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Ansorena M.R.,Grupo de Investigacion en Ingenieria de Alimentos | Ansorena M.R.,CONICET | Del Valle C.,Grupo de Investigacion en Ingenieria de Alimentos | Salvadori V.O.,CONICET | Salvadori V.O.,National University of La Plata
Food Science and Technology International | Year: 2010

Design and optimization of thermal processing of foods need accurate dynamic models to ensure safe and high quality food products. Transfer functions had been demonstrated to be a useful tool to predict thermal histories, especially under variable operating conditions. This work presents the development and experimental validation of a dynamic model (discrete transfer function) for the thermal processing of tuna fish in steam retorts. Transfer function coefficients were obtained numerically, using commercial software of finite elements (COMSOL Multiphysics) to solve the heat transfer balance. Dependence of transfer function coefficients on the characteristic dimensions of cylindrical containers (diameter and height) and on the sampling interval is reported. A simple equation, with two empirical parameters that depends on the container dimensions, represented the behavior of transfer function coefficients with very high accuracy. Experimental runs with different size containers and different external conditions (constant and variable retort temperature) were carried out to validate the developed methodology. Performance of the thermal process simulation was tested for predicting internal product temperature of the cold point and lethality and very satisfactory results were found. The developed methodology can play an important role in reducing the computational effort while guaranteeing accuracy by simplifying the calculus involved in the solution of heat balances with variable external conditions and emerges as a potential approach to the implementation of new food control strategies leading not only to more efficient processes but also to product quality and safety. © 2010 SAGE Publications. Source


Moreira M.D.R.,Grupo de Investigacion en Ingenieria de Alimentos | Moreira M.D.R.,CONICET | Ponce A.,CONICET | Ansorena R.,CONICET | And 2 more authors.
Journal of Food Science | Year: 2011

The use of edible coatings and mild heat shocks is proposed as postharvest treatments to prevent microbial deterioration of refrigerated broccoli. Minimally processed broccoli was coated with either chitosan or carboxymethyl-cellulose (CMC) combined or not with a previous application of a mild heat shock. The evolution of microbial populations (mesophilic, psycrotrophic, Enterobacteriaceae, molds and yeast, and lactic acid bacteria) was studied during 20 d of storage and fitted to Gompertz and logistic models. Results revealed that, at the end of the storage, chitosan coating significantly reduced all microbiological population counts, except lactic acid bacteria; while higher reduction was observed with chitosan coating combined with a heat shock treatment. A significant delay at the beginning of the exponential phase was observed for all the bacterial populations analyzed. On the other hand, CMC coating, with and without a previous thermal treatment, did not exert any antibacterial effect. Excellent agreement was found between experimental microbial counts and predicted values obtained from Gompertz and logistic models. Kinetic modeling was found to be valuable for prediction of microbiological shelf life of broccoli during storage. Results showed that the application of chitosan coating effectively maintained microbiological quality and extended shelf life of minimally processed broccoli. According to these results, the use of the edible chitosan coating alone or in combination with a heat mild shock appear to be a viable alternative for controlling microbiological growth and sensory attributes in minimally processed broccoli. © 2011 Institute of Food Technologists ®. Source


Ansorena M.R.,Grupo de Investigacion en Ingenieria de Alimentos | Ansorena M.R.,CONICET | Marcovich N.E.,CONICET | Marcovich N.E.,University of the Sea | And 2 more authors.
Postharvest Biology and Technology | Year: 2011

