Bacteriological profile of raw, frozen chicken nuggets

The bacteriological profile of raw, frozen chicken nuggets manufactured at a chicken processing facility in Queensland, Australia, was determined. Chicken nuggets are manufactured by grinding poultry, adding premixes to incorporate spices, forming the meat to the desired size and shape, applying a batter and breading, freezing, and packaging. A total of 300 frozen batches were analyzed for aerobic plate count, Escherichia coli, and Salmonella over a period of 4 years. The mean of the aerobic plate count was 5.4 log CFU/g, and counts at the 90th, 95th, and 99th percentiles were 5.7, 5.9, and 6.5 log CFU/g, respectively. The maximum number of bacteria detected was 6.6 log CFU/g. E. coli prevalence was 47%, and of the positive samples, the mean was 1.9 log CFU/g; counts at the 90th, 95th, and 99th percentiles were 2.3, 2.4, and 2.8 log CFU/g, respectively. The maximum number of E. coli was 2.9 log CFU/g. The Salmonella prevalence was 8.7%, and 57.7% of these isolates were typed as Salmonella subspecies II 4,12,[27]:b:[e,n,x] (Sofia), a low-virulence serotype well adapted to Australian poultry flocks. There was a significant relationship (P < 0.05) between season and both aerobic plate counts and E. coli counts, and no correlation between E. coli counts and Salmonella prevalence. This study provides valuable data on the bacteriological quality of raw, frozen chicken nuggets.     

Nutritional quality and protein value of exotic almonds and nut from the Brazilian Savanna compared to peanut

The aim of this study was to determine the nutritional quality and protein value of the baru almond, pequi almond, and cerrado cashew nut compared to the peanut. We determined the proximate chemical composition, mineral content, and amino acid profile. A biological assay was carried out to assess the protein value, by net protein ratio (NPR), relative net protein ratio (RNPR), and protein digestibility-corrected amino acid score (PDCAAS) indexes. We found that the exotic almonds and the nut are rich in proteins (22.7-29.9 g/100 g), lipids (41.9-50.0 g/100 g), fibres (baru and pequi almonds, around 10.0 g/100 g), iron and zinc (4.3-7.4 mg/100 g). Baru almond's protein did not show deficiency in essential amino acids and lysine was the first limiting amino acid in the proteins of the pequi almond and cerrado cashew nut. The baru almond showed a RNPR of 86%, similar to that of the cerrado cashew nut (78%), but higher than that of the peanut (72%) and of the pequi almond (54%). The PDCAAS value of the baru almond (91%) was the highest and cerrado cashew nut and peanut presented similar values of this index (82%), which were higher than that of the pequi almond (55%). The baru almond has the highest protein quality, but the cerrado cashew nut and peanut are sources of good quality protein, too. We recommend the inclusion of these exotic foods in healthy diets and in food industry, and the baru almond and cerrado cashew nut as sources of complementary protein.     

A survey of the microbiological quality of kangaroo carcasses processed for human consumption in two processing plants in Queensland, Australia

An investigation of the microbiological quality of kangaroo carcasses at two Queensland processing plants was carried out. A total of 836 whole muscle samples were taken, 801 from plant A and 35 from plant B. Samples were analyzed for aerobic bacteria, Escherichia coli, and Salmonella. The mean adjusted aerobic plate count (APC) was 2.8 log CFU/g, and counts at the 90th, 95th, and 99th percentiles were 4.2, 4.9, and 6.4 log CFU/g, respectively. The maximum number of bacteria recovered was 6.5 log CFU/g. E. coli was detected in 13.9% of samples, for which the adjusted mean was 0.7 log CFU/g, and counts at the 90th, 95th, and 99th percentiles were 1.4, 2.0, and 3.0 log CFU/g, respectively. Salmonella was detected in 0.84% of samples. There was no significant relationship (P < 0.05) between season and APC or E. coli count. There was a significant relationship (P < 0.001) between Salmonella prevalence and summer. The microbiological quality of Queensland kangaroo carcasses is similar to that obtained during other excision-based studies of kangaroo, wild boar, and beef carcasses.     

