What is crimping?

Crimping is a system that enables you to harvest and preserve grain when it is at its most digestible, to realise its full energy potential.

Freshly harvested grain is processed through a crimping machine to break the outer husk and expose the carbohydrate and/or protein.

CrimpSafe 300, a proven preservative, is applied while crimping and the resultant feedstock is sealed in a clamp, in the same way as maize or wholecrop silage, to allow the fermentation process to take place. It is ready to use in three weeks.

  • All cereal crops are at their optimal nutrient value and digestibility when their natural moisture content is between 35-45% moisture. As moisture content decreases the digestibility of the grain reduces.
  • Maize grain should be crimped as close to 30% moisture content as possible. It will very rarely go below this in the UK when standing in the field.
  • Crimped grain is cost-effective in terms of gas yield per hectare, especially on land that is some distance from the farm supplying the crop.
  • The only storage requirement is a clean, airtight clamp or a flat, hard-standing surface to ensile in a plastic tube.

NOTE: For grains we talk about moisture content, unlike silages where dry matter is used. A moisture content of 35% has a dry matter value of 65%.

Crimped grain treated with CrimpSafe 300 before being sealed in the clamp.

Crimping Maize and Hybrid Rye

Crimped maize or rye gives you the option you need to manipulate your feedstock according to your needs.

With at least 80% of the biogas produced from the grain, it gives you much more flexibility when used alongside silages, especially around retention times.

Why Use Crimped Maize Grain?

  • As wholecrop maize matures its dry matter increases and digestibility, energy content and total harvestable yield decline.
  • As it dies the plant becomes more prone to fungal infection in the field, increasing the mycotoxin risk and greatly increasing the challenge of aerobic spoilage of the silage at feed-out.
  • Any mycotoxins produced will have a detrimental effect on the biology in the digester.

Crimped maize can overcome these problems and is especially useful when the maize crop has long passed the foraging stage. By harvesting the grain for crimping, the energy value of the crop can still be capitalised on.

Why Use Crimped Rye Grain?

  • Like Maize, rye also becomes more lignified as it matures, becoming increasingly difficult for the straw and seed coat to be digested.
  • The more mature the crop, the more challenging wholecrop rye can become for the digester, particularly where retention time is short or where there is no maceration.
  • Once the dry matter of the wholecrop increases to over 50% it is much more likely to cause issues such as the formation of floating layers, which may have detrimental effects on mixing and efficiency.

As rye approaches this level of maturity, a switch to crimping from whole-cropping should be considered.

CrimpSafe 300-treated rye has been proven to be higher yielding than using dry grain, not just because fresh-weight yield per hectare is higher but dry matter yield is higher too. This is because the grain is harvested in better condition, before any disease or shrivelling, thus avoiding grain losses.

Contact us for more information

What is CrimpSafe 300

CrimpSafe 300 is a non-corrosive preservative which will prevent heating and loss of energy value caused by undesirable microbial populations of yeasts and moulds in high moisture cereals.

  • CrimpSafe 300 contains food-grade preservatives that ensure the controlled lactic acid fermentation of the grain, maximising retention of nutrients and energy value:
    • Sodium benzoate
    • Potassium sorbate
    • Ammonium propionate
  • For use on grain with a moisture content of 25% – 45%. (Not to be used on grain at <25%. There is another option for grain this low in moisture. Contact us for more information.
  • Stored in the same way as silage, under anaerobic conditions.
  • The feedstock is ready to use in three weeks.

“For our anaerobic digester it’s all about getting the highest possible gas yield from our crops and we’ve opted to use CrimpSafe-treated grain as part of our feedstock as we believe it’s the most cost-effective in terms of gas yield per hectare on land that is some distance from the farm. By leaving the straw on the field we are not bringing in the part of the crop with lower gas value but returning it as organic matter to the soil as well as benefiting from a longer retention period in the digester.”

Frans De Boer – AD plant owner/ AD Advisor/ Farmer

Why use CrimpSafe 300?

CrimpSafe 300 is the ideal preservative for crimped maize or hybrid rye when managing feedstocks for the optimum digester performance, helping to achieve increased biogas yields.

With the high energy value and high biogas potential of grain, it is important to preserve it correctly. CrimpSafe 300 is the only answer.

The Benefits

  • Produces a highly digestible, high value feedstock for biogas production.
  • The process is simple – crimp, clamp, feed to the digester.
  • No heating and spoilage from yeast and moulds on opening, preserving the high energy value of this top-quality feedstock.
  • Once opened, CrimpSafe 300 has been proven to keep the feedstock stable for 300 hours – hence the name! This includes not only at the clamp face but even when it has been removed from the clamp.
  • Reduces grain loss in the field.
  • No drying or specialist storage is required.
  • In wet harvesting conditions, often found in the maize season, harvesting for crimp causes less soil movement, contamination and damage than for maize silage.
  • The declining digestibility of wholecrop as the growing season progresses is a driver to make the switch from forage to crimp.
  • Can yield about 500 cubic metres of biogas per fresh tonne depending on dry matter and quality.
  • Lower costs per hectare to haul product.
  • On-going product support from AD Feedstock Solutions who, with parent company Kelvin Cave Ltd, are the UK market leader in crimping technology – able to also work with your contractor to get the best from the crimping process.

“Our customers tend to take delivery of full lorry-loads of crimped maize which may need to last them outside the clamp for a week to 10 days. They report that the crimp keeps really well and stays cold – right down to the dregs at the end, so I have no hesitation in preserving rye in the same way.”

Frans De Boer, Contractor supplying crimped maize and hybrid rye to AD plants.

The Golden Rules of Crimping Grains

Crimped grain can be stored in a conventional clamp or in a plastic tube.

When crimping grains make sure to follow these Golden Rules:

  • Prepare the clamp/bagging site – all areas that will come into contact with the grain should be thoroughly cleaned, along with any vehicles used for handling and consolidation.
  • Line clamp walls with heavy-duty side sheeting.
  • Use CrimpSafe 300 on the grain as it is passed through a crimping machine.
  • Ensile within 24 hours of combining, filling the clamp in thin layers and consolidating it well to remove the air pockets.
  • Once filled and consolidated, cover immediately with O2 Barrier sheeting.
  • Line the shoulders with a layer of gravel bags pushed tight into the edges.
  • Fold over the side sheets and, again, fix with a layer of gravel bags.
  • Weigh down the sheeting evenly over the surface of the clamp.
  • Pay particular attention to sealing the front of the clamp by using gravel bags touching end to end to create a seal between the concrete and the sheeting.
  • Use ClampNet or the Silage Safe surface-tensioning system to protect from birds and vermin. However, ClampNets still need to be weighted down and kept tight.
  • Keep the clamp sealed for three weeks before feed-out.
  • On opening, as with silage, keep the leading edge of the sheeting at the top of the face weighted down; cutting the feed neatly; working across the whole face at least once a week.
  • Do not pull the sheet down over the face once opened – it can act as an incubator for unwanted micro-organisms.

An alternative to clamping the crimped grain is to store it in plastic tubes:

For more detailed advice on the crimping process and the storage of crimped grains please contact us.