How much water is required for conversion

1.) Is there a minimum qt./lb. ratio required for starch conversion in the mash?
2.) What is the difference between "extraction" and "conversion"?

 

1.25 qt to lb of grain.

 

1.0 to 1.5 qt/lb is the range most brewer's shoot for. I tend to be right at 1.2 qt /lb most of the time. 1.0 qt/lb tends to get a little thick sometimes making it more difficult to stir your mash.

Unless you have some other volume management issues going on, shooting for the middle of the range is a good place to be.

In lay use, I tend to think of conversion as the actual process of turning the starches into sugars. When I think of extraction, I tend to think of some sort of quantification of the process itself. But really this is usage. I'm sure someone will specify - with scientific backing - that extraction is pulling the starches from the grains, and conversion is the enzymatic reaction that converts them to sugars - or something along those lines.

Whether you are "extracting" or "converting" starches, at the end of the session you wind up with fermentable wort, and that is what it is all about.

 

Theoretically the minimum is just enough to fully wet the grains. Of course this isn't going to work very well with brewing. If for some reason you wanted to use the minimum, then enough water to give it a porridge consistency should to the trick.

I think of conversion as a biochemical process where the starch is converted to sugars. Extraction is a physical process where sugars and other flavor compounds are removed from the remainder of the grains (husks, etc.) Or in other words, you can have extraction without any conversion (like steeping specialty grains in an extract beer)