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  • Author or Editor: J. J. Córdoba x
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In the commercial processing of croquettes a 80 °C heat treatment for 30 min is applied to the raw materials to make a semi-solid paste called „bechamel”. Since the heat treatment is not that of sterilization, some micro-organisms surviving it may proliferate in the next steps, which could introduce two microbial hazards; the presence of pathogenic bacteria and croquettes spoilage. To evaluate microbiological hazards, microbiological analysis of the bechamel cooled and stored under refrigeration following commercial processing were developed at different times of cooling. In addition a fast cooling method was assayed. Immediately after heat treatment used to obtain the bechamel, microbial counts were always under 1 log CFU g-1, except for mesophilic aerobes which were at least of 1.2 log CFU g-1. During cooling used in commercial process of croquettes, levels of most micro-organisms investigated showed high increases as compared with behamel after cooking. In this step mesophilic organisms, psychotropic organisms and yeast reached levels of around 6 log CFU g-1. Enterococci counts increased during cool storage, although always were at levels below 3.2 log CFU g-1.EnterobacteriaceaeandClostridiumsp. only slightly increased at the end of cold storage reaching levels of around 3 log CFU g-1. Although rates which could be considered as being inadmissible were reached at day 5, the use of over 1-day old bechamel could be associated with microbiological sanitary hazards or with the spoilage of the croquettes made afterwards. In contrast, the bechamel cooled at -20 °C air temperature for 12 h, only showed total aerobic counts of under 1 log CFU g-1. Cooling of bechamel is a decisive critical control point and a fast cooling should be considered in the implementation of an HACCP program in the prepared and frozen croquettes process.

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Abstract  

Several ornaments named tezcacuitlapilli (coccyx-mirrors) are described and chemical analyses of raw materials (slate and pigments) were carried out by neutron activation, X-ray diffraction, scanning electron microscopy and radiography. Elemental and statistical analyses revealed that three different kinds of slate were used in their manufacture. The white pigment contains gypsum while ochre, yellow and red pigments contain iron oxide. These ornaments were identified as coming from the Cave of the Sun Pyramid of Teotihuacan. An attempt was undertaken to reconstruct the contexts of their manufacture and symbolic interpretation.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: J. Santana Romero, F. Martínez Luzardo, E. Codorniú Hernández, L. Vargas Guerra, P. Melo Cala, M. García Guillén, K. Isaac Olivé, P. Estevez, A. Roque Córdoba, and M. Benítez

Abstract  

Vegetable tannins are polyphenolic plants secondary metabolites, widely distributed in all parts of trees and herbs. The role of these substances in many metabolic processes is very important. Vegetable tannins have been implicated as probable antinutritional factors, decreasing the assimilation of diet protein assimilation by cattle. On the other hand, protective antioxidant and antimutagenic properties have been ascribed for these compounds. Characterization of vegetable tannins is important in order to find new sources of natural raw materials with medical and pharmaceutical applications. Protein precipitation capacity as a function of pH, competitive protein and ADN binding assays and the determination of tannins concentration are described. Radioisotope labeled protein and tannins were used in all of the determinations.

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