May 23, 2003 News Releases
Released 5/21/03 & 5/22/03
ASK
A SPECIALIST: WHAT IS THE ROLE OF ENZYMES IN FOOD PRODUCTS?
LOGAN - When cooks and food producers handle food, sometimes
they want active enzymes and other times they prefer enzymes
that are not active to maintain optimum food quality. Consider
this information to understand the role of enzymes in food.
• In many cases, when the cook or processor seeks active
enzymes, the enzymes are in a living microorganism. Enzymes
in yeast break sugar down to produce the gas that makes bread
rise. Cheese makers appreciate the enzymes in their cultures
that produce the changes necessary to turn milk to cheese.
• Commercial meat tenderizers are based on the use of
papain, an enzyme extracted from papaya, or of bromelin, an
enzyme found in pineapple. On the other hand, fresh pineapple
is not recommended in gelatin-based salads or deserts because
the bromelin breaks down the gelatin, resulting in a runny product.
Varying situations determine the desirability of having this
enzyme still active.
• In living plant tissue, the enzymes are held in specific
parts of the cell. When a fruit or vegetable is sliced, chopped
or pureed, the enzymes are released and can bring about changes
in color, flavor and texture. This is the reason that apples,
pears and bananas turn brown within a few minutes after slicing.
Heating the apple slice would inactivate the enzyme but would
also give the apple slice a cooked texture. Therefore, cooks
use other techniques to overcome this detrimental enzymatic
reaction by dipping the fruit in lemon juice or sprinkling it
with a commercial ascorbic acid powder such as Fruit Fresh when
serving the product raw. If apples are to be used in a pie at
a later time, blanching will ensure that the color remains intact.
• Most vegetables are blanched before being frozen. This
brief heat process is used specifically to inactivate enzymes
to avoid detrimental changes in the product. Corn on the cob
will have undesirable flavor changes over long frozen storage
unless blanched. If the corn is to be eaten within a few months
of freezing, the family may not notice any difference between
blanched and unblanched corn; however, if it is to be held until
almost time for the next crop, the flavor may be cardboard-like.
This is due to enzymatic changes in the fats in the corn.
• The role of enzymes in onions, garlic and horseradish
is especially interesting. Enzymatic action produces the strong
flavors unique to these products once the tissue is disrupted.
The enzymes involved cause the release of sulfur compounds from
chemical molecules held in a different part of the cell. Until
the onion or garlic cells are crushed, they have either no aroma
or a very mild aroma. Garlic that is roasted has the enzymes
inactivated before the pungent flavor compounds are released,
and thus has a very mild flavor.
• Heating foods not only inactivates enzymes, it also
kills microorganisms and decreases the likelihood of foodborne
illnesses. Pasteurization of apple cider and cooking hamburger
kills E. coli 0157H7, the organism responsible for kidney failure
in some infected children.
• As long as fruits and vegetables are still intact,
they are alive and less vulnerable to changes. Once they are
sliced, chopped or grated, both enzymatic and microbial changes
begin to occur. Both can be slowed by refrigeration.
• Active enzymes in foods can be desirable or undesirable,
depending on the product. They are simply organic catalysts
that bring about reactions in the food.
* Visit http//extension.usu.edu/publica/news/aska/ to see other
"Ask A Specialist" columns.
________
Direct column topics to Julene Reese, Utah State University
Extension, Logan, UT 84322-4900; 435-797-1363; julener@ext.usu.edu
May 22, 2003
Answer by Charlotte Brennand, Utah State University Extension
food science specialist
UTAH STATE NEWS RELEASES FOR 05-21-03
GIFT SUPPORTS
USU WRIGHT FLYER TOUR
LOGAN — Utah’s school children will see Utah State
University’s Wright Flyer for themselves, thanks to a
$25,600 gift from the George and Dolores Doré Eccles
Foundation.
The USU Wright Flyer, a replica of the Wright brothers’
historic plane made out of space-age materials, is touring the
state of Utah early this summer, and in July it will be transported
to Dayton, Ohio, for the centennial celebration of powered flight.
U.S. Senator-astronaut Jake Garn will pilot the plane, which
was designed by USU engineering and technology students.
