Hocine Benmoussa

Softening of Overdried ‘Deglet Nour’ Dates to Obtain High-Standard Fruits: Impact of Rehydration and Drying Processes on Quality Criteria

The postharvest hydrothermal treatment of date palm fruit was studied in order to enhance the quality and consumer acceptance of ‘Deglet Nour’ hard dates, because these dates are unfit for direct consumption. Hot water hydration was performed by soaking at 25, 45, and 65°C and convective hot air drying at 35, 45, 60, 75, and 85°C at various levels of air humidity. Numerous quality parameters—i.e., texture, color, moisture and sugar contents—were investigated. Artificial maturation due to the softening of texture and the equilibration of sugars was achieved using the hydration pretreatment. A 6-h soaking at 45°C could be the best option to obtain a product of highest quality, but the moisture content would exceed that required for safe storage. Drying and quality tests led to the selection of a pretreatment step of soaking at 30°C for 8 h, followed by drying at an intermediate temperature (60°C) as the optimum condition to obtain a final product of high quality with the standard moisture content of 0.35 kg/kg d.b.

Étude du traitement thermique à l’eau chaude en vue d’amélioration de la qualité des dattes sèches

Une etude experimentale de la rehydratation, par impregnation a l’eau chaude, de la datte Deglet-Nour a ete faite en vue d’ameliorer la qualite des dattes seches. A cet effet plusieurs parametres de qualite ont ete testes simultanement : humidite, sucres, texture et couleur afin de permettre une bonne appreciation du produit fini. Differents echantillons ont ete rehydrates a 25, 45 et 65°C dans des solutions d’eau pure sucrees a 0°, 10° et 20° Brix. Les resultats obtenus ont mis en evidence une maturation complementaire par prise en eau et inversion de sucres. Le phenomene de diffusion eau-datte a ete accelere par l’augmentation de la temperature de trempage mais celui-ci a ete freine par l’augmentation de concentration des solutions sucrees et les pertes de sucres dans la solution de trempage etaient negligeables. Parmi plusieurs conditions operatoires investies, le trempage a 30°C, pendant environs huit heures, a ete choisi comme traitement optimal pour un produit fini de meilleure qualite. Afin de restituer au produit sa teneur en eau normale pour un stockage sain, une operation complementaire de sechage peut etre proposee.

Modeling of Heat Transfer in the PEMFC: Velocity Inlet and Current Density Effect

The purpose of this work is to present a two-dimensional transient model of the gas flow in the fuel cell (PEMFC). The model includes various conservation equations such movement and energy equations. The governing equations were resolved by the finite volume method. The objective of this work is to know the maximum temperature and its location in PEMFC and to determine the performance conditions of the fuel cell under the current density and velocity inlet effect. The polarization curve obtained numerically is compared with much numerical work. The numerical results show the regime flow effect and the nature of porous middle on the gas distribution in the membrane electrode assembly (MEA).