Mash Efficiency and Quality of Wort

Question

I recently achieved a 94% mash efficiency on a batch of Saison and was pretty stoked thinking, wow, 94% is much better than the the 72% I did last time. I must be getting better at this...

But then I read on several brew forums that a higher mash efficiency will negatively affect the quality of the wort.

Is this true, and if so, how? How is the wort affected and why does it happen?

Lastly, if this is the case, how does a brewer determine appropriate balance of efficiency and wort quality.

Thanks!

Answer 1

I suspect the line about higher efficiency leading to off flavors came to be because there are certain situations during a mash where if you over-sparge and your pH drops too low, then you can extract tannins and thus get some off flavors. So what happens was that some guys were over-sparging, which WILL increase your efficiency, and were noticing the tannins, and thus incorrectly assumed that it was their increased efficiency that made for a poor beer.

I've had this same line said to me by a brewery tour guide (Liveoak in Austin), so its pretty common. But again, if your mash pH is in line during the sparge, then you won't get off-flavors no matter how much you sparge.

Caveat: This is all pretty theoretical for me, as I target 75-80% efficiency, don't oversparge, and mostly make standard strength beers. I also don't specifically measure my sparge pH, but I WOULD if I were sparging a lot (for whatever reason).

Answer 2

My experience is that higher efficiency does not negatively impact the quality of the wort. A case in point is Sierra Nevada, which achieves close to 100% efficiency. In the end, let your own tastebuds be your guide.