The Experts below are selected from a list of 582 Experts worldwide ranked by ideXlab platform
Jorge Chirife - One of the best experts on this subject based on the ideXlab platform.
-
Evaluation of Norrish’s Equation for Correlating the Water Activity of Highly Concentrated Solutions of Sugars, Polyols, and Polyethylene Glycols
Food and Bioprocess Technology, 2010Co-Authors: Rosa Baeza, Adriana Pérez, Virginia Sánchez, María C. Zamora, Jorge ChirifeAbstract:Norrish’s equation, $$a_{{\text{w}}} = X_{{\text{w}}} \exp {\left( { - KX^{2}_{{\text{s}}} } \right)}$$ , where a _w is water activity, X _w and X _s are molar fractions of water and solute, respectively, and K is the correlating constant, has been widely used to predict a _w of aqueous nonelectrolyte solutions in connection with development of Intermediate Moisture Foods, i.e., food having a _w ≥ 0.85. Present work evaluated the ability of Norrish’s equation to model the water activity of solutions of sugars, polyols, and some polyethylene glycols, in a wide range of concentration, i.e., from low to highly concentrated solutions. For sugar and polyols, a relatively small modification of the “most accepted” literature parameters K allowed the fitting of the data for the wide range of solute concentrations corresponding to a range of a _w from 0.99 to about 0.3 for same solutes. However, a modified Norrish’s model needs to be used to model the behavior of polyethylene glycols 400 and 600 up to water activities as low as 0.5.
-
application of ross equation for prediction of water activity in Intermediate Moisture food systems containing a non solute solid
International Journal of Food Science and Technology, 2007Co-Authors: Jorge Chirife, Silvia L Resnik, Ferro C FontanAbstract:Summary. This work investigates the use of the Ross (1975) equation for the prediction of water activity (a), in aqueous electrolyte or non-electrolyte solutions to which a non-solute (casein) was added. Water activity of the ternary mixtures (casein-water-solute) was in the range of a, = 0.85-0.90 which is of interest for the development of Intermediate Moisture Foods for human consumption. It was found that the use of the Ross equation coupled with a correction for the water strongly bound to casein gives good predictions of a.
-
Application of Ross' equation for prediction of water activity in Intermediate Moisture food systems containing a non‐solute solid
International Journal of Food Science and Technology, 2007Co-Authors: Jorge Chirife, Silvia L Resnik, C. Ferro FontanAbstract:Summary. This work investigates the use of the Ross (1975) equation for the prediction of water activity (a), in aqueous electrolyte or non-electrolyte solutions to which a non-solute (casein) was added. Water activity of the ternary mixtures (casein-water-solute) was in the range of a, = 0.85-0.90 which is of interest for the development of Intermediate Moisture Foods for human consumption. It was found that the use of the Ross equation coupled with a correction for the water strongly bound to casein gives good predictions of a.
-
Prediction of water activity in Intermediate Moisture Foods
International Journal of Food Science and Technology, 2007Co-Authors: Jorge ChirifeAbstract:Summary Ross' equation for estimating the water activity of multicomponent solutions was tested with experimental data in solid Intermediate Moisture Foods. Literature experimental data on water activity and food system composition in a wide variety of Intermediate Moisture Foods (IMF) were utilized to test the validity of Ross' equation. The results obtained were satisfactory and indicate that Ross' equation constitutes a simple and reasonably accurate method for predicting the water activity in IMF.
-
The prediction of water activity in aqueous solutions in connection with Intermediate Moisture Foods IV. aW Prediction in aqueous non electrolyte solutions
International Journal of Food Science and Technology, 2007Co-Authors: Jorge Chirife, C. Ferro Fontan, E. A. BenmerguiAbstract:Summary A system of theoretical equations for the osmotic coefficient in aqueous electrolyte solutions, developed by Pitzer (1973), has been used for predicting the water activity (aw) in aqueous solutions of thirty different ‘food additive-like’ strong electrolytes. Water activity versus solute concentration curves have been plotted for the range of aw of most interest for Intermediate Moisture Foods (IMF). The Raoult's law behaviour of several of the above electrolytes has also been examined. The results are discussed in connection with the formulation of IMF.
