What's going on with these gravities?

I'm a new home brewer. Since Christmas I've brewed 5 beers, all of which have been drinkable. The first I didn't have a hydrometer, the second I accidentally put in twice as much carapils as I was supposed to, but the last three have all given me the same anomaly in that og and fg are much lower than stated in the recipe. I can understand og being lower, and am aware of causes of mash inefficiency, some of which I intend to try and mitigate in future brews. What I don't understand is why the og and fg are off by the same amount.

For example my last brew is a Belgian strong golden ale. OG in the recipe was 1.070, and fg was 1.012. my gravities were 1.060 and 1.003. I would expect, if the amount of fermentables was in proportion, that an OG of 1.060 would give a FG more like 1.010. If for some reason the amount of fermentables was not in proportion (i.e the mash resulted in a lower OG of mostly fermentable sugars) I would expect a watery tasting beer, which they're not.

Has anyone experienced anything similar or have any ideas what is happening?

I've used two different hydrometers and have tried to degass samples post fermentation so I don't think these are factors. I'm doing a single step infusion mash in a cooler, which sits at 65c for an hour and maybe loses 1c during that time, followed by 2x batch sparges involving a good stir and 10 mins sitting in ~65c water, then vorlaufing again before running off.

Topic final-gravity mashing original-gravity all-grain homebrew

Category Mac

1
answered at

My first thought would be to check your efficiencies, if the recipe targets 1.070, usually aimed around 75% efficiency, and you only reach 1.060 (=56%?) than your mash is off. Being a Belgian strong I guess this beer used some sort of sugar adjunct, so keep that in mind.

But if your hydrometers are off the measurements are wrong of course. Perhaps ‘calibrate’ it with a sugar solution? Dilute a specific amount of sugar in a specific amount of water to get a pre calculated gravity.

The mash temp is fine, heavy Belgians usually tend to aim for a very fermentable wort. How often do you check the temp during the mash, and do you stir it? I’ve heard other brewers have similar results, due to loosing too much heat on the sides of the mash tun and thus parts of the mash basically being too cold. Could be the issue?

1
answered at

Your mash temp favors beta-amylase which makes a more fermentable wort.

While beta-amylase denatures beginning at 149°F / 65°C it takes a little time.

It's possible your thermometers are slightly out of adjustment and you may be further in beta range than realised.

For a less fermentable wort mash at 154-156°F, this will denature beta-amylase quicker and allow alpha-amylase to convert your starches.

As far as a dry beer 1.003 FG, it won't always be watery or even light in mouth feel if there are proteins to augment it.

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