I have recently been suffering from some poor efficiency in my last 3 brews. I have brewed them before and usually get around 70-75% efficiency. The latest 2 recipes were suppose to hit original gravity of 1.068 and 1.067…the results 1.056 and 1.054. I have a JSP Maltmill with no gap settings and it therefore did not change.
I had bought some grain in bulk when the LHBS went out of business 2 years ago. I stored in a large 50 gallon rubbermaid container. Could grain this old be an issue? I have used the same single infusion mash with no mash out for the last 5 years and have brewed all of the recipes before. The mash ratio is around 1.2 to 1.3 depending on the recipe.
I was wondering if I should double crush my grains and try another known recipe to see if this helps or would the old grains be an issue with the efficiency. The beers taste fine with no off flavors and taste to the originals with fresh malt.
Any help or thought would be appreciated.