Grain Quality
The Importance of the Chopin
Alveograph in the Export Market
With almost a quarter of UK wheat production being exported,
the successful marketing of UK cereals is increasingly dependent
on an accurate and timely assessment of cereal crop quality.
The Chopin Alveograph indices, such as W and p/l (see next page)
are used by flour millers and others engaged in export markets,
to indicate the suitability of their offerings towards making
bread or biscuits. Nearly all overseas millers test wheat by
Chopin Alveograph to get early indications of the resultant flour
quality. The key measures used are the ratio of p to l and the W value
(see next page for more details).
When buying milling wheat, it is essential for millers to know the
quantity and quality of protein. The following help estimate these:
Protein %
determines the quantity of protein
Hagberg Falling
Number
the enzyme level indicating dough
stickiness.
Chopin Alveograph
indicates the quality of gluten, which is
hydrated protein. This is the substance
that holds the loaf together, enveloping
the starch: water matrix.
Other tests such as Brabender Farinograph, Extensograph and wet
chemistry tests such as Zeleny can also be used to provide an
assessment of protein quality.
When buying milling wheat, many overseas buyers will demand a
Chopin Alveograph specification in addition to the standard measures
of protein, Hagberg Falling Number, specific weight and moisture,
irrespective of its origin.
In general the protein quality, and thus the Chopin Alveograph values,
are inherent in a variety and are not greatly affected by environmental
conditions or crop treatments. This factor makes varietal purity at
sowing and varietal segregation in store of key importance when
supplying to meet overseas customers' requirements.
British Cereal Exports,
HGCA, Caledonia House,
223 Pentonville Road, London N1 9HY
Tel: +44 (0) 20 7520 3925 Fax: +44 (0) 20 7520 3902
Email: [email protected] Web: www.hgca.com
How does the Chopin Alveograph work?
What the graph means
W=
L=
P/L =
baking strength of dough
(the area under the curve)
extensibility of dough
(time taken for bubble to burst)
dough strength and extensibility
(ratio of curve height to length)
High W =
P=
Low P/L =
strong flour
maximum pressure required
very extensible and low strength
nabim Group 1
nabim Group 2
nabim Group 3
nabim Group 4
• high pressure (P)
• long time (L) to burst
Suitable for bread and baking flours
– most varieties having bread-making
potential.
Stage 3 & 4
Dough produced and formed into a disc
Typical range
Alveograph P/L
Alveograph W
P
W
Stage 1
Wheat conditioned to standard moisture
Stage 2
Wheat milled and left to rest
Typical characteristics of different wheat varieties
Suitable for bread flour – makes
strong elastic dough and has
excellent bread-making potential.
Five stages of the Alveograph
test take place over three days
0.5 - 0.9
>200
L
Stage 5
Air is pumped into dough to test
resistance and elasticity
Typical range
Alveograph P/L
Alveograph W
P
W
• low P/L ratio important
0.4 - 0.9
170 - 310
L
Suitable for biscuit and blending flours –
makes extensible dough, good for biscuits
and blending with strong wheats.
• low pressure (P)
• long time (L)
• area under the curve (W) less critical
Typical range
Alveograph P/L
Alveograph W
P
W
0.2 - 0.4
70 - 100
L
Chopin Alveograph showing stage 5 air being pumped into dough
Typical range
Suitable for animal feed only –
makes tough, inelastic dough
• high pressure (P)
• short time (L) to burst
Alveograph P/L
Alveograph W
P
W
L
0.3 - 1.5
60 - 140
British Cereal Exports is the
Export Promotion
Department of the HomeGrown Cereals Authority