Some English period recipes call for oat malt, but that's not commercially available. If I use oatmeal, will I have to let the beer sit longer during mashing so that all the oat starches are converted to sugars, or will this happen in the same time as if I used 100% malt in the recipe? My theory is that because the amount of enzymes per starch is less than in a recipe calling for 100% malt, it would take longer for the enzymes in the wort to convert all the starches, including those in the oats. Are there any consequences for letting it sit at the right temperature for too long, say 3 hours? Or does conversion of the starches continue at a slower rate during primary fermentation?