What's the most efficient way to clean produce when the water isn't safe?

July 9, 2011 8:40 AM

What is the most efficient and effective way to wash produce when my tap water is unsafe (microbes/heavy metals)? I live in China, and cook a lot.

Right now my procedure looks like this:

Rinse in tap water to get most of the dirt off

Fill a shallow bowl with a mild tap water/bleach solution, dunk and swish produce for 15-30 seconds

Fill a shallow bowl with bottled water, dunk and swish

The bottled water is cheap ($1.55 for a 5-gallon bottle) but this process is slow and strikes me as inefficient, both in terms of time and materials. We cook 5-6 nights a week, and buy fresh produce every day from the market.

What's a better solution?

I was thinking of a big food-grade plastic tub filled with bottled water and a small amount of bleach. Rinse with tap water, then place the produce in the top half of the big tub and gently agitate. The heavy metals and remaining excess dirt sink to the bottom, and the bleach kills the microbes. This tub (3-5 gallons?) would last me for a week or so, provided I didn't agitate too much to stir up the bad stuff from the bottom.

Would this be sufficient, or would the bleach lose its effectiveness, or stick to the food in dangerous amounts, or would the heavy metals dissolve in sufficient concentration to still be dangerous?

What other methods could I use on a daily basis that are easier but still effective?

posted by joshwa to science & nature (11 answers total)

Vinegar soak/spray?
posted by MonkeyToes at 8:54 AM on July 9, 2011

When I was in China, the grocery stores actually sold special fruit-cleaning soap for this very reason. It would take the place of bleach in your procedure. I don't think anyone bothered rinsing with bottled water either.
posted by showbiz_liz at 8:58 AM on July 9, 2011

I should mention that I'm not in a major city (I'm in Kunming, Yunnan, where we have particularly bad water). We do have 4 Walmarts, though.
posted by joshwa at 9:03 AM on July 9, 2011

Is Fit Fruit & Vegetable Wash available where you are? I've never tried it, but I have a few friends who swear by it.
posted by Gator at 9:26 AM on July 9, 2011

What kind of microbes are we talking about? I doubt a vegetable wash is going to do the trick, as they are marketed as being able to get rid of pesticide residues, not water-born microbes.

Bleach doesn't seem to be a great solution, either. Clorox itself recommends boiling water, plus adding bleach.

So that will add significant effort to your workflow.

If you have heavy metals + microbes + pesticides, getting an actual filtration system would seem to be the best bet.

But if you have bottled water, and it's cheap, and it means you can avoid bleach and heavy metals, wouldn't it make sense to use it instead?
posted by KokuRyu at 9:30 AM on July 9, 2011

You don't say whether you cook the produce after washing, or eat it raw. If you cook it, the microbes will get killed even if you wash with tap water (this is the traditional approach and is probably the path of least effort). I'd use tap water + ordinary dishwashing soap for vegetables that will get cooked, because the soap will get rid of pesticide residues and dirt.

Heavy metals need soap. You have to remove them physically since bleach won't affect them. Heavy metals in the soil travel along with soil particles, so wash off dirt thoroughly with soap.

If you want to eat raw vegetables or unpeeled fruits, you'll need something like bleach or that special soap. I'd go with the soap, assuming it actually works as advertised, because soaps take care of pesticides and dirt as well as microbes. Bleach only kills microbes. (It's an oxidizing agent and potentially could oxidize pesticides, but I bet that at the low concentrations that won't trash your vegetables, it also won't affect pesticides.)

Do you have high levels of heavy metals in your tap water? If not, then skip the bottled water rinse for cooked veggies. If so, an in-line filtration system is probably the easiest in the long run.

Summary:
No heavy metal in water + cooked veggies = regular soap + tap water all the way.
No heavy metal in water + raw veggies = special soap/tap water wash + bottled water final rinse

Heavy metal in water = regular soap/tap water wash + bottled water final rinse for everything.
posted by Quietgal at 10:28 AM on July 9, 2011

More specific parameters per Quietgal:

Some produce eaten raw (e.g. fruit, lettuce, tomato), some cooked (i.e. veg).

Produce: dirt, microbes, pesticides, heavy metals.

Water: microbes, heavy metals.

Really, though, what I'm interested in is what I can do to safely speed the process—it's the making 2 bowls of solutions for every meal that I'm trying to safely optimize.

Can I keep big buckets of the stuff around for a while?
posted by joshwa at 7:37 PM on July 9, 2011

I don't think you need to make 2 bowls of solution - you only need regular dishwashing soap and tapwater, plus a rinse of bottled water. No bleach needed. I also would not re-use the soap solution and I don't think making a big batch ahead of time would save you any time.

Here's what I would do (which is basically how I treat my veggies here in SF, minus bottled water): first get a very big plastic bowl with a colander insert like this. (Get a couple of sizes - they're really handy and super cheap).

1. Put bowl + colander in sink and dump all veggies into it.

2. Fill with tap water and squirt in the soap while the water runs.

3. Swish everything around until clean. Use a brush or sponge when possible for best cleaning.

4. Pull colander out and dump soapy water.

5. Put colander back in bowl and rinse a few times with tap water to get rid of soap.

6. Rinse a few times with bottled water. On the final rinse, stand colander in sink without bowl and pour the water over the veggies.

Done!
posted by Quietgal at 8:34 PM on July 9, 2011

But if I'm rinsing in step 5 with tap water, aren't I depositing more microbes from the water onto the food? Is rinsing with bottled water afterwards sufficient to sufficiently eliminate them?
posted by joshwa at 11:19 PM on July 9, 2011

Honestly, from what I understand, the microbes are only a huge deal if you drink a big honking glass of tap water. My friends and I all brushed our teeth in tap water, because we were told that such small amounts wouldn't cause any problems for us.

You could wash the produce in boiled and cooled tap water, which would take care of the microbes, and then do a rinse with bottled water to rinse off any heavy metals. I really don't think bleach is necessary.
posted by showbiz_liz at 9:18 AM on July 10, 2011

> Is rinsing with bottled water afterwards sufficient

In my opinion, it is. (However, I seem to have a pretty robust immune system and don't get sick from food-borne microbes as much as other people.) The microbes in tap water just go with the flow, so if you displace the tap water completely with bottled water you'll displace the germs too.

Veggies that get cooked are a non-issue because heat will kill any lingering germs. However, if you want to play it safe, you can process your raw veggies differently, going straight from tap water/soap to bottled water for rinsing. You can use the special microbicidal soap too if you prefer. This is a more expensive and inconvenient approach, but only you can decide how to balance the factors.

Your food doesn't have to be absolutely sterile - between our immune system and the harsh conditions in our digestive tract (acid! killer enzymes!), most bugs don't stand a chance. Basically this comes down to your subjective feelings about how clean you think your food is/should be. Unless you actually do microbiological testing on it, you are working from an emotional perspective (which we all do, all the time - it's the human condition) and in a fairly low-stakes situation like this, just do what makes you feel comfortable.
posted by Quietgal at 9:23 AM on July 10, 2011