Flour from common wheat (grano tenero) is widely available and is used extensively for foods such as; pasta, breads, pastries etc. Hard grain Durum (grano duro) is prized for its special properties that make it perfect for pasta. The flour it makes is yellow (from beta carotene) and it has a short and hard gluten which traps the flavour from sauces. Durum is grown in the hot and dry regions of southern Italy. Durum is the hardest of all wheat varieties and so the flour it makes is quite coarse and gritty.
Farina di grano tenero (soft wheat) – Triticum aestivum
This flour is graded as type 00, 0, 1, 2 and integrale which indicates how white the flour is. Theses grades are defined by Italian law* and specify a maximum ash content. Flour analyses denotes ash as the remaining residue of a sample which has been incinerated and this indicates mineral content. Whole flour (integrale) retains all of its minerals while the most refined 00 includes little mineral content. However 00 flour is prized for it starch and gluten quality and is suitable for use with lievito madre.
|Ash (%)||Protein min. N×5.7 (%)|
|Type 00||0.55 max||9|
|Type 0||0.65 max||11|
|Type 1||0.80 max||12|
|Type 2||0.95 max||12|
|Integrale||1.30 – 1.70||12|
NB. These grading numbers do not in anyway represent flour fineness (granulometry). This is a common misconception. Fineness can be related to the wheat type and milling decisions. It is the case that soft wheat naturally breaks into smaller particles compared to hard wheat during milling.
Farina di grano duro (hard wheat) – Triticum durum
Semola di grano duro aka durum wheat comes in a few varieties; Farina di grano duro, Integrale, semolato, and rimacinata (re-milled).
|Ash (%)||Protein min. N×5.7 (%)|
|Semolato||0.90 – 1.35||11.5|
|Semola integrale di grano duro||1.40 – 1.80||11.5|
|Farina di grano duro||1.36 – 1.70||11.5|
Alveograph – W, P and L
On a professional level it’s helpful to have an idea of how strong a flour is. The W value indicates this. This data comes from a test of the flour done using the Chopin alveograph. Flour with a high W value will have a high gluten content.
The physical properties of dough can be described as viscoelastic and in context the property of extensibility is specific to dough rheology concepts. Extensibility can be defined as the degree of stretch before breaking and that’s what the alveograph measures as L. Whereas viscosity describes flow rate / fluidity.
The results recorded from testing with the alveograph produces an alveogram. This graph shows P (y-axis) and L (x-axis), they are both measured in millimetres (mm). L describes the growth of the dough bubble and P indicates resistance to deformation based on pressure.
P (mm H2O) – Resistance / tenacity
L (mm) – Extensibility
W (×10-4 Joules) – Deformation energy
P/L – resistance vs extensibility ratio
As the test begins a line is drawn, P will increase as the dough resists deformation. The peak height (P) is where the dough resistance has equalized with input pressure, the line then descends as the resistance has been overcome. At the same time L is drawn horizontally as the dough bubble expands. The test is complete when the dough bubble ruptures.
The P/L ratio describes the resistance proportional to extension length. It is a dimensionless property but for those familiar, it’s a good indicator of flour performance and specifically how ‘balanced’ the flour is.
Flour milled from hard North American wheats can be characterized as having high P/L ratios. They are typically more resistant than softer European wheats. For Italian millers this balance between tenacity and extensibility is very important and you can expect to find that most soft wheat flours have been milled to meet the optimal target of P/L 0.55.
Some of the finest flour producers (Italy):