Releasing the summery stuff from the blend: Michael Jackson raises his glass to the delicate notes of Invergordon Single Grain whisky

WHAT could be more cooling than the melted snow of the Highlands? Pour it over grains of malted barley and unmalted wheat; distil it, mature it, bottle it and serve the pale, golden liquid in a tall glass packed with rocks. No need for mixers or garnishes.

Did I mention wheat? Not just barley? Yes, this is grain whisky, the lighter, more summery liquor that comprises two-thirds or three-quarters of your typical bottle of blended Scotch. It is only the remaining third or quarter of the bottle that is made up from the richer malt whiskies, sometimes smoky, peaty, seaweedy, sherryish or wintry.

Why can't we release the summery stuff from the blend? Why can't we have single grain whiskies? We do, after all, have plenty of single malts.

For many years, the odd single grain Scotch has been bottled, but none has been widely available. Nor did any of them highlight the qualities of the style: clean and crisp but still with some of the flowery, grainy, sea-breezy flavours that are an essential element of Scotch.

Now someone has done it properly. With the slogan 'abandon your conventional spirit', the Invergordon Single Grain has sauntered on to the market. It is produced in the Invergordon grain distillery, at the village of the same name, overlooking the Cromarty Firth, north of Dingwall and Inverness. The distillery's parent company is also called Invergordon. The company additionally owns four malt whisky distilleries: Tamnavulin, in the glen of the Livet, on Speyside; Tullibardine, in Perthshire; Bruichladdich, on the island of Islay; and Isle of Jura. As well as being available as singles, the grain whisky and the four malts also go into Mackinlay and other blends.

The Invergordon Single Grain is probably too off-beat an idea to become a major brand, and that is not the intention. But it deserves points for enterprise. Because grain whisky is lighter in flavour than the malts, connoisseurs of Scotch have tended always to treat it as nothing more than a curiosity. This is a shame.

Invergordon is grain whisky in a confident mood. It is the only grain whisky made in the Highlands - all the others are produced in the Lowlands - and this makes a difference. The water flows from Ben Wyvis (3,400ft), which is capped with snow for most of the year. It is soft water, flowing through fissures in the granite - and sometimes over peat, which is very faintly evident in the finished whisky.

Mountain streams fill a loch four miles long, at about 700ft, with rock and boulders on one side, a forest of Scotch pine, spruce and birch forest and stretches of heathery moorland on the other. The air is sharp with the aroma of pine. These waters spill into a glen of gorse, whence they are piped 15 or 20 miles to the distillery, just above sea-level. There, the water meets the grains.

A blend of malted barley and other cereals is used in the fermentation and distillation of all grain whiskies. At Invergordon, the proportion of malted barley is 11 per cent, which is marginally higher than average. The rest of the grist is wheat, most of it grown in the Highlands around Thurso and Wick, Easter Ross, the Black Isle and the Moray coast. Distillers of grain whisky are happy to use wheat or maize, and deny there is a difference in the end product, but I find that hard to accept. Russian vodka-distillers swear that wheat gives the cleaner spirit, and the odd night's study of the real thing in Moscow has convinced me that is true.

Both vodka and grain whisky are distilled in a continuous system, in vessels shaped like columns. There are two of these columns each 60ft high, at Invergordon. One is made from stainless steel, the other copper, and it takes a pass through each to turn the fermented grain into spirit. Column stills produce a more refined, less complex, spirit than their 'pot'-still, malt whisky counterparts.

Nevertheless, single grain whisky emerges from the columns with several hundred natural flavour components deriving from the water, the grain, the yeast and the changes that take place during fermentation and distillation.

While vodka need not be aged, Scotch whisky must have a minimum of three years in wood. Invergordon Single Grain is matured for 10 years in casks previously used for Bourbon. New wood would overpower such a delicate whisky, and is rarely used in Scotland. Invergordon has half a dozen coopers to repair its casks, and they provide a touch of handcrafted romance in a somewhat industrial-looking distillery.

Maturation is at the distillery, so the casks will over those 10 years breathe in a healthy draught of sea air. There are more than half a million casks, in 36 warehouses. When I tested the whisky at three years old, it seemed to me quite piney and resiny. I rather liked it at seven, when it seemed rounder, with a buttery sweetness, notes of vanilla and a hint of Bourbon. At 10, the aroma had rounded out to become very appetizing, indeed, with a hint of saltiness, but I found the palate a little blander.

Initially, 10-year-old Invergordon Single Grain has been marketed at about pounds 16, at Tesco and in many other retailers. For all that it may be regarded as a curiosity, it has enjoyed sufficient success to be now appearing also as a 22-year-old, at about pounds 40, in specialist shops.

Could this flirtation with the lighter stuff outlast the summer? Or will I want something stronger when winter returns?