Alcohol and Lemon Juice Testing

How well do Vodka, Isopropanol, Moonshine and lemon juice kill bacteria?

Answer: The 70% isopropanol and the 64% ethanol Moonshine did well killing bacteria in the kitchen sink when I sprayed a lot to fully cover the sink. The pure lemon juice killed some bacteria. The 20% ethanol Vodka did not kill a significant amount of germs. 

I have tested some other food products and you can find those results on the Cleaning Product Page. 

(5/5/2017)

So many people have asked me to test vodka. I was excited to do it! To test the bacteria killing power of vodka and lemon juice, I did one of my usual countertop experiments. I purchased Kamchatka 42 proof vodka and ReaLemon 100% Lemon Juice

 from Walmart. I also used 70% isopropanol, cleaning vinegar, 3% hydrogen peroxide, and lemon juice that I squeezed myself in these experiments. As usual, I made germ water using a tiny bit of dirt from outside, bacteria from a previous days "dirty sink" plate, juice from a package of raw chicken, and water. I put 1mL of this germ water onto each countertop square, rubbed it around to cover the square, and let it dry. Once dry, I put .5mL of each test product onto the square and spread it around completely. After 5 minutes, I swabbed each square and rubbed the swabs on an agar plate. The plates were incubated for 24 hours. Click here if you would like more details of this countertop experiment procedure.

Understanding Agar Plates

In case you are new at looking at agar plates, let me explain. Agar is a Jello-like substance that bacteria and fungus like to grow on. The whitish/yellowish dots you see are colonies (or piles) of millions of bacteria. Some types of bacteria are not able to grow on these agar plates. Viruses can not grow on these agar plates. So, just because a plate looks clean, doesn't mean that no microorganisms whatsoever were present. We assume that a clean plate means that most bacteria were killed. However, there is the tiny possibility that the cleaning product just stopped the bacteria from growing as opposed to actually killing it. Also, I can't make any determination as to the time it took the product to kill the bacteria since the product was still with the bacteria on the agar plate. (Both the bacteria and the cleaner would be picked up in the sterile swab.) So, I don't know if it took 1 minute to kill the bacteria or hours. These experiments are still very useful when used to compare cleaning products and cleaning methods. 

Results

As you can see from the results, the vodka, isopropanol, cleaning vinegar, and lemon juice did not show any significant bacteria killing power in these countertop experiments. Neither did the orange juice and cran-grape juice that I had in there for fun. This is not a surprise. Many products don't do well in these experiments because my experiments contain an overwhelming amount of dirt and bacteria. So, I also tested products in a real-life situation--the kitchen sink. You can see a small amount of contamination around the edges of the 3% hydrogen peroxide plates in the above experiments. When bacteria are growing only at the very edge of a plate, this is contamination that creeped in during incubation. 3% hydrogen peroxide still did a great job killing bacteria. 

Lemon juice in the sink

I decided to test how well lemon juice works in a real life situation--the kitchen sink. A good cleaning product should be able to disinfect a relatively clean looking kitchen sink. So, I did my usual sink experiments in my neighbors' sinks. The sinks were relatively clean looking with no debris. I made sure my neighbors had not cleaned their sinks for a week. I swab both sides of the dirty sink and rub those swabs onto agar plates. Then I sprayed 30 sprays of freshly squeezed lemon juice all around one side of the sink. I sprayed 30 sprays of 3% hydrogen peroxide all around the other side of the sink. I made sure the sinks were completely covered in the product. I let the cleaners sit for 5 minutes and then swabbed each side. The plates were incubated for 24-48 hours. 

As you can see, lemon juice did a pretty darn good job killing bacteria. It didn't kill everything, but it definitely has some bacteria killing power. I repeated this with bottled lemon juice and got similar results. Both bottled and fresh lemon juice have some germ-killing power. 

Vodka in the sink

In order to see if vodka would kill germs in a real life situation, I did my usual sink experiments with the vodka. I made sure my neighbors had not cleaned their sinks for a week. The sinks were clean looking with no debris. First, I swab both sides of the dirty sink and rub those swabs onto agar plates. Then I sprayed 30 sprays of vodka all around one side of the sink. I sprayed 30 sprays of 3% hydrogen peroxide all around the other side of the sink. I let the cleaners sit for 5 minutes then I swabbed each side of the sink. The plates were incubated for 24-48 hours. 

As you can see, I did not detect any impressive bacteria killing from the vodka. It just must not contain enough alcohol. It is true that I have only tested one bottle of vodka and it was only 42 proof. It is possible that other kinds of vodka might be better. I'm going to find the highest percentage alcohol vodka that I can find and test it. 

Disclaimer: I can't be 100% certain that any product that I test is actually killing bacteria as opposed to somehow preventing the bacteria from growing on the agar plate by some other means. I also can't tell how long it takes a product to kill the germs since the product is picked up in the swab with the germs and stays on the agar plate during incubation. 

