The frequencies of coliform bacteria (CB), thermotolerant coliforms (TC), Escherichia coli, and Salmonella were determined for jalapeño and serrano peppers. In addition, the behavior of four serotypes of Salmonella and three E. coli strains on whole and sliced jalapeño and serrano peppers as well as in blended sauce at 25 ± 2°C and 3 to 5°C was investigated. Chili peppers were collected from markets in the city of Pachuca, Hidalgo, Mexico. CB, TC, E. coli, and Salmonella were detected on serrano peppers in 100, 90, 50, and 10 % of the samples, and on jalapeño peppers in 100, 86, 32, and 12 % of the samples. Concentrations of CB ranged from 3.8 to 7.9 log CFU per serrano sample and from 5.3 to 8.2 log CFU per jalapeño sample, whereas concentrations of TC and E. coli were between < 3 and 1,100 most probable number per serrano and jalapeño samples. On whole serrano and jalapeño peppers stored at 25 ± 2°C or 3 to 5°C, no growth was observed for rifampin-resistant strains of Salmonella and E. coli. After 6 days at 25 ± 2°C, the tested Salmonella serotypes and E. coli strains had decreased from an initial inoculum level of 5 log CFU to 1 and 2.5 log on serrano and jalapeño peppers, respectively, and at 3 to 5°C they decreased to approximately 1.8 and 1.2 log, respectively, on serrano and jalapeño. Both the Salmonella serotypes and E. coli grew on sliced chili peppers and in blended sauce; after 24 h at 25 ± 2°C, both bacteria types had grown to approximately 4 and 5 log CFU on pepper slices and in sauce, respectively. At 3 to 5°C the bacterial growth was inhibited.

Coliform bacteria (CB), faecal coliforms (FC), Escherichia coli, diarrhoeagenic E. coli pathotypes (DEP) and Salmonella frequencies were determined for fresh carrot juice from restaurants in Pachuca city, Mexico. Two hundred and eighty carrot juice samples were purchased in three types of restaurants: (A), national chain restaurants; (B), local restaurants; and (C), very small restaurants. Two restaurants for each A and B, and three for C, were included. Forty juice samples were purchased at each restaurant. All tested juice samples had poor microbiological quality. Of these samples, 100, 96·8, 54·3, 8·9 and 8·6% had CB, FC, E. coli, DEP and Salmonella, respectively. CB were present in all juice samples regardless of source, with limits ranging from 3·6 × 102 to 8·5 × 107 CFU ml−1, and the limits for FC and E. coli were <3 to 1100 MPN ml−1 and <3 to 460 MPN, respectively. DEP and Salmonella were isolated from samples from all the restaurants at levels of 5% or above: DEP, 5% (A1, B2), 10% (A2, B1, C1, C2) and 12·5% (C3); Salmonella, 5% (A1, A2, B2), 7·5% (C2), 10% (C1), 12·5% (B1) and 15% (C3). Significance and Impact of the Study This is the first report of microbiological quality and Salmonella, enteroinvasive E. coli (EIEC), enterotoxigenic E. coli (ETEC) and Shiga toxin‐producing E. coli (STEC) isolation from fresh carrot juice in Mexico. Fresh carrot juice from restaurants could be an important factor contributing to the endemicity of EIEC‐, ETEC‐ and STEC‐ and Salmonella‐caused gastroenteritis in Mexico.

No abstract

Pulque is a typical fermented alcoholic beverage of central Mexico, produced from the nectar of maguey agave plants. Production systems are largely artisanal, with inadequate hygiene conditions and exposure to multiple contamination sources. No data exist on pulque microbiological safety and the behavior of pathogenic microorganisms in agave nectar and pulque. An initial trial was done of the behavior of Salmonella Typhimurium, Staphylococcus aureus, Listeria monocytogenes, and Shigella flexneri and Shigella sonnei during fermentation of nectar from a single producer, nectar mixture from different producers, and seed pulque. A second trial simulating artisanal pulque production was done by contaminating fresh nectar with each of the five strains, storing at 22°C for 14 h, adding seed pulque, and fermenting until pulque was formed. During incubation at 16 or 22°C in the first trial, all the pathogenic strains multiplied in both the single producer nectar and the nectar mixture, reaching maximum concentrations at 12 h. Strains concentration then decreased slowly. In the seed pulque, the strains did not multiply and tended to die. In the second trial, all strains increased concentration from 0.7 to 1.6 log at 22°C, and from 0.5 to 1.1 at 16°C in the first 14 h. After addition of seed pulque, they were quickly deactivated until none was detected in the final product. The results suggest that the potential risk to consumers of contracting any of the five tested pathogenic bacterial strains from pulque is low.

Diarrheagenic Escherichia coli pathotypes (DEP) are important foodborne pathogens in various countries, including Mexico. However, no data exist on the presence of DEP on fresh tomatoes (Solanum lycopericum) from Mexico. The frequency of fecal coliforms (FC), E. coli, and DEP were determined for two tomato varieties. One hundred samples of a saladette tomato variety and 100 samples of a red round tomato variety were collected from public markets in Pachuca, Mexico. Each tomato sample consisted of four whole tomatoes. For the 100 saladette samples, coliform bacterial, FC, E. coli, and DEP were identified in 100, 70, 60, and 10% of samples, respectively. For the 100 red round samples, coliform bacterial, FC, E. coli, and DEP were identified in 100, 75, 65, and 11% of samples, respectively. Identified DEP included Shiga toxin-producing E. coli (STEC), enteroinvasive E. coli (EIEC), enteropathogenic E. coli (EPEC), and enterotoxigenic E. coli (ETEC). STEC were isolated from 6% of saladette samples and 5% of red round samples. ETEC were isolated from 3% of saladette samples and 4% of red round samples. EPEC were isolated from 2% of saladette samples and 3% of red round samples, and EIEC were isolated from 1% of saladette samples. Both STEC and ETEC were identified in two saladette samples and 1 red round sample. E. coli O157:H7 was not detected in any STEC-positive samples.