MONTE CARLO SIMULATION OF ORANGE JUICE PECTINMETHYLESTERASE (PME) INACTIVATION BY COMBINED PROCESSES OF HIGH HYDROSTATIC PRESSURE (HHP) AND TEMPERATURE

The variability effect of kinetic data was investigated by simulating orange juice pectinmethylesterase (PME) inactivation with combined processes of high hydrostatic pressure-temperature (100-500 MPa; 20-40°C), applying the Monte Carlo method. Parameters from an Eyring-Arrheniius model that predicts the kinetic inactivation constant (k) as a function of both pressure and temperature were found reported in literature and considered for the analysis. The kinetic analysis was carried out with both Monte Carlo simulations and the traditional deterministic approach, which only considers mean values and does not take into account data variability. Simulations with the Monte Carlo method demonstrated that residual PME activity predicted with deterministic calculations greatly differed from those obtained through confidence intervals of simulated probabilistic distributions. Mean values overrated residual enzyme activity from 4% to ≈2,800% when compared to the 95% confidence intervals generated with the Monte Carlo method. This divergence augmented as both applied pressure and temperature levels increased. Similar risk analysis projects can be further developed to establish the foundations for future food processing regulations of enzymatic control.This is an author's peer-reviewed final manuscript, as accepted by the publisher. The published article is copyrighted by Universidad Autónoma Metropolitana Unidad Iztapalapa and can be found at: http://www.redalyc.org/revista.oa?id=620.Keywords: Process simulation, High hydrostatic pressure (HHP), Orange juice, Pectinmethylesterase (PME), Monte CarloKeywords: Process simulation, High hydrostatic pressure (HHP), Orange juice, Pectinmethylesterase (PME), Monte Carl

Benefits and limitations of food processing by high-pressure technologies: effects on functional compounds and abiotic contaminants

The continuing and worldwide growth of pressure processing technologies to pasteurize and sterilize foods justifies the need to study the effects on functional compounds and nonbiotic contaminants as affected by high pressure processing (HPP) and pressureassisted thermal processing (PATP). Substantially more research will be required to determine the complex effects of the food matrix on chemical reactions leading to losses of nutrients and functional components, production of toxic compounds, and to modifications of toxic residues of chemicals used in food production or coming from food contact materials. In PATP treatments, pressure can also increase, decrease or have no effect on the thermal degradation rate of these substances. HPP has no major negative and often beneficial effects on the retention of nutrients and functional components. However, information on PATP effects is very limited and additional research will be required before implementing this promising new technology.Keywords: polyphenols, pressure-assisted thermal processing (PATP), abiotic contaminants, antioxidants, food packaging plastic materials, heterocyclic aromatic amines (HCAs), acrylamide, polycyclic aromatic hydrocarbons (PAHs), chloropropanols, vitamins, nonbiotic contaminants, pesticides, high-pressure processing (HPP

Monte Carlo analysis of the product handling and high-pressure treatment effects on the Vibrio vulnificus risk to raw oysters consumers

A Monte Carlo procedure considering the variability in oyster handling from harvest to raw consumption estimated reductions in the number of Vibrio vulnificus induced septicemia cases achieved by high-pressure processing (HPP). The calculations yielded pathogen load distributions in raw oysters from harvest to consumption. In the warm season, 2-6 min treatments at 250 MPa and 1°C would lower the predicted number of septicemia cases associated with raw oyster consumption from 4,932 to less than four per 100 million consumption events (95% confidence). This study highlighted that HPP conditions should be selected according to the seasonal pathogen load and environment temperature. Finally, the procedure emphasized that the variability in the V. vulnificus population at harvest, before and after HPP treatments, reflecting in part the microbiological quantification methods used, significantly affected the estimated number of septicemia cases. Therefore, improving microbiological quantification should provide better predictions of the number of septicemia cases.Keywords: Beta-Poisson dose response models, Monte Carlo analysis, Vibrio vulnificus, Oyster, High pressure processing, Seafood poisoning ris

Minimally processed foods

One of the major growth segments in the food retail industry is minimally processed (MP) foods. This relatively new market trend has strived to develop new technologies or new applications of traditional technologies to preserve the characteristics of excellence in the products, extend shelf-life and improve their microbiological safety. Most of these technologies for gentle preservation are based on the hurdle concept. Additives, modified-atmosphere packaging, the use of essential oils as antioxidants and antimicrobials, the application of edible films, high hydrostatic pressure, high intensity pulsed electric field, high-intensity light pulses, ultraviolet radiation, high-power ultrasound, pulsed light and ozone are some of the leading preservation factors in recent years. The aim of this chapter is to revise the minimal process concept and to give an overview of mild technologies developed to extend the shelf-life of these products.Fil: Alzamora, Stella Maris. Universidad de Buenos Aires; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lopez Malo, A.. Universidad de las Américas Puebla; MéxicoFil: Tapia, M. S.. Universidad Central de Venezuela; VenezuelaFil: Welti Chanes, J.. Tecnológico de Monterrey; Méxic

Formation risk of toxic and other unwanted compounds in pressure-assisted thermally processed foods

Consumers demand, in addition to excellent eating quality, high standards of microbial and chemical safety in shelf-stable foods. This requires improving conventional processing technologies and developing new alternatives such as pressure-assisted thermal processing (PATP). Studies in PATP foods on the kinetics of chemical reactions at temperatures (approximately 100 to 120 °C) inactivating bacterial spores in low-acid foods are severely lacking. This review focuses on a specific chemical safety risk in PATP foods: models predicting if the activation volume value (V a) of a chemical reaction is positive or negative, and indicating if the reaction rate constant will decrease or increase with pressure, respectively, are not available. Therefore, the pressure effect on reactions producing toxic compounds must be determined experimentally. A recent model solution study showed that acrylamide formation, a potential risk in PATP foods, is actually inhibited by pressure (that is, itsV avalue must be positive). This favorable finding was not predictable and still needs to be confirmed in food systems. Similar studies are required for other reactions producing toxic compounds including polycyclic aromatic hydrocarbons, heterocyclic amines, N-nitroso compounds, and hormone like-peptides. Studies on PATP inactivation of prions, and screening methods to detect the presence of other toxicity risks of PATP foods, are also reviewed. © 2011 Institute of Food Technologists ®.Peer Reviewe

Cambios en contenido de compuestos fenólicos y color de extractos de Jamaica (Hibiscus sabdariffa) sometidos a calentamiento con energía de microondas

En este trabajo se realizó la extracción acuosa de compuestos fenólicos, principalmente antocianinas, provenientes de cálices de jamaica (Hibiscus sabdariffa). El extracto fue calentado por microondas a diferentes temperaturas (30, 40, 50, 60, 70 y 80°C) durante 20 min, tomando una alícuota cada 5 min. En el extracto con y sin calentamiento se determinó el contenido de compuestos fenólicos y los parámetros colorimétricos. Para el contenido de compuestos fenólicos totales se observaron pérdidas al incrementarse la temperatura, las pérdidas fueron del orden de 9.28, 8.22 y 11.34% a 60, 70 y 80°C respectivamente. Los parámetros de color a* y b* disminuyeron después de los tratamiento con, microondas mientras que L* aumentó, presentándose el cambio mayor fue observado en el extracto sometido a 80°C