... eo=15 mm). (*) Yv, (0) V. Figura 1. Perfiles de concentraci6n experimentales en muestras de m... more ... eo=15 mm). (*) Yv, (0) V. Figura 1. Perfiles de concentraci6n experimentales en muestras de manzana deshidratada osm6ticamente durante 34 h a 20 °C en una disoluci6n de sacarosa de 65 °Brix (eo=15 mm). (*) Yv, (0) Y . ...
ABSTRACT Salted cod is used as raw material to elaborate many traditional dishes in the Mediterra... more ABSTRACT Salted cod is used as raw material to elaborate many traditional dishes in the Mediterranean countries, being usually desalted prior to its consumption. The objective of this study is the thermodynamic analysis of the cod desalting operation, defining the mass fluxes, the driving forces and the description of the changes in cod throughout the process in order to understand the operation. The obtained results show that the mass transfer fluxes that succeed during the desalting operation are due not only to the diffusion mechanism, but also to the Hydrodynamic Mechanisms promoted by pressure gradients that appear during the cod matrix leaching and rehydration.
Microwave-assisted hot-air dehydration of cassava slices was performed under different drying con... more Microwave-assisted hot-air dehydration of cassava slices was performed under different drying conditions. The objective of the investigation was to compare hot air drying and microwave-assisted hot-air drying and to analyze the influence of the osmotic dehydration prior to drying. Osmotic pre-treated samples were obtained by submerging the cassava slices in a 20% -salt solution (w/w) for 60 minutes at 30ºC. The microwave output power and the air temperature were the variables in the experiments. An important reduction in the drying time was observed when applying microwaves, mainly for samples osmotically pre-treated as a consequence of the influence of salt ions in the dielectric properties of the material.
Different dehydration techniques are widely used to stabilize fruits. A lot of works about dehydr... more Different dehydration techniques are widely used to stabilize fruits. A lot of works about dehydration methods like air drying or osmotic dehydration are being published around the world. In these works, product humidity is considered as the main variable related with quality characteristics of the final product and it is correlated with process conditions, mainly air temperature and velocity. Nowadays, consumers are much more exigent and they demand products with a good texture, colour, and nutritive value. Quality is becoming a more complex concept which affects functionality of the product. In this situation, foods have to be defined considering structural, sensorial, physical-chemical and nutritive aspects. The changes in every considered characteristic along drying process are needed to be considered and mechanistic correlations among these characteristics and process variables must be established. A new methodology that allows us to consider structural, physical-chemical and n...
Salted cod is one of the main heavy-salted products consumed in Mediterranean countries and it is... more Salted cod is one of the main heavy-salted products consumed in Mediterranean countries and it is usually desalting before its consumption. The SAFES methodology was applied to cod process where three matrix-changes were defined corresponding to the three main stages of the process. This analysis allows analyzing the migrations of components between phases and their aggregation state into food matrix in order to achieve a better understanding of internal process which could be related to product's final quality. A migration of water from extra-intracellular liquid to solid matrix and to external fluid took place in the salting and drying stages. On the other hand, an intake of salt occurred during process and an amount of it precipitated. However, in desalting operation the inverse tendency was observed. Moreover, important changes related to protein component were taken into account. During salting, some proteins from raw cod (60%) were denatured (solubilized) due to the high i...
The differences in the external osmotic medium, dry or dissolved osmotic agent and its concentrat... more The differences in the external osmotic medium, dry or dissolved osmotic agent and its concentration (constant or variable) can significantly influence the kinetics of mass transfer. The objective of this work was to compare water and solute transport during the osmotic dehydration of strawberry pieces under different external conditions, wet or dry osmotic agent, with varying types of sugar (sucrose, fructose and isomaltulose). The evolution of the liquid phase concentration as well as the net fluxes under the different scenarios was described and modelled. Results showed that mass transfer kinetics were higher when the concentration of the external medium was variable, in the wet process slightly
This paper investigated the effect of air-frying technology, in combination with a pretreatment b... more This paper investigated the effect of air-frying technology, in combination with a pretreatment based of soaking the samples in different chemical agent solutions (citric acid, glycine, calcium lactate, sodium chloride, or nicotinic acid [vitamin B3]), on the generation of acrylamide in fried potatoes. The influence of reducing sugars on the development of surface's color was also analyzed. The experiments were conducted at 180 °C by means of air-frying and deep-oil-frying, as a reference technology. Based on the evolution of color crust with frying time, it could be concluded that the rate of Maillard reaction decreased as the initial reducing sugars content increased in the raw material, and was also lower for deep-oil-frying than for air-frying regardless of pretreatments applied. Air-frying reduced acrylamide content by about 90% compared with conventional deep-oil-frying without being necessary the application of a pretreatment. However, deep-oil fried potatoes pretreated w...
