Wheat Quality Parameters

Under normal intake situations at the mill, the following tests are typically done to determine the quality of the wheat being delivered. This information will validate the contract specifications as ordered. Elements of quality which do not meet the expected standard can provide the basis for rejection of the consignment or for a claim to be made on the contract price. This list is not definitive and individual companies may vary or extend the number and range of tests undertaken. Smell
Most contracts will stipulate the required condition of the grain be "sound, sweet and clean, free from bug damage, foreign grains, smut, decay, insect and grain storage pests, vermin, visible sprout, and any other blemish or damage" or similar wording. Some microbial infection or diseases are not visible with the naked eye, but their effects can be smelled quite easily.

Visual appearance
Similar to the smell criteria, it is sometimes possible to identify varieties by their physical characteristics alone. It is not uncommon, due to shared storage facilities, that some contamination may occur, and even at levels as low as 2 or 3% can affect the milling/baking quality of the contracted grain variety.

Protein content
Most wheat is purchased on a protein basis, as this dictates the potential end use(s) of the the flour.

Moisture Content
The moisture content of a wheat will dictate its' suitability for long term storage (see Hagberg Falling Number below).

Hagberg Falling Number test
This is a measure of the enzyme activity in the wheat. If wheat has been stored in damp and moist conditions prior to delivery, or harvested incorrectly, it may begin to germinate (or sprout). The enzymes released during this process will make the resultant flour almost useless for breadmaking, as these enzymes will no longer be available for the fermentation process.

Gluten Quality
Gluten is a protein made from a combination of the proteins glutenin and gliadin (which forms around 85% of the total protein). Protein quality is important for baking purposes. Strong elastic gluten indicates it is good for breadmaking, a weak and slack gluten is better used in biscuits and cakes.

Gluten quantity and quality is usually dictated by varietal origin, but can be affected by such things as heat damage caused during drying for example.

Specific Weight
Measured as kilograms per hectolitre, this test checks the density of the grain. Typically, denser grains have a higher extraction potential compared to less dense grains of a similar size. Lower or higher than expected hectolitre weights for a given variety will pick up such things as shrivelled grains, higher or lower than normal moisture, or other contaminants which all serve to reduce the potential extraction of flour. 

Admixture (screenings or contaminants)
Even with the best intentions, wheat can be contaminated during the harvesting and on-farm storage process. Contaminants can include ergot, insects, other cereal grains,straw, stones, chaff and soil. It is normal to have between 1% and 3% "admix", at levels above this it may be possible to make a claim on the contract price, as this admixture may adversely affect the perfomance of the cleaning process, or interfere with transport elements in the process.