How do I minimize the risk of bacteria growth in bean sprouts?

Question

I have been experimenting with sprouts lately. Most recently I've been sprouting mung beans.

Last week I had a salad with a larger than usual portion of bean sprouts. I spent the next day with a delicious case of food poisoning. I don't have any proof that the sprouts were the cause but I have since read online that sprouts are prone to bacterial contamination and they were the only potentially risky thing I ate that day.

My process is simply:

• Rinse the beans,
• Place them in a mason jar with a mesh lid
• Cover with water,
• After one day drain the beans,
• Twice a day, rinse them with fresh water and allow to drain,
• Eat the sprouts after 3-7 days.

If bean sprouts do have an elevated risk of bacterial growth, how can I minimize that risk?

Answer 1

Some of my local supermarkets stopped selling sprouts because bacterial contamination was so widespread, but that's probably more of a problem for big batches. I'm thinking that the best things you can do at home to prevent unwanted bacterial growth might be:

• Sanitize your jar before use. I think a hot water bath would work, or soak in a 10% bleach solution for 30 minutes (that's how I've sanitized in a lab).
• Make sure to use beans that aren't old or of poor quality. This matters less when you're cooking them but is really important for sprouting.
• Maybe try using a finer cover for the sprouts, like a layer or two of cheesecloth (I don't think this should matter too much though).
• Use filtered water, not tap water to soak the beans.

I generally follow these rules when I'm sprouting and haven't had a problem.

As a relevant side note I believe the beans themselves contain their own endophytes, or native microbes that live inside, which is something to consider when sprouting. Not all bacteria/fungi are bad, and having more of the good ones there could prevent pesky pathogens (which reinforces my suggestion of using "good beans").

Answer 2

I am not sure why you need to store them in water. I have read that giving fruit and veggies a brief wash in a water and vinegar solution (say, 3 cups water to 1 cup vinegar) and then spinning them dry gently in a salad spinner, and storing in paper towels in a plastic bag helps keep those things fresh and mold-free longer -- perhaps it would work for sprouts, too?