Nutrition, Family and Consumer Sciences
University of California
Nutrition, Family and Consumer Sciences

Posts Tagged: citrus

Lemon water tasting at UC research center kicks off an 18-month citrus sensory study

What flavors do you detect in a sip of lemon water? Are there notes of sweetness, sour, off flavors or fresh citrus taste? Scientists at the UC Kearney Agricultural Research and Extension Center and the USDA want to know every subtle taste sensation for a research project continuing over the next 18 months.

Participants will taste the major types of citrus to confirm that treatments used to eliminate pests in overseas shipments don't have an impact on fruit enjoyment. Lemon tasting will be followed by mandarins, navel and Valencia oranges, and grapefruit.

USDA plant physiologist David Oberland, left, and UC Cooperative Extension subtropical specialist Mary Lu Arpaia prepare lemons for tasting in the sensory laboratory.

“This work is critical for the citrus industry,” said Mary Lu Arpaia, UC Cooperative Extension specialist in subtropical fruit. “A huge amount of California citrus is exported, but if there are quarantined pests in the shipment, that triggers treatments with a fumigant.”

In the past, importers treated citrus with methyl bromide. However, the pesticide has been phased out because it depletes the ozone layer. An alternative fumigant, phosphine, kills the insects, but scientists don't yet know what impact the chemical will have on the fruit.

“We're hoping there's no taste difference,” Arpaia said. “But we don't know. That's why we're doing the testing.”

USDA technician Paul Neipp presents a tray for lemon water tasting in one of the sensory lab booths.

USDA plant physiologist David Obenland, based at the USDA office across the street from Kearney in Parlier, is working with Arpaia to conduct the study at Kearney's sensory laboratory. The 1,100-square-foot laboratory features neutral white paint and broad-spectrum lighting; the ventilation system minimizes distracting odors. Six tasting booths each have small windows that open to the kitchen area, where samples are prepared.

“Previous research has resolved residue issues and determined phosphine is effective in killing the pests,” Obenland said. “But they didn't fully determine whether the process would hurt the fruit.”

The current project compares fruit treated with methyl bromide, phosphine and a cold temperature protocol in which the fruit is held just above freezing for three weeks. In addition to tasting the fruit, volunteers evaluate the fruit's appearance.

The visual component of the testing session allows scientists to determine whether subtle impacts of treatment will deter buyers from selecting the fruit.

“People buy with their eyes,” Arpaia said. “We're asking our participants to compare the fruit visually to see if they detect any differences.”

The research is funded by the California Citrus Quality Council through a grant from the USDA Foreign Agricultural Service.

Posted on Friday, December 7, 2018 at 8:06 AM
Tags: citrus (15), Mary Lu Arpaia (7)
Focus Area Tags: Food

Citrus industry, UC Riverside and UCCE team up to fight a citrus killer

Leaves on a Florida tree show symptoms of HLB disease. The new biosafety lab at UC Riverside will help scientists battle the disease. (Photo: Beth Grafton-Cardwell)
Researchers at the University of California, Riverside, will soon have a new resource to help them fight a disease devastating the citrus industry.

On June 6, citrus industry, university and government leaders gathered at UC Riverside Citrus Variety Collection to announce a joint effort to fight huanglongbing (HLB), also known as citrus greening disease. Huanglongbing is a bacterial plant disease fatal to citrus trees

The effort will result in construction of a biosafety-level 3 plant facility in Riverside, about two miles north of UC Riverside.

The biosafety-level 3 plant facility will allow researchers, including many from UC Riverside who are experts on citrus pests, diseases and breeding, to conduct work with plant pathogens that previously couldn't be done in Southern California. (There is only one other such facility in California – at UC Davis.)

The new biosafety-level 3 building will be built and owned by the California Citrus Research Foundation, which is funded by citrus growers.

At the June 6 gathering, Kim Wilcox, chancellor of the UC Riverside, spoke about the establishment in 1907 of the Citrus Experiment Station in Riverside. That research station eventually grew into UC Riverside. He noted that the research station received a boost after a 1913 freeze that devastated the citrus industry.

“Now, unfortunately, 100 years later, we have a different kind of natural threat, Wilcox said. “It's not weather in this case but an insect. And again the university, the federal government and private partners have come together and said ‘We can address this.'”

Georgios Vidalakis and Mark Hoddle are two UC Cooperative Extension specialists based at UC Riverside who will benefit from the facility.

