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4. A study into how thickness, infrared intensity, and airflow affect drying kinetics, modeling, activation energy, and quality attributes of apple slices using infrared dryer.

Author

El‐Mesery, Hany S., Hu, Zicheng, Ashiagbor, Kwami, and Rostom, Merit

Subjects
AIR flow, ACTIVATION energy, INFRARED radiation, ORCHARDS
Abstract

Drying is a widely recognized process that reduces the need for storage and shipping weight, keeps free water out of the product, and prolongs its shelf life. An infrared dryer was designed to dry apples under different drying conditions. Apple slices of 6‐, 4‐, and 2‐mm thicknesses were dried at intensities 0.130, 0.225, and 0.341 W/cm2 and airflow 1.0, 0.5, and 1.5 m/s. The dehydrating period was prolonged with higher airflow and shortened with higher infrared intensity (IR). The shortest dehydrating period was verified by 190 min at 0.341 W/cm2, 0.5 m/s under 2 mm thickness. Increasing the sample thickness from 2 to 4 mm and then to 6 mm resulted in an 84% and 192% increase in drying time, respectively. Dehydrated apples had water activity values ranging from 0.30 to 0.40. The shrinkage ratio increased with an increase in infrared radiation intensity. However, it decreased with an increase in air velocity, while the rehydration ratio decreased with an increase in radiation intensity and increased with an increase in air velocity. Regarding total color change, apple slice thickness was a major factor. The effective diffusivities varied between 2.6 and 9.0 헑10−10 m2/s under different drying conditions. The dehydrating curves of apples were best described by the model developed by Midilli et al. [ABSTRACT FROM AUTHOR]

Published
2024
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12. Bioflocculation of (Iron oxide – Silica) system using Bacillus cereusbacteria isolated from Egyptian iron ore surface

Author

Selim, Khaled A. and Rostom, Merit

Abstract

In mineral bio-beneficiation, it is very important to understand the microbial surface characteristics and its behaviour onto the mineral surface. Bacillus cereusbacterium has never been used before as a bio-reagent for separation of different mineral systems. In this work, complete characterization of such type of bacteria, isolated from Egyptian iron ore surface, including gram stain, growth curve, Biolog microbial identification, Zeta potential characterization, Fourier Transform Infrared Spectrometer, FTIR characterization as well as protein and polysaccharide analysis have been studied. The results confirmed that Bacillus cereusis a gram positive bacterium, rod shaped, smooth and circular with different types of by-products as polysaccharides, carboxylic acids and amino acids that gives an amphoteric behaviour on the cell surface. The results of zeta potential showed that the iso-electric points (IEP) of iron oxide (≈6.3) and silica (≈1.8) were significantly displaced to low values (≈2.2) and (≈1) respectively after treatment with the bacterial isolates. The results obtained showed a better affinity of Bacillus cereusto hematite mineral surface rather than silica surface and could be used in separation of such mineral from its associated gangue minerals. On applying B. cereusbacterial strain as a sole flocculating agent, to selectively separate hematite from its mixture with silica, succeeded in the removal of 80% of SiO2as a concentrate containing about 2% SiO2and 98% Fe2O3with 82% flocculated by Wt. and a good recovery of 89.20%.

Published
2018
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