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Thermal Processing (thermal + processing)
Selected AbstractsNEURAL NETWORK MODELING OF END-OVER-END THERMAL PROCESSING OF PARTICULATES IN VISCOUS FLUIDSJOURNAL OF FOOD PROCESS ENGINEERING, Issue 2010YANG MENG ABSTRACT Modeling of the heat transfer process in thermal processing is important for the process design and control. Artificial neural networks (ANNs) have been used in recent years in heat transfer modeling as a potential alternative to conventional dimensionless correlation approach and shown to be even better performers. In this study, ANN models were developed for apparent heat transfer coefficients associated with canned particulates in high viscous Newtonian and non-Newtonian fluids during end-over-end thermal processing in a pilot-scale rotary retort. A portion of experimental data obtained for the associated heat transfer coefficients were used for training while the rest were used for testing. The principal configuration parameters were the combination of learning rules and transfer functions, number of hidden layers, number of neurons in each hidden layer and number of learning runs. For the Newtonian fluids, the optimal conditions were two hidden layers, five neurons in each hidden layer, the delta learning rule, a sine transfer function and 40,000 learning runs, while for the non-Newtonian fluids, the optimal conditions were one hidden layer, six neurons in each hidden layer, the delta learning rule, a hyperbolic tangent transfer function and 50,000 learning runs. The prediction accuracies for the ANN models were much better compared with those from the dimensionless correlations. The trained network was found to predict responses with a mean relative error of 2.9,3.9% for the Newtonian fluids and 4.7,5.9% for the non-Newtonian fluids, which were 27,62% lower than those associated with the dimensionless correlations. Algebraic solutions were included, which could be used to predict the heat transfer coefficients without requiring an ANN. PRACTICAL APPLICATIONS The artificial neural network (ANN) model is a network of computational elements that was originally developed to mimic the function of the human brain. ANN models do not require the prior knowledge of the relationship between the input and output variables because they can discover the relationship through successive training. Moreover, ANN models can predict several output variables at the same time, which is difficult in general regression methods. ANN concepts have been successfully used in food processing for prediction, quality control and pattern recognition. ANN models have been used in recent years for heat transfer modeling as a potential alternative to conventional dimensionless correlation approach and shown to be even better performers. In this study, ANN models were successfully developed for the heat transfer parameters associated with canned particulate high viscous Newtonian and non-Newtonian fluids during an end-over-end rotation thermal processing. Optimized configuration parameters were obtained by choosing appropriate combinations of learning rule, transfer function, learning runs, hidden layers and number of neurons. The trained network was found to predict parameter responses with mean relative errors considerably lower than from dimensionless correlations. [source] Onion Cells After High Pressure and Thermal Processing: Comparison of Membrane Integrity Changes Using Different Analytical Methods and Impact on Tissue TextureJOURNAL OF FOOD SCIENCE, Issue 7 2010Maria E. Gonzalez Abstract:, Two different analytical methods were evaluated for their capacity to provide quantitative information on onion cell membrane permeability and integrity after high pressure and thermal processing and to study the impact of these processing treatments on cell compartmentalization and texture quality. To determine changes in cell membrane permeability and/or integrity the methodologies utilized were: (1) measurement of a biochemical product, pyruvate, formed as a result of membrane permeabilization followed by enzymatic activity and (2) leakage of electrolytes into solution. These results were compared to previously determined methods that quantified cell viability and 1H-NMR T2 of onions. These methods allowed for the monitoring of changes in the plasma and tonoplast membranes after high pressure or thermal processing. High pressure treatments consisted of 5 min holding times at 50, 100, 200, 300, or 600 MPa. Thermal treatments consisted of 30 min water bath exposure to 40, 50, 60, 70, or 90 °C. There was strong agreement between the methods in the determination of the ranges of high pressure and temperature that induce changes in the integrity of the plasma and tonoplast membranes. Membrane rupture could clearly be identified at 300 MPa and above in high pressure treatments and at 60 °C and above in the thermal treatments. Membrane destabilization effects could already be visualized following the 200 MPa and 50 °C treatments. The texture of onions was influenced by the state of the membranes and was abruptly modified once membrane integrity was lost. Practical Application:, In this study, we used chemical, biochemical, and histological techniques to obtain information on cell membrane permeability and onion tissue integrity after high pressure and thermal processing. Because there was strong agreement between the various methods used, it is possible to implement something relatively simple, such as ion leakage, into routine quality assurance measurements to determine the severity of preservation methods and the shelf life of processed vegetables. [source] Efficacy of Pressure-Assisted Thermal Processing, in Combination with Organic Acids, against,Bacillus amyloliquefaciens,Spores Suspended in Deionized Water and Carrot PureeJOURNAL OF FOOD SCIENCE, Issue 1 2010Wannasawat Ratphitagsanti ABSTRACT:, Effect of organic acids (acetic, citric, and lactic; 100 mM, pH 5) on spore inactivation by pressure-assisted