World Grain - October 2015 - 82

MILLING OPERATIONS

Figure 1: Particle size distribution

Percentage retained on sieve

100
80

0.841 mm (no. 20)
0.718 mm (no. 30)
0.507 mm (no. 40)
0.358 mm (no. 50)
0.273 mm (no. 60
0.230 mm (no. 70)
<0.230 mm (pan)

60
40
20
0

1

2

3
Brand

4

5

Particle size distribution of five brands of whole wheat flour obtained from
a local market. Brand 1: All natural premium whole wheat flour; Brand 2:
Old-fashioned 100% stone ground all natural whole wheat flour; Brand 3:
All natural whole wheat flour; Brand 4: 100% stone ground whole wheat
flour; Brand 5: Premium 100% whole wheat flour.
Figure 2: Lipid degradation
Whole wheat lipids
Lipase
Non-esterified fatty acids
Lipoxygenase
and moisture

Autoxidation

Lipid oxidation products

{

{

Functional properties
Sensory acceptability
Nutritional quality
Functional properties
Sensory acceptability

Causes and consequences of lipid degradation in whole wheat flour during
storage.

Lipoxgenase activity (umol O2/10 min/g)

Figure 3: Lipoxygenase activity

40
30
20
10
0
0

20

40

60

80

100

120

140

Non-esterified fatty acids (umol/g)

Lipoxygenase activity in aqueous suspensions of whole wheat flour as a
function of non-esterified fatty acid content.
82

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more research is necessary to identify components with the
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World Grain - October 2015

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