Long delay between crushing grains and brewing beer -- explanation for low OG?

General Homebrew Discussion
1

Hi all – first post from me here – so please take it easy :).

First the backstory – I live in China and started home brewing ~3 years ago (first because I was tired of drinking Tsingtao or imported Budweiser, and then later because I found out I loved it). I mostly brew extract batches with specialty grains and just did my 3rd BIAB.

Since I don’t really trust the quality of the ingredients here in China I typically buy my ingredients in the US (when I visit a few times a year) and then bring them in my luggage back to China. As a result the grains I use typically end up sitting around for a month (or more) after crushing. I know this is not ideal but it’s the best I can do as I have not made the investment in a grain mill (which would allow me to buy unmilled grains and mill them right before I brew).

So for my attempt to brew the Weldworks Juicy Bits clone (from the Jul/Aug 2018 issue of Zymurgy) there was a lag of 12 weeks between when I bought (and crushed) the grains and when I finally brewed the beer. When I opened the plastic bag with grains I noticed a few small (ant-sized) animals (weevils?) crawling around in the grains. I did a bit of research and after that decided to plow ahead and brew with the affected grains anyway (not that I had any other options).

Here now comes the problem statement – when I was about to pitch the yeast I measured the OG and it was only 1.045 (vs. the recipe target of 1.062) – am wondering now if the old grain / bugs had anything to do with the low OG.

This was my 23rd batch of home-brew and I have used similarly old grains several times before (it’s actually rare for me to brew within a month of milling the grains), and I have never seen any significant impact on my OG so am wondering if there is any relationship here or if something else went wrong this batch.

2

That is disgusting.  You are brave to admit to this online.  That being said, I will try to help.

The larvae probably ate some of the starches which could reduce yield.  However, my primary bet is:

Local homebrew shops here in the USA typically will do a really bad job of crushing the malt for you, with average reported brewhouse efficiencies in the 60s percent from most shops.  The extent of the crush is a primary factor in determining your efficiency.  In any case, obviously you would be better served by getting your own mill and crushing your own grains, as fine as you can get away with on your system to avoid a stuck mash.  Get a mill.

Better luck next time.

3

I have used old malt, sometimes with insects, and I can say that it will lower the mash efficiency.  Try to keep it tightly sealed and as dry as possible in storage next time.  When the malt starts to get soft and mealy it has lost some of its starch.

4

Grains should keep very well sealed in their bang and un crushed for a month so why not just wait until you are ready to use them and crush them yourself? Even if you have to do it by hand with a rolling pin it should work better than using stale, bug infested grain.

5

I don’t think that the crushing caused the infestation, there were likely bugs (or their larvae or similar stage) in the grain itself and they were small enough to survive the crush…I say this, because I once had an uncrushed bag of wheat malt that got infested from the inside out - it was in an unopened bag sealed in a Rubbermaid container…I was just happy to discover it before using it - Yuck!