controls after 30 days. Apparently, the natural competitive microflora prevented growth and thus limited higher concentrations of aflatoxin in maize.  相似文献   

10.
Sixty frozen samples (30 hamburger patties and 30 minced meat) purchased from different retail markets in Ismailia, Egypt were examined for incidence of proteolytic and lipolytic bacteria. Mean values of proteolytic psychrophiles in the examined samples of hamburger and minced meat were 2×105 and 6×104, respectively. Lipolytic psychrophiles in hamburger were 8×105 and 3×105 in minced meat. Proteolytic mesophiles in hamburger and minced meat were 6×105 and 5×104, respectively. Mean values of lipolytic mesophiles were 5×104 for hamburger and 5×103 for minced meat. Proteolytic thermophiles in hamburger and minced meat were 3×103 and 103, respectively. Both proteolytic and lipolytic activities were exhibited by various bacteria that were identified.  相似文献   

11.
Samples of 124 different foods purchased from local markets were examined to determine the incidence of Bacillus cereus. The foods examined were pulses, rice and rice products, oils, fish, meat, spices, milk and milk products and ice creams. Isolations were made on mannitol-egg yolk-polymyxin B agar medium and confirmed by morphological and biochemical tests. B. cereus was present in 28.5% of rice and rice products (100% of boiled rice), 40% of fish, 80% of chicken and meat products, 30% of spices and 87% of ice creams. Pasteurized milk and milk products and protein-rich food powders containing milk or cocoa were also contaminated with B. cereus. The average count of B. cereus varied from 2 × 102 to 5 × 105/g. The response of cells and spores from 6 randomly selected isolates of B. cereus to antibiotics and to heat treatment was identical. However, both vegetative and spore forms of these isolates exhibited subtle differences in radiation resistance. Pathogenicity of all isolates was determined by their ability to lyse human erythrocytes. Five of the six isolates selected produced a strong nonhemolytic toxin which is lethal to mice.  相似文献   

12.
Production of Enterotoxin-B in Cured Meats   总被引:1,自引:0,他引:1  
SUMMARY— A variety of laboratory cured hams were inoculated with 103−106 cells of S. aureus strain S-6 and incubated at 10, 22 and 30°C anaerobically for up to 16 weeks. Enterotoxin-B was detected by gel-diffusion in hams with original pH over 5.30, up to 9.2% NaCl (brine) and 0.54 ppm undissociated nitrous acid. There was better toxin production at 30° than at 22° or 10°C. Toxin was detected at 10°C after at least 2 weeks incubation and in most samples after 8 weeks when pH was greater than 5.6. Toxic hams had more than 4 × 106 cells/g. Contaminants were always less than 105/g. Tween 80 inhibited toxin production at 30° but not at 10°C. Toxic hams looked normal even after 2 months incubation at 10°C.  相似文献   

13.
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.  相似文献   

14.
In order to isolate, identify and characterize the microflora of cacao beans before, during and after fermentation and locate possible sources contributing to microbial contamination, cacao beans from the Centeno and San Louis Estates in Trinidad were investigated. Prior to fermentation, the interior and exterior of the pods, hands of employees, utensils, dried pulp material of the sweatboxes and finally fruitflies ( Drosophila melanogaster ) were studied microbiologically. At Centeno Estate, beans were sampled at 5, 45 and 90 cm depths at 8-hr intervals for the first 72 hr and every 12 hr thereafter for 7 days. Sampling at San Louis Estate was carried out at 24 hr intervals for the same period. The changes in microbial population of the beans sampled at Centeno Estate ranged from 1.48 × 105/g at 0 hr to 4.1 × 105/g at the completion of the fermentation, whereas, at San Louis Estate they ranged from 6.8 × 105/g to 9.2 × 105/g during the same period. Taxonomical studies of isolates obtained during the fermentation period revealed the identification of 44 microorganisms at both Estates. Yeasts Zymomonas mobilis and several species of lactic acid organisms dominated the flora during the early stages of fermentation. As the fermentation progressed, these and other isolates were taken over by several species of genus Bacillus. Microbiological examination of dried and polished beans resulted in the identification of 22 organisms at Centeno Estate and 15 organisms at San Louis Estate  相似文献   

