Non-enzymatic browning in an 11 °Brix apple juice during thermal treatment was studied through ch... more Non-enzymatic browning in an 11 °Brix apple juice during thermal treatment was studied through changes in colour by colorimetric parameters (A 420 , colour difference and index of browning), and HMF and sugars (fructose, glucose and sucrose) evolution. Zero and first order kinetics were applied to describe evolution of colorimetric parameters. The formation of HMF was fitted to auto-catalytical and first order equations. Sucrose tends to disappear according to a first order kinetics giving fructose and glucose. For the reducing sugars (fructose and glucose), no clear tendency was observed. The effect of temperature can be described by an Arrhenius-type equation.
In this paper is reported a study of rheological caracterization of blackcurrant juices and a new... more In this paper is reported a study of rheological caracterization of blackcurrant juices and a newtonian behaviour is described. The effect of the temperature on a 66,5o Brix concentrate is studied and an equation of Arrhenius type to describe this influence is found. The influence of the soluble solids contents on the viscosity of the blackcurrant juices at 25oC was also studied and two models of expressions (potential and exponential) were tried to describe this effects.
Because of the non-enzymatic browning reactions are the main factor in the browning of fruit juic... more Because of the non-enzymatic browning reactions are the main factor in the browning of fruit juices and concentrates, this paper presents a review and a theoretical study of the use of the cinetic models to these reactions. Simple cinetic models, used in the determination of the color generation rate, and the variables, which have influence in the non-enzymatic browning rate, are described and analyzed.
En muchos zumos de frutas y soluciones acuosas aparecen restos de plaguicidas que pueden resultar... more En muchos zumos de frutas y soluciones acuosas aparecen restos de plaguicidas que pueden resultar peligrosos para la salud de los consumidores, por lo que es necesario realizar tratamientos de eliminacion de estos compuestos toxicos. En el presente trabajo se presenta la aplicacion de un tratamiento fotoquimico con radiacion UV para eliminar benomilo (metil-1-[butilcarbamoil]-2-benzimidazol-carbamato) en solucion acuosa a pH = 4, utilizando una lampara de mercurio de media presion. Se presenta una modelizacion cinetica de la fotodegradacion, obteniendo que los resultados experimentales se ajustan de modo adecuado a una ecuacion de primer orden. Se ha observado que la concentracion inicial de benomilo en la solucion acuosa no influye en la constante global de fotodegradacion. A pesar de que el benomilo puede hidrolizarse para formar benzimidazol-2-il carbamato de metilo (MBC), la etapa fotoquimica predomina sobre la de hidrolisis en la desaparicion de benomilo del medio acuoso.
Although knowledge of the microstructure of food of vegetal origin helps us to understand the beh... more Although knowledge of the microstructure of food of vegetal origin helps us to understand the behavior of food materials, the variability in the microstructural elements complicates this analysis. In this regard, the construction of learning models that represent the actual microstructures of the tissue is important to extract relevant information and advance in the comprehension of such behavior. Consequently, the objective of this research is to compare two machine learning techniques—Convolutional Neural Networks (CNN) and Radial Basis Neural Networks (RBNN)—when used to enhance its microstructural analysis. Two main contributions can be highlighted from this research. First, a method is proposed to automatically analyze the microstructural elements of vegetal tissue; and second, a comparison was conducted to select a classifier to discriminate between tissue structures. For the comparison, a database of microstructural elements images was obtained from pumpkin (Cucurbita pepo L....
Food science and technology international = Ciencia y tecnologia de los alimentos internacional, 2017
This work studies the adsorption of colored compounds in cane juice using a food-grade macroporou... more This work studies the adsorption of colored compounds in cane juice using a food-grade macroporous adsorber resin without functional groups. The adsorption equilibrium was studied through the adsorption isotherms at 30, 40, and 50 ℃. The absorbance at 420 nm was used to measure the concentration of colored compounds, which enables correlation of the residual concentration with the adsorbed concentration. Furthermore, the efficiency of the adsorption process was studied, from which it was observed that there was an improvement in efficiency with increasing resin content, while the increase in temperature was less important in the process. The kinetic study was performed using the Ibarz model and intraparticle diffusion model, which correctly account for the kinetics of the adsorption process. The adsorption kinetic constant was always greater than the desorption kinetic constant, indicating that the adsorption step predominates over the desorption step.
