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Mashing temp and effects

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  • Mashing temp and effects

    Hi all. Trying to get BIAG correct and I am struggling. Most of my beers are not fermenting down to the correct estimated final gravity's. Always finishing too high giving me low abv but they all taste fine after fermentation and bottling. I am adding the grain and starting at 70C and usually finishes at 65/66C. It is mashing in the brewpot on the stove.
    Example. Brewed a stout and put in the fermentor on 7.2. OG was 1.047 and est was 1.013. After 10 days was still 1.022 and this has been in my living room to keep fermenting temp good.

    Ideas please
    Cheers

  • #2
    I too do BIAB and have suffered similar problems, especially when I started out with stove-top mashing. Is that 70C before you add the grain or after? Grain generally absorbs some heat so it's ok to start with 70C before adding grain. However after you've added the grain don't exceed 69C or you can start breaking down the starch converting enzymes. Higher mash temps (65-69) will convert less starches, while lower mash temps (62-64) will convert more, making a more fermentable beer. I found stove top mashing quite limiting to start with, especially as when applying heat the bottom of the pan becomes hotter than the water temp so it's easy to over-heat the grain. You could try starting a degree or two lower. Also be gentle with applying heat during the mash. I now insulate my pan with several thick blankets to minimise heat loss and apply as little heat as possible. Longer mashes can also sometimes help. If you think mash conversion is the problem you could buy iodine to test a sample of your mash for leftover starch. There could be plenty of other explanations for missing the FG, including yeast health (such as underpitching or sudden drop of temperature causing early end to fermentation) and recipe (too high in specialty grains like crystal). Brewing software can't perfectly estimate FG as there are lots of variables. The most important thing is that you are enjoying the taste and the good news is your beer will improve with experience as you get used to new techniques.

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    • #3
      I found it much easier to use a cool box mash.
      While heating your brew water, chuck a kettle of boiling water in the cool box to warm it through. Leave the lid on until required.
      Re boil the kettle.
      Once your brew water is up to temperature 70°c (ish) drain the cooler. add brew water. Add grains. Stir to avoid any lumps.
      Adjust to 66° C with boiling water from kettle..
      Do not worry about the volume too much.
      seal cooler box come back in 90 minutes - temperature will probably have dropped to 65° C . That's okay.
      Sparge and ferment.
      Gluten free, caffeine free, dairy free, fat free – you gotta love this red wine diet!

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      • #4
        Thanks for that. will try a lower temp next like 68 and it can then reduce to 63/64C. any ideas what I could try with the 2 stouts that I have at 1.020 now? I hav tried pitching 1/2 a sachet of GV12 in each 6ltr batch but with the bucket lids sealed on tight but they have not started to ferment any further?
        Both of these recipies were 90% marris otter with roast barley, torrified wheat and a little torrified barley in one.

        I wil have to look at the cool box later in the year for the next step. At the moment trying to get these beers ready for the Doncaster show at the end of march.

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        • #5
          The higher temperatures (68), will produce more non-fermentable sugars. So you will end up with a sweet finish & less alcohol.

          If you are splitting the yeast. Make it up with some water first and half a teaspoon of sugar to about 500 ml. Make sure it is foaming nicely (about half an hour at 25° C) and only then split it between the two batches.

          Coolbox will be easier than stovetop - you can still use a grain bag. It is also less risk of maillard reaction (caramelised) giving you a burnt sugar taste.
          Gluten free, caffeine free, dairy free, fat free – you gotta love this red wine diet!

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