Frank Devlieghere - One of the best experts on this subject based on the ideXlab platform.
-
Strategies to increase the stability of Intermediate Moisture Foods towards Zygosaccharomyces rouxii: the effect of temperature, ethanol, pH and water activity, with or without the influence of organic acids.
Food Microbiology, 2014Co-Authors: An Vermeulen, C. L. Marvig, Jeff Daelman, Ramize Xhaferi, Dennis S. Nielsen, Frank DevlieghereAbstract:Intermediate Moisture Foods (IMF) are in general microbiologically stable products. However, due to health concerns consumer demands are increasingly forcing producers to lower the fat, sugar and preservatives content, which impede the stability of the IMF products. One of the strategies to counteract these problems is the storage of IMF products at lower temperatures. Thorough knowledge on growth/no growth boundaries of Zygosaccharomyces rouxii in IMF products, also at different storage temperatures is an important tool for ensuring microbiologically stability. In this study, growth/no growth models for Z. rouxii, developed by Vermeulen et al. (2012) were further extended by incorporating the factor temperature. Three different data sets were build: (i) without organic acids, (ii) with acetic acid (10,000 ppm on product basis) and (iii) with sorbic acid (1500 ppm on product basis). For each of these data sets three different growth/no growth models were developed after 30, 60 and 90 days. The results show that the influence of temperature is only significant in the lower temperature range (8–15 °C). Also, the effect of pH is negligible (pH 5.0–6.2) unless organic acids are present. More specific, acetic acid had only an additive effect to ethanol and aw at low pH, whereas sorbic acid had also an additive effect at the higher pH values. For incubation periods longer than 30 days the growth/no growth boundary remained stable but enlarged gradually between day 60 and 90, except for the lower temperature range (
-
screening of different stress factors and development of growth no growth models for zygosaccharomyces rouxii in modified sabouraud medium mimicking Intermediate Moisture Foods imf
Food Microbiology, 2012Co-Authors: An Vermeulen, Jeff Daelman, J Van Steenkiste, Frank DevlieghereAbstract:Abstract The microbial stability of Intermediate Moisture Foods (IMF) is linked with the possible growth of osmophilic yeast and xerophilic moulds. As most of these products have a long shelf life the assessment of the microbial stability is often an important hurdle in product innovation. In this study a screening of several Zygosaccharomyces rouxii strains towards individual stress factors was performed and growth/no growth models were developed, incorporating aw, pH, acetic acid and ethanol concentrations. These stress factors are important for sweet IMF such as chocolate fillings, ganache, marzipan, etc. A comparison was made between a logistic regression model with and without the incorporation of time as an explanatory variable. Next to the model development, a screening of the effect of chemical preservatives (sorbate and benzoate) was performed, in combination with relevant stress factors within the experimental design of the model. The results of the study showed that the influence of the investigated environmental stress factors on the growth/no growth boundary of Z. rouxii is the most significant in the first 30–40 days of incubation. Incorporating time as an explanatory variable in the model had the advantage that the growth/no growth boundary could be predicted at each time between 0 and 60 days of incubation at 22 °C. However, the growth/no growth boundary enlarged significantly leading to a less accurate prediction on the growth probability of Z. rouxii. The developed models can be a useful tool for product developers of sweet IMF. Screening with chemical preservatives revealed that benzoic acid was much less active towards Z. rouxii than sorbic acid or a mixture of both acids.
