New Ways To Make
ARS scientists are studying
which aroma compounds best
give orange juice from
frozen concentrate that
Florida's citrus industry employs more than 100,000 people and contributes
$8 billion a year to the state's economy. In addition to lemons, limes,
tangerines, grapefruit, and other citrus, growers there raise and harvest
over 200 million 90-pound boxes of oranges, on average, every year.
Around 80 percent of them are processed, much of them into nutritious
orange juice (O.J.)
Flavor is one of the most important qualities of O.J., and aroma compounds are significantly responsible for the fresh-squeezed taste consumers prefer. Unfortunately, those aroma compounds evaporate away during the condensing process used to make frozen concentrated orange juice. The aroma compoundsblended into mixturesare sold to juice companies as "flavor packs" and are added back into the juice along with water before the juice is marketed.
Washington navel oranges
growing in Florida.
| Finding the Source of Great
At the ARS Citrus and Subtropical
Products Laboratory in Winter Haven, Florida, Elizabeth Baldwin, horticulturist
and research leader, chemist Kevin Goodner, project leader of the flavor
group, and chemist Anne Plotto are developing information about the
thresholds of so-called flavor-impact aroma compounds that make fresh
orange juice taste so good. A threshold is the minimum level at which
a compound can be detected by smell or taste.
To improve O.J.'s flavor, it is necessary to unravel the interactions
between all the compounds in juice, which is a complex mixture. In addition
to flavor compounds, juice contains sugars, acids, pulp, pectin, salts,
and phenolic compounds, which can influence perception of flavor. To
understand interactions among the compounds and how they affect flavor
perception, the researchers identified odor and taste thresholds of
compounds considered to be important contributors to O.J. flavor. The
researchers mixed the compounds into deodorized juice rather than water.
The team solicited the help of some 50 nonprofessional taste testers.
In evaluating various aroma compounds, volunteers were sent to a booth
illuminated by red light, so they wouldn't be able to see and be influenced
by a sample's color. The booth had positive outgoing air pressure so
that outside smells couldn't get inside and affect the testers.
Each volunteer was then given 15 samples of chilled orange juice, distributed
in 5 rows of 3 cups. In each row, two cups contained just deodorized
O.J. and one cup contained juice spiked with a particular unidentified
aroma compound. Each row differed in taste and odor intensity, with
the top row containing the least amount of the compound and the bottom
row the most.
For each row, the volunteers had to smell the cups, guess which one
was spiked with a compound, and describe the smell. Then, they had to
sip through the rows and do the same for taste.
Responses differed greatly. Various compounds were described as smelling or tasting like paint thinner, fruit, mothballs, gasoline, pineapple, citrus, cheesy feet, musty, earthy, roses, lilacs, and even cotton candy.
Why Test Both Smell and Taste?
"Your taste buds may be on your tongue, but aroma compounds are
perceived by the olfactory bulb in your nose. It's accessed through
the front of the nose or through the back of your throat when food enters
the mouth," explains Baldwin. "This combined orthonasal (smelling
through the front of the nose) and retronasal (the aroma going to the
nose through the back of the throat) olfactory testing is really important
to those in the citrus industry who are trying to formulate flavors."
So far, giant juice companies like Tropicana, Coca-Cola North America
(makers of Minute Maid juices), Florida's Natural, and Cargill Citro-America
have all shown interest in this project and have offered to help find
sources of O.J. aroma compounds to help Baldwin and her team. Flavor
companies Kerry Food Ingredients and Danisco Cultour have also been
Providing scientific and technical support have been Rene Goodrich,
a professor at the University of Florida's Citrus Research and Education
Center in nearby Lake Alfred, and the Florida Citrus Processors Association.
The O.J. matrix contains well over 40 detectable compounds. Research
at the Winter Haven facility over the last 40 years has determined that
terpenes, alcohols, esters, and aldehydes are the compounds that are
by far the most valuable when determining the best tasting O.J. Aldehydes
and esters proved to be what Baldwin refers to as the "top-note"
compounds, while terpenes provide the background. Now the O.J. scientific
team is trying to find out what relative amounts of these types of compounds
are needed to get that fresh-squeezed taste into reconstituted O.J.
Developing flavor packs that more closely mimic fresh juice flavor
would improve the desirability of U.S. processed orange juice and help
it better compete in the global marketplace.By Alfredo
Flores, Agricultural Research Service Information Staff.
This research is part of Quality and Utilization of Agricultural
Products, an ARS National Program (#306) described on the World Wide
Web at www.nps.ars.usda.gov.
"New Ways To Make Condensed O.J. Taste More Like Fresh" was published in the September 2004 issue of Agricultural Research magazine.