What is the best way to wash grapes and remove germs?

My kids love grapes and I wanted to find the most effective way to wash them. Whenever I can find it, I spray grapes with Fit fruit and Veggie wash because it leaves them so clean and does a great job removing germs.


For this experiment, I wanted to determine if simply rinsing grapes with tap water (like I have done my entire life) was enough to get them clean. First, I rubbed 3 dirty grapes on one half of an agar plate using sterile swab.

Then, I rinsed a bunch of red grapes under tap water for 1 minute. 

Then I rubbed 3 clean grapes on the other half of the agar plate using a sterile swab. 

I incubated the plate overnight and examined it in the morning. The dirty grapes had a lot of bacteria and rinsing them in water for 1 minute made a big improvement. Even though, I think the just the water rinse is good enough, I am going to test the Fit fruit and vegetable wash on grapes later this week. 

I repeated this experiment with another batch of grapes another day. 

I rolled 3 dirty grapes around on an agar plate using a sterile swab.

I rinsed some grapes under warm water for 1 minute. I used my other hand to mix them around.

I rolled 3 of those rinsed grapes around on another agar plate.

Then I sprayed a small bunch of grapes with 5 sprays of Fit Fruit and Vege wash. I mixed the grapes up with my hand for 30 seconds. Then I rinsed the grapes under warm water for 1 minute.

Then I rolled 3 of these washed and rinsed grapes around on another agar plate.

The plates were incubated overnight. As you can see, rinsing for 1 minute in warm water gets the grapes very clean. Washing with Fit first, gets them really, really clean. The Fit spray smells a little bad when you first use it but the smell is gone after you rinse the grapes. My very picky son taste tested all of the grapes and could not tell which ones were sprayed with Fit. It did not affect the taste. The Fit sprayed grapes looked significantly cleaner than the grapes rinsed with just water. I am going to keep using Fit on my grapes. 

Negative Control

I wanted to make absolutely certain that my tap water and clean gloves were not contributing bacteria to my experiments. So, I put on a clean pair of gloves, got them wet under the tap water, and rubbed them on a clean agar plate. I do this control for all of my fruit and vegetable washing experiments. 

I incubated the plate overnight and was pleased that there was no bacterial growth at all the next day.