ABSTRACT The presence of antioxidant compounds and therefore the antioxidant capacity of persimmo... more ABSTRACT The presence of antioxidant compounds and therefore the antioxidant capacity of persimmon leaves and their extracts have been reported by many authors. Furthermore, it is known that both the method of drying and the temperature at which this process takes place substantially affect the properties of the final product. However, there are no studies in the literature that examine how drying variables can affect the quality of persimmon leaves, especially as refers to preservation of their antioxidant properties. Therefore, the aim of this paper was to compare some antioxidant properties of aqueous extracts of persimmon leaves obtained under different drying methods (shade drying, hot air drying at 100 and 180 °C, and freeze drying) and infusion conditions (70, 80 and 90 °C for 1, 3, 5, 60 and 1440 minutes). The results in terms of total phenol content, flavonoids and antioxidant capacity indicated that air drying at 100 °C would be the optimal process for the stabilization of persimmon leaves, and their subsequent use in brewed beverages. Likewise, the best conditions of aqueous extraction in order to maximize the extractability of antioxidant compounds corresponded to 90 °C for 60 minutes. A short experiment performed in this study confirmed that small persimmon leaves (axial axis: 9±1 (cm); equatorial axis: 7.0±0.9 (cm)) had around 9% more flavonoids, and 7% more total phenolic content and antioxidant capacity than the large ones (axial axis: 17±2 (cm); equatorial axis: 10±1 (cm)).
... eo=15 mm). (*) Yv, (0) V. Figura 1. Perfiles de concentraci6n experimentales en muestras de m... more ... eo=15 mm). (*) Yv, (0) V. Figura 1. Perfiles de concentraci6n experimentales en muestras de manzana deshidratada osm6ticamente durante 34 h a 20 °C en una disoluci6n de sacarosa de 65 °Brix (eo=15 mm). (*) Yv, (0) Y . ...
ABSTRACT Salted cod is used as raw material to elaborate many traditional dishes in the Mediterra... more ABSTRACT Salted cod is used as raw material to elaborate many traditional dishes in the Mediterranean countries, being usually desalted prior to its consumption. The objective of this study is the thermodynamic analysis of the cod desalting operation, defining the mass fluxes, the driving forces and the description of the changes in cod throughout the process in order to understand the operation. The obtained results show that the mass transfer fluxes that succeed during the desalting operation are due not only to the diffusion mechanism, but also to the Hydrodynamic Mechanisms promoted by pressure gradients that appear during the cod matrix leaching and rehydration.
Microwave-assisted hot-air dehydration of cassava slices was performed under different drying con... more Microwave-assisted hot-air dehydration of cassava slices was performed under different drying conditions. The objective of the investigation was to compare hot air drying and microwave-assisted hot-air drying and to analyze the influence of the osmotic dehydration prior to drying. Osmotic pre-treated samples were obtained by submerging the cassava slices in a 20% -salt solution (w/w) for 60 minutes at 30ºC. The microwave output power and the air temperature were the variables in the experiments. An important reduction in the drying time was observed when applying microwaves, mainly for samples osmotically pre-treated as a consequence of the influence of salt ions in the dielectric properties of the material.
Different dehydration techniques are widely used to stabilize fruits. A lot of works about dehydr... more Different dehydration techniques are widely used to stabilize fruits. A lot of works about dehydration methods like air drying or osmotic dehydration are being published around the world. In these works, product humidity is considered as the main variable related with quality characteristics of the final product and it is correlated with process conditions, mainly air temperature and velocity. Nowadays, consumers are much more exigent and they demand products with a good texture, colour, and nutritive value. Quality is becoming a more complex concept which affects functionality of the product. In this situation, foods have to be defined considering structural, sensorial, physical-chemical and nutritive aspects. The changes in every considered characteristic along drying process are needed to be considered and mechanistic correlations among these characteristics and process variables must be established. A new methodology that allows us to consider structural, physical-chemical and n...