The USU Wright Flyer team will present information on engineering,
aviation and aerospace technology, the history of the Wright
Brothers and their accomplishments and the history of aviation.
A total of 23 stops have been scheduled for school children
so far. To date, more than 3,100 students and their teachers
have seen the USU Wright flyer.
For more information about he USU Wright Flyer, visit www.usuwrightflyer.org.
May 21, 2003
Contact: Bob Davis, College of Engineering development officer,
435-797-2762
Writer: Jane Koerner, 435-797-1353
COLUMNAR TREES
LOGAN — “I come from a family of ‘vertically-challenged’
people,” said Jerry Goodspeed, Utah State University Extension
horticulturist. “At 5 foot 8 inches tall, I am the tallest
member of my immediate family.
“My height may have something to do with the fact that
I like columnar trees. Their upright stance gives a noble, even
majestic feel to some homes. I am not talking about those nasty
cottonwoods that clutter the sky and give other columnar trees
a bad image. The trees I am referring to are the long-lived,
stately specimens that are not affected by every insect that
merely crawls across their bark,” he said.
There are a number of columnar trees grown in northern Utah
that outclass a poplar and still provide an upright feeling
to the landscape. One of the most prominent, awe-inspiring trees
is the columnar English oak (Quercus robur Fastigiata). Like
most oaks, it is a slow to moderate grower, but is well worth
the wait and investment, said Goodspeed.
The columnar oak has few problems with major insects or diseases.
It prefers well-drained soil to help prevent chlorosis and root
rot. It can reach heights of more than 40 feet, but maintains
a spread of 15 feet or less, he noted. It has dark-green foliage
and produces acorns, which can sometimes be messy.
“Another very stately tree is the columnar or Dawyck European
beech (Fagus sylvatica Fastigiata). Beech trees are slow-growing
and rarely have problems. They are outstanding trees and, in
my opinion, are not planted nearly enough,” said Goodspeed.
“After many years of growth, they can reach a height of
more than 70 feet with a spread of about 20 feet.”
There are two other varieties of columnar beech trees that can
be hard to find, but are worth the trouble. Dawyck purple (F.
s. Dawyck Purple) beech has deep-purple leaves, while Dawyck
Gold (F. s. Dawyck Gold) has gold-colored foliage. Both have
nice fall color in the yellow to gold range, he noted. All beeches
prefer well-drained soil.
“A tree that is planted throughout our USU Botanical Garden
in Ogden is the columnar hornbeam (Carpinus betulus Fastigiata).
For some years, I believed it was one of the best trees for
our area. However, I have started seeing some oddities with
a few of these trees in northern Utah that makes me question
their adaptability,” said Goodspeed.
“Columnar hornbeams prefer a deep, well-drained soil,
yet need the deep moisture that Utah has lacked lately,”
he said. “Its mature height is no more than about 30 feet,
making the tree a good choice for small lots and landscapes.
They tend to get a little wider with age, with some spreading
to about 20 feet.”
Another popular columnar tree is the columnar Norway maple (Acer
platanoides Columnare). This is a less formal tree than some.
Although it is somewhat neat and tidy when young, as it ages
it tends to become disheveled, resembling a well-worn broom
turned upside down, he said. Some branches occasionally move
off in their own direction, giving it a unique look. This tree
is a great choice for a more natural, asymmetrical look. It
has acceptable fall color, and the only pest that causes it
much grief is the aphid, which is more of a nuisance than a
health concern.
Another columnar maple is the crimson sentry (A. p. Crimson
Sentry). It resembles the columnar maple, except its foliage
is dark-purple. It is a slow to moderate grower that reaches
about 25 feet tall, with a 15-foot spread, he said.
Other columnar trees include the linden, several crabapple trees
and a columnar birch, Goodspeed said. Check with your local
nurseries and garden centers and see what they have to offer.
May 21, 2003
Writer: Julene Reese, 435-797-1363
Contact: Jerry Goodspeed, 801-392-8908
utah
state today/archives/May
2003/archives
prior to Sept 2002/
Brought
to you by Utah State University Public Relations and Marketing
|