thermal processing (PATP; 700 MPa and 105 °C), high pressure processing (HPP; 700 MPa, 35 °C), and thermal processing (TP; 105 °C, 0.1 MPa) was investigated.,Bacillus amyloliquefaciens,spores were inoculated into sterile organic acid solutions to obtain a final concentration of approximately 1.3 × 108 CFU/mL.,B. amyloliquefaciens,spores were inactivated to undetectable levels with or without organic acids after 3 min PATP holding time. At a shorter PATP treatment time (approximately 2 min), the inactivation was greater when spores were suspended in citric and acetic acids than in lactic acid or deionized water. Presence of organic acids during PATP resulted in 33% to 80% germination in the population of spores that survived the treatment. In contrast to PATP, neither HPP nor TP, for up to 5 min holding time with or without addition of organic acids, was sporicidal. In a separate set of experiments, carrot puree was tested, as a low-acid food matrix, to study spore recovery during extended storage following PATP. Results showed that organic acids were effective in inhibiting spore recovery in treated carrot puree during extended storage (up to 28 d) at 32 °C. In conclusion, addition of some organic acids provided significant lethality enhancement (P,< 0.05) during PATP treatments and suppressed spore recovery in the treated carrot puree. [source] The Effect of Brine Ingredients on Carrot Texture during Thermal Processing in Relation to Pectin Depolymerization due to the ,-Elimination ReactionJOURNAL OF FOOD SCIENCE, Issue 9 2006Trong Son Vu ABSTRACT:, Thermal texture degradation of carrots was studied at a temperature of 100 °C in aqueous solutions containing sodium chloride, citric acid, ascorbic acid, and ethylenediaminetetraacetic acid (EDTA) at different concentrations. To enhance the texture of the final product, the carrot samples were pretreated at 65 °C for 30 min in an aqueous calcium chloride solution (5 g/L). For all case studies considered, the pH of the solutions was adjusted to pH = 6.0. In parallel, both the changes in degree of esterification (DE) and the progress of the ,-elimination reaction of carrot pectin under the same conditions were investigated. The kinetic parameters for texture degradation (rate constant kt and final texture value [TP,/TP0]) were estimated using a fractional conversion model. The results indicate that both the rate constant for texture degradation (kt) and the rate constant for the ,-elimination reaction (kb) increased with increasing additive concentration, while the final texture values (TP,/TP0) and DE decreased with increasing additive concentration in all systems studied. A high correlation was observed between the relative rate constant for texture degradation and the relative rate constant for the ,-elimination reaction on the one hand, and the relative final texture value and the relative rate constant for the ,-elimination reaction on the other hand, suggesting that the influence of the solutes on texture degradation can be explained by their influence on the ,-elimination reaction. [source] Effects of High-Pressure Pretreatment and Calcium Soaking on the Texture Degradation Kinetics of Carrots during Thermal ProcessingJOURNAL OF FOOD SCIENCE, Issue 5 2004D.N. Sila ABSTRACT: Carrots (Daucus carota) pretreated under different high-pressure conditions were thermally processed at temperatures in the range of 90°C to 110°C. Texture degradation (hardness) was monitored objectively using a texture analyzer. For a given thermal treatment, the rate constant (k-value) decreased with increasing pretreatment pressure. A high-pressure pretreatment (200 to 500 MPa) at 60°C for 15 min resulted in a more pronounced texture improvement compared with the same pretreatment at 20°C and 40°C, respectively. Calcium impregnation conferred more beneficial effects when applied immediately after the high-pressure pretreat-ment. The observed changes in texture characteristics were associated with the degree of methylation of carrot pectins, which is dependent on pectinmethylesterase (PME) activity. [source] Thermal processing of biomass natural fibre wastes by pyrolysisINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 2 2004Anton R. Reed Abstract Waste biomass material in the form of natural fibres used in the production of textile products were examined for their potential to produce activated carbon by physical activation. The five biomass types were hemp, flax, jute, coir and abaca. Each biomass was pyrolysed in a fixed bed reactor and the char characterized. The char was subsequently, activated with steam in a char activation reactor. The surface area and porosity of the derived activated carbon was determined. Surface areas of between 770 and 879 m2 g,1 were achieved. The yield of activated carbon was mostly less than 20 wt% of the original biomass. The five biomass samples were also pyrolysed in a thermogravimetric analyser. The thermal degradation of the biomas samples were discussed in terms of the thermal degradation of the main components of the biomass, cellulose, hemicellulose and lignin. Copyright © 2004 John Wiley & Sons, Ltd. [source] Thermal processing of prawn ,kuruma' in retortable pouches and aluminium cansINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2008Chitradurga O. Mohan Summary Prawn ,kuruma' was prepared from Indian white shrimp (Fenneropenaeus indicus), packed in conventional 301 × 206 and 401 × 411 aluminium cans and in thin profile retort pouches having a three-layer configuration of 12.5 , polyester, 12.5 , aluminium foil and 85 , cast polypropylene of size 16 × 20 cm and 17 × 30 cm. The physico-chemical tests conducted on these containers showed their suitability for thermal processing. Prawn to kuruma ratio of 65:35 was maintained in all the containers and heat processed to equal lethality in an over pressure autoclave with the facility to record the time,temperature data, F0 value and cook value. The process time was calculated by using formula method. The processing in 