Salted cod is one of the main heavy-salted products consumed in Mediterranean countries and it is... more Salted cod is one of the main heavy-salted products consumed in Mediterranean countries and it is usually desalting before its consumption. The SAFES methodology was applied to cod process where three matrix-changes were defined corresponding to the three main stages of the process. This analysis allows analyzing the migrations of components between phases and their aggregation state into food matrix in order to achieve a better understanding of internal process which could be related to product's final quality. A migration of water from extra-intracellular liquid to solid matrix and to external fluid took place in the salting and drying stages. On the other hand, an intake of salt occurred during process and an amount of it precipitated. However, in desalting operation the inverse tendency was observed. Moreover, important changes related to protein component were taken into account. During salting, some proteins from raw cod (60%) were denatured (solubilized) due to the high i...
The differences in the external osmotic medium, dry or dissolved osmotic agent and its concentrat... more The differences in the external osmotic medium, dry or dissolved osmotic agent and its concentration (constant or variable) can significantly influence the kinetics of mass transfer. The objective of this work was to compare water and solute transport during the osmotic dehydration of strawberry pieces under different external conditions, wet or dry osmotic agent, with varying types of sugar (sucrose, fructose and isomaltulose). The evolution of the liquid phase concentration as well as the net fluxes under the different scenarios was described and modelled. Results showed that mass transfer kinetics were higher when the concentration of the external medium was variable, in the wet process slightly
This paper investigated the effect of air-frying technology, in combination with a pretreatment b... more This paper investigated the effect of air-frying technology, in combination with a pretreatment based of soaking the samples in different chemical agent solutions (citric acid, glycine, calcium lactate, sodium chloride, or nicotinic acid [vitamin B3]), on the generation of acrylamide in fried potatoes. The influence of reducing sugars on the development of surface's color was also analyzed. The experiments were conducted at 180 °C by means of air-frying and deep-oil-frying, as a reference technology. Based on the evolution of color crust with frying time, it could be concluded that the rate of Maillard reaction decreased as the initial reducing sugars content increased in the raw material, and was also lower for deep-oil-frying than for air-frying regardless of pretreatments applied. Air-frying reduced acrylamide content by about 90% compared with conventional deep-oil-frying without being necessary the application of a pretreatment. However, deep-oil fried potatoes pretreated w...
ABSTRACT The presence of antioxidant compounds and therefore the antioxidant capacity of persimmo... more ABSTRACT The presence of antioxidant compounds and therefore the antioxidant capacity of persimmon leaves and their extracts have been reported by many authors. Furthermore, it is known that both the method of drying and the temperature at which this process takes place substantially affect the properties of the final product. However, there are no studies in the literature that examine how drying variables can affect the quality of persimmon leaves, especially as refers to preservation of their antioxidant properties. Therefore, the aim of this paper was to compare some antioxidant properties of aqueous extracts of persimmon leaves obtained under different drying methods (shade drying, hot air drying at 100 and 180 °C, and freeze drying) and infusion conditions (70, 80 and 90 °C for 1, 3, 5, 60 and 1440 minutes). The results in terms of total phenol content, flavonoids and antioxidant capacity indicated that air drying at 100 °C would be the optimal process for the stabilization of persimmon leaves, and their subsequent use in brewed beverages. Likewise, the best conditions of aqueous extraction in order to maximize the extractability of antioxidant compounds corresponded to 90 °C for 60 minutes. A short experiment performed in this study confirmed that small persimmon leaves (axial axis: 9±1 (cm); equatorial axis: 7.0±0.9 (cm)) had around 9% more flavonoids, and 7% more total phenolic content and antioxidant capacity than the large ones (axial axis: 17±2 (cm); equatorial axis: 10±1 (cm)).
Uploads
Papers by Ana Andrés
in the wet process
slightly
in the wet process
slightly