Market lighting affects nutrients

May 03, 2011

Many people reach toward the back of the fresh-produce shelf to find the freshest salad greens with the latest expiration dates. But a study led by U.S. Department of Agriculture (USDA) scientists may prompt consumers to instead look for packages that receive the greatest exposure to light--usually those found closest to the front.

The study was led by postharvest plant physiologist Gene Lester while at the Agricultural Research Service (ARS) and Fruit Insects Research Unit in Weslaco, Texas. ARS is USDA's chief intramural scientific research agency.

Lester and colleagues Donald Makus and Mark Hodges found that spinach leaves exposed to continuous light during storage were, overall, more nutritionally dense than leaves exposed to continuous dark. Lester now works at the ARS Food Quality Laboratory in Beltsville, Md.

For the study, the researchers exposed spinach leaves to light similar to the 24-hour artificial fluorescent light received by spinach in packages located at the front of the display case. A second group was enclosed in two-layer-thick, brown-grocery-bag paper to represent the "dark treatment."

Both experimental groups were housed in market-type, light-transmissible polymer tubs with snap-tight lids and were kept in walk-in storage chambers at 4 degrees Celsius, the same temperature at which markets currently display packaged spinach. The light reaction of photosynthesis is not temperature-dependent and can occur at 4 degrees C in the right type of light.

The researchers found that the continuous light affected the leaves' photosynthetic system-resulting in a significant increase in levels of carotenoids and vitamins C, E, K, and B9, or folate.

While the simulated retail light conditions actually helped the stored leaves gain in content of several human-healthy vitamins, some wilting occurred after three days of storage in flat-leaf , but not crinkled-leaf types.

Results from this work were published in the Journal of Agricultural and Food Chemistry.

Explore further: How to prevent organic food fraud

Provided by United States Department of Agriculture

not rated yet
add to favorites email to friend print save as pdf

Related Stories

E. coli an unlikely contaminant of plant vascular systems

Apr 01, 2011

A technique developed by U.S. Department of Agriculture (USDA) scientists for tracking pathogens has helped confirm that Escherichia coli is not likely to contaminate the internal vascular structure of field-grown leafy ...

Light, photosynthesis help bacteria invade fresh produce

Sep 28, 2009

Exposure to light and possibly photosynthesis itself could be helping disease-causing bacteria to be internalized by lettuce leaves, making them impervious to washing, according to research published in the October issue ...

Infrared sheds light on beneficial microbes

Dec 09, 2010

Infrared spectroscopy can quickly spot beneficial fungi on roots in soil, according to U.S. Department of Agriculture (USDA) soil scientist Francisco Calderon.

Recommended for you

How to prevent organic food fraud

Aug 27, 2014

A growing number of consumers are willing to pay a premium for fruits, vegetables and other foods labelled "organic", but whether they're getting what the label claims is another matter. Now scientists studying ...

Rice chemist wins 'Nobel Prize of Cyprus'

Aug 21, 2014

Rice University organic chemist K.C. Nicolaou has earned three prestigious international honors, including the Nemitsas Prize, the highest honor a Cypriot scientist can receive and one of the most prestigious ...

User comments : 0