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Lighting affects nutrients in fresh produce.


Many people reach toward the back of the fresh produce shelf to find the freshest salad greens with the latest expiration dates. However, a study led by Agricultural Research Service (A.R.S.) scientists may prompt consumers to look instead for packages that receive the greatest exposure to light--usually found closed to the front.

The study was led by post-harvest plant physiologist Gene Lester while he was with the A.R.S. Crop Quality and Fruit Insects Research Unit, in Weslaco, Texas. Dr. Lester and colleagues found that spinach leaves exposed to continuous light during storage were, overall, more nutritionally dense than leaves exposed to continuous dark.

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 of produce was enclosed in two-layer-thick brown grocery-bag paper to represent the "dark treatment."

Both experimental groups were housed in market-type, light-transmittable polymer tubs with snap-tight lids and were kept in walk-in storage chambers at 4[degrees] centigrade (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 fight type of light.

Continuous light affected the leaves' photosynthetic system, resulting in a significant increase in levels of carotenoids and vitamins C, E, K, and [B.sub.9], or folate. Although the simulated retail light conditions actually helped the stored leaves gain in content of several vitamins, some wilting occurred after three days of storage in flat-leaf but not crinkled leaf types.

Continued light exposure during retail display, combined with crinkled_leaf types and leaf maturity (baby-leafed size) appears to be the strategy for preserving and enhancing the concentration of spinach-derived bioactive compounds that enhance human health.

(Source: Journal of Agriculture and Food Chemistry, June 2011.)

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Publication:Nutrition Health Review
Geographic Code:1USA
Date:Mar 22, 2011
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