The effects of edible coatings and mild heat shocks on quality aspects of refrigerated broccoli were studied. Minimally processed broccoli was coated with either chitosan or carboxymethyl-cellulose with or without a previous application of a mild heat shock of 1.5. min at 50°C. Product was packaged in multilayered polyolefin bags and stored at 5°C for 18. d. Quality parameters such as weight loss, texture, colour, ascorbic acid content, total chlorophyll content, oxygen concentration inside the bags, browning potential, mesophilic aerobic counts, and sensory quality, were evaluated during storage. Edible coatings exhibited a beneficial impact on broccoli quality. The weight loss in uncoated broccoli was found to be between 2 and 5 times higher compared to coated samples. During storage, coated florets from both thermally and non-thermally treated samples, presented higher retention of the (-aa*/ba*) ratio indicating better green colour retention and a reduced rate of floret yellowing. Chitosan coating always presented the lower ascorbic acid degradation rates (twofold lower compared with control samples). Broccoli texture for uncoated samples increased significantly during storage. However, for carboxymethyl-cellulose coated broccoli a slight increase in texture was observed while for chitosan coated broccoli no significant changes in texture were observed throughout the storage period. After the edible coating application the microbial broccoli load dropped by around 1.5 and 0.9. logarithmic units in chitosan and carboxymethyl-cellulose films, respectively. During storage, the application of chitosan coating significantly reduced total microbial counts in the thermally and non-thermally treated uncoated samples. Among the assayed edible coatings, chitosan effectively maintained quality attributes and extended shelf life of minimally processed broccoli. The single application of a mild heat shock had a measurable influence in reducing weight loss, enzymatic browning in broccoli stems, and in delaying yellowing of broccoli florets. Moreover, chitosan coating combined with a mild heat shock showed the best performance for long-term refrigerated storage of minimally processed broccoli. © 2010 Elsevier B.V. Source


Tomadoni B.,Grupo de Investigacion en Ingenieria de Alimentos | Tomadoni B.,CONICET | Cassani L.,Grupo de Investigacion en Ingenieria de Alimentos | Ponce A.,Grupo de Investigacion en Ingenieria de Alimentos | And 5 more authors.
LWT - Food Science and Technology | Year: 2016

Optimum combination of ultrasound, vanillin and pomegranate extract to improve quality of strawberry juice was determined using response surface methodology. Samples were stored at 5 °C for 14 days. The optimal conditions to simultaneously minimize native microflora, maximize nutritional parameters and minimize the impact on sensory quality resulted in: 7.5 min of ultrasound treatment, pomegranate extract concentration of 360 μg/mL and vanillin concentration of 0.925 mg/mL. A new batch of strawberry juice was treated at these optimal conditions and stored for validation of the optimization and to evaluate the performance of the optimum treatment on quality parameters throughout storage. Furthermore, a second batch of juice was inoculated with Escherichia coli O157:H7 and processed at optimal conditions to evaluate the effectiveness of the treatment on the pathogen survival. The native microflora of the juice, as well as inoculated pathogen, decreased significantly using the proposed hurdle technologies, with no impact on sensory parameters. Ascorbic acid retention was slightly decreased by the optimum treatment; however, DPPH and polyphenolic compounds were significantly higher than those in untreated sample. Overall, a combination of ultrasound, vanillin and pomegranate extract showed interesting potential to enhance quality and safety of strawberry juice, extending the shelf-life of the product. © 2016 Elsevier Ltd. Source


Tomadoni B.,Grupo de Investigacion en Ingenieria de Alimentos | Tomadoni B.,CONICET | Cassani L.,Grupo de Investigacion en Ingenieria de Alimentos | Moreira M.R.,Grupo de Investigacion en Ingenieria de Alimentos | And 3 more authors.
LWT - Food Science and Technology | Year: 2015

In the present study, vanillin (Van) and geraniol (Ger) were studied as potential food biopreservatives. Minimal Inhibitory Concentration (MIC) was obtained in vitro using four different pathogens as indicators. Studies in vivo in strawberry juice inoculated with Escherichia coli O157:H7 were conducted to evaluate the pathogen survival. Biopreservatives were applied at 1 and 2 MIC concentration. Samples were stored at 5 °C during 14 days, in order to study the effects of the treatments against the inoculated pathogen. At day 0, untreated sample showed counts of 5.4 log CFU/mL. Samples treated with Van2MIC, Ger1MIC, Ger2MIC showed a significant control on E. coli population at day 0 (immediately before application of the compounds), with counts of 3.0-3.2 log. Furthermore, from day 3 until the end of storage, those samples showed E. coli counts below the detection limit. More studies should be made in order to investigate the impact of vanillin and geraniol application on sensory and nutritional characteristics of strawberry juice, and the effects on its native microflora and spoilage microorganisms. © 2015 Elsevier Ltd. Source

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