Magnetic Stirrer – Yeast Stir Plate (comes with a magnetic stir bar) เครื่องคนสาร เครื่องกวนสาร
ใช้สำหรับเตรียม Yeast Starter เพื่อเพิ่มจำนวนเซลยีสก่อนเริ่มการหมัก สามารถใช้คนสารได้มากถึง 3 ลิตร
1. Magnetic Stir Plate
2. 9V Adapter
3. Magnetic Stir Bar
Can be used to stir liquid up to 3 litres.
This is a brewing tool to take your home brewery to next level and it’s fun to use. Many homebrewers don’t pitch nearly enough yeast. A stir plate helps you culture higher cell counts of healthy yeast for quicker fermentations, lower risk of infections and better tasting beer. All in less time than it takes to make a conventional yeast starter.
Good brewing practice calls for a count of one-billion cells per liter per degree Plato. For a standard 5-gallon batch, this means you should be pitching in the neighborhood of 200 billion cells into your cooled wort. Higher gravity worts and lagers require even higher cell counts. A starter becomes necessary for a number of reasons:
- Poor storage temperature control and using yeast close to its use by dates diminishes the viable cell counts in a liquid yeast product.
- A starter will help you proof yeast by allowing you to visually determine if the yeast you purchased, maybe a month, ago still has enough viable cells for fermentation.
- Low pitching rates may result in infected finished beer, higher than normal final gravity, excess production of objectionable flavors caused by fusel alcohols, esters, diacetyl and sulfur compounds.
- A starter allows you to step up the cell counts to the appropriate level for the style you are brewing. As wort gravity increases, the need for more yeast increases also.
A typical yeast starter is made using a ratio of 1 gram of light dry malt extract (DME) to 10 mL of water to give a solution with specific gravity of 1.030. For a 1.5-liter starter, one would use 150 grams of DME, boiled in water for 10 minutes, then cooled to 70° F.
The next step up in your yeast starter regimen is to stir the starter continuously, which grows more yeast in a shorter period of time. Studies show that stirred starters have up to a ten-fold increase in cell counts than a non-stirred starter. Why is this so?
- Stirred starters continuously aerate the wort. Oxygenated wort is essential for yeast propagation
- Stirring knocks carbon dioxide, a by-product of yeast growth, out of suspension. Carbon dioxide in solution inhibits yeast growth.
- Stirring keeps the yeast in suspension and in constant contact with nutrients.