Detection of sesame seed DNA in foods using real-time PCR

The detection of potentially allergenic foods, such as sesame seeds, in food products is a major concern for the food-processing industry. A real-time PCR method was designed to determine if sesame seed DNA is present in food products. The PCR reaction amplifies a 66-bp fragment of the sesame seed 2S albumin gene, which is detected with a sesame-specific, dual-labeled TaqMan probe. This reaction will not amplify DNA derived from other seeds present in baked goods, such as pumpkin, poppy, and sunflower seeds. Additionally, this assay will not cross-react with DNA from several tree nut species, such as almond, Brazil nut, cashew, hazelnut, and walnut, as well as four varieties of peanut. This assay is sensitive enough to detect 5 pg of purified sesame seed DNA, as well as sesame seed DNA in a spiked wheat cracker sample.     

A national survey of the microbiological quality of beef carcasses and frozen boneless beef in Australia

The third national baseline microbiological survey of Australian beef carcasses and frozen boneless beef was conducted in 2004. Carcasses (n=1155) sampled at 27 slaughter establishments had a mean aerobic plate count (at 25 degrees C) of 1.3 log CFU/cm2. Escherichia coli was isolated from 8.0% of the cacasses, with a mean count of -0.8 log CFU/cm2 for positive samples. On samples from 24 boning (fabrication) plants (n=1082), the mean aerobic plate count for frozen boneless beef was 1.3 log CFU/g, and the mean count for the 1.8% of samples with detectable E. coli was 1.5 log CFU/g. E. coli O157: H7 was isolated from 1 of 1,143 carcasses and from 0 of 1082 boneless samples. Salmonella was isolated from 0 of 1155 carcasses and from 1 of 1082 samples of boneless product. No Campylobacter spp. were isolated from carcasses or boneless beef. Coagulase-positive staphylococci were isolated from 28.7% of beef carcasses and 20.3% of boneless beef samples, and positive samples had a mean count of 0.3 log CFU/cm2 and 0.8 log CFU/g, respectively.     

Multi-allergen screening immunoassay for the detection of protein markers of peanut and four tree nuts in chocolate

A multiresidue enzyme immunoassay was developed to check for the presence of markers of peanut, hazelnut, almond, cashew and Brazil nuts in a single run. The assay was designed under the competitive indirect format and adapted for screening purposes applied to chocolate samples. The limit of detection for this assay was below 1 µg g^-1 protein for each allergenic food. In most cases, the high specificity of the antibodies used allowed the identification of each particular allergenic food with no possible confusion. This assay was proven to be useful as part of an analytical procedure involving the identification of the unknown allergenic food among peanut and other tree nuts in recalled samples before the application of a quantitative technique to determine the level of cross-contamination.     

Microbial quality of shrimp products of export trade produced from aquacultured shrimp