Alimentaria Revista De Tecnologia E Higiene De Los Alimentos, 2001
In the fruit juices and purees industrial manufacturing, there are some steps where the fruit pul... more In the fruit juices and purees industrial manufacturing, there are some steps where the fruit pulp is ground and other steps where treatments at high temperature are applied. In these steps dark colors called browning can appear, causing deterioration on the final products. There are two important browning groups: enzymatic, due to the polyphenoloxidase enzyme present in the fruit tissue which acts on phenolic substrates also present in the fruit pulp starting a reactions sequence producing a compounds named melanins, causing the dark colors on the final products. There are influence of the fruit degree maturation on the enzymatic browning in such a way that the more immature the fruit the more rapid the browning is observed. The second browning group is non-enzymatic. This deterioration is due to the polymers called melanoidins formed from three principal chemical reactions: Maillard, caramellisation and ascorbic acid decomposition. Studies carried out to establish a kinetic model on the color evolution lead to a model based on a two-stage mechanism applied to the color evolution. The first stage, color formation, is zero order and the second stage, pigment destruction, is first-order. The most important factors influencing on the reaction rate are: temperature, monosaccharides and aminoacids concentration, water activity and pH.
Alimentaria Revista De Tecnologia E Higiene De Los Alimentos, 1998
Non-enzymatic browning in an 11 Brix pear juice during heating at relative high temperatures (80 ... more Non-enzymatic browning in an 11 Brix pear juice during heating at relative high temperatures (80 to 98 °C), was studied through changes in colour by different colorimetric parameters (relative absorbance at 420 nm, CIELAB parameters, colour and chroma difference). The evolution of relative absorbance, lightness, sucrose, and HMF formation were described by first order kinetics, but evolution of colour and chroma difference followed a zero order kinetics. The effect of temperature on different parameters studied can be described by an Arrhenius type equation.
Alimentaria Revista De Tecnologia E Higiene De Los Alimentos, 1995
The reological behaviour of clarified loquat fruit juice was measured for a wide range of concent... more The reological behaviour of clarified loquat fruit juice was measured for a wide range of concentrations (35-71°Brix) and temperatures (5-65°C), using a concentric cylinder viscometer. The results indicated that clarified medlar fruit juices behaves as Newtonian fluid. The effect of temperature can be described by an Arrhenius-type equation. The activation energy for viscous flow was in the range 17.24-45.20 kJ/mol, depending on the concentration. The effect of soluble solids content cab by described by two types of equation, power-law and exponential. Finally, an equation for the dependence of dinamic viscosity on temperature and soluble solids content was developed : η=1.3.10 -6 exp(0.099C+3.370/T)
Alimentaria Revista De Tecnologia E Higiene De Los Alimentos, 2006
The knowledge of the viscosity or rheological behaviour for the different types of juices it is u... more The knowledge of the viscosity or rheological behaviour for the different types of juices it is used as a characteristic of the quality for these products. On the other hand, the data of viscosity are essential for the design, evaluation and operation of the process devices for liquid and semiliquid foods. With regard to the engineering applications it is indispensable their knowledge for the use of the flow models in the design of systems and other applications. It is carried out a brief exhibition of temperature, soluble solid content and shear rate influence, as well as the effect of thixotropy on the rheology behaviour of fruit derivatives. Also, the process considerations on the rheological aspects of heat transmission and momentum transport unit operations (pumping and agitation) are presented. The influence of the type of fluid in this kind of operations for the more usual processing systems for juices and purees is exposed.
In the enzymatic hydrolysis of proteins up to peptides or amino acids, by the action of proteolyt... more In the enzymatic hydrolysis of proteins up to peptides or amino acids, by the action of proteolytic enzymes, the final composition and therefore the use of the hydrolizates will depend on the protein source, on the type of protease used, on the hydrolysis conditions and on the hydrolysis grade reached in the reaction. Hydrolizates are used widely in food technology due to their nutritional or functional properties (solubility, emulsifient power, foaming capacity). This work shows the present trend in the skills used to obtain hydrolizates by means of enzymes as well as the different methods used for the control of these preparations; besides theirs likely applications are also indicated.
