Ong, Law - Hygrothermal Properties of FVFs2.4. CLOSING REMARKS
Heat and moisture are two important elements in food drying. Simultaneous heating and
moisture removal during drying affect both the physical and biochemical properties of
food materials. Overview on the hygrothermal data of various foods, vegetable and fruits
indicates that the effects of temperature, moisture content and water activity to hygro-
thermal behavior of foodstuffs vary from product to product. Vast hygrothermal data for
various quality properties is available in literature. Nonetheless, basic knowledge on the
measurement and interpretation of the hygrothermal properties is of fundamental im-
portance for the design, control and optimization of the drying process.
NOMENCLATURE
[A] concentration, mol dm-^3
aw water activity
cp specific heat capacity, kJ kg-^1 K-^1
Deff effective moisture diffusivity, m^2 s-^1
Ea activation energy, J mol-^1
k thermal conductivity, W m-^1 K-^1 or temperature dependent rate constant, s-^1 or
min-^1
k 0 constant or absolute rate constant, s-^1 or min-^1
R universal gas constant, 8.314 J mol-^1 K-^1
T absolute temperature, K
t time, min or s
X moisture content, kg kg-^1 dry solid
X 0 monolayer moisture content, kg kg-^1 dry solid
Greek letters
α thermal diffusivity, m^2 s-^1
ρ density, kg m-^3
REFERENCES
Aghbashlo, M., Kianmehr, M.H. and Hassan-Beygi, S.R. 2008. Specific Heat and Thermal
Conductivity of Berberies Fruit (Berberis vulgaris). American Journal of Agricultural and
Biological Sciences 3 (1):330-336.
Arntfield, S.D., Ismond, M.A.H. and Murray, E.D. 1985. The Fate of Antinutritional Factors
During the Preparation of a Fababean Protein Isolate Using a Micellization Technique. Ca-
nadian Institute of Food Science and Technology Journal 18:137-143.
Baini, R. and Langrish, T.A.G. 2008. An Assessment of the Mechanisms for Diffusion in the
Drying of Bananas. Journal of Food Engineering 85 (2):201-214.
Beauchat, L.R. 1981. Microbial Stability as Affected by Water Activity. Cereal Foods World
26 (7):345-349.