Members Log-in
01 January 2000
More to malt than meets the eye
By
Peter Clarke
The recycling of distillery by-products has its origins in the days when many distilleries were farm-based, and feeding the protein-rich draff. spent grist left in the mashtun. to the cattle was as logical as feeding them on home-grown hay.
In the 1860's, Thomas Borthwick of Glasgow was converting distillery co-products into animal feed on a commercial basis, and the sheer concentration of distilleries in the borough led to the Campbeltown Distillers. Association operating a grain-drying plant from 1892. Cargoes of dried grains were regularly shipped to Rotterdam, ending up as feed for horses of the German army. Wet draff was sold locally at 4d per bushel and in some cases, the draff was dried and processed into pellet form, known as 'light grains'. Following tradition, many distilleries still sell their wet draff directly to local farmers.
In addition to draff, whisky-making also creates pot ale (the residue in the wash still after initial distillation has taken place) and spent lees (the residue which remains in the spirit still after the second distillation).
For many years, pot ale and spent lees were allowed to run into rivers or directly into the sea, depending on the distilleries location, but increasingly demanding environmental regulations have rendered such disposal methods largely unacceptable. As early as the 1890's, the rapid expansion of distilling on Speyside led to problems of pollution of the Spey, one of Scotland's leading salmon rivers, and one solution was for pot ale to be spread as fertiliser onto farm land.
In 1906, a plant was set up in the Speyside distilling town of Rothes to evaporate pot ale into concentrated syrup, after which it was spray-dried into powder form and sold as fertiliser under the trade name Maltassa.
The Distillers' Company subsidiary, Scottish Malt Distillers, began a project in 1952 at Aultmore distillery to improve on that process and produce a product which could be used as animal feed. Three years later a facility was installed at Imperial distillery to produce 'distillers dried solubles', and further plants were constructed by the company at some of their other distilleries.
The next significant step in re-processing con-cerned the development of 'dark grains', produced by evaporating pot ale into a concentrated syrup and incorporating it with dried draff to form cubes or pellets.
Dark grains plants were developed in the USA and Canada, and were first introduced into Scotland by Hiram Walker at their Dumbarton distillery in 1964. Soon they were widespread in the industry in Scotland, with SMD replacing the Aultmore dried solubles plant with a dark grains facility in 1965. Dark grains have a much higher protein content . up to 24% . than light grains, and have become popular as a feedstuff supplement, and also as a feedstuff in their own right. Today, up to 50% of the original tonnage of grain used in whisky-making can be recovered in the form of animal feeds.
Another by-product of the distilling process is a surplus of warm water, and various experiments have been conducted to discover effective, commercial ways of utilising that water. Tamdhu distillery tried breeding trout, while Tomatin opted for something more exotic and started rearing eels. Better known is Glengarioch's tomato-growing enterprise, which began after the distillery became the first in the industry to convert to the use of North Sea gas in 1982. Hot water was drawn from the still condensers and piped into a series of greenhouses. Nearly 200 tons of tomatoes per year were produced at the peak of the project.
Glengarioch was purchased in1970 by Stanley P Morrison (now Morrison Bowmore Distillers Ltd), and the company also found an innovative use for waste hot water at its Bowmore distillery on Islay, where a disused warehouse was converted into a public swimming pool.
Increasingly stringent environmental regulations have forced distillers to invest a considerable amount of time and money in research concerning disposal procedures. United Distillers & Vintners Environmental Manager, Ian Lambert, points to a four year study undertaken by the whisky industry into effects on trout and salmon when the temperature in rivers is raised by distilleries discharging cooling water. An EC proposal seeks to limit the temperature rise to a maximum of one and a half degrees centigrade, while independent analysis suggests that a temperature rise of up to seven or eight degrees actually has a beneficial effect on salmon development.
The industry has also been involved in extensive experiments to determine the viability of the recovery of copper from spent lees, in order to achieve compliance with Environmental Quality Standards. Lambert notes that 'Copper is dissolved during the distillation process by action of acids on the copper oxide layer which forms, between distillations, on the inner surfaces of the still and condenser systems'.
On Islay, tougher EC legislation has led to proposals to develop a long sea outfall at Caol Ila distillery, where liquid residues from a number of the island's distilleries would be collected for disposal into the Sound of Islay. At present, wet draff is sold to island farmers, and pot ale and spent lees are released into the sea. A dark grains plant would not be viable on Islay, as the cost of the processed feed to farmers would be prohibitive, necessitating its ship-ment to the mainland for sale, and denying the island's farmers a low cost animal feedstuff.
So it might just be a combination of malted barley, water and yeast, but there is more to show from it than just whisky!"
Unfiltered on Facebook