Sanitation in Wine
It appears that a fair number of winemakers, not limited to beginners, don’t understand the differences between “washed”, “disinfected”, “sanitized”, and “sterilized”. In this post I take a stab at defining these terms in the context of winemaking.
Note: I’m not describing products in detail in this post. A description of the many washing, disinfecting, and sanitizing products is several posts.
First, a basic definition of these terms:
Wash – remove visible dirt and residue from equipment, typically by washing with water and substances such as soap, and rinsing with water to remove all foreign material, including the soap.
Disinfect – kill microbial life on equipment, typically performed with chemicals. This does not mean the equipment is clean; it just means all microbial life is killed.
Sanitize – remove microbial life from equipment, greatly reducing the numbers of such life and greatly reducing the likelihood of any type of infection.
Sterilize – kill all microbial life on the equipment, typically performed with heat and/or chemicals. This is a much more stringent version of disinfection and is typically associated with medical equipment.
In winemaking, washing should be the first step in preparing a work area and equipment. Wash and/or rinse all surfaces and equipment to remove all evidence of visible dirt and foreign material. Realistically, this is also sanitizing, as a lot of microbial life is swept away in the rinsing process.
Plain water can be used, or some cleaning materials (soap, etc.) may be necessary. Before using any cleaning material, research that it doesn’t produce problems with regard to winemaking, e.g., bleach residue can produce TCA, which gives the wine a musty odor, so bleach should be avoided.
In general, disinfection is performed with chemicals that are not fit for human consumption, e.g., ammonia. Anything touching food or drink must be rinsed before use to remove any trace of the disinfection chemical(s). This can be counter-productive, as the water itself may contain microbial life. However, disinfection outside of winemaking is generally concerned with viruses and bacteria harmful to humans and animals, so the concern is destroying the harmful microbial life, and there is no concern regarding the microbial life that may be present in the potable water used to rinse.
Sanitizing, in winemaking context, is very similar to disinfection mixed with washing, as chemicals are used that kill selected microbial life AND wash away the residue. The purpose is to reduce microbial numbers to an extent that the wine environment (low pH, alcohol, etc.) is a deterrent against such life surviving and reproducing in any significant numbers.
There are numerous compound used for sanitation, most commonly potassium metabisulfite and food grade phosphoric acid (sold commercially as Star San), as the excess can be shaken off and the equipment immediately used. In my opinion, any sanitizing product that needs rinsing is a waste of time and resources, as the use of anything other than purified or distilled water chances the re-introduction of microbial life.
Sterilizing is almost never used in winemaking. When correctly done, sterilization is 100% killing of microbial life, and is most commonly used in the medical field, to reduce the chance of infection following medical procedures. The usage of this term in winemaking is very rarely correct.
I wash all equipment immediately after use, which for tubing includes running how water through it. If I see visible debris, I use a dedicated sponge/scrubby pad that has never been used with any chemicals, with which I gently scrub all equipment to remove all visible (and probably invisible) debris. Which side I use (sponge or abrasive) depends on the material I’m scrubbing and how hard the debris is to remove.
Periodically, I use Oxyclean or One-Step to deep clean equipment. This includes racking the cleaning liquid through racking canes, racking tubes, and filler tubes. Wine thieves and other equipment are soaked for an hour or two. All are well rinsed with hot water when done.
For sanitation, I make a solution of 3 Tbsp potassium metabisulfite and 1 Tbsp acid blend or tartaric acid, mixed 1 in US gallon of water, which I term “K-meta water”. This solution is good for months if kept in a capped jug — as long as it’s clear and it stinks, it’s still good and can be re-used.
Note: When working with sulfite in any form, open windows and run a small fan to disperse fumes.
For sanitation, I use a 1-1/2 gallon food grade bucket. Equipment goes into the bucket and I pour K-meta water over everything. For racking canes, racking tubes, filler tubes, and wine thieves I run the liquid through the equipment. A common tactic is to rack a gallon of K-meta water from the jug into the first primary or carboy, splashing the insides. Following that I rack into all other containers, until all have been treated. When done the K-meta water goes back into the jug.
When the jug gets down to half full (some gets wasted during usage), or if the solution doesn’t stink, or if it has significant visible debris floating in it, or if it’s been in use for 12 months — I make a fresh batch. Realistically I make a new batch every 6 months or so.
Note: K-meta water and Star San do not produce immediate sanitation. Different sources recommend different standing times after treatment, so I let all equipment stand for at least 10 minutes after touching the sanitizing solution.