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Corzo C.A.,Juarez Autonomous University of Tabasco | Waliszewski K.N.,Instituto Tecnologico De Veracruz | Welti-Chanes J.,Monterrey Institute of Technology
Food Chemistry | Year: 2012

Optimal pH and temperature conditions for proteolytic activity of pineapple fruit bromelain were determined using five different substrates: azocasein and azoalbumin (pH 3-10 at 20-70°C), casein and sodium caseinate (pH 2-10 at 20-70°C), and haemoglobin (pH 2-6.5 at 30-60°C). Fruit bromelain has shown optimum activity at pH 7.5 for azoalbumin and at 6.5 for azocasein, all at 55°C. Fruit bromelain activity determined with casein and sodium caseinate has shown optimum activity at 59°C, while the optimum pH was 7.7 for casein and 6.5 for sodium caseinate. Optimum hydrolysis conditions of fruit bromelain towards haemoglobin showed a sharp peak at an acidic pH 2.9 at 37°C. The lowest results of K m and the highest results of V max/ K m were found for azocasein and azoalbumin. These substrates are highly recommended for fruit bromelain activity determination. © 2012 Elsevier Ltd. All rights reserved. Source

Hernandez-Campos F.J.,Zacatepec Institute of Technology | Brito-De La Fuente E.,Fresenius Kabi Deutschland GmbH | Torrestiana-SANCHEZ B.,Instituto Tecnologico De Veracruz
Journal of Agricultural and Food Chemistry | Year: 2010

Immunoglobulin Y (IgY) was purified from hen egg yolk water-soluble protein fraction by ultrafiltration-diafiltration with different membranes. The effect of changing solution properties (pH and Ionic strength) on purification factor (P), process selectivity (ψ), and IgY recovery (RIgy) was studied. Salt presence (150 and 1500 mM) decreased the selectivity and purity factor. This effect was more evident at pH values closer to or higher than the IgY's isoelectric point. The best results were obtained in the absence of salt at pH values of 5.7 and 6.7 using poliethersulfone (PES) and modified PES (MPES), respectively. Process selectivity was doubled, and IgY's purification factors were increased in more than 1 order of magnitude when diafiltration was used. Results from this work show the potential of membrane technology for the purification of IgY from hen's egg yolk. © 2009 American Chemical Society. Source

Rascon M.P.,Instituto Tecnologico De Veracruz | Beristain C.I.,University of Veracruz | Garcia H.S.,Instituto Tecnologico De Veracruz | Salgado M.A.,Instituto Tecnologico De Veracruz
LWT - Food Science and Technology | Year: 2011

The performance of gum arabic (GA) and soy protein isolate (SPI) on paprika oleoresin microcapsules preparation and their storage were evaluated. Paprika oleoresin emulsions with a ratio of paprika oleoresin/wall material of 1:4 (w/w) were prepared using high-pressure homogenization, and then spray dried. Both treatments showed that carotenoid retention in the microcapsules increased as inlet air temperature was increased from 160 to 200 °C, and the yellow fraction was more stable than the red fraction at all temperatures tested. Microcapsules with the highest carotenoid retention were stored at different aw's at 35 °C. Maximal stability for carotenoid oxidation was found at aw's of 0.274 and 0.710 for microcapsules prepared with GA and SPI respectively. In both treatments the lowest carotenoid degradation was associated to the minimum integral entropy zone and affected in the same way to the red and yellow pigments, during storage at 35 °C. Additionally, in contrast to microcapsules prepared with SPI, GA microcapsules were unable to retain their structural integrity at water activities above 0.743. © 2010 Elsevier Ltd. Source

Mani-Lopez E.,Instituto Tecnologico De Veracruz | Garcia H.S.,Instituto Tecnologico De Veracruz | Lopez-Malo A.,Universidad de Las Americas Puebla
Food Research International | Year: 2012

Salmonella, a food-borne pathogen, has a recurrent incidence in meat and poultry products. Currently, cases of salmonellosis represent very important economic losses in many countries. An alternative for the prevention of Salmonella outbreaks due to consumption of meat and poultry products, are organic acids (acetic, citric, lactic, malic, propionic, and tartaric among others). Organic acids have been utilized for many years for decontamination of beef, pork and poultry products from several bacteria including Salmonella. Current reports describe new treatments with organic acids using the hurdle technology approach to inhibit Salmonella. Also, preventive actions should be taken in order to decrease the appearance of resistant strains of Salmonella as a result of insufficient or sub-lethal treatments with organic acids in meat and poultry products. This review presents general insights on the use of the organic acids to control Salmonella in meat and poultry products. Also, information of the action mechanism, types and doses of treatments, as well as how resistance can occur from improper application of organic acids. © 2011 Elsevier Ltd. Source

Ovando-Chacon G.E.,Instituto Tecnologico De Veracruz | Ovando-Chacon S.L.,Instituto Tecnologico de Tuxtla Gutierrez | Prince-Avelino J.C.,Instituto Tecnologico De Veracruz
International Journal of Heat and Mass Transfer | Year: 2012

Entropy generation due to steady state heat transfer and the motion of the vertical boundaries in a two-dimensional square cavity is numerically studied, using the value of the velocity and temperature obtained by solving the Navier-Stokes equation coupled with the energy equation with the finite element method and an operator splitting scheme. Increasing the Richardson number, the entropy generation by fluid friction is intensified inside the cavity due to the vortex formation at the central part of the cavity. The entropy generation by heat transfer becomes more intense at the vertical walls and the central low part of the cavity due to the stronger temperature gradients at this region. © 2011 Elsevier Ltd. All rights reserved. Source

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