Spotting Calcium Oxalate in the brewhouse?

[prettythings]

Hi all,

Even though our deep well water is calcium rich and we add quite a bit calcium to the mash, we've seen a creation and carry-over calcium oxalate crystals to the final product - so much so that we've had gushing issues. We know they're there because they're easy to spot in the microscope at 40x.

So we're working on various ways to reduce the oxalate. In the meantime, does anyone out there have a program in place at their brewery to spot the crystals using microscopy on brewdays? How do you go about it?

I'm not sure how common this problem is.

Cheers,

Dann

[GarySped]

Dann,

How do you know for sure you have oxalates? Typically under the scope you see characteristic "Maltese crosses" ranging in size from tiny (seed crystals) to ones as big as yeast. But they can take on needle shapes and barrel shapes. You would need to spin down a small amount of beer or wort to see them. So a small bench centrifuge would be a good addition along with your microscope

The suggested way to prevent them forming is to have about 50-80 ppm. calcium in the final beer. The reason being that oxalates preciptate out as the Ca salt before they get to bottle. But Brauwelt covered the topic and suggested that the issue is more complex than this depending upon actual process/filtration/treatment and a delicate equilibrium of calcium and oxalate ions. However it would be good to start with more calcium. Problem is most do not realize that you lose 50% of calcium from start to finish (much in the mash bed - a great ion exchanger!). Also malt conveys 30-50 ppm. Ca. So taking that into account and 50% loss of that make sure you double up in water, mash or boil to end up with twice the final amount of calcium upfront. Ca chloride or Ca sulfate can be chosen as to desired style and the ProBrewer Tinseth Calculator is a good one to play with salt additions to see what you need to add.

Hopefully this will help resolve your issue. We see many beers with some oxalates in them usually the diamond/crosses but sometimes barrels. Many are in small numbers but we also see our fair share of gushers during testing so it may be a more common problem than you or others realize.

Gary.