Abstract
In Sub-Saharan Africa, drying maize on their stem was the traditional technique frequently used; this technique must be improved to avoid contaminations and to increase the quality of drying. However, the method of storage is accountable for the most significant losses after harvest, because mildew develops when the conditions of storage (too high temperature and moisture of the air) do not tally with the final content of the dried product. Sorption isotherms of products are most important to model moisture uptake during storage and distribution. Sorption isotherms of intermediate moisture content maize grains were determined using the gravimetric static method of saturated salt solutions at 30°C, 40°C, 50°C, and 60°C, and GAB equation was applied to discuss the results. This model correctly describes the evolutions of maize sorption isotherms, with maximum deviation of 0.0080 kg water/kg db. The net isosteric heat of sorption was determined also, using the Clausius–Clapeyron equation, and it was varied from 463 kJ/kg to 1,264 kJ/kg, decreasing with increasing moisture content. This effect was well described by an exponential function with a regression coefficient R2 > 97%. The monolayer moisture content was found to decrease with increasing temperature. These results can be used to predict the potential changes in the stability of maize grains and later for the development of a system of suitable drying.
Acknowledgments
The author expresses his sincere thanks to National Advanced School of Engineering, University of Yaounde I, for material support for this work.
Nomenclature
- aw
Water activity
- C
Parameter linked to monolayer heat of sorption
- Hw
Condensation heat of pure water (J/mol)
- Hm
Total sorption heat of the monolayer (J/mol)
- Hq
Total sorption heat of other layers (J/mol)
- K
Parameter linked to multilayers heat of sorption
- m
Product mass (kg)
- M
Absorbing material molecular mass (kg/mol)
- N
Avogadro number (/mol)
- Qsorp
Sorption heat (kJ/kg)
- Sm
Specific area (m2/m3)
- X
Moisture content (kg water/kg db)
- Xm
Monolayer moisture content
- T
Absolute temperature (K)
- R
Perfect gas constant [J/(mol K)]
- ρ
Density (kg/m3)
- θ
Temperature (°C)
- Indices
- 0
Initial
- db
Dry basis
- eq
Equilibrium
- exp
Experimental
- ref
Reference
- W
Water
- wb
Wet basis
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©2014 by De Gruyter
Articles in the same Issue
- Frontmatter
- Grinding Characteristics of Black Soybeans (Glycine max) at Varied Moisture Contents: Particle Size, Energy Consumption, and Grinding Kinetics
- Design and Development of Low-Cost Makhana Grading and Roasting Machine
- Investigation of Consecutive Fouling and Cleaning Cycles of Ultrafiltration Membranes Used for Whey Processing
- Kinetic Models of Evaporation and Total Phenolics Degradation during Pomegranate Juice Concentration
- Predicting Sorption Isotherms and Net Isosteric Heats of Sorption of Maize Grains at Different Temperatures
- Estimating Some Physical Properties of Sour and Sweet Cherries Based on Combined Image Processing and AI Techniques
- Functional Properties of Re-fabricated Rice as Affected by Die During Extrusion Process
- Isolation and Characterization of Corncob Cellulose Fibers using Microwave-Assisted Chemical Treatments
- Physical Properties of Red Guava (Psidium guajava L.) Pulp as Affected by Soluble Solids Content and Temperature
- Levels of Fluoride in the Ethiopian and Imported Black Tea (Camellia sinensis) Infusions Prepared in Tap and Fluoride-Rich Natural Waters
- Process Optimization and Quality Analysis of Carambola (Averrhoa carambola L.) Wine
- Physical Properties of Gluten-Free Bread Made of Corn and Chickpea Flour
- In Vitro Anti-tumor Effects of Chemically Modified Polysaccharides from Cherokee Rose Fruit
- Optimization of Ohmic Heating of Fish Using Response Surface Methodology
- Response Surface Modeling for Optimization of Textural and Color Characteristics of Dried Grapes
- Response Surface Analysis for Preparation of Modified Flours using Twin Screw Extrusion Cooking
- Modeling the Effects of the Quantity and Particle Size of Wheat Bran on Some Properties of Bread Dough using Response Surface Methodology
- Testing of a Condensation-type Heat Pump System for Low-temperature Drying Applications
- Comparison of Chemical, Textural and Organoleptic Properties of Pastry Sheets with Two Different Additives
Articles in the same Issue
- Frontmatter
- Grinding Characteristics of Black Soybeans (Glycine max) at Varied Moisture Contents: Particle Size, Energy Consumption, and Grinding Kinetics
- Design and Development of Low-Cost Makhana Grading and Roasting Machine
- Investigation of Consecutive Fouling and Cleaning Cycles of Ultrafiltration Membranes Used for Whey Processing
- Kinetic Models of Evaporation and Total Phenolics Degradation during Pomegranate Juice Concentration
- Predicting Sorption Isotherms and Net Isosteric Heats of Sorption of Maize Grains at Different Temperatures
- Estimating Some Physical Properties of Sour and Sweet Cherries Based on Combined Image Processing and AI Techniques
- Functional Properties of Re-fabricated Rice as Affected by Die During Extrusion Process
- Isolation and Characterization of Corncob Cellulose Fibers using Microwave-Assisted Chemical Treatments
- Physical Properties of Red Guava (Psidium guajava L.) Pulp as Affected by Soluble Solids Content and Temperature
- Levels of Fluoride in the Ethiopian and Imported Black Tea (Camellia sinensis) Infusions Prepared in Tap and Fluoride-Rich Natural Waters
- Process Optimization and Quality Analysis of Carambola (Averrhoa carambola L.) Wine
- Physical Properties of Gluten-Free Bread Made of Corn and Chickpea Flour
- In Vitro Anti-tumor Effects of Chemically Modified Polysaccharides from Cherokee Rose Fruit
- Optimization of Ohmic Heating of Fish Using Response Surface Methodology
- Response Surface Modeling for Optimization of Textural and Color Characteristics of Dried Grapes
- Response Surface Analysis for Preparation of Modified Flours using Twin Screw Extrusion Cooking
- Modeling the Effects of the Quantity and Particle Size of Wheat Bran on Some Properties of Bread Dough using Response Surface Methodology
- Testing of a Condensation-type Heat Pump System for Low-temperature Drying Applications
- Comparison of Chemical, Textural and Organoleptic Properties of Pastry Sheets with Two Different Additives