Bacteriological quality of individually quick frozen (IQF) shrimp products produced from aquacultured tiger shrimp (Penaeus monodon) has been analysed in terms of aerobic plate count (APC), coliforms, Escherichia coli, coagulase-positive staphylococci, Salmonella, and Listeria monocytogenes. Eight hundred forty-six samples of raw, peeled, and deveined tail-on (RPTO), 928 samples of cooked, peeled, and deveined tail-on (CPTO), 295 samples of headless, undeveined shell-on (HLSO), and 141 samples of raw, peeled, and deveined tail-off (RPND) shrimps were analysed for the above bacteriological parameters. Salmonella was isolated in only one sample of raw, peeled tail-on. Serotyping of the strain revealed that it was S. typhimurium. While none of the cooked, peeled tail-on shrimp samples exceeded the aerobic plate count (APC) of 10(5) colony forming units per gram (cfu/g), 2.5% of raw, peeled, tail-on, 6.4% of raw, peeled tail-off, and 7.5% of headless shell-on shrimp samples exceeded that level. Coliforms were detected in all the products, though at a low level. Prevalence of coliforms was higher in headless shell-on (26%) shrimps followed by raw, peeled, and deveined tail-off (19%), raw, peeled tail-on (10%), and cooked, peeled tail-on (3.8%) shrimps. While none of the cooked, peeled tail-on shrimp samples were positive for coagulase-positive staphylococci and E. coli, 0.6-1.3% of the raw, peeled tail-on were positive for staphylococci and E. coli, respectively. Prevalence of staphylococci was highest in raw, peeled tail-off (5%) shrimps and the highest prevalence of E. coli (4.8%) was noticed in headless shell-on shrimps. L. monocytogenes was not detected in any of the cooked, peeled tail-on shrimps. Overall results revealed that the plant under investigation had exerted good process control in order to maintain superior bacteriological quality of their products.     

Functional properties of raw and heat processed cashew nut (Anacardium occidentale, L.) kernel protein isolates

The functional properties viz. solubility, water and oil absorption, emulsifying and foaming capacities of the protein isolates prepared from raw and heat processed cashew nut kernels were evaluated. Protein solubility vs. pH profile showed the isoelectric point at pH 5 for both isolates. The isolate prepared from raw cashew nuts showed superior solubility at and above isoelectric point pH. The water and oil absorption capacities of the proteins were slightly improved by heat treatment of cashew nut kernels. The emulsifying capacity of the isolates showed solubility dependent behavior and was better for raw cashew nut protein isolate at pH 5 and above. However, heat treated cashew nut protein isolate presented better foaming capacity at pH 7 and 8 but both isolates showed extremely low foam stability as compared to that of egg albumin.     

Bacteriology of unshelled frozen blue swimming crab (Portunus pelagicus)

In this study, 45 (10 whole specimens and 35 frozen claws) frozen samples of Portunus pelagicus imported into Sicily (Italy) from the west coast of Africa were examined to assess their bacteriological characteristics and suitability for consumption. Bacteriological examination was performed on two subsamples for each whole crab. The first was the body and claw muscle; the second was a pool of viscera and gills. In the case of frozen claws, each muscle claw was a sample. An aerobic plate count at 30 degrees C (mesophilic aerobic plate count [MAPC]) and 18 degrees C (psychrotrophic aerobic plate count [PAPC]) for 3 days, sulfite-reducing anaerobes, total coliforms, Escherichia coli, enterococci, and Aeromonas spp. were enumerated. Detection of halophilic Vibrio spp. was also performed using salt polymixin broth as an enrichment medium and thiosulfate citrate bile salts sucrose agar as a selective medium; a further morphological and biochemical identification of suspected colonies was performed. The bacterial load of muscle and viscera and gills was low. The MAPC ranged from 0.78 to 3.26 log CFU/g, and the PAPC ranged from 0.48 to 2.41 log CFU/g. Vibrio spp., Aeromonas spp., sulfite-reducing anaerobes, and E. coli were never isolated from muscles or viscera and gills. In contrast to the findings of others, this study showed good bacteriological quality of crabs imported into Sicily from the west coast of Africa. This study also demonstrated the positive influence of the characteristics of environment of origin and postharvest handling hygiene; these parameters could be useful in the context of the application of the hazard analysis critical control point system to this production.     

