I have a question about sanitizing. The Master Vintners wine kits instruct to clean with Oxygen Wash, rinse thoroughly, then sanitize with metabisulfite solution. If you are using One step, is the Metabisulfite solution really necessary for sanitization?There were a variety of answers proposed by some well-intentioned commenters, some containing decent advice, others less so, but there wasn't a great deal of consensus among them. Some thought that as long as a wine bottle wasn't too dirty it would be okay just to clean it and skip the metabisulfite. Others thought that most cleaners didn't need rinsing anyway. Some advised the powerful sanitizers used by beer brewers, while some talked about how they rinsed their bottles as soon as they were empty, so they only needed a quick shot of sulfite to be ready for next time.
As it turns out, cleaning and sanitizing are more complex than this, not the least of reasons is that they're two different things entirely.
Cleaning wine equipment is the removal of organic and inorganic contaminants from a surface until the can no longer be observed or felt. It's kind of a clumsy thing to say, but anyone who's ever hand-washed a plate knows what it means: you wash until you can't see or feel anything on the surface of the dish--that's clean.
Sanitizing wine equipment is treating the cleaned surfaces with a product that will decrease the population of spoilage organisms to the point where they can't harm the wine or influence its flavor.
How to Clean
The first step in cleaning is to remove the gross materials on the surface of your equipment. If we go back to our dishwashing analogy, you first scrape dirty plates into the compost bucket, and then you rinse them before they go into the hot, soapy water. If you skip this step your cleaning solution will get overloaded with material and cease to be effective, just as though you'd poured a cup of bacon grease into the sink and then tried to wash the crystal--that's not gonna work, so rinse away the bulk of the goop first.
Next, you need a chemical solution which can break down and dissolve the organic matter on your equipment. There are a lot of different home wine and beer cleaners out there, but all of the good ones, including Oxygen Wash, One Step, and PBW all have the ability to get under soils and lift them off, disperse them, and break them down. Follow the instructions, and if your equipment is really heavily soiled or stained you can soak it overnight in cleaning solution, although with very strong cleaners this can damage surfaces or degrade things like soft plastic--when in doubt, don't soak anything for extended periods, except glass or stainless steel.
If it's stubbornly stained and icky, I recommend throwing it away, especially if it's something cheap and simple to replace like hoses or tubing--the cost of a dollar or two's worth of tubing is pretty small compared to losing a batch of wine.
Finally, you need to scrub the surface mechanically to remove debris. Without this step you'll leave a film of material that not only might contain spoilage organisms, but might also provide refuge to nasties hiding underneath it. One more time back to our sink full of dishes, no matter how long you left them to soak in soapy water, you still need to scrub those plates with a dishcloth to get the stuck-on stuff off.
Note that while it's acceptable to use abrasive scrubbing pads and stiff brushes on glass and stainless, that will pretty much ruin any plastic surface instantly. The abrasions left by rough cleaning tools provide excellent places for bacteria to hide in, and they'll leap out and spoil the next batch they touch, no matter how hard you try to sanitize them again. Don't scrub with anything more aggressive than a dishcloth-- microfiber or lint-free cotton is best.
You can wash something easily accessible like spoons or hydrometers as you would anything else. A Big Mouth Bubbler has that excellently large port on top that lets you reach right inside and scrub with a soft cloth.
For carboys, with their small neck opening and large interiors it can seem impossible to get in there with anything but a brush--but they don't really need that kind of scrubbing, and with a little bit of trickiness, you can let a soft cloth do your work for you.
Take your carboy, rinse the gross debris off and put two cups of your cleaning solution in. Warm is better, but it doesn't have to be hotter than tap water. Next, stuff a soft your cloth into the carboy. Move the carboy around to get the cloth wet, and then gently swirl and roll the carboy across a tabletop or floor to move the cloth around all of the inside surfaces.
The weight of the wet cloth is sufficient to scrub the carboy clean all by itself: all you need to do is to make sure it gets run over every surface a few times. It sounds more complicated than it is, so have a look here:
Once it's all clean, rinse well and you're good to sanitize.
There are a lot of different sanitizers out there, some from beer brewing, some from other sources. The beer ones are wild overkill for winemaking and some of them are corrosive and others are expensive. Home sanitizers like bleach should never be used--they can cause a biochemical reaction that produces very unpleasant odors in wine.
Sulfite is the only sanitizer you need for winemaking. It's cheap, very effective, and easy to use and handle. It's also exceptionally safe, as long as you don't go inhaling the powder or huff the fumes from the solution--like any other cleaning product you might use.
To make up a sulfite sanitizing solution mix up 3 tablespoons into one gallon of water (50 grams in four litres). This makes a concentration just over 1%, which will sanitize any surface it's in contact within ten minutes. Don't soak things in sulfite solution, especially plastic, as it will make them brittle and subject to cracking. It can also make rubber bungs lose elasticity, so once they're sanitary, if you're not going to use them, let them dry and store them in a sealed container.
The good news about sulfite solutions made up like this is that they don't need to be rinsed off. Let your bottles or carboys drip dry upside down for a minute or two and the residue on the surface won't affect your wine in any way.
It doesn't matter whether you use the sodium or the potassium form of metabisulfite powder. They're almost exactly the same, and neither one will affect your wine.
If you've heard some folks say that sulfites are concerning or harmful, please don't worry: everyone is wrong about that, 100% guaranteed.
Well, one final tip: if you're still sanitizing bottles by pouring your sulfite solution from one to another with a funnel, here's the hottest tip you'll get all year: get yourself a bottle rinser and a bottle drying tree. They turn the chore of sulfiting each bottle into a quick spritz on the pump and then a drip-dry on the handy tree, saving a lot of shuffling around and labor.