-
Screening of different stress factors and development of growth/no growth models for Zygosaccharomyces rouxii in modified Sabouraud medium, mimicking Intermediate Moisture Foods (IMF)
Food Microbiology, 2012Co-Authors: An Vermeulen, Jeff Daelman, J. Van Steenkiste, Frank DevlieghereAbstract:Abstract The microbial stability of Intermediate Moisture Foods (IMF) is linked with the possible growth of osmophilic yeast and xerophilic moulds. As most of these products have a long shelf life the assessment of the microbial stability is often an important hurdle in product innovation. In this study a screening of several Zygosaccharomyces rouxii strains towards individual stress factors was performed and growth/no growth models were developed, incorporating aw, pH, acetic acid and ethanol concentrations. These stress factors are important for sweet IMF such as chocolate fillings, ganache, marzipan, etc. A comparison was made between a logistic regression model with and without the incorporation of time as an explanatory variable. Next to the model development, a screening of the effect of chemical preservatives (sorbate and benzoate) was performed, in combination with relevant stress factors within the experimental design of the model. The results of the study showed that the influence of the investigated environmental stress factors on the growth/no growth boundary of Z. rouxii is the most significant in the first 30–40 days of incubation. Incorporating time as an explanatory variable in the model had the advantage that the growth/no growth boundary could be predicted at each time between 0 and 60 days of incubation at 22 °C. However, the growth/no growth boundary enlarged significantly leading to a less accurate prediction on the growth probability of Z. rouxii. The developed models can be a useful tool for product developers of sweet IMF. Screening with chemical preservatives revealed that benzoic acid was much less active towards Z. rouxii than sorbic acid or a mixture of both acids.
Theodore P. Labuza - One of the best experts on this subject based on the ideXlab platform.
-
molecular migration in high protein Intermediate Moisture Foods during the early stage of storage variations between dairy and soy proteins and effects on texture
Food Research International, 2016Co-Authors: Naiyan Lu, Peng Zhou, Theodore P. Labuza, Liang Zhang, Xuan Zhang, Juan LiAbstract:Abstract Effect of molecule migration on the hardening of high-protein Intermediate-Moisture Foods (HPIMF) in the early stage of storage was investigated through low-field NMR, texture analysis, confocal laser scanning microscopy, scanning electron microscopy, and protein solubility analysis. Model systems were made of water, glycerol and sorbitol, together with sodium caseinate (NaCN), soy protein isolate (SPI) or whey protein isolate (WPI), and stored at 25 °C to monitor molecular migration and the changes of texture, microstructure, and protein solubility. Both yield strain and yield stress of NaCN and SPI systems increased rapidly right after preparation, together with decreases in small molecules mobility and changes of microstructure, while WPI system showed more uniform structure without significant change of small molecules mobility. In addition, changes in protein solubility were observed in the SPI systems, but not in NaCN and WPI systems. These results suggested that the migration of small molecules (water, glycerol, and sorbitol) into protein particles during the early stage of storage could reduce the mobility of small molecules and might cause changes in microstructure, which could further cause hardening of HPIMF. In addition, the variation in protein sources was also a major factor contributing to the difference in texture properties.
-
storage stability of a commercial hen egg yolk powder in dry and Intermediate Moisture food matrices
Journal of Agricultural and Food Chemistry, 2013Co-Authors: Mary Catherine Fisher, Theodore P. LabuzaAbstract:Quality loss in Intermediate-Moisture Foods (IMF) such as high-protein nutrition bars (HPNB) in the form of hardening, nonenzymatic browning, and free amino group loss is a general concern for the manufacturers. To measure the extent of quality loss over time in terms of these negative attributes, through changing the ratio by weight between two commercial spray-dried hen egg powders, egg white (DEW) and egg yolk (DEY), the storage stability of 10 IMF systems (water activity (aw) ∼ 0.6) containing 5% glycerol, 10% shortening, 35% protein, and 50% sweetener (either maltitol or 50% high-fructose corn syrup/50% corn syrup (HFCS/CS)) were studied. Additionally, the storage stability of the DEY powder itself was investigated. Overall, during storage at different temperatures (23, 35, and 45 °C), the storage stability of DEY in dry and IMF matrices was mainly controlled by the coaction of three chemical reactions (disulfide bond interaction, Maillard reaction, and lipid oxidation). The results showed that by re...