16 × 20 cm and 17 × 30 cm retortable pouch resulted in 35.67% and 56.56% reduction in process time compared with 301 × 206 and 401 × 411 cans, respectively, with equal pack weight. The amino acid content did not vary considerably in both containers. In the canned samples the reduction of sulfhydryl content was 50.54% more when compared with the pouched product. Products packed in pouches were found to be superior to canned products with regard to sensory and textural attributes such as colour, firmness, hardness, chewiness, and overall acceptability. [source] Antioxidant capacity of human milk: effect of thermal conditions for the pasteurizationACTA PAEDIATRICA, Issue 8 2008Dolores Silvestre Abstract Aim: Pasteurization is the thermal treatment usually applied in milk banks to eliminate the risk of transmission of infectious agents. The aim of this study was to investigate the effect of heat processing upon the antioxidant properties of human milk. Methods: Milk samples collected from 31 healthy women were subjected to two different pasteurization techniques: Holder pasteurization (63°C for 30 min) and high pasteurization (75°C for 15 sec) and oxidative stress markers (glutathione, glutathione peroxidase activity, malondialdehyde and total antioxidant capacity) were determined in comparison to fresh milk. Results: Malondialdehyde concentration was the same in all samples, while there was a decrease in glutathione concentration and total antioxidant capacity in milk samples subjected to thermal processing versus fresh milk samples. However, the drop in these parameters was seen to be significantly greater when applying Holder pasteurization. Both thermal treatments induced considerable and similar loss of glutathione peroxidase activity. Conclusion: Thermal processing of human milk implies a decrease in its antioxidant properties but, when necessary, high pasteurization should be the election method in terms of milk oxidative status. [source] High-Performance Air-Processed Polymer,Fullerene Bulk Heterojunction Solar CellsADVANCED FUNCTIONAL MATERIALS, Issue 22 2009Chang-Yong Nam Abstract High photovoltaic device performance is demonstrated in ambient-air-processed bulk heterojunction solar cells having an active blend layer of organic poly(3-hexylthiophene) (P3HT): [6,6]-phenyl-C61 -butyric acid methyl ester (PCBM), with power conversion efficiencies as high as 4.1%, which is comparable to state-of-the-art bulk heterojunction devices fabricated in air-free environments. High-resolution transmission electron microscopy is combined with detailed analysis of electronic carrier transport in order to quantitatively understand the effects of oxygen exposure and different thermal treatments on electronic conduction through the highly nanostructured active blend network. Improvement in photovoltaic device performance by suitable post-fabrication thermal processing results from the reduced oxygen charge trap density in the active blend layer and is consistent with a corresponding slight increase in thickness of an ,4,nm aluminum oxide hole-blocking layer present at the electron-collecting contact interface. [source] Distributed parameter thermal controllability: a numerical method for solving the inverse heat conduction problemINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 7 2004Marios Alaeddine Abstract This paper addresses the inverse heat conduction problem encountered in thermal manufacturing processes. A numerical control algorithm is developed for distributed parameter conduction systems, based on Galerkin optimization of an energy index employing Green's functions. Various temperature profiles of variable complexity are studied, using the proposed technique, in order to determine the surface heat input distribution necessary to generate the desired temperature field inside a solid body. Furthermore, the effect of altering the iterative time step and duration of processing time, on the convergence of the solution generated by the aforementioned method is investigated. It is proved that despite the variations in numerical processing, the iterative technique is able to solve the problem of inverse heat conduction in the thermal processing of materials. Copyright © 2004 John Wiley & Sons, Ltd. [source] Thermal processing of prawn ,kuruma' in retortable pouches and aluminium cansINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 2 2008Chitradurga O. Mohan Summary Prawn ,kuruma' was prepared from Indian white shrimp (Fenneropenaeus indicus), packed in conventional 301 × 206 and 401 × 411 aluminium cans and in thin profile retort pouches having a three-layer configuration of 12.5 , polyester, 12.5 , aluminium foil and 85 , cast polypropylene of size 16 × 20 cm and 17 × 30 cm. The physico-chemical tests conducted on these containers showed their suitability for thermal processing. Prawn to kuruma ratio of 65:35 was maintained in all the containers and heat processed to equal lethality in an over pressure autoclave with the facility to record the time,temperature data, F0 value and cook value. The process time was calculated by using formula method. The processing in 16 × 20 cm and 17 × 30 cm retortable pouch resulted in 35.67% and 56.56% reduction in process time compared with 301 × 206 and 401 × 411 cans, respectively, with equal pack weight. The amino acid content did not vary considerably in both containers. In the canned samples the reduction of sulfhydryl content was 50.54% more when compared with the pouched product. Products packed in pouches were found to be superior to canned products with regard to sensory and textural attributes such as colour, firmness, hardness, chewiness, and overall acceptability. [source] Effect of thermal processing on the texture of canned apricotsINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 5 2002Constantin G. Mallidis The effect of thermal processing on the texture of canned apricots was studied by using the main cultivar canned in Greece, Bebecou. The test temperature ranged from 82 to 95 °C. The loss of hardness was tested immediately after processing and after 3 months storage. The z -value was 16.7 °C and the energy of activation 116.5 kJ mol,1. Some restoration in the hardness was found after 3 months storage, which might be attributable to the absorption of sucrose by the fruit. [source] Three-dimensional MRI mapping of minimum temperatures achieved in microwave and conventional food processingINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2001John R. Bows Microbiological assurance protocols for food preservation are based on the ,worst-case' slowest heating point within the food product. For conduction-limited processing, this leads to well-known overheating near surface regions of products, with resultant quality loss. For volumetric heating processes such as microwave heating, it is practically impossible to guarantee where the slowest heating point will be. Consequently, microwave heating regimes are generally excessive and product quality is often similar to conventional conduction-limited heating processes. It is well known that Magnetic Resonance Imaging (MRI) can provide three-dimensional (3D) images which quantify the spatial distribution of water in foods, and also that the MRI parameters of water are temperature dependent. The present study demonstrates that a combination of these two concepts has led to a new approach for the validation of thermal processing in food manufacture. The potential for on-line assurance of minimum and maximum temperatures for manufacture of microbiologically assured, minimally processed, high quality food is discussed. [source] Synchrotron X-ray reflectivity studies of nanoporous organosilicate thin films with low dielectric constantsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2007Weontae Oh Quantitative, non-destructive X-ray reflectivity analysis using synchrotron radiation sources was successfully performed on nanoporous dielectric thin films prepared by thermal processing of blend films of a thermally curable polymethylsilsesquioxane dielectric precursor and a thermally labile triethoxysilyl-terminated six-arm poly(,-caprolactone) porogen in various compositions. In addition, thermogravimetric analysis and transmission electron microscopy analysis were carried out. These measurements provided important structural information about the nanoporous films. The thermal process used in this study was found to cause the porogen molecules to undergo efficiently sacrificial thermal degradation, generating closed, spherical nanopores in the dielectric film. The resultant nanoporous films exhibited a homogeneous, well defined structure with a thin skin layer and low surface roughness. In particular, no skin layer was formed in the porous film imprinted using a porogen loading of 30,wt%. The film porosities ranged from 0 to 33.8% over the porogen loading range of 0,30,wt%. [source] NEURAL NETWORK MODELING OF END-OVER-END THERMAL PROCESSING OF PARTICULATES IN VISCOUS FLUIDSJOURNAL OF FOOD PROCESS ENGINEERING, Issue 2010YANG MENG ABSTRACT Modeling of the heat transfer process in thermal processing is important for the process design and control. Artificial neural networks (ANNs) have been used in recent years in heat transfer modeling as a potential alternative to conventional dimensionless correlation approach and shown to be even better performers. In this study, ANN models were developed for apparent heat transfer coefficients associated with canned particulates in high viscous Newtonian and non-Newtonian fluids during end-over-end thermal processing in a pilot-scale rotary retort. A portion of experimental data obtained for the associated heat transfer coefficients were used for training while the rest were used for testing. The principal configuration parameters were the combination of learning rules and transfer functions, number of hidden layers, number of neurons in each hidden layer and number of learning runs. For the Newtonian fluids, the optimal conditions were two hidden layers, five neurons in each hidden layer, the delta learning rule, a sine transfer function and 40,000 learning runs, while for the non-Newtonian fluids, the optimal conditions were one hidden layer, six neurons in each hidden layer, the delta learning rule, a hyperbolic tangent transfer function and 50,000 learning runs. The prediction accuracies for the ANN models were much better compared with those from the dimensionless correlations. The trained network was found to predict responses with a mean relative error of 2.9,3.9% for the Newtonian fluids and 4.7,5.9% for the non-Newtonian fluids, which were 27,62% lower than those associated with the dimensionless correlations. Algebraic solutions were included, which could be used to predict the heat transfer coefficients without requiring an ANN. PRACTICAL APPLICATIONS The artificial neural network (ANN) model is a network of computational elements that was originally developed to mimic the function of the human brain. ANN models do not require the prior knowledge of the relationship between the input and output variables because they can discover the relationship through successive training. Moreover, ANN models can predict several output variables at the same time, which is difficult in general regression methods. ANN concepts have been successfully used in food processing for prediction, quality control and pattern recognition. ANN models have been used in recent years for heat transfer modeling as a potential alternative to conventional dimensionless correlation approach and shown to be even better performers. In this study, ANN models were successfully developed for the heat transfer parameters associated with canned particulate high viscous Newtonian and non-Newtonian fluids during an end-over-end rotation thermal processing. Optimized configuration parameters were obtained by choosing appropriate combinations of learning rule, transfer function, learning runs, hidden layers and number of neurons. The trained network was found to predict