I'm sharing different methods I have tried to keep bean sprouts fresh longer and the method I like the most as it is the most effective way to keep mung bean sprouts fresh longer.
It's important to start with fresh good looking beansprouts. Discard any that don't look good to you anymore
Transfer the beansprouts into a large container with a lid. Pour water (you don't need ice water) to submerge the beansprouts. Cover with a lid
Put the container in the fridge. Discard the soaking water and change with a fresh water daily. Sometimes I forgot and I change after 2 days, no big deal
They can be kept this way for about 7 days or longer. At day 7, the beansprouts are still looking fresh and crisp. I didn't go any further, but I believe I can probably keep it for up to 10 days if I want to
When ready to use them, simply discard the soaking water and give the sprouts a quick rinse and you are good to go