Jangam, Mujumdar - Basic Concepts and Definition
tive diffusivity correlations obtained with simple geometric shapes (e.g., slab, cylinder or
sphere) to the more complex shapes actually encountered in practice as this may lead to
incorrect calculated results (Gong et al., 1997).
Table 1.6. Approximate ranges of effective moisture diffusivity in some food materials
(Zogzas et al. (1996), Marinos-Kouris and Marouris (1995) and other sources)Material Moisture content (kg/kg, d.b.) Temperature(oC) Diffusivity (m^2 /s)
Alfalfa stems 3.70 26 2.6× 10 -^10 - 2.6× 10 -^9
Animal feed 0.01 - 0.15 25 1.8× 10 -^11 - 2.8× 10 -^9
Apple 0.10 - 1.50 30 - 70 1.0× 10 -^11 - 3.3× 10 -^9
Avocado - 30 - 58 3.3 × 10 -^10 - 1.2× 10 -^9
Banana 0.01 - 3.50 20 - 40 3.0× 10 -^13 - 2.1× 10 -^10
Beef raw (freeze
dried)
0.127 25 3.07× 10 -^11
Beet - 65 1.5× 10 -^9
Biscuit 0.10 - 0.60 20 - 100 8.6× 10 -^10 - 9.4× 10 -^8
Bread 0.1-0.75 20 - 100 2.8× 10 -^9 - 9.6× 10 -^7
Carrot 0.01 - 5.00 30 - 70 1.2× 10 -^9 - 5.9× 10 -^9
Cauliflower 11.5 - 0.05 60 - 90 2.54× 10 -^12 - 3.8× 10 -^12
Coconut (albumen) 0.2-0.6 45 - 110 4.6× 10 -^11 - 6.6× 10 -^10
Coffee extra 0.08-1.5 30 - 70 1.0× 10 -^11 - 3.3× 10 -^10
Corn 0.04-0.4 10 - 90 1.0× 10 -^12 - 1.0× 10 -^10
Egg liquid - 85 - 105 1.0× 10 -^11 - 1.5× 10 -^11
Fish muscles 0.05 - 0.30 30 8.1× 10 -^11 - 3.4× 10 -^10
Garlic 0.2-1.6 22 - 58 1.1× 10 -^11 - 2.0× 10 -^10
Garlic 0.06-1.89 40 - 70 1.3× 10 -^10 – 3.2× 10 -^9
Grain (sorghum) 0.021 55 2.8× 10 -^11
Glucose 0.08 - 1.50 30 - 70 4.5× 10 -^12 - 6.5× 10 -^10
Lentil 0.1-0.2 30 - 50 2.8× 10 -^11 - 2.8× 10 -^9
Milk (dry) 0.13 25 2.1× 10 -^11
Muffin 0.10 - 0.95 20 - 100 8.5× 10 -^10 - 1.6× 10 -^7
Onion 0.05-18.7 60 - 80 2.3× 10 -^10 - 6.6× 10 -^9
Peanut (roasted) 0.01-0.02 25 3.8× 10 -^12
Pepper (Green) 0.04-16.2 60 - 80 3.8× 10 -^10 - 1.2× 10 -^8
Pineapple 0.2-2.0 20 - 60 1.62× 10 -^10 - 1.2× 10 -^9
Potato 0.03-5.0 60 - 100 2.8× 10 -^10 - 5.3× 10 -^9
Potato (sweet) 0.1-3.5 32 3.7× 10 -^10 - 4.35× 10 -^10
Raisins 0.15 - 2.40 60 5.0× 10 -^11 - 2.5× 10 -^10
Rice 0.10 - 0.25 30 - 50 3.8× 10 -^8 - 2.5× 10 -^7
Soybeans 0.07 30 7.5× 10 -^13 - 5.4× 10 -^12
Starch gel 0.20 - 3.00 30 - 50 1.0× 10 -^10 - 1.2× 10 -^9
Tobacco leaf - 30 - 50 3.2× 10 -^11 - 8.1× 10 -^11
Tomato (concen-
trate)
5.7 60 - 100 1.7× 10 -^10 - 6.5× 10 -^9Wheat 0.12 - 0.30 21 - 80 6.9× 10 -^12 - 2.8× 10 -^10
In addition to being dependent on geometric shapes, diffusivity depends as well on
the drying conditions. At very high activity levels, no differences might be observed but
at lower activity levels, the diffusivities may differ by an order-of-magnitude due to the
inherently different physical structure of the dried product. Thus, the effective diffusivi-