Peach Wit Part III: Fermentation

If there ever was a natural process that could be described as magical it's fermentation.  Create an environment with the right nutrients, nourishment and living conditions then add your yeast and let them do their thing until you have a wonderfully flavored beverage.  It's even responsible for adding the bubbles.

Once I added my yeast (known as 'pitching' to brewers) I wrapped my carboy up in HVAC insulation and a sweater to help keep it warm and prevent UV exposure.  These warm temperatures will help ensure a thorough fermentation as Belgian yeasts really like it warm.  It also promotes the formation of esters and phenols, the most intense varieties of flavor compounds that yeast can make.  The photo on the left shows what the beer looked like 24 hours after pitching.  The color is creamy and homogeneous from the yeast in suspension. It also has a bubbly, pale green-gray colored cloud of protein and yeast on top known as krausen.  The yeast is consuming the sugars in the wort and producing alcohol and CO2, which is being released through the one way valve on top known as an airlock.  This is what you want to see!

After a week, the beer on the right looks very different.  The yeast has dropped out of suspension (flocculated) and fallen to the bottom of the carboy where it has formed a (hopefully) compact cake known as the yeast trub.  Trub can be harvested for future uses, or another wort could be poured directly onto this trub once i siphon off the beer.  This leaves the liquid relatively clear (remember theres a lot of wheat protein that will never clear out of this particular beer).  The krausen is no longer, all that remains is a ring of residue stuck to the inside of the carboy.  Under normal circumstances, one could leave the beer like this for two more weeks to complete secondary fermentation (clearing and conditioning), however, because I am going to be adding peaches, it is recommended to transfer to a clean vessel.  I also need to transfer into a container with a wider opening to spare me from having to add the peaches piece by piece through the mouth of the carboy. 

I reviewed my initial recipe a bit and decided to up the quantity of peaches from 6 pounds to 10.  I really wanted the peach flavor to shine, and went all the way down to Niagara on the Lake to buy some of the best peaches that Ontario has to offer.  I cut and pasteurized all the fruit by vacuum packing them into bags and cooking them in 170F water bath for an hour.  This makes sure that any bacteria on the peaches doesn't make it into my beer alive and cause it to spoil.  This all went into the bottom of my plastic fermenter bucket (a little less glamorous than a carboy, but equally effective).

The beer was racked over the peaches, and secondary fermentation ensued over the next two weeks.  During this time the yeast first ate and fermented the new sugars from the peaches. Afterwards it refines the existing flavor compounds.  This refinement is known as conditioning, and really cleans up the flavor of the final product.

After the two weeks have passed I bottled up the beer.  I add a little bit of additional malt sugar before bottling to give the yeast something to feed on in order to make the carbonation for the beer.  Wits are highly carbonated styles so I added more malt sugar than usual.  Over the course of the next three weeks the beer will eat up this last little bit of sugar, and flocculate to the bottoms of the bottles.  At this point the beer is ready for consumption!

Stay tuned for Peach Wit Part IV: The Final Product!