Stir Plate

Welcome back to Off The Hinge Brewing!  I wanted better yeast starters, so I built my own stir plate.  My beer has improved due to the starters that I have made in the past, yet that is not enough for my standards.  I have read many threads on the subject and decided to go a bit more pro by making a stir plate.  This project made me feel like Richard Dean Anderson!

A stir plate is a rotating magnetic force that turns a piece of metal (stir bar) inside the starter causing a vortex within the wort.  The reason for this motion is to keep the yeast in constant suspension.

There are several advantages to doing this.  First, it provides the wort and the yeast with an ample amount of oxygen.  Wyeast Laboratories states, "Oxygen is used by yeast for synthesis of sterols and unsaturated fatty acids that are necessary growth factors.  Without oxygen, these lipids can't be biosynthesized and growth will be very limited.  The sterols and fatty acids produced are also very important in the structure of the cell membrane and the ability of the yeast to respond to external and internal stresses.  Adequate oxygen in the wort when the yeast is pitched is essential to a successful fermentation and long-term health of the culture."  As you can see oxygen is important.  Secondly, once the yeast begins fermenting the starter, the stirring will push the CO2 out of solution, this will aid in healthier yeast cells.  Lastly, the yeast will stay in contact with the sugars for a longer time.  This helps them propagate more rapidly and create healthier cells.  The benefits are that the yeast will take off quicker once pitched into the carboy, the speed of fermentation will increase, and the fermentation will be more complete.

My Stir plate Stir Crazy

With all that jargon in mind, I set off and made my own stir plate.  The total cost was $18, which is pretty cheap.  You can purchase stir plates at about $45 - $200, if you are lucky you might find one cheaper, but they are fairly easy to make.  I used a computer fan that I already had, cut out the metal grate leaving one ring so that the Erlenmeyer flask could sit on top of it.  Next, I took apart an old hard drive that did not work and extracted a rare earth magnet (this was no easy feat).  I then cut out the center metal piece from the fan grate and glued it in the center of the fan, so that the magnet would stay put in the center.  Lastly, I went out and spent $18 on the flask and stir bar.  I was expecting Murphey's law to kick in, but nothing went wrong!  Stir Crazy is a champ.  Can't wait for the next brew!  Remember to drink good beer responsibly and be merry.  Salute!

This is a stir bar

In action

In action up close