15.
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.  相似文献   

16.
Freshly caught sardines contained high levels of bacteria located mainly on the skin and the gills. These bacteria invaded and grew rapidly in sardine muscle, reaching 5x108 c.f.u. g-1 and 6x108 c.f.u. g-1 respectively after 24h at ambient temperature and 8 days in ice.
Histidine, arginine, lysine, tyrosine and methionine levels decreased during storage. The other amino acids, except proline and taurine, accumulated in the fish muscle, indicating an extensive proteolysis.
Histamine, cadaverine and putrescine accumulated to levels of 2350ppm, 1050ppm and 300ppm respectively, after 24h storage at ambient temperature. Histamine and cadaverine reached similar levels after 8 days storage in ice, whereas putrescine formation was insignificant. Spermidine and spermine levels increased slightly under ambient conditions.
Salting the fish at 8% delayed bacterial and chemical changes but only in iced sardines.
The high content of free histidine found in sardines and the susceptibility of its muscle to histamine and cadaverine formation could explain its increasing implication in incidents of histamine poisoning.  相似文献   

17.
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.  相似文献   

18.
H.J. Kim    M.Y. Lee    D.B. Min 《Journal of food science》2006,71(8):C465-C468
ABSTRACT:  The reaction rate constants of 5 × 10−4 M, 10 × 10−4 M, and 20 × 10−4 M α-, γ-, and δ-tocopherols with singlet oxygen in methylene chloride containing 1 × 10−5 M chlorophyll under light at 25 °C for 60 min were studied. The oxidation of tocopherols determined by a spectrophotometric method showed that the losses of 20 × 10−4 M α-, γ-, and δ-tocopherols after 60 min under light were 21%, 16%, and 9%, respectively. The degradation of α-, γ-, and δ-tocopherols was undetectable in the absence of chlorophyll under light or in the presence of chlorophyll in dark. The losses of tocopherols under light were mainly due to singlet oxygen oxidation. The degradation rates of 20 × 10−4 M α-, γ-, and δ-tocopherols were 6.6 ×10−6 M/min, 5.0 × 10−6 M/min, and 2.9 × 10−6 M/min, respectively. The reaction rates between α-, γ-, or δ-tocopherol and singlet oxygen were 4.1 ×106/M s, 3.3 × 106/M s, and 1.4 × 106/M s, respectively. The singlet oxygen oxidation rate of δ-tocopherol was significantly lower than α- or γ-tocopherol at α= 0.05. As the electron density in the chromanol ring of tocopherol increased, the singlet oxygen oxidation was increased.  相似文献   

19.
Enhancement of Fermentation Process in Pu-Erh Tea by Tea-Leaf Extract   总被引:1,自引:0,他引:1  
C.W. Hou    K.C. Jeng    Y.S. Chen 《Journal of food science》2010,75(1):H44-H48
ABSTRACT:  Pu-erh tea is known as a fermented tea and longer storage enhances its flavor and taste. Recently,  Aspergillu s,  Blastobotrys , and  Streptomyces  are found to play important roles in nutritional enhancement of Pu-erh tea by fermentation. Since water and temperature affect the microbial growth, we therefore explored the factors that might enhance the Pu-erh tea fermentation. The results showed that the addition of fresh tea-leaf extract (TLE) enhanced the withered tea fermentation (at 37 °C, 80 to 85% RH) as compared with the water only. Contents of statin, GABA, gallic acid, DPPH scavenging and polyphenol oxidase (PPO) activities were increased, whereas polyphenols and caffeine were decreased over 6 mo. TLE dose-dependently enhanced some of the qualities (that is, statin, PPO) of Pu-erh tea significantly as compared with the water only. The effect was related to the increase population of  A. niger  and  A. carbonarius  at 6 mo (from 7.6 ± 1.2 × 101 and 3.2 ± 1.3 × 101 to 3.1 ± 1.2 × 106 and 2.4 ± 1.1 × 105 colony forming units [CFU]/g, respectively). After drying process (90 °C, 30 min), the total microbial count from these samples returned to background level (3 ± 0.5 × 102 CFU/g). None of ochratoxin and fumonisin, toxins from  Aspergillus , was detected in the final products. The flavor and taste were also enhanced by treatment with TLE. The inoculation with  S. cinereus  Y11 with 2% TLE further enhanced these functional contents (about 2-fold increase of statin level) in the experimental Pu-erh tea. Therefore, this result may add a new process for Pu-erh tea manufacture.  相似文献   

20.
Twenty-five random fresh market samples of Van herby cheese and pickled white cheese were examined for molds and aflatoxins. The mean total mold count in Van herby cheese was 2.50 × 105/g; in pickled white cheese it was 4.95 × 104/g. The mycoflora on the cheeses were determined. In all cheeses, over 65% of molds were Penicillium species . Aspergillus made up 0 to 1.6 % and 2.6 % to 4.0 % of the mold on pickled white cheese and Van herby cheese, respectively. Other isolated molds belonged to Mucor, Geotrichum and Trichoderma genera. None of the samples contained aflatoxins and none of the 6 Aspergillus isolates was an aflatoxin producer .  相似文献   

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