parameter responses with mean relative errors considerably lower than from dimensionless correlations. [source] NONLINEAR CONSTRAINED OPTIMIZATION of THERMAL PROCESSING II.JOURNAL OF FOOD PROCESS ENGINEERING, Issue 3 2003FINITE CYLINDRICAL GEOMETRIES, VARIABLE PROCESS TEMPERATURE PROFILES to REDUCE PROCESS TIME, to IMPROVE NUTRIENT RETENTION IN SPHERICAL ABSTRACT Conventional methods for thermal processing of foods use constant processing temperature profiles (CPTPs) for a prescribed processing time, which is based on achieving a required microbial lethality to comply with public health standards. This also results in degradation of nutrients and quality factors. the variable process temperature profiles (VPTPs) obtained by using optimization methods can reduce quality losses and/or processing time compared to CPTPs. the objective of this research was to evaluate VPTPs using the Complex Method to reduce the processing time and/or improve quality retention for a specified level of lethality in thermal processing of conduction heated foods. the VPTPs were obtained for volume average retention of thiamine considering different sizes of spheres (small and large) and finite cylinders (small and large), and the thiamine retention and processing time results were compared with a conventional method (processing at 121.1C) for a specified lethality level. the use of VPTPs resulted in a 37 and 10% decrease in processing times in spherical and 40 % and 6 % for finite cylindrical shapes, for the same objective function value and specified lethality compared to the CPTP process. For the same processing time, the improvements in thiamine destruction were 3.7 and 2 % for spheres, and 3.9 and 2.2% for finite cylinders. [source] OPTIMIZATION CRITERIA FOR BATCH RETORT BATTERY DESIGN AND OPERATION IN FOOD CANNING-PLANTSJOURNAL OF FOOD PROCESS ENGINEERING, Issue 6 2003R. SIMPSON ABSTRACT Optimization of thermal processing in the commercial sterilization of canned foods is of great interest because the canning industry plays an important role within the economy of the food processing sector. Many food canning plants operate in a batch mode with a battery of individual batch retorts. The aim of this study was to propose and analyze several criteria and methodologies for optimum design and operation of such retort systems. Two criteria were proposed in the case of choosing the optimum number of retorts to be installed when designing a new batch-operated canning line. The third criterion dealt with seeking optimum process conditions for maximizing output from a fixed number of retorts when processing small batches of different products and container sizes. In the case of new plant design optimization, one objective was to determine the optimum number of retorts that would minimize on-going processing costs related to labor and energy. Retort scheduling (programming) was studied from which a simple mathematical expression was derived for this purpose. A second objective was to determine the optimum number of retorts that would maximize the net present value of initial investment. Approaches based upon engineering economics were studied from which to develop a mathematical procedure for this purpose. In the case of maximizing output from a fixed number of retorts for different products and container sizes, isolethal processes were identified for various product/containers from which a common set of process conditions could be chosen for simultaneous processing of different product lots in the same retort. [source] Onion Cells After High Pressure and Thermal Processing: Comparison of Membrane Integrity Changes Using Different Analytical Methods and Impact on Tissue TextureJOURNAL OF FOOD SCIENCE, Issue 7 2010Maria E. Gonzalez Abstract:, Two different analytical methods were evaluated for their capacity to provide quantitative information on onion cell membrane permeability and integrity after high pressure and thermal processing and to study the impact of these processing treatments on cell compartmentalization and texture quality. To determine changes in cell membrane permeability and/or integrity the methodologies utilized were: (1) measurement of a biochemical product, pyruvate, formed as a result of membrane permeabilization followed by enzymatic activity and (2) leakage of electrolytes into solution. These results were compared to previously determined methods that quantified cell viability and 1H-NMR T2 of onions. These methods allowed for the monitoring of changes in the plasma and tonoplast membranes after high pressure or thermal processing. High pressure treatments consisted of 5 min holding times at 50, 100, 200, 300, or 600 MPa. Thermal treatments consisted of 30 min water bath exposure to 40, 50, 60, 70, or 90 °C. There was strong agreement between the methods in the determination of the ranges of high pressure and temperature that induce changes in the integrity of the plasma and tonoplast membranes. Membrane rupture could clearly be identified at 300 MPa and above in high pressure treatments and at 60 °C and above in the thermal treatments. Membrane destabilization effects could already be visualized following the 200 MPa and 50 °C treatments. The texture of onions was influenced by the state of the membranes and was abruptly modified once membrane integrity was lost. Practical Application:, In this study, we used chemical, biochemical, and histological techniques to obtain information on cell membrane permeability and onion tissue integrity after high pressure and thermal processing. Because there was strong agreement between the various methods used, it is possible to implement something relatively simple, such as ion leakage, into routine quality assurance measurements to determine the severity of preservation methods and the shelf life of processed vegetables. [source] Recovery of,Salmonella enterica,Serovars Typhimurium and Tennessee in Peanut Butter after Electron Beam ExposureJOURNAL OF FOOD SCIENCE, Issue 7 2010Kristen E. Matak Abstract:, The