The microbiological quality of ice used to cool drinks and ready-to-eat food from retail and catering premises in the United Kingdom

A survey of 4,346 samples of ice from retail and catering premises examined 3,528 samples (81%) used to cool drinks and 144 samples (3%) from food displays. For 674 samples (15%), the origin was not recorded. Most samples of ice used to cool drinks or ready-to-eat food on displays did not contain coliforms, Escherichia coli, or enterococci. Of the ice used to cool drinks, 9% contained coliforms, 1% E. coli, and 1% enterococci in excess of 10(2) CFU/100 ml, and 11% had an aerobic plate count at 37 degrees C in excess of 10(3) CFU/ml. The microbiological quality of ice used to cool drinks was poorer when melt water was present in the ice buckets. Ice used in food displays was more contaminated than ice used to cool drinks, with 23% containing coliforms, 5% E. coli, and 8% enterococci at 10(2) CFU/100 ml or more. Twenty-nine percent of samples had an aerobic plate count greater than 10(3) CFU/ml. Ice that had been used to cool shellfish was of a lower microbiological quality than samples used to cool ready-to-eat fish, salads, or dairy produce. Samples of ice produced in commercial production facilities were of higher microbiological quality than samples of ice that were not. The microbiological quality of ice was dependent on the type of use, the type of premises, and the type and place of production. Although most ice samples were of acceptable microbiological quality, evidence from this study suggests that the microbiological quality of ice prepared and used at certain premises in the UK is a cause for concern.     

Inhibition of growth of pathogenic bacteria in raw milk by legume protein esters

Protein isolates from soybean and chickpea, as well as their methylated esters, were tested for their inhibitory action against the propagation of pathogenic bacteria in raw milk during its storage either at room temperature or under refrigeration. Raw milk was inoculated with a mixed culture of Listeria monocytogenes Scott A and Salmonella enterica serovar Enteritidis strain PT4 at ca. 2 log CFU ml?1. Aerobic plate count, coliform count, and presumptive E. coli in raw milk treated with esterified legume proteins were inhibited by 2 to 3 log relative to a control after 6 to 8 days of storage at 4°C. At room temperature, bacterial populations (aerobic plate count, coliform count, and presumptive E. coli) in raw milk treated with esterified legume proteins were inhibited by ca. 1.5 to 1.6 log relative to the control after 12 h. Supplementation of raw milk with esterified soybean protein could significantly inhibit the counts of the two inoculated pathogens (L. monocytogenes Scott A and Salmonella Enteritidis PT4), which were initially inoculated at ca. 2 log CFU ml?1, by ca. 2.4 log and 1.6 log CFU ml?1, respectively, on day 8 of storage under cold conditions. Corresponding reductions amounting to 2.7 and 1.8 log CFU ml?1 were observed after 12 h of storage at room temperature. Supplementation of raw milk with esterified soybean protein (0.5%) reduced the maximum level of titratable acidity to 0.21 and maintained the pH level at 6.4 after 8 days of storage under cold conditions as compared with 4 days for untreated raw milk. Similar results were observed when raw milk was stored at room temperature for 10 h.     

Most-probable-number determination of salmonella levels in naturally contaminated raw almonds using two sample preparation methods

Pathogens occurring in particulate foods may be unevenly distributed, which may impact interpretation of most-probable-number (MPN) values. The MPN analysis of Salmonella in naturally contaminated raw almonds was conducted using two sample preparation methods. Raw almond kernels (3,698 samples) and inshell almonds (455 samples) were collected from almond processors throughout California during the 2006 and 2007 harvests, and 100-g samples were enriched for Salmonella. The prevalence of Salmonella on kernels and inshell almonds was 1.6 and 0.9%, respectively, in 2006, and 0.83 and 2.2%, respectively, in 2007. Almond kernel samples from 2006 were further enriched for Salmonella, and levels of the organism were determined for positive samples by three-tube MPN analysis (25 g, 2.5 g, 0.25 g). Almonds were either divided into subsamples prior to blending and enrichment (method A), or samples were blended in enrichment broth prior to preparation of subsamples (method B). Salmonella was not isolated (<1.2 MPN/100 g) upon retesting of 19 of 31 (method A) or 23 of 29 (method B) positive samples. When detected, levels were 1.4 to 15.5 MPN/100 g (average 2.3 MPN/100 g) or 1.4 to 18.3 MPN/100 g (average 2.1 MPN/100 g) using methods A or B, respectively. A total of 23 different Salmonella serovars were identified from the original almond samples. Salmonella Muenchen was the most frequently isolated serovar (15%) from the 53 Salmonella-positive samples, followed by Newport (12%), Enteritidis (10%), and Typhimurium (8%). No correlation was found between presence of Salmonella and E. coli levels, aerobic plate counts, or counts of yeasts or molds.     