Non-enzymatic browning in an 11 °Brix apple juice during thermal treatment was studied through ch... more Non-enzymatic browning in an 11 °Brix apple juice during thermal treatment was studied through changes in colour by colorimetric parameters (A 420 , colour difference and index of browning), and HMF and sugars (fructose, glucose and sucrose) evolution. Zero and first order kinetics were applied to describe evolution of colorimetric parameters. The formation of HMF was fitted to auto-catalytical and first order equations. Sucrose tends to disappear according to a first order kinetics giving fructose and glucose. For the reducing sugars (fructose and glucose), no clear tendency was observed. The effect of temperature can be described by an Arrhenius-type equation.
In this paper is reported a study of rheological caracterization of blackcurrant juices and a new... more In this paper is reported a study of rheological caracterization of blackcurrant juices and a newtonian behaviour is described. The effect of the temperature on a 66,5o Brix concentrate is studied and an equation of Arrhenius type to describe this influence is found. The influence of the soluble solids contents on the viscosity of the blackcurrant juices at 25oC was also studied and two models of expressions (potential and exponential) were tried to describe this effects.
Because of the non-enzymatic browning reactions are the main factor in the browning of fruit juic... more Because of the non-enzymatic browning reactions are the main factor in the browning of fruit juices and concentrates, this paper presents a review and a theoretical study of the use of the cinetic models to these reactions. Simple cinetic models, used in the determination of the color generation rate, and the variables, which have influence in the non-enzymatic browning rate, are described and analyzed.
En muchos zumos de frutas y soluciones acuosas aparecen restos de plaguicidas que pueden resultar... more En muchos zumos de frutas y soluciones acuosas aparecen restos de plaguicidas que pueden resultar peligrosos para la salud de los consumidores, por lo que es necesario realizar tratamientos de eliminacion de estos compuestos toxicos. En el presente trabajo se presenta la aplicacion de un tratamiento fotoquimico con radiacion UV para eliminar benomilo (metil-1-[butilcarbamoil]-2-benzimidazol-carbamato) en solucion acuosa a pH = 4, utilizando una lampara de mercurio de media presion. Se presenta una modelizacion cinetica de la fotodegradacion, obteniendo que los resultados experimentales se ajustan de modo adecuado a una ecuacion de primer orden. Se ha observado que la concentracion inicial de benomilo en la solucion acuosa no influye en la constante global de fotodegradacion. A pesar de que el benomilo puede hidrolizarse para formar benzimidazol-2-il carbamato de metilo (MBC), la etapa fotoquimica predomina sobre la de hidrolisis en la desaparicion de benomilo del medio acuoso.
Although knowledge of the microstructure of food of vegetal origin helps us to understand the beh... more Although knowledge of the microstructure of food of vegetal origin helps us to understand the behavior of food materials, the variability in the microstructural elements complicates this analysis. In this regard, the construction of learning models that represent the actual microstructures of the tissue is important to extract relevant information and advance in the comprehension of such behavior. Consequently, the objective of this research is to compare two machine learning techniques—Convolutional Neural Networks (CNN) and Radial Basis Neural Networks (RBNN)—when used to enhance its microstructural analysis. Two main contributions can be highlighted from this research. First, a method is proposed to automatically analyze the microstructural elements of vegetal tissue; and second, a comparison was conducted to select a classifier to discriminate between tissue structures. For the comparison, a database of microstructural elements images was obtained from pumpkin (Cucurbita pepo L....
Food science and technology international = Ciencia y tecnologia de los alimentos internacional, 2017
This work studies the adsorption of colored compounds in cane juice using a food-grade macroporou... more This work studies the adsorption of colored compounds in cane juice using a food-grade macroporous adsorber resin without functional groups. The adsorption equilibrium was studied through the adsorption isotherms at 30, 40, and 50 ℃. The absorbance at 420 nm was used to measure the concentration of colored compounds, which enables correlation of the residual concentration with the adsorbed concentration. Furthermore, the efficiency of the adsorption process was studied, from which it was observed that there was an improvement in efficiency with increasing resin content, while the increase in temperature was less important in the process. The kinetic study was performed using the Ibarz model and intraparticle diffusion model, which correctly account for the kinetics of the adsorption process. The adsorption kinetic constant was always greater than the desorption kinetic constant, indicating that the adsorption step predominates over the desorption step.
