Say I washed a bag of grapes, set it in a glass bowl, and left it in the refrigerator. Given time, the grapes will become soft and rotten. I've tried draining the water completely, but this doesn't have any noticeable effect.
What can I do to make the fruit last as long as possible?
Wash them in vinegar. This is for berries, but I use it on all produce.
Make the solution a very mild vinegar solution.
The vinegar kills any mold spores and other bacteria that might be on the surface of the fruit
From the Fox News Magazine:
Dry produce, you can keep them dry after washing them in vinegar by putting them in a strainer, drying every individual fruit and placing towels and paper towels around them. Moisture leads to mould even in the refrigerator.
It's a good idea to wash fresh greens, but tossing them in the fridge while damp may make them soggy
Store ethylene producing products properly
Certain fruits and vegetables release ethylene, which speeds the ripening process. Apples, apricots, cantaloupe, and honeydew are best kept in the fridge to keep them fresh longer. But store separate from greens! The ethylene emitted will wilt your future salad.
Don't bruise them
Store them at the proper temp.
Watch out for cold-sensitive items. Storing potatoes, onions, and garlic in cool, dark spots elongates life for up to a month. But these cold-sensitive items don't do well in the fridge, where temps dip too low for their liking.
For Grapes:
Put grapes on a paper towel. Grapes have a tendency to mold due to moisture build-up. Remove grapes from the bag or container the fruit came, wash, and gently pat dry. Place on a paper towel in an open container and pop in the fridge.
For berries:
Remove berries from containers. Berries are delicate things, and don't like moisture. Remove from containers they came in, gently wash and pat dry, and place in a single layer on a paper towel in an open container. Store in the fridge.
For Citrus:
Store citrus fruits on the counter. Citrus fruits do just fine when stored at room temperature. Instead of displaying in a bowl, simply let the fruit hang out on the counter to resist mold growth.
From the POPSUGAR Fitness:
Store in the fridge only when ripe
Store unripe fruits and veggies on the counter. Once they're ripe, move them to the fridge. Banana peels will turn dark brown, but it won't affect the flesh.
For pineapple:
Cut the leafy tops of your pineapple off and store your pineapple upside down. This helps redistribute sugars that sink to the bottom during shipping and also helps it keep longer.
Separate rotten produce from the rest
If you notice any rotten produce, compost it immediately before it starts to spoil the rest of the produce.
Pat them with paper or cloth towels to remove the excess water before storing them.
Use a sealed container lined with paper towels for storing the fruit in the refrigerator. Paper towels absorb the excess moisture and prevent the fruit from rotting.
In case you don't have a sealed container, you can use fridge storage bags lined with paper towels to store the fruit.
Regularly check the container and change the paper towels because natural moisture of the fruit will build up and the paper towels will become moist. If you don't change them, the fruit will rot due to the excess moisture.
However, avoid storing fruits for too long, they are best eaten fresh.
Executive summary: dish soap, bleach solution, a mix thereof, or Star San are excellent options.
Pobrecita has the right idea, but if you want them to last as long as possible (and save money), you will use a better wash than vinegar. Ideal characteristics: it should be nontoxic, it should be cheap, it should kill microbes (both spoilage and food poisoning), it should have a good shelf life, and it should have enough cleansing power to wash off pesticides and waxes.
Convenient solution: a very dilute solution of bleach and dish soap, rinsed afterwards. Bleach is nontoxic in low doses--we even drink it, especially when hikers need to purify stream water. UC Davis writes about how to do this, and they suggest 30 mL bleach (1 tablespoon) per gallon (yielding 200 ppm chlorine), rinsed after a one minute soak. Adding dish soap should not hurt the effectiveness (and may increase it due to increased wetting and dislodging of soil), and adding vinegar (add to the water, never add to the bleach) will strongly increase the effectiveness. This mix has no shelf life and is consumed by use, so discard it afterwards.
If you have fish, you might be able to use a better solution: chlorine dioxide and dish soap. Chlorine dioxide has less smell and taste than bleach, and is similarly nontoxic. But please rinse it to get the dish soap out.
Homebrewers: wash the vegetables with Star San (acid anionic sanitizer) or iodophor. Don't rinse. PAA is also used for this purpose in the food processing industry.
Perfectionists: buy a sanitizing vegetable wash that's targeted at restaurants and vegetable processors. (The stuff in the supermarket is just soap.) This ecolab vegetable rinse--I found it online and this is not a recommendation--meets all the requirements and more, except that it's almost certainly expensive. This choice and brewing sanitizer are the only options that don't need to be rinsed off.
Since Star San (or the upcoming competitor Stellar San) is low cost, kills spoilage and pathogenic microbes, can be stored in a sealed container until needed, it is cheap, and comes in small bottles (diluted to make lots of solution), this is the best option by just about every criterion.
What do I use? Soap. Washing away the microbes is good enough for the amount of time I store my produce.