A field study of the microbiological quality of fresh produce

The Centers for Disease Control and Prevention has reported that foodborne disease outbreaks associated with fruits and vegetables increased during the past decade. This study was conducted to characterize the routes of microbial contamination in produce and to identify areas of potential contamination from production through postharvest handling. We report here the levels of bacterial indicator organisms and the prevalence of selected pathogens in produce samples collected from the southern United States. A total of 398 produce samples (leafy greens, herbs, and cantaloupe) were collected through production and the packing shed and assayed by enumerative tests for total aerobic bacteria, total coliforms, total Enterococcus, and Escherichia coli. These samples also were analyzed for Salmonella, Listeria monocytogenes, and E. coli O157:H7. Microbiological methods were based on methods recommended by the U.S. Food and Drug Administration. For all leafy greens and herbs, geometric mean indicator levels ranged from 4.5 to 6.2 log CFU/g (aerobic plate count); less than 1 to 4.3 log CFU/g (coliforms and Enterococcus); and less than 1 to 1.5 log CFU/g (E. coli). In many cases, indicator levels remained relatively constant throughout the packing shed, particularly for mustard greens. However, for cilantro and parsley, total coliform levels increased during the packing process. For cantaloupe, microbial levels significantly increased from field through packing, with ranges of 6.4 to 7.0 log CFU/g (aerobic plate count); 2.1 to 4.3 log CFU/g (coliforms); 3.5 to 5.2 log CFU/g (Enterococcus); and less than 1 to 2.5 log CFU/g (E. coli). The prevalence of pathogens for all samples was 0, 0, and 0.7% (3 of 398) for L. monocytogenes, E. coli O157:H7, and Salmonella, respectively. This study demonstrates that each step from production to consumption may affect the microbial load of produce and reinforces government recommendations for ensuring a high-quality product.     

Microbiological evaluation of sprouts marketed in Mumbai, India, and its suburbs

A study was undertaken to assess the microbiological quality of sprouts marketed in Mumbai and its suburbs. A total of 124 sprout samples of four different legumes--mung (Phaseolus aureus), matki (Phaseolus aconitifolius), chana (Cicer arietinum), and vatana (Pisum sativum)--were analyzed over a period of 12 months for aerobic plate counts, coliforms, yeast and mold counts, staphylococci, Salmonella, Listeria monocytogenes, Escherichia coli, E. coli O157:H7, and coagulase-positive Staphylococcus aureus. Aerobic plate counts ranged from 7.6 to 8.9 log CFU/g, coliform counts ranged from 5.4 to 7.9 log CFU/g, yeast and mold counts ranged from 3.6 to 7.3 log CFU/g, and staphylococci counts ranged from 3.3 to 6.6 log CFU/ g. Nonpathogenic E. coli was detected in 13% of the mung, 26% of the matki, 40% of the chana, and 19% of the vatana samples. Salmonella Typhimurium was detected in 21% of the mung, 40% of the matki, and 4% of the chana samples. Salmonella Dublin was detected in 2% of the mung samples, and Salmonella Washington was detected in 4% of the matki samples. L. monocytogenes and E. coli O157:H7 were not detected in any of the samples examined. Coagulase-positive S. aureus was detected in 4% of the mung, 11% of the matki, and 4% of the chana samples. The results indicated that the marketed sprouts were of poor microbiological quality; therefore, further processing, such as radiation processing, is needed to ensure their safety.     

