Etude de l’effet des conditions du séchage sur la texture et la couleur des filets de Sardina pilchardus

Le but de ce travail est d’étudier l’effet des conditions opératoires de séchage convectif par air chaud sur la couleur et la texture des filets de la sardine (Sardina pilchardus). Les filets de sardine ont été déshydratés par séchage convectif à vitesse d’air constante (Va = 1,5 m/s), différentes températures (40, 50 et 70°C) et à humidité relative d’air ambiante. Le critère final des expériences de séchage a été fixé de manière à avoir une teneur en eau finale des filets de l’ordre de 25% en base humide. La texture (mesure de la dureté par un texturomètre) et la couleur (paramètres L*a*b*) des filets ont été analysées à différents temps du séchage. L’évaluation des paramètres de qualité au cours du séchage (texture et couleur) montre que ces derniers dépendent de la teneur en eau du produit et des conditions de séchage. L’évaluation de latexture par le test de flexion trois points montre que l’augmentation de la température engendre une augmentation de la dureté des filets. Les paramètres L* et a* ont tendance à diminuer au fur et à mesure que la température de l’air augmente et la teneur en eau du produit chute. The aims of this work is the study of the effects of air drying process on the dehydration kinetics of sardine muscles (Sardina pilchardus).The effects of the air temperature (from 40 to 80°C) and the relative humidity (ambient and 40%) on the drying kinetics and on the color (L*a*b* parameters) and the textural (TAXT2i texturometer measurements)properties of the muscles were examined. Air drying kinetics were accelerated by increasing the air temperature and were attenuated by the humidification of drying air. The L* and a* parameters decreased with the increasing of air temperature. The injection of the moisture vapor on the air decreases this effect. The increasing of air temperature induced the hardness of the muscle and this effect was attenuated by moisture vapor’s injection. The moisture loss of the product induces a considerable decreasing of the muscle length

Effect of Combined Air-Drying-Osmotic Dehydration on Kinetics of Techno-functional Properties, Color and Total Phenol Contents of Lemon (Citrus limon. v. lunari) Peels

Abstract Combined osmotic dehydration (sucrose solution: 50–70 % w/w, 30–50 °C for 2 h followed by air drying at 40 and 60 °C) is an appropriate process for preservation of oil retention capacity, lightness and yellowness of lemon peels (Citrus limon. v. lunari). Incorporation of sugars to lemon cuboids pieces increased drying rate during the first falling rate phase of the air dehydration step and improved their color stability. Osmotic dehydration process allows protective effect against further total phenol loss during air drying: significant loss of total phenol content (70–80 %) was recorded during osmotic dehydration and then it remains constant during air drying at 40 and 60 °C. For the investigated temperature of osmotic pre-treatment (30–50 °C), water retention capacities were reduced by up to 70 % and were maintained constant during air drying.</jats:p

Water desorption of osmotic dehydrated apple and pear at different water activities: desorption isotherms and glass transition temperature

Water desorption of osmotic dehydrated apple and pear at different water activities: desorption isotherms and glass transition temperature. Journée AFSI

Moisture desorption isotherms and glass transition temperatures of osmo-dehydrated apple and pear

The aim of this work was to evaluate osmo-dehydrated pear and apple stability on the basis of combined data of moisture desorption isotherms and glass transition temperatures (Tg) investigated in the temperature range of 30-60 degrees C. Parallelipedic pieces of pears and apples were osmo-dehydrated at 30 degrees C in sucrose syrups at 70% during 65 min. To study their hygroscopic properties behavior, the osmo-dehydrated fruits were stored in static desiccators at 30,45 and 60 degrees C, and relative humidities ranging from 6 to 80%. The Gmodel satisfactory described the relationship between the water activity (aw) and water content (X) of osmo-dehydrated fruits (r(2) >= 0.994). Differential scanning calorimetry was used to measure Tg of osmo-dehydrated fruits conditioned at various water activities. A strong plasticizing effect of water on Tg was found with a large reduction of Tg when the water content increased. The dependence of Tg on water activity data was satisfactory correlated by the Roos model (0.993 <= r(2) <= 0.999). Whereas the Tg similar to X-w was adequately described by Gordon and Taylor model (0.898 <= r <= 0.990). The changes of Tg similar to aw and Tg similar to X-w were established and the critical values of water contents were determined for the investigated range of temperature. (C) 2012 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved

Water desorption of osmotic dehydrated apple and pear at different water activities: desorption isotherms and glass transition temperature

Water desorption of osmotic dehydrated apple and pear at different water activities: desorption isotherms and glass transition temperature. Journée AFSI

Water desorption of osmotic dehydrated apple and pear at different water activities: desorption isotherms and glass transition temperature

Water desorption of osmotic dehydrated apple and pear at different water activities: desorption isotherms and glass transition temperature. Journée AFSI

Convective drying kinetics and physical properties of silver carp (Hypophthalmichthys molitrix) fillets

10.1080/10498850.2011.575536Journal of Aquatic Food Product Technology204361-378JAFP