Thanks for your great question! The short answer is that washing
vegetables and fruit removes nasty pesticides, dirt and bacteria, and
is a must.
And now for the long answer. :)
"Fruits and vegetables can pick up dust, soil, and bacteria as they
are being harvested, handled, packed, and shipped," Lynda Zimmerman
writes in an article titled 'Washing Produce Helps Prevent Food
Poisoning.' "If mishandled, germs can grow to levels that make people
sick. Pesticide residues also may be present on some fruits and
vegetables in trace amounts." (
Alarming stuff. More alarming, however, is this, from LifeScript
Nutrition News ("Water washes well"):
"Unwashed fresh produce has been responsible for about as many cases
of food poisoning as eggs and meat combined. Scientists argue the best
way to prevent contaminated produce from making you sick is to
thoroughly wash everything under running water before eating it."
Furthermore, "They do not believe that commercially available produce
washes provide any more protection from bacteria and other
I found no evidence that rinsing produce can leach vitamins from the
skin. Soaking, however, can, and can also allow contaminants to spread
among vegetables/fruits soaking in the same bowl. More from
ABCnews.com's "Preserving vitamin content in foods":
"When it comes to preparing fresh produce, experts advise limited
contact with water, as it can whisk away water-soluble vitamins like
vitamin C and the B vitamins.
'It's important from a food safety standpoint to wash fruits and
vegetables thoroughly - but soaking vegetables or cooking and
exposing the water-soluble vitamins to fluids for extended periods of
time reduces the nutritional value of those foods,' says Lisa
Tartamella, a registered dietitian at Yale New Haven Hospital in New
The article goes on to explain how nutrients are commonly lost through
"Avoid cooking in water, as some of the nutrients will dissolve.
Instead try steaming, stir frying, or microwaving. When cooking in
water, use just enough water to prevent burning. Try using the water
that the vegetables were cooked in as gravies, stocks and soups."
( http://abcnews.go.com/sections/living/DailyNews/vitamins_produce020411.html )
While some of the sources I consulted recommended using a commercial
produce wash like Fit, it seems that water and a gentle scrubbing, if
necessary, are just as effective. Never use dish soap or similar
non-consumables - they can leave a film on produce or even be absorbed
through the skin.
A few more tips for you to consider:
- Wash produce just before using, not before storing
- A warm water rinse brings out the flavor and aroma of produce
- Don't put washed produce back in the original bag unless the bag
itself has been washed
- Before rinsing leafy vegetables such as lettuce and cabbage, remove
and discard outer leaves
- Wash fruits and vegetables even if the skin or rind will not be
eaten - knives can spread bacteria from the outside to the inside
( http://www.gov.mb.ca/agriculture/homeec/cbe05s01.html )
- Wash vegetables and fruit *before* slicing - rinsing cut or peeled
produce can wash nutrients away from the inside of the fruit/vegetable
- Cook vegetables in large pieces in a small amount of water
A note on canned vegetables:
Rinsing canned vegetables removes excess sodium, but also destroys
water-soluble vitamins like B and C. Buy low-sodium canned vegetables
so rinsing isn't necessary.
For canned fruit: Purchase fruits packed in their own juice and drink
the juice. This will ensure that none of the vitamin C is lost, and
help you avoid the sugars and extra calories present in heavy syrups.
In conclusion, the only favourable claim I found for eating unwashed
produce is that vegetarians, who need the vitamin B-12 they don't
obtain from animal products, can obtain it from micro organisms living
in the dirt on unwashed fruits and veggies. Considering the presence
of pesticides, germs and chemical residue on unwashed produce,
however, I'm not sure the risk is worth it!
A resource you might wish to explore:
Preparing fruits and vegetables
Food and Agriculture Organization of the United Nations
< http://www.fao.org/english/newsroom/focus/2003/fruitveg4.htm >
I used the following search strings to find your answer:
rinsing vegetables downside
disadvantage rinsing vegetables
rinsing produce nutrient loss
wash produce lose nutrients
preserve fruit vegetable skin nutrients
clean produce dirt pesticides
rinsing canned produce
scrub produce lose nutrients
prevent nutrient loss vegetable skin
benefit unwashed produce
In response to your "bonus" questions, the green growths on garlic
bulbs are simply shoots which sprout as the garlic ages. They are
sometimes called "garlic greens," and can be used in salads, stir
fries, and generally anywhere you would use green onions or scallions.
"As garlic ages, it will begin to produce green sprouts in the center
of each clove. These infant green sprouts can be bitter, so discard
them before chopping the garlic for your recipe. However, if you plant
the cloves and let them sprout to a height of about six inches, you
can use the sprouts like chives in salads and such."
( http://homecooking.about.com/library/weekly/aa081197a.htm )
Garlic green growth
Finally, here's your answer on what makes shrimp turn pink, from the
"Science of Cooking" website:
"Lobster, crab, and shrimp are all crustaceans, which means they have
an exoskeleton (or external skeleton) that appears as a hard shell or
crust. In the sea, the shells of crustaceans display a variety of
colors, but when crustaceans are uncooked, the green-blue hue of the
protein complex of the outer shell predominates.
"In lobsters, crab, and shrimp, however, a pigment called
"astaxanthin" lies hidden, camouflaged by a protein covering.
Astaxanthin is a member of the carotene family of pigments, which are
responsible for coloring many of the yellow and orange (or "carotene")
fruits and vegetables.
"Because these protein chains are not heat-stable, their protein
wrapping uncoils as soon as crustaceans are put in boiling water.
Voila! Red-orange astaxanthin molecules are released. Because pigments
related to the carotenes are stable, the astaxanthins now display
their unique deep hues that are so appealing."
< http://www.exploratorium.edu/cooking/icooks/07-07-03.html >
Cooked shrimp turn pink
I hope that my answers have provided some enlightenment! :) Let me
know if you require any clarification whatsoever - thanks for using