Comparison of Bacterial Species Isolated from Ground Beef, Textured Soy Protein and Ground Beef Extended with Textured Soy Protein 1, 2.

A survey of the bacterial species of public health importance which could be isolated from ground beef (GB), textured soy protein (TSP) and ground beef extended with TSP (SGB) after 3 and 10 days of storage at 4 C was conducted. Escherichia coli was the most frequent gram-negative isolate from GB and SGB. Few gram-negative organisms were found in TSP. Clostridium perfringens was the most frequent gram-positive isolate from GB and SGB while Bacillus sp. was isolated most frequently from TSP. Salmonella enteriditis ser. worthington was isolated from GB and TSP. These products contained a wide variety of microorganisms, some of which might result in a food-associated infection or intoxication. However, if properly handled and cooked before consumption, these products should present few public health hazards.

Survey of the Bacterial Populations of Bologna Products 1, 2.

Bologna products most frequently are stored and consumed as refrigerated products. Thus bacteria that survive processing or those that contaminate the product subsequent to processing are not destroyed. Ten types of presliced, vacuum-packaged bologna products were purchased from a high-volume retail market and analyzed for total aerobic plate count (APC) and common foodborne pathogens. No Salmonella were isolated. Less than 1% of the 419 samples analyzed contained either Clostridium perfringens or Escherichia coli , Staphylococcus aureus was isolated from 4% of the samples, but only one sample contained more than 1000/g. Just over 5% of the samples contained coliform organisms. The manufacturer appeared to play an important role in bacterial quality of the finished items. An APC < 5 × 106/g is a realistic criterion for bologna products at the time of delivery to retail markets.

Bacterial Populations of Ground Beef, Textured Soy Protein and Ground Beef Extended With Soy Protein After 3 and 10 Days of Refrigerated Storage 1, 2.

A survey of the microbial populations of 31 samples of ground beef (GB), textured soy protein (TSP), and ground beef extended with TSP (SGB) after 3 and 10 days of storage at 4 C was done. Analyses included aerobic plate count (APC), psychrotrophic plate count (PPC), coliform Most Probable Number (CMPN) and plate determinations (CPC), Escherichia coli MPN (EMPN) and plate determinations (EPC), Staphylococcus aureus MPN, and fecal streptococcus plate count. Statistical analyses of data from the enumeration procedures showed significant increases in the total microbial flora after 10 days of storage. PPCs were significantly higher than APCs. CMPNs were significantly higher than CPCs for GB and SGB. The EMPNs were significantly higher than EPCs in SGB only. These products contained a variety of microorganisms many in large numbers; however if properly handled and cooked before consumption, these products should present no public health problems.

Analyst Variation in Doing the Standard Plate Count as Described in Standard Methods for the Examination of Dairy Products 1, 2.

Five analysts participated in a study to evaluate the following aspects of the 13th edition of Standard Methods for the Examination of Dairy Products (SMEDP): (a) analyst variation in overall Standard Plate Counts (SPC), and (b) analyst duplication of bacterial colony counts on agar places. Each analyst prepared 24 samples of pasteurized, homogenized milk during a successive 8-day period (i.e., 3 samples/day), and then the analysts estimated the numbers of bacterial colonies for these, as well as other analysts' plates, initially after 48 h of incubation, and then 1 h later and 24 h later. Statistically significant differences in colony enumerations were found between analysts in preparation of agar plates on 3 days. Significant differences were also noted between analysts for bacterial counts of agar plates. Mean bacterial estimates of certain analysts ranged between 565 and 948, and fluctuated greatly between the initial, 1-h, and 24-h determinations. These results indicate that the "standards of accuracy" currently specified in SMEDP are not realistic, i.e., (a) among-analyst variation of 18.2% compared to 10%, and (b) within-analyst variation of 7.7% compared to 5% in SMEDP.

Selected Food Microbiological Data Collected through a Computerized Program.

Selected results from a Computerized Food Microbiological Data Collection program are presented. Data are generated by 11 Department of Defense (DoD) laboratories and forwarded to a central location, coded into computer language, and entered into an existing program. As designed, the program is quite flexible, and selected retrievals for special purposes are easily accomplished. The total file contains data from over 30,000 food samples. Presented in this report are data on 810 samples of comminuted beef products, 215 samples of luncheon meats, 653 prepared sandwiches, and 1,023 delicatessen salads. Data are compared with existing microbiological criteria, if applicable. The retrieval of data from the file on such products should be useful in establishing future standards or guidelines.

A Microbial Survey of Various Fresh and Frozen Seafood Products.

The microbiological quality of four frozen and seven fresh seafood products (597 units in total) obtained from a local retail store were analyzed. Aerobic plate count means (geometric) ranged from 3.5 × 103/g to 9.3 × 104/g for the frozen products and from 7.8 × 104/g to 2.7 × 108/g for fresh products. Average (geometric) coliform Most Probable Number (MPN) values ranged from 1.0 to 7. 7/g for the frozen items and from 7.8/g to 4.8 × 103/g for the fresh seafoods. Employing the MPN method, 4.7% of the 597 units analyzed were positive for Escherichia coli . while 7.9% were positive for Staphylococcus aureus . Two percent of the samples contained Clostridium perfringens . Neither salmonellae nor Vibrio parahaemolyticus was isolated in any of the 597 units.

A Bacteriological Survey of Raw Ground Beef 1.

The microbiological quality of 150 units of raw ground beef obtained from a local retail store was determined. The range of aerobic plate counts was from 6.9 × 104 to 8.3 × 107/g. By using the most probable number method 96.7% of the 150 units were positive for coliforms, 94.7% for Escherichia coli and 61.3% for Staphylococcus aureus . By the plate methods, 99.3% of the units were positive for fecal streptococci and 56% were positive for Clostridium perfringens . No salmonellae were isolated. Aerobic and anaerobic organisms were isolated and identified. E. coli was the most frequently isolated aerobe followed by organisms in the Klebsiella-Enterobacter group. Among the anaerobic isolates, C. perfringens was the organism most frequently encountered.