effect of electron beam (e-beam) radiation on the recovery of,Salmonella,serotypes Tennessee (ATCC 10722) and Typhimurium (ATCC 14028) in creamy peanut butter over a 14-d storage period at 22 °C was studied. Each,Salmonella,type was independently inoculated into peanut butter and subjected to e-beam doses that ranged from 0 to 3.1 kGy, confirmed by film dosimetry. After 2-, 4-, 6-, 8-, and 14-d of storage, microbial analyses were conducted. Survivors were recovered on growth and selective media using standard spread-plating methods. Microbial counts (CFU/g) were log-converted and differences were determined by ANOVA and Tukey's Honestly Significant Differences test. When samples were not e-beam-treated, there were no significant changes (P,> 0.05) in microbial numbers over time. In e-beamed samples, microbial numbers decreased over time; however, reductions were not always significant. Initial recovery rates (R-rates) 2 d after e-beam treatment were significantly different for the 2 strains of,Salmonella,and between recovery media (P,< 0.05); however, these differences did not persist for the remainder of the storage period (P,> 0.05) indicating that injured cells were not able to survive in the high-fat, low-water activity peanut butter environment. R-rates for both strains of,Salmonella,were maintained until day 14 when there were significant reductions in,Salmonella,Typhimurium (P,< 0.05). These results indicate that,Salmonella,Tennessee and,Salmonella,Typhimurium will survive in peanut butter when exposed to nonlethal doses of e-beam irradiation. Practical Application: Electron beam (e-beam) irradiation is an alternative to thermal processing; this technique inactivates microorganisms and insects that might be present in a food by generating radiation by accelerated electrons that inactivate organisms directly because of interaction with cell components and indirectly by producing free radicals that disrupt integrity of the cell membrane. E-beam radiation will reduce the number of probable microbiological hazards that could be present while the food remains generally unaffected in texture, taste, and nutritional value. A recent study showed e-beam irradiation to be effective at reducing both,Salmonella,Tennessee and Typhimurium in peanut butter by one log after exposure to less than 1 kGy, highlighting the need to explore this process further. [source] Efficacy of Pressure-Assisted Thermal Processing, in Combination with Organic Acids, against,Bacillus amyloliquefaciens,Spores Suspended in Deionized Water and Carrot PureeJOURNAL OF FOOD SCIENCE, Issue 1 2010Wannasawat Ratphitagsanti ABSTRACT:, Effect of organic acids (acetic, citric, and lactic; 100 mM, pH 5) on spore inactivation by pressure-assisted thermal processing (PATP; 700 MPa and 105 °C), high pressure processing (HPP; 700 MPa, 35 °C), and thermal processing (TP; 105 °C, 0.1 MPa) was investigated.,Bacillus amyloliquefaciens,spores were inoculated into sterile organic acid solutions to obtain a final concentration of approximately 1.3 × 108 CFU/mL.,B. amyloliquefaciens,spores were inactivated to undetectable levels with or without organic acids after 3 min PATP holding time. At a shorter PATP treatment time (approximately 2 min), the inactivation was greater when spores were suspended in citric and acetic acids than in lactic acid or deionized water. Presence of organic acids during PATP resulted in 33% to 80% germination in the population of spores that survived the treatment. In contrast to PATP, neither HPP nor TP, for up to 5 min holding time with or without addition of organic acids, was sporicidal. In a separate set of experiments, carrot puree was tested, as a low-acid food matrix, to study spore recovery during extended storage following PATP. Results showed that organic acids were effective in inhibiting spore recovery in treated carrot puree during extended storage (up to 28 d) at 32 °C. In conclusion, addition of some organic acids provided significant lethality enhancement (P,< 0.05) during PATP treatments and suppressed spore recovery in the treated carrot puree. [source] Emulsion-Based Delivery Systems for Lipophilic Bioactive ComponentsJOURNAL OF FOOD SCIENCE, Issue 8 2007D.J. McClements ABSTRACT:, There is a pressing need for edible delivery systems to encapsulate, protect, and release bioactive lipids within the food, medical, and pharmaceutical industries. The fact that these delivery systems must be edible puts constraints on the type of ingredients and processing operations that can be used to create them. Emulsion technology is particularly suited for the design and fabrication of delivery systems for encapsulating bioactive lipids. This review provides a brief overview of the major bioactive lipids that need to be delivered within the food industry (for example, ,-3 fatty acids, carotenoids, and phytosterols), highlighting the main challenges to their current incorporation into foods. We then provide an overview of a number of emulsion-based technologies that could be used as edible delivery systems by the food and other industries, including conventional emulsions, multiple emulsions, multilayer emulsions, solid lipid particles, and filled hydrogel particles. Each of these delivery systems could be produced from food-grade (GRAS) ingredients (for example, lipids, proteins, polysaccharides, surfactants, and minerals) using simple processing operations (for example, mixing, homogenizing, and thermal processing). For each type of delivery system, we describe its structure, preparation, advantages, limitations, and potential applications. This knowledge can be used to facilitate the selection of the most appropriate emulsion-based delivery system for specific applications. [source] SENSORY AND INSTRUMENTAL TEXTURE MEASUREMENT OF THERMALLY PROCESSED RICEJOURNAL OF SENSORY STUDIES, Issue 5 2005M. PRAKASH ABSTRACT Rice is the staple food of many countries and its sensory quality is of great concern to the consumers. Its preservation through thermal processing in