Alimentaria Revista De Tecnologia E Higiene De Los Alimentos, 2001
In the fruit juices and purees industrial manufacturing, there are some steps where the fruit pul... more In the fruit juices and purees industrial manufacturing, there are some steps where the fruit pulp is ground and other steps where treatments at high temperature are applied. In these steps dark colors called browning can appear, causing deterioration on the final products. There are two important browning groups: enzymatic, due to the polyphenoloxidase enzyme present in the fruit tissue which acts on phenolic substrates also present in the fruit pulp starting a reactions sequence producing a compounds named melanins, causing the dark colors on the final products. There are influence of the fruit degree maturation on the enzymatic browning in such a way that the more immature the fruit the more rapid the browning is observed. The second browning group is non-enzymatic. This deterioration is due to the polymers called melanoidins formed from three principal chemical reactions: Maillard, caramellisation and ascorbic acid decomposition. Studies carried out to establish a kinetic model on the color evolution lead to a model based on a two-stage mechanism applied to the color evolution. The first stage, color formation, is zero order and the second stage, pigment destruction, is first-order. The most important factors influencing on the reaction rate are: temperature, monosaccharides and aminoacids concentration, water activity and pH.
Alimentaria Revista De Tecnologia E Higiene De Los Alimentos, 1998
Non-enzymatic browning in an 11 Brix pear juice during heating at relative high temperatures (80 ... more Non-enzymatic browning in an 11 Brix pear juice during heating at relative high temperatures (80 to 98 °C), was studied through changes in colour by different colorimetric parameters (relative absorbance at 420 nm, CIELAB parameters, colour and chroma difference). The evolution of relative absorbance, lightness, sucrose, and HMF formation were described by first order kinetics, but evolution of colour and chroma difference followed a zero order kinetics. The effect of temperature on different parameters studied can be described by an Arrhenius type equation.
Alimentaria Revista De Tecnologia E Higiene De Los Alimentos, 1995
The reological behaviour of clarified loquat fruit juice was measured for a wide range of concent... more The reological behaviour of clarified loquat fruit juice was measured for a wide range of concentrations (35-71°Brix) and temperatures (5-65°C), using a concentric cylinder viscometer. The results indicated that clarified medlar fruit juices behaves as Newtonian fluid. The effect of temperature can be described by an Arrhenius-type equation. The activation energy for viscous flow was in the range 17.24-45.20 kJ/mol, depending on the concentration. The effect of soluble solids content cab by described by two types of equation, power-law and exponential. Finally, an equation for the dependence of dinamic viscosity on temperature and soluble solids content was developed : η=1.3.10 -6 exp(0.099C+3.370/T)
Alimentaria Revista De Tecnologia E Higiene De Los Alimentos, 2006
The knowledge of the viscosity or rheological behaviour for the different types of juices it is u... more The knowledge of the viscosity or rheological behaviour for the different types of juices it is used as a characteristic of the quality for these products. On the other hand, the data of viscosity are essential for the design, evaluation and operation of the process devices for liquid and semiliquid foods. With regard to the engineering applications it is indispensable their knowledge for the use of the flow models in the design of systems and other applications. It is carried out a brief exhibition of temperature, soluble solid content and shear rate influence, as well as the effect of thixotropy on the rheology behaviour of fruit derivatives. Also, the process considerations on the rheological aspects of heat transmission and momentum transport unit operations (pumping and agitation) are presented. The influence of the type of fluid in this kind of operations for the more usual processing systems for juices and purees is exposed.
In the enzymatic hydrolysis of proteins up to peptides or amino acids, by the action of proteolyt... more In the enzymatic hydrolysis of proteins up to peptides or amino acids, by the action of proteolytic enzymes, the final composition and therefore the use of the hydrolizates will depend on the protein source, on the type of protease used, on the hydrolysis conditions and on the hydrolysis grade reached in the reaction. Hydrolizates are used widely in food technology due to their nutritional or functional properties (solubility, emulsifient power, foaming capacity). This work shows the present trend in the skills used to obtain hydrolizates by means of enzymes as well as the different methods used for the control of these preparations; besides theirs likely applications are also indicated.
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