How to clean and disinfect fruits and vegetables in Mexico

This is not a pretty topic, but it’s something not to be ignored: how to clean fresh fruits and vegetables. For those of us who live in Mexico, the practice of soaking all fresh produce in an antibacterial solution is necessary. Soil, microbes and bacteria are found on the skins of fruits and vegetables. In Mexico (and other countries, including those north of the border), where sanitary practices are not always followed, from the time produce is grown and harvested, until it is delivered to the store, there are opportunities for contamination: unclean hands, waste water run-off, animal wastes, fertilizing with fresh manure, irrigating with unclean water. Washing fruits and vegetables in tap water, or even purified drinking water, is not sufficient if you want a sanitary kitchen producing healthy food. Tap water, no matter how pure, will not kill bacteria. Purified drinking water does not kill bacteria. Using an antibacterial product in a soak solution will ensure clean produce, whether it is to be eaten raw or cooked.

Anything with a skin that you plan on removing before eating, like cantaloupes, watermelon, limes, and mangoes, should be soaked. Produce that grows close to the ground, like cilantro, especially needs to be soaked. Anything eaten raw needs to be soaked, whether it is peeled first or not. (Bacteria on the peel can be transferred to the peeled fruit by your hands or knife.) Any produce that will be cooked should be soaked, because it may not be cooked long enough to kill certain bacteria, or it may contaminate other, already cleaned produce (that will be eaten raw) if stored in contact with them. In short, everything fresh in the plant world that passes through your kitchen should be soaked in an antibacterial solution.

This lesson was driven home to me a few years ago when I walked to our neighborhood store very early one morning. Produce was being unloaded from a truck and placed directly on the pavement. No plastic bags or newspaper or anything, were between the cilantro, lettuces and watermelons and the cobblestones. I will not go into details of the other substances I sometimes see on the same cobblestones, stuff I would never want to come into contact with anything edible, but the sight of this was enough to make me turn around and vow never to shop there again.

Later, when I had time to think about this rationally, I realized that anything purchased in the cleanest supermarket may have spent some time on the ground or pavement on its way to the store. Or handled by unclean hands. Or other situations I don’t want to talk about here. So I did shop at this store again, but I am now extra careful about cleaning produce no matter where I purchase it. This is an easy practice if you make it part of your kitchen routine.

Common products used in Mexico are Microdyn and Bacdyn, both of which contain the active ingredient ionized silver (which I do not believe is the same thing as colloidal silver, but I am not a chemist), and both are equally effective. They are usually sold in grocery stores in the produce department and come in different sized bottles. North of the border, grapefruit seed extract is used, as well as other commercial products. A solution of Clorox (sodium hypochlorite) and water is effective, but a rinse with potable water is needed, plus chlorine has environmental issues. Microdyn and Bacdyn solutions don’t need to be rinsed off, a plus if you live in Mexico or another country where drinking water is purchased.

I use Microdyn, and have noticed that different sized bottles contain different concentrations. The largest bottles are not as concentrate as the smallest, so more Microdyn is needed.

To soak: first wash off any obvious soil. Always read the instructions for the proportion of solution to water and how many minutes to soak. Various brands and different sizes of the same brand call for different amounts of concentration to water. Use tap water, not purified water, because the antibacterial product kills any bacteria in the water as well. After all, this is the same procedure for purifying unclean drinking water.

After soaking for the specified time, place produce in a colander or on a  clean dish towel to drain. You don’t need to rinse off the soak solution (unless you used chlorine bleach, and then only with pure water). Allow to air dry completely, as drier produce stays fresher longer in the fridge.

If you elect to clean your fruits and vegetables with chlorine bleach, do not use scented chlorine or color-safe bleaches. The University of Nebraska, USA, suggests using 1 1/2 teaspoons bleach (5.25% sodium hypochlorite) in one gallon of water. Do not wash before storing. Rinse just before using. Clorox brand bleach contains 5.25% sodium hydrochlorite.

Ohio State University, USA, instructs to soak produce for 15-20 minutes in a chlorine bleach solution. The amount of bleach to add to water depends on the percentage of chlorine it contains. For 2% chlorine, use 3/4 tablespoon per quart of water. For 4% chlorine, use 1 teaspoon per quart of water. For 6% chlorine, use 1/2 teaspoon per quart of water. Rinse thoroughly with safe drinking water.