Vidalakis is a UCCE specialist in plant pathology and director of the Citrus Clonal Protection Program at UC Riverside. The program provides a safe mechanism for the introduction into California of citrus varieties from around the world.

“Having access to live plants that carry the bacteria is very, very important to our program because it allows us to develop and validate diagnostic techniques much more quickly,” Vidalakis said.

Vidalkis has ongoing projects at the biosafety-level 3 plant facility in Davis as well as one in Maryland. Having his experimental material hundreds or thousands of miles away is a difficult, costly and inefficient way to conduct science, he said.

“This new facility in Riverside will help tremendously in the fight against HLB,” he said. “It is also a great investment for future threats to the California citrus industry.”

Hoddle is a UCCE specialist in entomology and director of Center for Invasive Species Research at UC Riverside. In recent years, Hoddle has released two species of wasps native to Pakistan that are natural enemies of the Asian citrus psyllid, the vector of a bacterium that causes HLB.

Hoddle called the biosafety facility a critical resource for righting HLB that will greatly assist UC Riverside researchers.

“This investment will likely allow more rapid and cost effect progress in developing mitigation strategies and novel technologies for managing HLB in California's iconic citrus crop,” Hoddle said.

Posted on Monday, June 13, 2016 at 9:47 AM

Taste a colorful rainbow of citrus at UC research facility

Hundreds of different citrus varieties are available for tasting at last year's citrus tasting event.
The UC citrus research center swings open its doors this week to give farmers and the public the opportunity to view and taste dozens of mandarin varieties - which in recent years have emerged as Americans' favorite citrus – as well as sweet oranges, lemons, grapefruit, kumquats, blood oranges, tangors and many other types of citrus fruit.

The 175-acre UC ANR Lindcove Research and Extension Center is situated where the valley and Sierra Nevada foothills meet in eastern Tulare County. Research conducted at the center plays a major role in maintaining California's position at the forefront of high-quality citrus production for markets throughout the United States and the world.

Citrus Industry Day - Dec 12: From 9 a.m. to 12 noon, citrus growers, pest control advisers and other industry professionals are invited to taste citrus fruit at their leisure, discuss new low-seeded mandarin varieties with UC Riverside plant breeder Mikeal Roose, and consult with UC Cooperative Extension advisors Neil O'Connell of Tulare County and Craig Kallsen of Kern County. At 10 a.m., UC Riverside plant pathology specialist Georgio Vidalakis, director of the UC Citrus Clonal Protection Program, will explain the center's role in providing the citrus industry with disease-free citrus propagative material. Immediately following the CCPP presentation, UC Riverside principal museum scientist Tracy Kahn will lead a tour of the Lindcove demonstration orchard and discuss new citrus varieties.

General Public Day – Dec 13: From 9 a.m. to 12 noon, Lindcove is open to the public. In addition to citrus tasting, there will be a special activity for children and the opportunity to consult with UCCE Master Gardeners about backyard citrus horticulture and pest management. The tasting event is free. Visitors wishing to take home samples of Cara Cara, Washington navels, mandarins and assorted fruit, may purchase a tote bag full of fruit for $5. All funds raised by the bag sales will supplement educational activities at the center.

At both events, Mary Lu Arpaia, UC Riverside post harvest specialist and David Obenland, plant physiologist at the USDA-ARS San Joaquin Valley Agriculture Center, will be inviting visitors to participate in a research project that involves taste testing of citrus fruits.

The weekend's events mark the launch of Lindcove's Conference Center Outdoor Enhancement Campaign. Funds will be used to upgrade the conference center parking area, plant demonstration orchards and add an outdoor amphitheater where school children can learn about citrus.

“We want to increase our outreach to the community,” said Beth Grafton-Cardwell, Lindcove director and UC Riverside citrus entomology specialist. “These planned improvements will enhance our ability to accommodate school children, tour groups and community organizations for educational experiences at Lindcove.”

The Lindcove Research and Extension Center is at 22963 Carson Ave., Exeter. The tasting takes place in the conference center building, located at the end of Carson Ave. on the right. For more information about the tasting events, contact Anita Hunt, (559) 592-2408, ext 151, amdhunt@ucanr.edu.

