Why do some cheap beers taste sweet?

Question

I had a Tui (cheap New Zealand pale lager) the other day, and it tasted sweet!

Why is this? Is possible that sugar is added during the brewing? What else would make it taste sweet?

Answer 1

The alcohol in beer is created as a byproduct of the yeast consuming the sugar in wort during the fermentation process. For a beer to taste sweet, there are two possibilities:

1. The yeast died before the fermentation process ran to completion. There are various chemicals that can do this.

2. The wort contained some non-fermentable sugars. If the yeast can't feed on a particular type of sugar, then it is going to remain in the end product. Lactose is a traditional example of such a sugar but some artificial sweeteners have a similar effect.

Assuming that the flavour was intended, I would guess that this was (2): using non-fermentable sugars allows the brewer to know exactly how much will end up in the final beer. It is also the only option if they do in-bottle carbonation, since that requires live yeast in the bottle.

Answer 2

The price and quality (or lack thereof) of the beer doesn't particularly come into play in whether it is sweet or not but rather how much residual sugar is left. All beer has sugar in some form, as fermentable sugars are is what the yeast eat to turn into alcohol. No sugar, no alcohol. No alcohol, no beer.

The sugar in beer primarily comes from malted barley, though other grains are often used including rye, wheat, oats, and open in the case of cheap beer, rice and corn. In my experience, it's fairly rare to find a lager (particularly a cheap one, where they want to minimize the cost of the ingredients for a given batch) with enough residual sugar to taste sweet, but it could happen I suppose. Sweet beers are frequently heavier, like barleywine style ales, milk stouts, and chocolate stouts.

You can also add non-traditional ingredients to boost the amount of residual sugar in beer, and sugar itself, in a number of forms (table sugar, brown sugar, corn syrup, maple syrup, etc.) is certainly one of those ingredients that is used from time to time. Fruit is another common ingredient used to manipulate the flavor and sweetness in beer, and you'll find virtually all kinds used in various brews. Some or the more fruits that can particularly add to the final sugar content are cherries, berries, grapes, peaches, apricots, and grapefruit.