Survival of Salmonella enteritidis phage type 30 on inoculated almonds stored at -20, 4, 23, and 35 degrees C

To evaluate the survival of Salmonella on raw almond surfaces, whole almond kernels were inoculated with Salmonella Enteritidis phage type (PT) 30 collected from a 24-h broth culture or by scraping cells from an agar lawn. Kernels inoculated with lawn-collected cells to 8, 5, 3, and 1 log CFU per almond after a 24-h drying period were stored for 161 days at 23 +/- 3 degrees C. Calculated rates of reduction were similar for the four inoculum levels (0.22, 0.28, 0.29, and 0.22 log CFU/month, respectively). Kernels inoculated to 7.1 or 8.0 log CFU per almond after drying were stored for 171 or 550 days, respectively, at selected temperatures, including -20 +/- 2 degrees C, 4 +/- 2 degrees C, 23 +/- 3 degrees C, and 35 +/- 2 degrees C. No significant reductions of Salmonella were observed during storage at -20 and 4 degrees C over 550 days. At 35 degrees C, a biphasic survival curve was observed, with calculated reductions of 1.1 log CFU/month from days 0 to 59 and no significant reduction from days 59 to 171. At 23 degrees C, reductions of 0.18 and 0.30 log CFU/month were calculated for 171 and 550 days of storage, respectively. When combined with data from the study of inoculum levels, an overall average calculated reduction at 23 degrees C was 0.25 +/- 0.05 log CFU/month. Significantly greater reductions were observed during the 24-h drying period when broth-collected cells were used as the inoculum, suggesting that cells collected from agar lawns were more resistant to drying. However, after initial drying, the rates of reduction at 23 degrees C did not differ significantly between the inoculum preparation methods. Salmonella Enteritidis PT 30 survives for long periods on almond kernels under a variety of commonstorage conditions.     

A national survey of the microbiological quality of retail raw meats in Australia

A national survey of the microbiology of meat (ground beef and diced lamb) at the retail level in Australia was undertaken. For ground beef samples (n = 360), the mean aerobic plate count (APC) was 5.79 log CFU/g, and Escherichia coli was detected in 17.8% of samples; the mean population for these positive samples was 1.49 log CFU/g. Enterobacteriaceae were detected in 96.9% of samples (mean for positive samples, 3.01 log CFU/g), and coagulase-positive staphylococci were detected in 28.1% of samples (mean for positive samples, 2.18 log CFU/g). For diced lamb samples (n = 360), the mean APC was 5.71 log CFU/g, and E. coli was detected in 16.7% of samples (mean for positive samples, 1.67 log CFU/g). Enterobacteriaceae were detected in 91.1% of samples (mean for positive samples, 2.85 log CFU/g), and coagulase-positive staphylococci were detected in 22.5% of samples (mean for positive samples, 2.34 log CFU/g). Salmonella was recovered from 4 (1.1%) of the 360 ground beef samples (isolates were Salmonella Typhimurium phage types), and E. coli O157 was recovered from 1 (0.3%) of 357 samples; Campylobacter and Clostridium perfringens were not recovered from any of the 91 and 94 samples tested, respectively. Salmonella was recovered from 2 (0.6%) of the 360 diced lamb samples (serovars were Salmonella Infantis and Salmonella Typhimurium), Campylobacter was recovered from 1 (1.1%) of 95 samples, and C. perfringens was recovered from 1 (1.1%) of 92 samples.     

