All About Potassium Metabisulfite – WMA006

All About Potassium Metabisulfite – WMA006

http://traffic.libsyn.com/winemakersacademy/wma006.mp3Podcast: Play in new window | DownloadSubscribe: iTunes | Android | RSSAll About Potassium Metabisulfite Potassium metabisulfite is a complex additive. In this episode of the podcast I break down how it functions, what the difference is between potassium metabisulfite and sodium metabisulfite, as well as the difference between free and total sulfites (which come from potassium metabisulfite). It’s an important topic for many wine makers and consumers alike. One that deserves our attention to fully understand how best to work with it so that we can create the best possible wines. Adding to the complexity of it all are the many names by which it goes. You’ll see wine makers refering to potassium metabisulfite as PM, k-meta (the k stands for potassium on the periodic table of elements), and campden tablets. Winemaking Questions Here are all the questions addressed in this podcast. Listen using the player above to hear the answers. What temperature do I keep my wine at after fermentation? Can I degas my wine a second time if I didn’t get all the gas out the first time? Do you have to clean or wash grapes prior to crushing them? How long should I age a strawberry dessert wine? How long should I cold stabilize my wine for? Is there a difference between adding sugar at bottling vs during fermentation? Below are the resources mentioned in the show: Submit a recipe to be published at Winemaker’s Academy. Calculating Potassium Metabisulfite Additions Crushing and Destemming Grapes Photograph by: (WT-shared)...

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Adding Potassium Metabisulfite to Wine

Adding Potassium Metabisulfite to Wine

Potassium metabisulfite is a necessary preservative in wine making. It provides sulfur dioxide which helps prevent microbial spoilage and fight of oxygenation. However, figuring out how much to add can be complicated. By the end of this article you’ll understand how this stuff works, how to calculate what you need to add, and what equipment you need to do it. Let’s get to it. Why Adding Potassium Metabisulfite is Complicated With most wine additives you just measure out a specific amount to treat whatever volume of wine you have on hand. Not so with sulfites additives like potassium metabisulfite and campden tablets. The first thing to understand about sulfites is that they bind with other things in your wine. They bind with micro-organisms, oxygen, solids, yeast, acids, bacteria, and sugars. When this chemical bond happens the sulfite goes from being free to bound. Bound sulfite has already done its job and while it is still in your wine it is not free to bind with anything else. Thus we have to different sulfite levels to worry about, free and total. Free sulfites are unbound sulfer dioxide molecules that are available to bind with the bad guys to keep your wine safe. Total sulfites is a measurement of free sulfites and sulfites that have already chemically bonded with something in your wine. As winemakers we want to know that our wine is protected against the many things that can spoil it. Protection comes only from free sulfites. Thus we need to know how much we have in our wine already that is free and how much free sulfites we would like to have. When adding sulfites to wine, usually in the form of potassium metabisulfite, some of it will become bound while the rest will remain free. You can’t predict how much will become bound so you’ve got to add potassium metabisulfite, test it, then adjust as necessary. If that wasn’t enough variables here’s another twist. The effectiveness of sulfites change with the pH of the wine. The higher the pH the more sulfites you’ll need to do the same job as you would in a wine with a lower pH. Don’t worry though there’s any easy way to figure out what your ideal range is. The Effects of Time Over time the free sulfur dioxide will bind with things in your wine or it can also leave as a gas. Thus you’ll need to monitor your sulfite levels throughout the wine making and aging process. With each racking and addition of additives you’ll be using up free sulfites. These become bound and are not affected at protecting your wine. So don’t think that if you’ve added it once in the beginning that you’re good to go, you’ll likely have to add more. As you can see there are many variables we have to deal with when figuring out how much potassium metabisulfite we need to add to our wines. Now that we understand how sulfites work and where they go let’s take a look at how to calculate the right amount of potassium metabisulfite to add to your wine. How...

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Using Potassium Metabisulfite to Make Wine

Using Potassium Metabisulfite to Make Wine

Potassium metabisulfite comes with just about every wine kit and is used as an additive even in wineries. This article explores what potassium metabisulfite is and how it works. To learn how to figure out how much to add to your wine check out Adding Potassium Metabisulfite to Wine (includes a calculator). But what does it do? What is it for? Is it safe? Let’s find out. What is Potassium Metabisulfite? Simply put it’s an antioxidant. It slows down the aging, i.e. oxidation, of wine by removing free oxygen suspended in the wine. Oxygen is both harmful and beneficial to wine. It is harmful in large quantities because it rapidly accelerates the aging process. However, wine starved of all oxygen can develop off flavors. The solution? Remove all oxygen suspended in the wine, bottle it, and let tiny amounts back in through natural cork closures. This is what we call micro-oxygenation. Potassium metabisulfite is often called a stabilizer because it serves to prevent spoilage and further fermentation by removing oxygen. However, this serves another purpose it preserves the flavor and color of a wine. An over oxidized wine can taste cooked or flabby (lacking body). Additionally, an oxidized wine turns red wines orange and eventually brown. White wines turn a golden brown color. This additive is available in a powdered form as pictured here as well as in tablets called campden tablets (affiliate links). Potassium metabisulfite may also be used as a sanitizing agent due to its antioxidant properties. How Does it Work? When you dissolve PM (K2S2O5) in water it forms three different compounds, sulfur dioxide, bisulfite, and sulfite. Each of these is able to bond with free oxygen floating around in wine. When this happens the free oxygen is no longer available to be consumed by micro-organisms. The removal of oxygen chokes off most micro-organisms and will prevent them from reproducing. It does not, however, stop a fermentation. Yeast produces alcohol only when forced to live without oxygen but it does go on living. Read this post for more information on the how yeast is used to make wine. By adding potassium metabisulfite after you’ve stopped fermentation completely you can then back sweeten a wine with little risk of rekindling the fermentation of newly added sugar. A Common Misconception Sodium Metabisulfite can be used interchangeably with potassium metabisulfite. While they both have very similar chemical makeups the difference is that potassium metabisulfite leaves potassium behind and sodium metabisulfite leaves sodium behind. Potassium occurs naturally in grapes and is essential to their growth. So adding a bit more potassium to the mix isn’t going to hurt anything. There’s already some in your wine. Sodium on the other hand is not something we want to add to our wine. Can you see yourself pouring table salt into a glass of wine? No. Don’t use sodium metabisulfite. Things to Be Careful of When Using Potassium Metabisulfite There are a few things you should know about potassium metabisulfite before you use it again. First, the compounds it creates can be hazardous to your health in large quantities. SO2 is a toxic gas to breath. It can cause breathing difficulties, swelling, rashes,...

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