by Marion Nestle

Currently browsing posts about: Fruits-and-vegetables

Mar 13 2010

The fate of vitamins in vegetables, stored and cooked

Nothing about nutrition is simple.

I was intrigued by the Observatory column in the New York Times last week.  USDA researchers showed that supermarket spinach stored under continuous fluorescent light retained more vitamins than spinach stored in the dark for at least 9 days.  Their hypothesis: the light promotes continued photosynthesis and protects against degradation.

I was curious to know whether they measured vitamin C.  I checked the article in the Journal of Agricultural and Food Chemistry (February 2010, DOI: 10.1021/jf903596v).  Indeed they did.  This seems odd because this vitamin is well known to be degraded by light.  That is why orange juice is usually stored in opaque containers.  One explanation might be that orange juice is stored a lot longer than 9 days.

Cooking also destroys vitamin C.  While I was looking for that article I came across this one, which describes experiments looking at the effects of common cooking practices (boiling, microwaving, and steaming) on beneficial antioxidants and phytochemicals in Brussels sprouts.

Steaming increased phytochemicals in fresh and frozen sprouts.  Boiling did too, but only in the fresh vegetables.  Cooking reduced phytochemical content in frozen samples.  Microwaving was the best cooking method for retaining color and vitamin activity.  As expected, all cooking methods destroyed vitamin C.

So what to make of this?  Eat a mixture of cooked and uncooked vegetables and the vitamins will take care of themselves.  If you do cook, steaming is great and microwaving is better for preserving vitamin activity.  For vitamin C, raw wins every time.

Happy weekend!

Feb 12 2010

Bagged salads: safe or not?

Consumers Union tested a couple of hundred samples of bagged salads, organic and not.   The results? Nearly 40% contained levels of coliform bacteria higher than safety standards.  Coliforms indicate fecal contamination.  This is disgusting to think about but does not make anyone sick.

So the Consumers Union results could be reassuring or not, depending on whether you are an optimist or pessimist.  Yes, the coliform levels were high, but none of the samples contained toxic forms of E. coli, such as O157:H7.

Still, the high frequency suggests that bagged salads need either much better washing or much better maintenance of the cold chain (so the bacteria don’t grow), or both.  If nothing else, the report is a good reason why it’s important to give bagged salads a thorough washing before you eat them or serve them to anyone.

Consumers Union makes a big point of the need to get food safety legislation moving.  The House passed its version of a bill at the end of last July.  The Senate hasn’t budged on its bill.   In the meantime, we still have major national outbreaks and recalls.

The most recent?  225 people in 44 states plus the District of Columbia ill from Salmonella because they ate salami coated with contaminated black pepper. We still don’t have a food safety system that works.  We need one fast.

Nov 23 2009

You heard it here: the hot trend is cupuaçu (?)

What, you may well ask, is cupuaçu?  I confess never having heard of it but thank heavens for Wikipedia, which explains in somewhat limited detail that it is a chocolate-like tree with a sweet fruit.  Botanically, it is a Theobroma in the chocolate family.

Mintel, the market research firm, identifies it as the newest antioxidant-rich fruit craze.  It says this fruit is not only rich in antioxidants, but also in vitamins, essential fatty acids and amino acids.  Well, yes, but so are all fruits to a greater or lesser extent.  But never mind.  Anything this exotic has to be a marketers’ dream “superfruit,” no?

Can’t wait to taste it.  If you know anything about this, do say, especially about how it might taste.

Mintel has six other predictions for upcoming hot trends:  sweet potato, cardamom, rose water, hibiscus, and Latin spices. Yum.  Aren’t you happy to be the first to know?

Oct 27 2009

More veggies for kids and communities

For kids:

The Institute of Medicine has a new report out on setting standards for school meals.  As easily seen in the report summary, the committee offered three main recommendations:

* Increasing the amount and variety of fruits, vegetables, and whole grains

* Setting a minimum and maximum level of calories

* Focusing more on reducing saturated fat and sodium

Its report comes with a handy table summarizing the differences between current breakfast standards and those recommended by the IOM committee.  These are refreshingly food-based and follow the three main principles noted above.

For communities:

New York City’s ever active health department did a study on the availability of fruits and vegetables in low-income areas and found just what you might expect – few, if any, supermarkets carrying fresh produce.  To address the gap, the city has instituted the FRESH program, “Food Retail Expansion to Support Health,” to get healthier foods into the inner city.

So much is going on these days that it is hard to keep up with it.  Enjoy!

Aug 12 2009

What the FDA is doing while waiting for Congress to get busy

The FDA must be in a bit of a quandary as it waits to see what Congress orders it to do about food safety (see previous post).  But it is not sitting around doing nothing.  Instead, it seems to be unblocking regulations that have been in the works for a long time.

On July 9, the FDA announced a final rule for prevention of Salmonella Enteriditis contamination of shell eggs during production, storage, and transportation.  This might seem unremarkable except for two points: (1) it requires science-based food safety procedures – with pathogen testing – from farm to table (an all-time first), and (2) it was first proposed in 2004 and has been stuck ever since (that’s politics for you).

On July 31, the FDA proposed safety guidance for melons, tomatoes, and leafy greens that would apply to everyone involved in the supply chains for these foods – growers, packers, processors, transporters, retailers, and others.  Guidance, alas, is just that: voluntary.  But this puts the producers of such foods on alert that the guidance could swiftly turn into rules  if Congress gets busy and does what it ought to be doing about food safety.  The guidance is open for comment but it is designed to be implemented within two years.  This is quick in FDA regulatory time.

And now the FDA announces that it is speeding up its system for issuing warning notices to companies in violation of safety regulations.  This is a good step, although it falls far short of recall authority.  For that, Congress must act.

Applaud the FDA and keep fingers crossed that no new outbreaks occur while Congress takes its own sweet time to act.

Aug 4 2009

USDA carrot stats

The USDA does wonderful reports on arcane agricultural matters (maybe specialized is a better word than arcane?).  Whatever.  This one is about carrots.  Anything you want to know about carrot production and use?  Here it is.

Apr 1 2009

Fruits and vegetables: eat less, pay more

Nutritionists are always telling everyone to eat more fruits and vegetables.  You might think this would be harder to do when the economy goes bad, and you would be right.  The United Fresh Research and Education Foundation, an arm of the produce industry, keeps track of such things.  Its latest report makes interesting, if depressing, reading.  People bought about 3% less produce in 2008 than they did in 2007, but paid about 2% more for that smaller amount.  No wonder people are complaining that they can’t afford to buy fresh fruits and vegetables.  Don’t we need to do something about this?

Mar 11 2009

EWG’s guide to pesticides on produce

The Environmental Working Group has just issued its guide to coping with pesticides on fresh fruits and vegetables.  It’s handy shopping card identifies the Dirty Dozen (highest in pesticides) and the Clean Fifteen (lowest).  Organics, it says, are still the best choices!

And here’s how they did the study.