Cleaning a GMP production facility is essential for compliance, as well as safety of the products that are sold to dispensaries and consumers. Ethanol is one of the more popular cleaners used for production line equipment because it is effective, easy to recover, and food grade. Since it’s so effective at killing bacteria and microbes, many plant managers may wonder why 190 proof (or 95%) ethanol shouldn’t be used over 70% ethanol.

Types of Cleaning Agents

There are several types of cleaning agents that are effective at disinfecting laboratory and production spaces. The include bleach, isopropyl, and methanol. However, ethanol is the only of these that is food grade and safe to use on food-grade surfaces.

Ethanol has a quick drying time and does not leave a residual solvent. It is the safest method of sanitizing in any food or pharma setting.

70% Solution is Preferred

Even though ethanol is diluted to a 70% solution, it’s still effective at killing microbes, bacteria, and other microorganisms on the surfaces of counters and food manufacturing equipment.

There are two types commonly available in industry, 70% and 95% - also known as 140 proof and 190 proof. There is 100% but it’s harder to obtain and is only used for specific scientific purposes.

Pure Ethanol Prevents Cell Death

Testing has been done to show that when pure ethanol (at 100%) is poured onto a single celled organism, it will coagulate (clot) its protein. The ethanol penetrates its cellular wall in all directions. The protein located just within the cell wall is what coagulates. It’s much like a defense mechanism. This ring of coagulated protein actually prevents the ethanol from penetrating deeper into the cell wall of the organism. No more coagulation takes place. Basically, this renders the organism dormant, but doesn’t kill it. If the ethanol were to be washed away, then it’s possible the organism would come back to life.

This process defeats the purpose of using ethanol to kill microbes. Instead, scientists have found a way to trick these microbes with a lower percentage of ethanol

How 70% Ethanol Causes Cell Death

In the same study, when the 70% ethanol was poured onto a single celled organism, the ethanol also caused its protein to coagulate, but this occurred at a much slower rate. This actually allowed the ethanol to penetrate the entire cell before it had a chance for its coagulation to block it. The entire cell is then coagulated, causing the cell to die.

What Microbes Can 70% Ethanol Kill?

The water that has been mixed into the ethanol slows the drying time, creating a longer contact time. Ethanol needs to have a contact time of at least 10 seconds to kill Staphylococcus aureus and Streptococcus pyogenes. At a 10 second drying time, ethanol kills:

Pseudomonas aeruginosa

Serratia marcescens

E. coli

Salmonella typhosa

Staphylococcus aureus

Streptococcus pyogenes

Purchasing 70% Ethanol for Cleaning

There are two types of ethanol on the market. In many states, it’s impossible to buy 100% ethanol without a license due to safety requirements. 70% is preferred for cleaning, while 95% is used as a solvent. 70% ethanol is also much safer in the air and less likely to affect workers in a facility.

It is recommended that because of excise tax and the versatility of 95% ethanol, that ethanol be purchased at 190 proof or 90% and diluted in-house to a 70% concentration for cleaning.

It should also be noted that 100% ethanol would be highly flammable and not suitable for use in manufacturing industries. It can even be an explosion hazard if it gets too hot. Besides being hard to store due to its flammability, particularly in the summer, it’s hard to store for any length of time as it evaporates quickly.

For this reason, 70% ethanol is not only effective, it’s the safest cleaner to use in a cannabis-related products or dietary supplements GMP production facility.