North of the border, a product called Fit is sold for cleaning produce. The makers claim it removes chemicals on the surface, but their web site offers no claims that it kills surface bacteria.

Cleaning products that contain grapefruit seed extract are more effective, as GSE, as it is known, has been found to eliminate fungus and bacteria.(It is used in hospitals as a cleaning agent.) Look in health food stores and natural food stores for products containing grapefruit seed extract.

Produce can also be cleaned with a solution of one cup of vinegar to three cups of water. Either spray fruits and vegetables with this solution, waiting three minutes before rinsing in clean water, or soak produce for three minutes and then rinse in water. Use a scrub brush to clean dirt in crevasses.

Cross contamination is common. Unsoaked squash or broccoli  are cut up for cooking in your kitchen. Then salad ingredients are prepared on the same cutting board, using the same knife. Cross contamination has just occurred. Even hands contribute to cross contamination. By soaking every fresh fruit and vegetable, you will join the practice of the majority of cooks and kitchens in Mexico.

Soaking Tips:

Disinfect all your produce as soon as you come home from shopping. Make it a policy to not put any uncleaned fruits and veggies in the fridge. This way, everything is ready to grab and eat, or cook, without stopping to clean and soak. And an unsuspecting family member will not reach for an uncleaned apple.

The same disinfectant solution may be used many times over, provided the water appears clean and does not have dirt and spoiled plant parts accumulating. I normally prepare one container of Microdyn and water and re-use it until all the produce brought home from the market has been disinfected. This is on the advice of my husband, a former chemist, who says that ionized silver, the active ingredient in Microdyn and Bacdyn, does not break down or get “used up” with successive soakings.

Be aware of cross contamination. Don’t allow unsoaked produce to be stored with clean. If you used a cutting board and knife to trim before soaking, wash them thoroughly with hot water and soap before prepping soaked veggies.

Cilantro, tomatoes and other produce may have obvious soil or dried mud on the surface. Rinse off completely before using a soak solution.

To clean tight heads of  lettuce and cabbage, remove the outer leaves. The inner head is already clean, as it grew from the inside, protected by the outer leaves. If you buy a head of cabbage already cut in half, a common occurrence in Mexico, it will need to be soaked, as you have no way of knowing if the knife, hands and cutting board were properly cleaned first. Never buy watermelons or papayas that have already been halved at the store.

Mushrooms and strawberries are too absorbent to soak in a solution without becoming water-logged. Walmart sells a spray to use on fruits and vegetables, and this is probably the best way to clean these two. The active ingredient is “citrus seed extract”. Spray and wait 10 minutes. For other spray products, follow the instructions.

Update on cleaning mushrooms and strawberries: remove all detritus from mushrooms with a mushroom cleaning brush (sold for this purpose, then rinse — don’t soak — then cook tnoroughly. Don’t eat raw. For strawberries, rinse briefly, don’t soak, in a Microdyn/water solution that has already sat for 10 minutes to purify the water. Drain and eat fresh. Our area sells strawberries labeled Driscoll, the same strawberries sold in the US where produce is not routinely soaked to sanitize. Using the reasoning that Driscoll strawberries are not soaked north of the border, I don’t soak them here. THIS IS NOT MEDICAL ADVICE, JUST MY PERSONAL PRACTICE. (9/17/18)

A special note for travelers: if you are on the road in Mexico, or anywhere, and want to disinfect the fruits and vegetables you purchase in the markets, travel with a zip lock bag and a small bottle of Microdyn, available in any grocery store, even in the smallest Mexican towns. Disinfect your produce in the zip lock bag first before eating. You do not have to use purified water, as the Microdyn disinfects water, also. In fact, Microdyn will disinfect drinking water if you are unsure of its purity, though these days, purified water can be purchased anywhere in Mexico. We also travel with a small cutting board, knife and vegetable peeler.

More reading:

What Does it Take to Clean Fresh Food? (NPR)

How Clean is Your Grocery Shopping Cart? (SNOPES)