Impact of γ‐irradiation and thermal processing on the antigenicity of almond,cashew nut and walnut proteins

Whole unprocessed almonds, cashew nuts and walnuts were each subjected to γ‐irradiation (1, 5, 10 and 25 kGy) followed by heat processing including autoclaving (121 °C, 15 psi for 15 and 30 min), dry roasting (138 and 160 °C for 30 min each, 168 and 177 °C for 12 min each), blanching (100 °C for 5 and 10 min), oil roasting (191 °C, 1 min) and microwave heating (500 W for 1 and 3 min). Rabbit polyclonal antibodies were raised against each major protein isolated from defatted, but not subjected to γ‐irradiation and/or any thermal processing, almond, cashew nut and walnut flours. Immunoreactivity of almond, cashew nut and walnut proteins soluble in borate saline buffer, normalised to 1 mg protein ml^?1 for all samples, was determined by inhibition enzyme‐linked immunosorbent assay (ELISA) and Western blotting. ELISAs and Western blotting experiments indicated that almond, cashew nut and walnut proteins exposed to γ‐irradiation alone or followed by various thermal treatments remained antigenically stable. Copyright © 2004 Society of Chemical Industry     

绿芥末对即食鲜切生菜的保鲜效果

为明确绿芥末对即食鲜切生菜的保鲜效果,以清水和NaClO常规处理为对照组,考查了不同浓度的绿芥末液浸泡保鲜处理对即食鲜切生菜的失重率、腐烂率、褐变指数、感官评价、微生物菌落总数、沙门氏菌、单增李斯特菌、大肠埃希氏菌O157∶H7等指标的影响。结果表明,冷藏温度4℃,相对湿度85.6%~95%条件下,不同浓度的绿芥末均对即食鲜切生菜具有一定的保鲜效果。其中,以16 g/L的绿芥末对鲜切生菜的保鲜效果最好,保鲜期为7 d。该浓度下,生菜的感官品质最好,无腐烂、萎蔫、黄化,褐变指数最低(仅为1.67%),菌落总数为1.1×10⁵ CFU/g,且无沙门氏菌、单增李斯特菌和大肠埃希氏菌O157∶H7检出。该研究有望为今后生产上采用绿色保鲜剂替代化学保鲜剂,改善产品品质,延长产品货架期提供有益参考和借鉴。     

Evaluation of immunomagnetic separation and plating media for recovery of Salmonella from meat

Immunomagnetic separation (IMS) was compared with selective enrichment in selenite cystine (SC) broth for isolation of Salmonella from 86 artificially contaminated ground beef samples. Both Rambach agar (RA) and Hektoen enteric (HE) agar were used as selective plating media. The highest count of Salmonella colonies per plate was obtained after enrichment in SC broth and plating on RA (mean value: 111.1+/-58.1 CFU per plate); the lowest count was obtained after IMS and plating on HE agar (mean value: 65.4+/-36.6 CFU per plate). Salmonella in preenrichment was concentrated 1.7-fold by IMS and represented 31% of the microbial population captured by the beads, but nonspecific binding was high. As a result of the large numbers of competing bacteria, isolations on both RA and HE agar following IMS were quite difficult (mean value for Salmonella colonies: 79.9+/-42.7 CFU per plate; mean value for non-Salmonella colonies: 144.1+/-75.7 CFU per plate; ratio of Salmonella to non-Salmonella colonies: 0.8). This study indicates that SC broth is superior to IMS in the isolation of Salmonella from raw ground meat.     

津晋地区原料奶中微生物污染程度分析与鉴定

沙门氏菌是一种重要的人畜共患肠道疾病致病菌,它引起的食物中毒已成为一类最常见且危害性较大的细菌性食物中毒。本研究对我国津晋地区原料奶中微生物污染情况进行分析与鉴定,主要包括菌落总数、大肠菌群和沙门氏菌的检测。结果显示：津晋地区原料奶来源不同,奶源质量有较大差别。菌落总数平均在104～107CFU/mL之间,存在许多超标奶;大肠菌群数差别较大,晋奶源质量很好,大肠菌群数均低于110MPN/mL,天津地区乳品厂A大肠菌群数最高为1100MPN/mL,乳品厂B受到大肠菌群的严重污染,几乎均大于或等于11000MPN/mL;沙门氏菌未检出。研究证实了津晋地区原料奶的质量和安全性不容忽视。