Meeting the exacting specifications laid down by brewer and distiller customers is critical to the business of any maltster and is dependent on the barley used. The laboratory is the key to control, as the accuracy of its assessment determines if the barley is suitable to be taken into the plant and its tests are the basis upon which any subsequent dispute can be resolved.
Arrival of the purchased barley at the maltings
The first operation at intake is to take a representative sample of the barley from the vehicle bringing the grain to the maltings. This is usually done by a controlled pneumatic spear, which takes a repeatable sample from the load. Tests are then carried out for:
Germination (will it grow?)
Nitrogen content (a direct measure of protein)
Screenings (the percentage of small grains)
In addition, there is physical examination for varietal purity, any split, damaged or pre-germinated grain and other checks including the "nosing" the grain (check for the specific barley smell, which indicates good grain condition) and a visual check to ensure there is no sign of mould or fungi on the grain.
Importance of the assessment of grain at intake to the maltings.
The need for such rigorous assessment should be clearly understood. Maltsters have to take a firm line at intake not only to ensure that they receive the grain that they have purchased, but also to be able to show that they have been duly diligent in meeting barley quality requirements. By these means subsequent malt quality and food safety standards can be met.
Barley has to grow evenly during the malting process to ensure high quality malt. Dead or dormant corns cause problems; they do not producing any usable extract (or spirit yield for distilling), and they can impair the quality of the finished malt.
UK Maltsters have therefore set a minimum standard for germinative energy of 98% for barley to attain before it goes to steep.
In the UK, intake tests for germination are carried out by using a quick method, the tetrazolium staining test which takes about 10 minutes in total, and gives a germinative capacity result. This is an indication of what the germinative power of the barley is likely to be, that is 'will it grow?'. The test entails cutting 100 grains along the ventral crease, then immersing them in a solution of tetrazolium under vacuum for 5 minutes. The embryo of growing corns will be stained red; dead corns remain white or may be discoloured. The trained eye can also detect dormant and pre-germinated grains by the degree of staining. Photographs of a range of results from tetrazolium staining tests can be viewed HERE.
The germinative energy result is obtained by a visual check for rootlet growth on 100 wetted corns over 3 days. This test is used by maltsters to show how well the grain will grow if it is steeped.
The UK malting industry has always had a practice of drying malting barley down to around 12% for long-term storage. In the past this has simply been seen as an added cost for UK maltsters, but this practice is now being viewed by the rest of Europe as a positive action to prevent the growth of storage mould on barley, and the possibility of subsequent mycotoxin development.
Malting barley germinates most evenly and quickly if stored at the UK norm of 12% moisture, and cooled to below 12 degrees centigrade. The nature of our variable harvesting conditions, and normally higher moisture in grain further north, have resulted in maltsters traditionally taking a large part of their annual barley requirements into store soon after harvest and drying the grain themselves, to ensure good quality control.
To view the current statement on The moisture content of barley to be bought by maltsters click here
The amount of nitrogen within a barleycorn is a direct indication of its crude protein content; simply multiply the nitrogen analysis by 6.25. For brewing in the UK normally 1.60% to 1.75% nitrogen (10.0% to 10.9% crude protein) is required in the malting barley to achieve the malt specification for most brewers needs. If the nitrogen content is too low then the finished malt may not match the needs of the brewer's yeast and other brewing parameters. Conversely the starch content in the barley reduces as the protein increases, and it is the starch which is modified during malting, and ultimately converted in the brewers mash tun into sugars, which the brewers yeast then converts into alcohol.
Malt for export brewing requires higher nitrogen in the malting barley it is to be made from, usually in the range 1.70% to 1.85% (10.6% to 11.6% crude protein). This is predominantly for lager beer, and the higher protein content barley produces an excess enzyme level than is needed for malt starch conversion, which allows unmalted starch to be converted in the mash tun. Such starch can be in the form of rice, maize flakes etc.
Malt for distilling is measured in spirit yield, the production of which requires a high starch content (and hence lower protein) in the malting barley. A nitrogen level of about 1.5% in the barley is considered optimum and will be the maltster's target, if the crop quality allows, but distillers will use up to 1.65% nitrogen content.