70% Isopropanol and Moonshine (64% ethanol)

10/6/2017

I am always on the quest for products that are great at killing germs but won't harm our health. Isopropanol is supposedly safe to put on our skin and ethanol is safe for most adults to drink, so maybe we should be cleaning with them? I have already shown that 70% isopropanol does not kill germs well in my countertop experiments. (You can scroll up to the top if you want to see that experiment.) This is likely because there was an overwhelming amount of dirt and germs present. Only really powerful germ-killers do well in my countertop experiments (like 3% hydrogen peroxide, 10% chlorine bleach, and pure Thieves or On Guard essential oils). So, I always like to test products in a real-life situation, too. Any product that we depend on to disinfect SHOULD be able to kill the germs in our kitchen sinks. 

To do these experiments, I use my neighbors' sinks. I can't use my sink because I clean it too often. I use sinks that haven't been disinfected for a full week. First, I rinsed out the sink to remove any debris. The sink looked visibly clean. 

Then I swabbed both sides of the sink, and rubbed the swabs onto agar plates. 

Next, I poured 70% isopropanol into a spray bottle and sprayed it all around one side of the sink to completely cover it. I used 40 sprays which was a lot more than most people would use. Then I sprayed 40 sprays of 3% hydrogen peroxide all around the other side of the sink. I let them sit for 5 minutes and then swabbed both sides of the sinks again. I rubbed the swabs onto agar plates. The plates were incubated in my warm incubator for 48 hours. 

Isopropanol in the sink

In case you are new to looking at agar plates, let me explain. The whitish/yellowish dots are colonies (or piles) of millions of bacteria. Bacteria and fungus grow on these agar plates. Viruses do not grow on agar plates. Not all kinds of bacteria will grow on these plates. Just because a plate looks perfectly clean, does not mean that no germs whatsoever were present. There are some dangerous and harmless bacteria that can grow on these agar plates. There is a lot of work involved in determining what each type of bacteria on the plate is, and I don't do that. We use these results to compare the germ-killing power of cleaning products.

As you can see, the 70% isopropanol did a very good job killing bacteria in the sinks. It was not quite as good as 3% hydrogen peroxide, but it was very good. The isopropanol made strong fumes, and I coughed a lot. I wouldn't personally want to use it. However, if you like using isopropanol, it does kill germs pretty well on a surface without too much soil. 

Moonshine in the sink

Pure ethanol is not easily available in the US, and I haven't been able to get any to test. I might try to order some from a chemical company. If you all want to see more experiments with ethanol, let me know, and I'll try to get some. I did get some Moonshine which is 64% ethanol and tested that in my sink experiments. 

I did the same sink experiment that I always do. I swabbed both sides of my neighbors' sinks and rubbed those swabs onto agar plates as the dirty controls. Then I sprayed one side of the sink with the moonshine to completely cover it. I used 40 sprays which was more than anyone would think of using. I sprayed the other side with 40 sprays of 3% hydrogen peroxide. After 5 minutes, I swabbed both sides again. I rubbed the swabs onto agar plates and the plates were incubated for 48 hours.

The moonshine did great on Kelly and Jennifer's sinks. It did not do so well on Bethany's sink. The isopropanol did not do as well on Bethany's sink, either, compared to the other sinks. It is possible that  Bethany's sink has some bacteria living there that are more resistant to alcohol. Or it was a fluke. I could not repeat the moonshine sink experiment anymore, because I ran out of moonshine. If you would like me to try to order pure ethanol and do more ethanol based experiments, please let me know. 

The Moonshine and isopropanol both killed germs pretty well in my sink experiments. The moonshine did much, much, much better than the 20% ethanol Vodka that I tested earlier. So, I think both high concentration ethanol or 70% isopropanol are fine for disinfecting relatively clean surfaces without dirt. Ethanol is safe for most adults to drink whereas isopropanol is not safe to drink. So, maybe ethanol is the safer choice. However, it is hard to find ethanol and that moonshine was expensive! Also, just because something is safe to drink, doesn't mean it is harmless to your lungs (water, for example). Both the isopropanol and the ethanol made me cough a lot when I sprayed them during these experiments.

Disclaimer: I can't be 100% certain that any product that I test is actually killing bacteria as opposed to somehow preventing the bacteria from growing on the agar plate by some other means. I also can't tell how long it takes a product to kill the germs since the product is picked up in the swab with the germs and stays on the agar plate during incubation. 

If someone in the house comes down with any type of vomiting or diarrhea illness, I recommend using a solution of 10% chlorine bleach in water or the the Clorox Hydrogen Peroxide spray and wipes. The Clorox Hydrogen peroxide products have been tested and shown to kill the norovirus surrogates.