It may surprise some people to know that virtually all wines contain sugar. Obviously, say, Sauternes or cream sherry does, but even the driest of dry Champagnes carries a little.

This is because the fermentation almost always comes to a halt before the job is absolutely and completely done. The job? Well this is yeast converting sugar – fructose in the ripe grapes – into alcohol.

I once heard a Scottish distiller sum up fermentation very well. “Yeast is a wee organism that eats sugar, pees alcohol and farts carbion dioxide,” he told a group of somewhat nonplussed Japanese tourists on the Isle of Islay.

Anyway, there are two reasons why fermentation stops short of total conversion of sugar to alcohol. One is that alcohol, bizarrely, inhibits its own production by interfering with yeast metabolism, but the much commoner one is that the winemaker wants some residual sugar so that the finished wine tastes right.

And there are all sorts of levels of residual sugar, which is measured in grams per litre. A dessert wine might weigh in at 150g or more while a very dry Loire Sauvignon Blanc could be less than 1g/litre.

This matters, of course, if you’re concerned about how much carbohydrate you’re consuming and particularly if you are being strictly #LCHF (low carb, high fat) in order to lose weight. If you were to have a couple of glasses of very lush big brand Zinfandel, for example, it might contain enough residual sugar – 18g/litre – to interfere with your careful avoidance of all the “red” food groups.

High residual sugar is sometimes used to mask defects in wine but more often to woo consumers. All of us are programmed from the womb to like sweetness. Most of us had a Coca-Cola habit when we were at school and Coke has 108g/litre of sugar. Is it any wonder that sweetness in that grown-up drink, wine, sells.

There’s also a belief that “dry” on the label and sweet or, at least off-dry, in the mouth is a winning combination. Back in the 1970s there were hugely successful sherry brands that used precisely this ploy. And one of the reasons for the success of Croft Original is that it looks like dry sherry (i.e. sophisticated) but tastes sweet (i.e. a taste that doesn’t need to be acquired).

It’s hard to say what is the average RS (residual sugar) of the average wine but, very broadly speaking, we’re looking at somewhere between 4g and 8g/litre. There are plenty of wines that present themselves as dry but in fact contain 10g to 12g/l of sugar.

It certainly can be deceptive. I tasted a Godello recently and mentally put it down as pretty dry, in other words about 2g/litre. It turned out to be 5g.

Anyway, I have assembled a few wines that weigh in with low RS and very keen prices, all from Aldi Ireland (but available in Aldi UK too, of course).

Prices at time of writing, May 2017

JC Mas Estate Organic Blanc
€9.99, Aldi
Five separate areas in the Languedoc contribute the grapes for this unusual and attractive white wine. There’s Grenache Blanc and Vermentino for freshness, Viognier adds a kind of peachiness and the lovely touch of rose petals, and spice comes from the Muscat. Gloriously drinkable, delightfully different. And organic!
RS = 1.5g/l

The Forgotten One Sauvignon Blanc
€9.99, Aldi
This is brilliantly nettley (a word I’ve just made up to indicate the green, fresh smell of crushed nettles), fabulously fresh and full of zest in a true Loire Sauvignon kind of way (it’s from Haut-Poitou where there’s much beter value than in Sancerre and Pouilly-Fumé). A proper grown-up aperitif and stunning with fresh goat’s cheese. 
RS = 0.3g/l

Exquisite Collection Clare Valley Riesling
€9.99, Aldi
The dryness here is deceptive because there’s lovely Clare Valley fruit which gives a mouthfilling impression with lots of lime and a touch of passionfruit, even a classic Riesling whiff of four star unleaded! Just to underline the fact that RS can vary from vintage to vintage, the 2014 was 0.45g/l and the 2015 went up to 1.2g/l . The current 2016 is down again, registering 0.7g/l.

Pardon My French Fitou
€7.99, Aldi
A great value wine from this rather neglected southern French wine region with plenty of fruit from Grenache, Syrah and – interestingly – Carignan. Plums, pepper and black licquorice, even a suggestion of herbs, the scent of the sun-drenched garrigue here. Chunky, earthy and unprententiously flavoursome.
RS = < 2g/l

Pardon My French Minervois
€7.99, Aldi
From the mountainous vineyards way down south near Carcassonne, this blend of Syrah with a little Grenache is, in a sense, the essence of French bistro. It has terrific colour, plenty of fruit, a touch of black olives, round tannins and its savoury style demands simple, good food: charcuterie, crusty bread, patés and terrines, and – very LCHF - a rare steak.
RS = <2g/l

Lot 22 Les Terrasses du Larzac
€12.99, Aldi
This is serious stuff. Not only have we 70% Syrah, but the grapes are from low-yielding 40 year old vines growing on the Terrasses du Larzac on the lower slopes of Mont Baudile in the heart of the Languedoc. Expensively aged for almost a year in new oak casks. The result is a fabulous ripe, round red wine with lovely complexity and impressive length at a knockdown price. RS = 1.6g/l.