-
effects of polyols on the stability of whey proteins in Intermediate Moisture food model systems
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Amy Tran, Peng Zhou, Theodore P. LabuzaAbstract:The objective of this study was to investigate the influence of polyols on the stability of whey proteins in an Intermediate-Moisture food model system and to elucidate the effect of polyols on the hardening of whey protein-based bars during storage. Four major polyols, glycerol, propylene glycol, maltitol, and sorbitol, were evaluated in model systems, which contained whey protein isolate, polyols, and water. The results showed that glycerol was the most effective polyol in lowering water activity and provided the soft texture of Intermediate-Moisture Foods, followed by sorbitol and maltitol. These three polyols stabilized the native structure of whey proteins, provided a desired texture, and slowed the hardening of the model systems. Propylene glycol should not be used in whey protein-based high-protein Intermediate-Moisture Foods because it caused changes in protein conformation and stability as observed by differential scanning calorimeter and Fourier transform infrared spectroscopy and resulted in ag...
-
Effects of polyols on the stability of whey proteins in Intermediate-Moisture Food model systems
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Xiao Ming Liu, Amy Tran, Peng Zhou, Theodore P. LabuzaAbstract:The objective of this study was to investigate the influence of polyols on the stability of whey proteins in an Intermediate-Moisture food model system and to elucidate the effect of polyols on the hardening of whey protein-based bars during storage. Four major polyols, glycerol, propylene glycol, maltitol, and sorbitol, were evaluated in model systems, which contained whey protein isolate, polyols, and water. The results showed that glycerol was the most effective polyol in lowering water activity and provided the soft texture of Intermediate-Moisture Foods, followed by sorbitol and maltitol. These three polyols stabilized the native structure of whey proteins, provided a desired texture, and slowed the hardening of the model systems. Propylene glycol should not be used in whey protein-based high-protein Intermediate-Moisture Foods because it caused changes in protein conformation and stability as observed by differential scanning calorimeter and Fourier transform infrared spectroscopy and resulted in aggregation of whey proteins and hardening of the bar texture during storage, causing loss in product quality.
-
Role of Moisture in Maillard Browning Reaction Rate in Intermediate Moisture Foods: Comparing Solvent Phase and Matrix Properties
Journal of Food Science, 2003Co-Authors: C.p. Sherwin, Theodore P. LabuzaAbstract:ABSTRACT: In Intermediate-Moisture Foods, a mechanism describing how Moisture affects chemical reaction rate is unknown. Previously, research showed glycol addition to model systems allowed high rates of nonenzymatic browning below the monolayer Moisture value and an aw of 0.2. These works were replicated, focusing on a mechanism of either plasticization or reactant dissolution. Tg curves showed plasticization increased with added glycerol and sorbitol. The maximum rate of nonenzymatic browning with glycerol occurred at an aw= 0.25 and was 1.5 times higher than the control (aw= 0.65). Sorbitol showed rates similar to the control. Plasticization and aw were poor predictors of reaction rate. Dissolution of glucose in glycerol explained the effect.
Peng Zhou - One of the best experts on this subject based on the ideXlab platform.
-
molecular migration in high protein Intermediate Moisture Foods during the early stage of storage variations between dairy and soy proteins and effects on texture
Food Research International, 2016Co-Authors: Naiyan Lu, Peng Zhou, Theodore P. Labuza, Liang Zhang, Xuan Zhang, Juan LiAbstract:Abstract Effect of molecule migration on the hardening of high-protein Intermediate-Moisture Foods (HPIMF) in the early stage of storage was investigated through low-field NMR, texture analysis, confocal laser scanning microscopy, scanning electron microscopy, and protein solubility analysis. Model systems were made of water, glycerol and sorbitol, together with sodium caseinate (NaCN), soy protein isolate (SPI) or whey protein isolate (WPI), and stored at 25 °C to monitor molecular migration and the changes of texture, microstructure, and protein solubility. Both yield strain and yield stress of NaCN and SPI systems increased rapidly right after preparation, together with decreases in small molecules mobility and changes of microstructure, while WPI system showed more uniform structure without significant change of small molecules mobility. In addition, changes in protein solubility were observed in the SPI systems, but not in NaCN and WPI systems. These results suggested that the migration of small molecules (water, glycerol, and sorbitol) into protein particles during the early stage of storage could reduce the mobility of small molecules and might cause changes in microstructure, which could further cause hardening of HPIMF. In addition, the variation in protein sources was also a major factor contributing to the difference in texture properties.
