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.

No abstract

No abstract

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.

Se efectuó un estudio en el Parque Nacional El Chico, Hidalgo, con el objetivo de estimar labiomasa y el carbono aéreo almacenado en los árboles muertos en pie, en los árboles adultos vivos yen el renuevo establecido en forma natural de Abies religiosa “oyamel” después de 12 años de ocurridoun incendio forestal de tipo superficial que afectó 30,34 ha. Se realizó un inventario forestal de 15 sitioscirculares de 1000 m2 distribuidos de forma sistemática, para medir las variables de diámetro normal yaltura. Para determinar la biomasa se utilizó el valor de densidad de la madera de oyamel (360 kg/m3)y para el coeficiente de carbono se tomaron muestras que fueron analizadas con el equipo Solids TOCAnalyzer®, obteniendo un valor de 0,45. Las ecuaciones generadas para estimar biomasa y carbonoen árboles de Abies religiosa en un área afectada por un incendio forestal fueron B=0,06463*DN2,38322y C=0,029083*DN2,38322 respectivamente, ambas mostraron un buen ajuste (R2=0,99), por lo que sonadecuadas y confiables para usarse en áreas siniestradas con condiciones similares, para la mismaespecie y región, como Áreas Naturales Protegidas donde no es posible utilizar métodos destructivos.En las 30,34 ha siniestradas por el incendio forestal ocurrido en 1998 en el Parque Nacional El Chico,no se consumieron por el fuego un total de 665,05 t de carbono que no fueron liberadas hacia la atmósfera,sumándose una captura actual de 297,33 t de carbono por el renuevo establecido a 12 años deocurrido el siniestro

El objetivo fue determinar la petrología y distribución de óxidos de Fe, Al y Si en tres perfiles de suelos de origen volcánico con horizontes endurecidos (fragipán), en la región noroeste del Estado de México. Se utilizaron técnicas químicas selectivas para extraer Fe, Al y Si. El fragipán blanco clasifica petrográficamente como toba dacítica poco soldada y alterada. Los perfiles muestran incipiente a moderado grado de alteración de minerales primarios que contienen Fe y Al dadas las condiciones climáticas de la región. Los contenidos de alofano, ferrihidrita, y óxidos de hierro cristalino se presentan en pocas cantidades, escasos contenidos de Ald y Si lábil en los perfiles indican presencia de aluminosilicatos cristalinos. Bajas relaciones de Alp/Alo y Fep/Feo evidencia que la mayor parte de Al y Fe están unidos a compuestos inorgánicos pobremente cristalinos. Relaciones bajas de Fep/Fed y Alp/Ald indican limitada asociación de Fe y Al con compuestos orgánicos. La relación arcilla/Fed revela emigración de arcilla y óxidos de Fe del horizonte superior al fragipán.  El Si, Al y Fe en el fragipán forman parte de la estructura de los silicatos y mínimo grado de cristalinidad de Fe y Al pedogenético. Valores mayores de relación Sid(Sid+Ald) en el fragipán indican aumento en la dureza.

The mining district of Molango in the Hidalgo State, Mexico, possesses one of the largest deposits of manganese (Mn) ore in the world. This research assessed the impacts of Mn mining activity on the environment, particularly the interactions among soil, plants, and arbuscular mycorrhiza (AM) at a location under the influence of an open Mn mine. Soils and plants from three sites (soil under maize, soil under native vegetation, and mine wastes with some vegetation) were analyzed. Available Mn in both soil types and mine wastes did not reach toxic levels. Samples of the two soil types were similar regarding physical, chemical, and biological properties; mine wastes were characterized by poor physical structure, nutrient deficiencies, and a decreased number of arbuscular mycorrhizal fungi (AMF) spores. Tissues of six plant species accumulated Mn at normal levels. AM was absent in the five plant species (Ambrosia psilostachya, Chenopodium ambrosoides, Cynodon dactylon, Polygonum hydropiperoides, and Wigandia urens) established in mine wastes, which was consistent with the significantly lower number of AMF spores compared with both soil types. A. psilostachya (native vegetation) and Zea mays showed mycorrhizal colonization in their root systems; in the former, AM significantly decreased Mn uptake. The following was concluded: (1) soils, mine wastes, and plant tissues did not accumulate Mn at toxic levels; (2) despite its poor physical structure and nutrient deficiencies, the mine waste site was colonized by at least five plant species; (3) plants growing in both soil types interacted with AMF; and (4) mycorrhizal colonization of A. psilostachya influenced low uptake of Mn by plant tissues.

Native corn and potato starches were mixed in different proportions. Blends presented similar values to potato starch at onset temperature and at ending temperature to corn starch. CS20PS80 blend had the highest values for hardness between blends due to the formation of a three-dimensional network with corn starch granules that act as composite material. Some blends exhibited higher recovery viscosity than native starches, possibly due to interactions. Gelatinization temperature, swelling power, phosphorous content, granule size, and x-ray pattern played an important role in the resulting properties, however, the amylose content did not show influence due to both starches having a similar content.