Wednesday, October 20, 2010

Foraging the city: Olives

Olives will be ripening now through December in the Sonoran Desert.  So yesterday I took a trip to Encanto Park in downtown Phoenix to see if I could find any olives ready for harvesting.  At the park I found several olive trees ready for harvest.  Olives develop on the tree green and as they ripen their color changes to a reddish-purple color and then finally to black.  They are best to harvest just before they turn black.  Olives grow amazingly well in the desert and are a huge food crop that largely goes unnoticed by the general desert dwelling public.  Very few people actually do anything but be annoyed by and try to get rid of this abundant food source in Phoenix.  So, being that olives are one mans trash, I hope to make that mans trash into a delicious olive treasure.  So I picked three pounds of nice plump reddish-purple olives right off the tree.  The problem and reason why olives are largely considered annoying trash is that if you were to bite into one right off the tree it would be disgusting.  Unprocessed olives contain a bitter compound called oleuropein which makes them unpalatable.  It is so disgusting that if you taste an unprocessed olive once you will never do it again.  (Yes, I speak from experience.)

 One of the olive trees I collected three pounds of olives from in Encanto Park.

In order to make a disgusting olive into a tasty one we must fist brine and ferment it for at least a month.  Both interesting biological processes in themselves.  First the olives were rinsed off and a small cut made on one side of them.  The cut allows for the brine to access the inside of the olive easier and can speed up processing by a few months.  Once all the olives were cleaned and cut, they were placed in a one gallon jar and submerged in an 8% sea salt solution to brine and ferment them.  A weight must be placed on top of the olives so they will not float to the top (We used a one-gallon ziplock bag filled with water to weigh the olives down).  The salt solution will flush the oleuropein out the olives, kill bad bacteria, and allow for lactic acid fermentation to take place.  Lactobacillus sp. bacteria carry out this fermentation and process some of the oleuropein into more tasteful substances.  Once a week for three to four weeks the salt brine must be replaced with fresh brine.  At week three taste an olive, if it don't taste good to you brine it for another week.  At week three or four, or when the olives taste good, drain the olives of the brine and replace it with a flavored vinegar brine.  We will discuss this process and the final vinegar brine more when this batch of olives is done in about a month.
My jar of brining and fermenting olives.  Olives were cleaned, cut on one side, then submerged in an 8% sea salt solution.  To keep the olives submerged they were weighed down with a water filled zip-lock bag.  The opening to the container was covered with plastic wrap to prevent any contamination. 

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