retort pouches for ready-to-eat purposes was carried out by different time,temperature schedules with and without oil to achieve a minimum Foof 3 min. The sensory analysis of the cooked rice carried out using quantitative descriptive analysis showed that a process schedule of 118C, 8 min was optimum to have the optimal sensory characteristics. The same rice samples were subjected to instrumental texture measurements by texture analyzer using a crosshead speed of 0.5 mm/s with 90% compression for hardness and stickiness parameters. The instrumental hardness showed high correlation with sensory hardness, chewiness and overall quality (r = 0.72; r = 0.73; r = 0.79) and a negative correlation with sensory stickiness (r = ,0.75). Applying principal component analysis, thermally processed rice samples were further classified based on the sensory and instrumental texture attributes. [source] New Route for the Extraction of Crude Zirconia from ZirconJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 9 2002Nicholas J. Welham A commercial grade of zircon (ZrSiO4) concentrate was mechanically milled with MgO for up to 100 h in a laboratory-scale mill. The resultant powders were subjected to thermal processing, chemical leaching, and X-ray diffraction (XRD). There was no direct evidence of reaction during the milling step, with no new phases evident from XRD. Leaching of the powder showed that a reaction had occurred, and increased solubility with milling time was attributed to the formation of a nanostructured Mg-Zr-Si oxide, which dissolved congruently. Heating the powders resulted in a number of thermal events, including the formation/crystallization of ZrO2 and Mg2SiO4. Thermal treatment of the milled powders allowed selective chemical leaching of the magnesium and silicon, leaving a powder containing ,90% ZrO2. [source] Effect of thermal processing on genistein, daidzein and glycitein content in soymilkJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 7 2006Huihua Huang Abstract Soymilk was subjected to various heat treatments at 95, 121 and 140 °C for various lengths of time. The contents of the aglycones of isoflavone (daidzein, glycitein and genistein) of the soymilk were determined using C18 reversed-phase high-performance liquid chromatography. Genistein showed greater stability to heat treatment than daidzein and glycitein. Both the daidzein and glycitein contents decreased rapidly during the early stage of heating, but on continued heating the rates of decrease were much slower. Heating may cause an increase or decrease in the genistein content of soymilk depending on the temperature and time used. Upon heating at 95 and 121 °C, there was an increase in the genistein content in the early stage of heating, possibly due the conversion of genistin to genistein. Heating at 140 °C for more than 15 s and prolonged heating at 95 and 121 °C, however, caused a slow decline in the genistein content. Copyright © 2006 Society of Chemical Industry [source] Impact of high-pressure and traditional thermal processing of tomato purée on carotenoids, vitamin C and antioxidant activityJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 2 2006Concepción Sánchez-Moreno Abstract Bioactive compounds (carotenoids and vitamin C) and 2,2-diphenyl-1-picrylhydrazyl radical (DPPH,) scavenging activity [50% depletion of initial DPPH, radical (EC50) and antiradical efficiency (AE)], in aqueous (AQ) and organic (OR) fractions, were measured in tomato purée subjected to high-pressure (HP) (400 MPa/25 °C/15 min), low pasteurisation (LPT) (70 °C/30 s), high pasteurisation (HPT) (90 °C/1 min), freezing (F) (,38 °C/15 min), and HPT plus F (HPT + F). In addition, physical and physicochemical parameters were evaluated. CIELab uniform colour space parameters (lightness, L*; green-red tonality, a*; and blue-yellow tonality, b*) were significantly higher both in the untreated and in the HP tomato purée than in the rest of the samples. Individual and total carotenoids, and provitamin A carotenoids, were significantly higher in HP tomato purée than in the untreated and other treated tomato purées. Ascorbic acid and total vitamin C were significantly lower in HP, LPT, HPT, and HPT + F tomato purées than in the untreated and F purées. In the AQ fractions, we found an inverse significant correlation between both ascorbic acid and total vitamin C and EC50AQ; and a positive significant correlation with AEAQ. In the OR fractions, a significant correlation was found between EC50OR and AEOR parameters and lycopene and total carotenoids. Total scavenging activity (AQ + OR fractions) in HP tomato purée was similar to that in LPT, HPT, and HPT + F purées. Copyright © 2005 Society of Chemical Industry [source] Inactivation of orange juice peroxidase by high-intensity pulsed electric fields as influenced by process parametersJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 1 2006Pedro Elez-Martínez Abstract The inactivation of orange juice peroxidase (POD) under high-intensity pulsed electric fields (HIPEF) was studied. The effects of HIPEF parameters (electric field strength, treatment time, pulse polarity, frequency and pulse width) were evaluated and compared with conventional heat pasteurization. Samples were exposed to electric field strengths from 5 to 35 kV cm,1 for up to 1500 µs using square wave pulses in mono- and bipolar mode. Effect of pulse frequency (50,450 Hz), pulse width (1,10 µs) and electric energy on POD inactivation by HIPEF were also studied. Temperature was always below 40 °C. POD was totally inactivated by HIPEF and the treatment was more effective than thermal processing in inactivating orange juice POD. The extent of POD inactivation depended on HIPEF processing parameters. Orange juice POD inhibition was greater when the electric field strength, the treatment time, the pulse frequency and the pulse width increased. Monopolar pulses were more effective than bipolar pulses. Orange juice POD activity decreased with electric energy density input. The Weibull