As the energy value of oats depends on the size of the grain, one characteristic of high-quality oats is a large grain size.
The core of the grain must be light and transparent. A good quality level can be achieved by selecting a high-yielding, high-quality oat variety, by applying a sufficient amount of fertilizers to the crop, and by taking appropriate plant protection measures. The field and seasonal weather conditions also affect the quality of the end product.
Hulled oats must be fully ripened when harvested, threshed and dried carefully, free of mould and toxins, and healthy in terms of colour and taste. The quality requirements of fodder oats include appropriate humidity, sufficient weight per hectoliter and purity from foreign particles. The oat must meet the maximum limits set for mould toxins by the EU. Oats must not contain pesticide residues.
The key requirement for milling oats is to meet the quality specifications that will deliver the desired product to the consumer.
Essential quality traits are:
- Free from any odours and taints.
- Moisture of between 12 and 15%.
- Minimal staining or blackening of the kernel.
- Bright white flakes from the rolled kernel.
- No more than 2% of admix i.e. other grains.
- In addition the soluble fibre known as beta-glucan, must be at a level to meet the health claim but this is usually achieved naturally in oats.
- Economically the key requirements are for the mill to achieve a satisfactory yield from the grain and to be able to remove the hull or husk at a given rate.
- Milling yield is indicated by specific weight and by the kernel content of the grain. Specific weight of +50kg/hl is expected and will be part of the buying spec.
- The kernel content of around 72-75% of grain weight usually means that a reasonable yield will be obtained and that the grain will de-hull at the expected rate and efficiency.
- A further economic influence is the level of screenings. Too high a level of screenings affects throughput and yield as the small grains are removed at the cleaning stage and whilst a few can be recovered most end up in the by-product stream. A specification of no more than 2% through a 2mm screen is the usual requirement but allowances are often given.
- The millers rarely request specific varieties as all the HGCA recommendations are capable of meeting the specification. However some millers need to purchase oats which have been grown without the use of a growth regulator. Such oats are usually covered by a contract specifying this need and priced accordingly. In such cases, shorter varieties or spring sown are more likely to be suitable.
- Organic oats are also required. The specification for organic oats is similar to that for conventional