USA
July 18, 2008
Source:
American Society for Horticultural
Science (ASHS)
The lettuce cut and packaged for
food service and salad mixes is an increasingly important
component of the produce industry. Lettuce is highly perishable,
and the cutting required in processing further shortens its
shelf life.
Packaging cut lettuce and other fresh produce in semipermeable
plastic films extends shelf life via a technique called
"modified-atmosphere packaging". The success of
modified-atmosphere (MA) packaging for lettuce and certain salad
greens has led to innovative products, marketing strategies, and
enhanced sales to consumers.
Increased demand for the convenient, pre-cut salads and lettuce
has led to scientists to search for ways to select lettuce
cultivars that stay fresh, colorful, and crisp. Shelf life and
visual quality of salad-cut lettuce are affected by many things,
including production environment, vegetative maturity, and type
of lettuce chosen. Although an increasing variety of lettuce
types are being grown, romaine and "crisphead" (such as iceberg)
are the most widely produced for salad-cut products
Ryan J. Hayes, a research geneticist, and Yong-Biao Liu,
research entomologist at the U.S. Department of Agriculture's
Agricultural Research Service, published the results of a study
that should give lettuce breeders and producers enhanced product
information and a market edge. During the two-year study,
lettuce was processed from field-grown plants of 33 romaine and
three "crisphead" cultivars. Shelf life of each cultivar was
evaluated after storage in modified-atmosphere bags and in
CO2-free controlled-atmosphere chambers.
Lettuce cultivars 'Clemente', 'Darkland', and 'Green Forest'
performed consistently well, ranking in the top 10 in every
experiment. 'Alpi', 'Dark Green Romaine', and 'Queen of Hearts'
showed clearly unstable shelf life. Hayes noted, "cultivars that
performed well in our MA environments will likely be useful as
parents in breeding programs to develop new romaine cultivars
with an acceptable shelf life. It is also clear that not all
crisphead cultivars have good shelf life. Wide variation was
observed between the crisphead cultivars Pacific, Salinas 88,
and La Brillante."
In concluding the impact of the study outcomes, Hayes stated;
"Breeders can use these methods to characterize or identify
breeding lines that are suitable for salad-cut markets before
release, and to select for increased shelf life within breeding
populations. These practices should facilitate a consistent
release of germplasm with high quality in MA environments."
The complete study and abstract are available on the ASHS
Journal of the American Society
for Horticultural Science electronic journal web site:
http://journal.ashspublications.org/cgi/content/abstract/133/2/228
Founded in 1903, the American Society for Horticultural
Science (ASHS) is the largest organization dedicated to
advancing all facets of horticultural research, education and
application. More information at
www.ashs.org |
|