The University of California Global Food Initiative aims to put the world on a path to sustainably and nutritiously feed itself. By building on existing efforts and creating new collaborations among UC's 10 campuses, affiliated national laboratories and the Division of Agriculture and Natural Resources, the initiative will develop and export solutions for food security, health and sustainability throughout California, the United States and the world.

Posted on Tuesday, December 9, 2014 at 6:47 PM

About that lemoncello

One of the hazards of contributing to a shared blog, is that one forgets to post. So in this case, while I said in my last post that we would re-visit the lemoncello in mid-May, here it is September.  Time flies.

The lemoncello is a huge success, we've been enjoying it on the hot summer afternoons that are plentiful in Davis.  And here's how I got from pith to pleasure . . . .

The first steps in the lemoncello process were documented in this early Spring post.  The recipe calls for 6 weeks of steeping the lemon zest in the alcohol in a cool, dark place; preferably, in a place where it won't be disturbed.  I had placed mine in a place so cool, dark, and undisturbed it took me 45 minutes to find it.

But that resolved, I moved to the next step - filtering.

You can see that the zest from all of those lemons has settled to the bottom of the bottle.  Lemoncello aficionados recommend a 2-step filtering process.  The first step is to get most of the zest out using a fine sieve.

Look at all of this zest!

Quite a bit of solid material is left in the liquid after this process.

To remove these last solids, the liquid is filtered through a paper coffee filter. (Lemoncello purists, like coffee purists, would object to the use of a paper filter, saying it imparts a paper flavor.)

The next step is to add the cooled simple syrup.  The basic simple syrup recipe calls for equal parts of sugar and water, but for lemoncello less sugar is used.  For one 750ml bottle of base alcohol, you need 2-1/2 cups of water and 1-3/4 cups sugar.  Add the sugar to the water in a medium saucepan and heat over medium heat.  Bring to a gentle boil, stirring constantly, until the sugar is dissolved.  Let the mixture cool completely to room temperature before adding to the lemoncello base.

Decant the mixture, and put in a cool, dark place for another 45 days.  The addition of the simple syrup increases the volume, so you can't fit your mixture into the original bottle.

This mixture was moved into two tall glass bottles and set aside until early July.

You can put the finished lemoncello in the freezer or in the refrigerator.  Enjoy it alone or in a cocktail on a hot summer afternoon when you need a little something refreshing!

If you want to make your own lemoncello, an excellent resource is the blog LemoncelloQuest.

Posted on Tuesday, September 9, 2014 at 2:57 PM
Tags: alcohol (4), citrus (15), lemons (3)

Lemons are the zucchini of winter - take 2

It's early spring, and that means one thing: I am once again drowning in lemons.  This year with our tree well established, we had a bumper crop.  Even as an espalier, our tree produces more lemons than we can use.  And as anyone with a lemon tree knows - it's almost impossible to give away lemons. Lemons are the zucchini of winter.

The author's backyard lemon tree trained in espalier style.

With a pantry full of marmalade, a batch of salted lemons preserving, and all of the copper gleaming, I was looking for a new way to use my harvest.  A neighbor told me she distributed all of her lemons by having a lemoncello making contest with her friends. Lemoncello, the Italian lemon liqueur, is gaining popularity outside of Italy.  It uses a lot of lemons and is easy to make.

The basic recipe for lemoncello is the same. Lemon zest, alcohol, simple syrup, and time.  While recipes vary little, proportion and procedures are highly guarded secrets of the cognosenti.

Purists insist on using a base of grain alcohol; it imparts no flavor of its own to the lemoncello letting the lemons shine through.  Where grain alcohol is unavailable, a high quality vodka can stand in.  I chose a hand crafted corn based vodka, distilled 6 times, because corn seemed the closest to grain alcohol and it had a relatively high proof.

For my first try, I am halving the basic recipe. The first step was to zest the lemons. A lot of lemons.

A microplane is a must-have tool as you want pure zest with no pith.

Add the liquor to the lemon zest. Put it a cool, dark place. Wait. 45 days.

See you mid-May for the next step.

P.S. After the original mixing of the lemon zest and the vodka, and on an apéritif roll, we decided to make vin de pêche using the recipe from Chez Panisse Fruit.  The large glass jar photographed above was re-purposed for the vin de pêche, and the vodka and the zest were moved into the empty vodka bottle. This is probably a better solution as there is less air surface in the container.

Posted on Tuesday, April 8, 2014 at 8:57 AM
Tags: alcohol (4), citrus (15), lemons (3)

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