-
effects of polyols on the stability of whey proteins in Intermediate Moisture food model systems
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Amy Tran, Peng Zhou, Theodore P. LabuzaAbstract:The objective of this study was to investigate the influence of polyols on the stability of whey proteins in an Intermediate-Moisture food model system and to elucidate the effect of polyols on the hardening of whey protein-based bars during storage. Four major polyols, glycerol, propylene glycol, maltitol, and sorbitol, were evaluated in model systems, which contained whey protein isolate, polyols, and water. The results showed that glycerol was the most effective polyol in lowering water activity and provided the soft texture of Intermediate-Moisture Foods, followed by sorbitol and maltitol. These three polyols stabilized the native structure of whey proteins, provided a desired texture, and slowed the hardening of the model systems. Propylene glycol should not be used in whey protein-based high-protein Intermediate-Moisture Foods because it caused changes in protein conformation and stability as observed by differential scanning calorimeter and Fourier transform infrared spectroscopy and resulted in ag...
-
Effects of polyols on the stability of whey proteins in Intermediate-Moisture Food model systems
Journal of Agricultural and Food Chemistry, 2009Co-Authors: Xiao Ming Liu, Amy Tran, Peng Zhou, Theodore P. LabuzaAbstract:The objective of this study was to investigate the influence of polyols on the stability of whey proteins in an Intermediate-Moisture food model system and to elucidate the effect of polyols on the hardening of whey protein-based bars during storage. Four major polyols, glycerol, propylene glycol, maltitol, and sorbitol, were evaluated in model systems, which contained whey protein isolate, polyols, and water. The results showed that glycerol was the most effective polyol in lowering water activity and provided the soft texture of Intermediate-Moisture Foods, followed by sorbitol and maltitol. These three polyols stabilized the native structure of whey proteins, provided a desired texture, and slowed the hardening of the model systems. Propylene glycol should not be used in whey protein-based high-protein Intermediate-Moisture Foods because it caused changes in protein conformation and stability as observed by differential scanning calorimeter and Fourier transform infrared spectroscopy and resulted in aggregation of whey proteins and hardening of the bar texture during storage, causing loss in product quality.
An Vermeulen - One of the best experts on this subject based on the ideXlab platform.
-
Strategies to increase the stability of Intermediate Moisture Foods towards Zygosaccharomyces rouxii: the effect of temperature, ethanol, pH and water activity, with or without the influence of organic acids.