distribution function adequately described orange juice POD inactivation as a function of the majority of HIPEF parameters. Moreover, reduction of POD activity related to the electric field strength could be well described by the Fermi model. Copyright © 2005 Society of Chemical Industry [source] Influence of enrofloxacin administration on the proteolytic and antioxidant enzyme activities of raw and cooked turkey productsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 14 2005Irene Carreras Abstract The objective of this study was to assess the effect of enrofloxacin administration with and without withdrawal period on the quality of fresh meat and cooked products from turkey breasts. Cathepsin B and L activities were inactivated by the thermal process but were not affected by the presence of enrofloxacin. The level of enrofloxacin in samples without withdrawal time was higher than the regulatory maximum residue limit (MRL). The antioxidant enzymes glutathione peroxidase (GSHPx) and catalase (CAT) were affected by both the thermal process and the antibiotic residues in cooked meat. In no cases were differences found in superoxide dismutase (SOD) activity, supporting the theory that this enzyme could play a major role in preventing lipid oxidation of cooked meat. Enrofloxacin residues could contribute to an increase in the oxidative stress produced by thermal processing, as can be deduced by the reduction in GSHPx and CAT activities. Copyright © 2005 Society of Chemical Industry [source] Extent of thermal ablation suffered by model organic microparticles during aerogel capture at hypervelocitiesMETEORITICS & PLANETARY SCIENCE, Issue 10 2009M. J. Burchell Commercial polystyrene particles (20 ,m diameter) were coated with an ultrathin 20 nm overlayer of an organic conducting polymer, polypyrrole. This overlayer comprises only 0.8% by mass of the projectile but has a very strong Raman signature, hence its survival or destruction is a sensitive measure of the extent of chemical degradation suffered. After aerogel capture, microparticles were located via optical microscopy and their composition was analyzed in situ using Raman microscopy. The ultrathin polypyrrole overlayer survived essentially intact for impacts at ,1 km s,1, but significant surface carbonization was found at 2 km s,1, and major particle mass loss at ,3 km s,1. Particles impacting at ,6.1 km s,1 (the speed at which cometary dust was collected in the NASA Stardust mission) were reduced to approximately half their original diameter during aerogel capture (i.e., a mass loss of 84%). Thus significant thermal ablation occurs at speeds above a few km s,1. This suggests that during the Stardust mission the thermal history of the terminal dust grains during capture in aerogel may be sufficient to cause significant processing or loss of organic materials. Further, while Raman D and G bands of carbon can be obtained from captured grains, they may well reflect the thermal processing during capture rather than the pre-impact particle's thermal history. [source] Molecular and isotopic indicators of alteration in CR chondritesMETEORITICS & PLANETARY SCIENCE, Issue 9 2006V. K. Pearson However, in contrast to other chondrite groups, the CR organic fraction is poorly characterized. The carbonaceous chondrite literature shows that relatively anhydrous thermal processing results in a condensed, poorly alkylated, O-poor macromolecular material, while for aqueous processing the converse is true. Such characteristics can be used to discern the alteration histories of the carbonaceous chondrites. We have performed bulk elemental and isotopic analysis and flash pyrolysis on four CR chondrites (Renazzo, Al Rais, Elephant Moraine [EET] 87770, and Yamato [Y-] 790112) to determine the nature of their organic component. Renazzo, Al Rais, and Y-790112 release qualitatively similar pyrolysis products, although there are some variations. Al Rais' macromolecular structure contains substantially higher relative abundances of alkylated and oxidized species and relatively lighter ,15N, suggesting that it has endured more extensive aqueous processing than the other CR chondrites. Renazzo appears relatively unprocessed, with a low degree of alkylation, a lack of detectable nitrogen-bearing components, and low methylnaphthalene ratio. EET 87770's low abundance of alkylated species suggests its macromolecular structure may be relatively condensed, with condensation potentially assisted by a period of mild thermal alteration. [source] The impact of pollen-related food allergens on pollen allergyALLERGY, Issue 1 2007B. Bohle Patients with birch pollen allergy frequently develop hypersensitivity reactions to certain foods, e.g. apples, celery, carrots and hazelnuts. These reactions are mainly caused by IgE-antibodies specific for the major birch pollen allergen, Bet v 1, which cross-react with homologous proteins in these foods. Analyzing the T-cell response to Bet v 1-related food allergens revealed that these dietary proteins contain several distinct T-cell epitopes and activate Bet v 1-specific T cells to proliferate and produce cytokines. Several of these cross-reactive T-cell epitopes were not destroyed by simulated gastrointestinal digestion of food allergens and stimulated Bet v 1-specific T cells despite nonreactivity with IgE antibodies. Similarly, cooked food allergens did not elicit IgE-mediated symptoms (oral allergy syndromes) but caused T-cell-mediated late-phase reactions (deterioration of atopic eczema) in birch pollen-allergic patients with atopic dermatitis because thermal processing affected their conformational structure and not the primary amino acid sequence. Thus, T-cell cross-reactivity between Bet v 1 and related food allergens occurs independently of IgE-cross-reactivity in vitro and in vivo. We speculate that symptom-free consumption of pollen-related food allergens may have implications for the pollen-specific immune response of allergic individuals. [source] | |||||||||||||||||||||||||