Tomato Flavor: Where Did it Go and How They’re Bringing It Back
Southwest Yard & Garden by Dr.
Marisa Thompson
Dr. Mark Marsalis, NMSU Extension Forages Specialist, helped harvest ‘Big Beef’ tomatoes at the NMSU Agricultural Science Center at Los Lunas in October 2018. Photo credit M. Thompson. |
Tomatoes harvested from 'Big Beef' and 'Bella Rosa' plants in 2018. Photo credit M. Thompson. |
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Question: I’ve
heard that homegrown tomatoes shouldn’t be stored in the refrigerator because
they’ll lose their flavor. How does that work?
-
Sarah
M., Las Cruces
Answer: The short answer is that volatile organic chemicals (aka
volatiles) in tomato fruits are responsible for providing complex
flavors—beyond plain old sweet and tangy tastes—and many of these volatiles are
released when chilled to around 55°F or lower, thereby creating a noticeable
loss in flavor. That’s why we’re told to keep tomatoes out in the open instead
of in the crisper. Store-bought tomatoes are likely to have already been kept in cold storage, so it just may not matter as much where you keep them. The long answer winds up being a rich story of customer
relations, plant breeding, plant physiology, chemistry, marketing, classical
music, disappointment, and hope.
Have you heard the saying “If you want a flavorful tomato, grow it
yourself”? One reason for this is that the vast majority of grocers store their
produce, including tomatoes, in coolers with temperatures that range between
45-55°F. Another reason is that most commercial growers produce fruit from hybridized
tomato plants that, via breeding, have lost some of the genes that regulate flavor.
Hybridized means they’re bred by cross-pollinating two different varieties and
evaluating the offspring for desirable traits.
We’ve all experienced the disappointment of cutting into a
perfectly ripe-looking red tomato that’s pale white inside. Maybe we’ve all
heard the explanation that over the past 50 or so years hybridized tomatoes
have been bred more and more for qualities that ensure packability, shippability,
longer shelf-life, uniformity, and surface-level ripeness, and not for flavor
or nutrient content. In general, heirloom tomato plants, in comparison, are
expected to produce fruits with more flavor, but at the price of reduced
overall yields and higher disease vulnerability. More on this in a minute.
At the annual American Society for Horticultural Science conference
two weeks ago, I attended a keynote address by Dr. Harry Klee of the University
of Florida about biochemical genetics of tomatoes and ongoing efforts to
identify genes that control flavor qualities with the end consumer in mind,
without giving up traits that are important for growers. Klee explained that
tomato breeders have been working to please their customers: the growers, not
tomato-loving consumers. Because growers value traits like disease resistance,
high yields, and storage qualities, the flavor traits have been inadvertently
lost. In plant breeding programs, Dr. Klee warns: “If you don’t select for something,
you’re selecting against it.” It may seem great to breed for increased drought
resistance, but if you aren’t careful to also monitor and select for other
important tomato traits, you might get a drought-resistant plant that tastes
like wet sand. “Failure to monitor nutrient content leads to less-healthy
foods,” Dr. Klee added, and the same is true for flavor.
But these trait changes don’t happen all at once. Dr. Klee made a
helpful analogy for understanding how traits are lost inadvertently in breeding
programs. Imagine you’re at a symphony when one of the violinists stops playing
and quietly leaves. You probably wouldn’t notice just by listening. More
musicians stop playing one by one, and slowly but surely you can hear the
change. The end result is something that doesn’t resemble the original music at
all.
People think flavor is perceived in your mouth, but the mouth only
tastes. The five basic tastes are sweetness, sourness, saltiness, bitterness,
and umami. For the most part, sugar and salt contribute to a food’s sweetness
or saltiness. Sourness or tanginess is associated with acidity levels. Bitterness
is derived from compounds that, in many cases, developed evolutionarily as a
toxic deterrent to hungry grazers and foragers. Finally, umami is also
described as savory or meaty—think low-sodium chicken broth. Umami can also be
tasted in unassuming foods, such as cheeses, grains, and even tomatoes.
But these tastes only explain part of what we experience as
flavor. Flavor also includes smell, temperature, texture, coolness (think
menthol-flavored products), spiciness, and so many other factors.
Tomatoes are native to the mountainous regions of South America
and were domesticated by growers in present-day Mexico. Today, there are tomato
breeders who are growing and testing tomato varieties from the Andes Mountains
and other colder regions of Peru and Bolivia in hopes of breeding new cultivars
with fruit that are able to withstand 55°F and below without degrading the
delicious and nutritious volatile chemicals we crave.
There’s a lot more to report on chemical profiling of over 500 tomato varieties, matching
those chemical profiles with consumer preferences, how growing conditions are also
hugely important for determining flavor, and why high sugar content translates
to lower yields (perhaps via smaller fruits), but we’ll have to save that for
another time. For now, one last tidbit: the sugars and acids that make tomatoes
sweet and tangy are not altered by exposure to cold temperatures. In order to
test this yourself, compare the flavors of tomatoes (harvested from the same
plant and at the same time) that were refrigerated versus not. If you notice a
difference, that’s the volatile chemicals showing their true colors.
What's YOUR favorite tomato cultivar? Let us know on social media: FACEBOOK, INSTAGRAM, TWITTER, and SNAPCHAT.
What's YOUR favorite tomato cultivar? Let us know on social media: FACEBOOK, INSTAGRAM, TWITTER, and SNAPCHAT.
Sneak peek of the first-year data from our tomato root pruning study at the NMSU Ag Science Center at Los Lunas. |
Tomato hornworm is a demon, but if allowed to metamorphosize, these chubby devourers will become amazing hawkmoths as adults! https://www.fs.fed.us/wildflowers/pollinators/pollinator-of-the-month/hawk_moths.shtml |
Recognize these symptoms? Likely the dreaded curly top virus. :( More info at https://nmsudesertblooms.blogspot.com/2019/05/undercover-tomatoes-beating-beet.html and https://nmsudesertblooms.blogspot.com/2018/02/curly-top-virus-hints-for-healthy.html |
For more gardening information, including
decades of archived Southwest Yard & Garden columns, visit the NMSU Extension
Horticulture page (http://desertblooms.nmsu.edu/), follow us
on social media (@NMDesertBlooms), or contact your County Extension office
(https://aces.nmsu.edu/county).
Marisa Thompson, Ph.D., is the Extension
Horticulture Specialist for New Mexico State University and is based at the
Agricultural Science Center at Los Lunas.
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