Food Microbiology, 2014Co-Authors: An Vermeulen, C. L. Marvig, Jeff Daelman, Ramize Xhaferi, Dennis S. Nielsen, Frank DevlieghereAbstract:Intermediate Moisture Foods (IMF) are in general microbiologically stable products. However, due to health concerns consumer demands are increasingly forcing producers to lower the fat, sugar and preservatives content, which impede the stability of the IMF products. One of the strategies to counteract these problems is the storage of IMF products at lower temperatures. Thorough knowledge on growth/no growth boundaries of Zygosaccharomyces rouxii in IMF products, also at different storage temperatures is an important tool for ensuring microbiologically stability. In this study, growth/no growth models for Z. rouxii, developed by Vermeulen et al. (2012) were further extended by incorporating the factor temperature. Three different data sets were build: (i) without organic acids, (ii) with acetic acid (10,000 ppm on product basis) and (iii) with sorbic acid (1500 ppm on product basis). For each of these data sets three different growth/no growth models were developed after 30, 60 and 90 days. The results show that the influence of temperature is only significant in the lower temperature range (8–15 °C). Also, the effect of pH is negligible (pH 5.0–6.2) unless organic acids are present. More specific, acetic acid had only an additive effect to ethanol and aw at low pH, whereas sorbic acid had also an additive effect at the higher pH values. For incubation periods longer than 30 days the growth/no growth boundary remained stable but enlarged gradually between day 60 and 90, except for the lower temperature range (
-
screening of different stress factors and development of growth no growth models for zygosaccharomyces rouxii in modified sabouraud medium mimicking Intermediate Moisture Foods imf
Food Microbiology, 2012Co-Authors: An Vermeulen, Jeff Daelman, J Van Steenkiste, Frank DevlieghereAbstract:Abstract The microbial stability of Intermediate Moisture Foods (IMF) is linked with the possible growth of osmophilic yeast and xerophilic moulds. As most of these products have a long shelf life the assessment of the microbial stability is often an important hurdle in product innovation. In this study a screening of several Zygosaccharomyces rouxii strains towards individual stress factors was performed and growth/no growth models were developed, incorporating aw, pH, acetic acid and ethanol concentrations. These stress factors are important for sweet IMF such as chocolate fillings, ganache, marzipan, etc. A comparison was made between a logistic regression model with and without the incorporation of time as an explanatory variable. Next to the model development, a screening of the effect of chemical preservatives (sorbate and benzoate) was performed, in combination with relevant stress factors within the experimental design of the model. The results of the study showed that the influence of the investigated environmental stress factors on the growth/no growth boundary of Z. rouxii is the most significant in the first 30–40 days of incubation. Incorporating time as an explanatory variable in the model had the advantage that the growth/no growth boundary could be predicted at each time between 0 and 60 days of incubation at 22 °C. However, the growth/no growth boundary enlarged significantly leading to a less accurate prediction on the growth probability of Z. rouxii. The developed models can be a useful tool for product developers of sweet IMF. Screening with chemical preservatives revealed that benzoic acid was much less active towards Z. rouxii than sorbic acid or a mixture of both acids.
-
Screening of different stress factors and development of growth/no growth models for Zygosaccharomyces rouxii in modified Sabouraud medium, mimicking Intermediate Moisture Foods (IMF)
Food Microbiology, 2012Co-Authors: An Vermeulen, Jeff Daelman, J. Van Steenkiste, Frank DevlieghereAbstract:Abstract The microbial stability of Intermediate Moisture Foods (IMF) is linked with the possible growth of osmophilic yeast and xerophilic moulds. As most of these products have a long shelf life the assessment of the microbial stability is often an important hurdle in product innovation. In this study a screening of several Zygosaccharomyces rouxii strains towards individual stress factors was performed and growth/no growth models were developed, incorporating aw, pH, acetic acid and ethanol concentrations. These stress factors are important for sweet IMF such as chocolate fillings, ganache, marzipan, etc. A comparison was made between a logistic regression model with and without the incorporation of time as an explanatory variable. Next to the model development, a screening of the effect of chemical preservatives (sorbate and benzoate) was performed, in combination with relevant stress factors within the experimental design of the model. The results of the study showed that the influence of the investigated environmental stress factors on the growth/no growth boundary of Z. rouxii is the most significant in the first 30–40 days of incubation. Incorporating time as an explanatory variable in the model had the advantage that the growth/no growth boundary could be predicted at each time between 0 and 60 days of incubation at 22 °C. However, the growth/no growth boundary enlarged significantly leading to a less accurate prediction on the growth probability of Z. rouxii. The developed models can be a useful tool for product developers of sweet IMF. Screening with chemical preservatives revealed that benzoic acid was much less active towards Z. rouxii than sorbic acid or a mixture of both acids.