Troubleshooting

• Stuck mash
  • Your grind may be too fine. You want a good crush not flour.
  • Add some rice hulls. If your grain bill includes malted rice that's a start, but you can purchase rice hulls on their own from GFHB.
  • Grains high in beta glucan (e.g. oats and buckwheat) can create a gummy mess that makes lautering difficult. Consider a beta glucan rest at the outset of the mash.
• Poor mash efficiency (low starch to sugar conversion)
  • Insufficient enzymes or enzyme contact time.
  • Mash thickness (water to grain ratio in mash). Too thick makes it difficult to disperse enzymes. Too thin may dilute added enzymes.
  • Mash regime may not be synchronized with enzyme requirements (temperature range and gelatinization process). Many enzymes will denature at higher temperatures (see the Enzymes page for details). If you raised the mash temperature above the denature point prematurely, those enzymes may not have had time to break starch molecules into sugars.
  • pH and/or mineral content of mash may need to be adjusted
• Stuck fermentation
  • Perform a forced fermentation test to determine whether your wort is capable of higher attenuation. This can be a good standard practice to perform on each batch of beer to compare fermenter conditions versus the potential fermentability of your wort with that yeast strain.
  • Poor yeast health. Adding yeast nutrients and encouraging FAN production during mash (protein rest) can help. Ensuring sufficient oxygen in the wort at the start of fermentation is another key yeast performance factor.
  • Ensure yeast is not too old and that you have a sufficient cell count for the beer you're making. Yeast starters (on GF media) can help boost cell count before pitching (though generally not necessary with dried yeast packages).
  • Changes in temperature (especially reduction in temperature) can cause stuck fermentations. Ideally use temperature control to keep the fermenting beer at a stable, and gradually rising temperature during fermentation.
  • Yeast attenuation. Some yeast are better suited to continuing to ferment as ethanol creation increases.
• Poor attenuation (high FG)
  • May be a result of stuck fermentation (see above).
  • May also reflect the carbohydrate composition of the wort (wort higher in complex sugars and dextrins will not be as fermentable as those made from simpler sugars like glucose, maltose and maltotriose). A beer with a higher concentration of unconverted starch and complex sugars will not attenuate as well.
  • Yeasts capable of hydrolyzing complex sugars (i.e. some saison strains with the STA1 diastaticus gene) can continue to break down some more complex polysaccharides into more fermentable simple sugars.
• Too much attenuation (very low FG)
  • Usually indicates that the wort was composed of simple sugars, i.e. glucose and perhaps maltose.
  • Review your fermentables to ensure there are some less fermentable dextrins and complex sugars.
  • Crystal malts and maltodextrin may help provide some unfermentable sugars.
  • Check that you're using a non-diastaticus yeast.
  • High attenuation can sometimes indicate an infection by other microorganisms capable of working through dextrins that would not typically be fermented by saccharomyces yeast.
• No or slow yeast activity
• Beer lacking body
  • Your fermentables may be composed primarily of simple, highly-fermentable sugars (glucose and fructose for example). You can increase body by using grains and other additions that will diversity the carbohydrate profile, including more complex sugars (maltose, maltotriose) and unfermentable dextrins.
  • You may be adding enzymes that are a little too aggressive in their conversion of starch to sugar (i.e. enzymes that are focused on glucose production).
  • Consider adding some gluten free maltodextrin to your recipe.
  • You can also achieve greater viscosity with grains high in beta glucan (e.g. buckwheat and gluten free oats)
• Poor clarity
  • Can be an indication that there are some unconverted starches in the beer. You can perform a starch test during the mash process by using a drop of iodine in a sample of beer (if it turns purple or black, there are starches present). This may require you to extend the mash time, add additional enzymes, or increase the mash temperature to ensure grains have gelatinized sufficiently.
  • Haze in a finished beer may also be yeast that has not settled out yet (some yeast strains are slow flocculators).
  • Unprecipitated proteins, grain and hop material may be another source of haze. Cold crashing the beer (generally in a carboy or keg) is one way to help precipitate out this haze causing material.
  • Using gelatin or another "fining agent" in a cold crashed beer is another way to remove unprecipitated material.
• Off flavors. Common off flavors include:
  • Diacetyl (buttery, microwave popcorn) -
  • Acetaldehyde (green apple)
  • Phenols (band-aid, medicinal, cloves)
  • Grassy
  • Moldy
  • Oxidized (wet cardboard)
  • Skunky
• Lack of carbonation in packaged beer
• Poor head retention
  • Beer foam and head retention