The ability to test bulks accurately for nitrogen content is imperative to the success of the maltster in making malt to the customer's specification.
To view the latest information on the nitrogen levels in which maltsters will be looking to purchase barley this year click here
The Institute & Guild of Brewing's Recommended Method of Analysis is now the Dumas procedure, whereby nitrogen compounds are combusted at a high temperature to produce nitrogen gas, which is then measured. This method has the advantage that it does not involve hazardous or toxic substances and can be automated.
When barley is delivered to the maltings, each load is tested against the purchase details, and it is graded for its ultimate use. If the barley nitrogen does not match the barley sample purchased, then the maltster has to consider if it can be used against other customer requirements. The standard practice is for scaled financial deductions for non-compliance on nitrogen content, with a load rejection as a last resort.
Good malting requires plump, even sized corns, which must be covered by an even husk without gape or splitting. Water uptake into the grain must be at an even rate and amount; to ensure that germination all takes place at the same time and with equal vigour. Variation in husk thickness, or incomplete husk coverage will affect water uptake. Small or under-sized grains will not perform as well as ideal corns, so standards are set, based upon the percentage of grains retained over a screen.
The standard of most countries, except England and Wales, is 90% retained over a 2.5mm screen. Scottish growers trade malting barley on the 2.5mm standard, however, the standard is different for barley purchased in England, where maltsters normally accept 94% retained over a 2.25mm screen. UK brewers are attuned to this practice, and the resultant malt.
Most maltsters are willing to accept a small excess of screenings, with an appropriate price adjustment.
Barley intended for malt to be made for export is dressed by all UK maltsters, to meet the standard specified by the customer.
Skills of judging barley by eye have been helped by technology. However, there are some aspects where examination by trained technicians is still paramount. Checking of variety by traditional methods and inspecting for damaged grains is a task requiring great care and attention to detail, as every load has to be dealt with individually.
The malting barley variety is critical to the character of the final malt and varietal purity is of great concern to the maltster. Not only do single variety bulks of barley malt uniformly, most brewing and distilling customers select malt by specific variety and maltsters are bound contractually to deliver accordingly.
Mixed variety loads can be the result of different varieties having been bulked together in a grain store or of insufficient records having been kept in respect of farm-saved seed. UK maltsters will reject mixed variety loads.
Each consignment is therefore visually inspected at intake by trained technicians. If there is any doubt about the varietal purity of a load, it could either be rejected or, if arrangements permit, held for electrophoresis tests to be carried out.
Taint or musty odour
Good, sound grain has its own distinctive aroma that can be recognised by experience. Any mustiness or taint odour on the grain is treated by maltsters as a warning sign of possible adverse storage conditions, and will lead to closer investigation of the load of barley waiting to be delivered into the maltings. Barley with an adverse "nose" is unlikely to be accepted for malting. The warnings signs indicate that there could be potential problems with toxins from storage moulds, or threats to grain germination . This decision is based on subjective experience, not analysis, but UK maltsters have been using this skill for over 100 years.
At point of intake, all documentation with the load is checked. Confirmation is needed that all Assured grain purchases are from an assured grain producer. This means that the grower must be licensed by one of the UK schemes producing cereal crops under an auditable protocol, to ensure grain quality and food safety requirements are maintained. The UK was the first country in the world to initiate such a system, which is now being copied by many countries.
Another UK first, the pesticide passport paperwork is examined and a note taken of any post-harvest treatment to ensure that no excess chemical has been applied inadvertently and that correct pre-delivery procedures have been followed. Maltsters are frequently asked by their customers, during their regular audit meetings, to produce the passports relative to particular bulks of barley.
Detailed records are taken of all tests results, and the information is used to select barley into single variety, heterogeneous bulks of barley, which will germinate evenly to produce well-modified malt.
Maltsters have been supplying the MAGB with records of the tonnage of barley rejected since the 2002 crop year, and the reasons for the rejections. To view this information CLICK HERE