Market lighting affects nutrients.
Subject: Agricultural research (Analysis)
Plants (Development)
Plants (Research)
Author: Bliss, Rosalie Marion
Pub Date: 05/01/2011
Publication: Name: Agricultural Research Publisher: U.S. Government Printing Office Audience: Academic; General Format: Magazine/Journal Subject: Agricultural industry; Biotechnology industry; Business Copyright: COPYRIGHT 2011 U.S. Government Printing Office ISSN: 0002-161X
Issue: Date: May-June, 2011 Source Volume: 59 Source Issue: 5
Topic: Event Code: 310 Science & research
Product: Product Code: 9108521 Agricultural Research NAICS Code: 92614 Regulation of Agricultural Marketing and Commodities
Geographic: Geographic Scope: United States Geographic Code: 1USA United States
Accession Number: 273420954
Full Text: Many people reach toward the back of the fresh-produce shelf to find the freshest salad greens with the latest expiration dates. But a new study led by Agricultural Research Service 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 in ARS's Crop Quality and Fruit Insects Research Unit, in Weslaco, Texas. 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 is now with the USDA-ARS Food Quality Laboratory in Beltsville, Maryland.

For the study, the researchers exposed spinach leaves to light similar to the 24hour 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]C--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 3 days of storage in flat-leaf but not crinkled-leaf types.

Continuous light exposure during retail display combined with specific cultivar selection (crinkled-leaf types) and leaf maturity (baby-leafed size) appears to be the strategy for preserving and enhancing the concentration of spinach-derived human-health bioactive compounds.

Results from this work were published in the Journal of Agricultural and Food Chemistry.--By Rosalie Marion Bliss, ARS.

Gene E. Lester is with the USDA-ARS Food Quality Laboratory, 10300 Baltimore Ave., Beltsville, MD 20705-5129; (301) 504-6128, gene.lester@ars.usda.gov.*
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