UC Food Safety
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UC Food Safety

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In the backyard orchard, pluot reigns supreme

When it comes to planting stone fruit at home, pluots are the way to go, says Chuck Ingels, UC Cooperative Extension advisor in Sacramento County. Cherries are delicious, but with a new maggot pest, are hard to grow. Peaches and nectarines are susceptible to leaf curl disease, which is challenging to manage because the most effective products have been removed from store shelves. Apples and pears can suffer from fire blight and coddling moths worms.

Dapple Dandy pluot. (Photo: Wikimedia Commons)
“I think plums and pluots are the best choices for backyard trees,” Ingels said. “Especially pluots.”

“Pluot” is a trade name for varieties of interspecific plum-apricot bred by private Modesto breeder Floyd Zaiger. Pluots’ skin is typically dappled but smooth and without the bitterness in the skin of plums. The flesh is unusually sweet and juicy with complex plum-apricot flavors.

“I really like Flavor Grenade,” Ingels said. “The taste just explodes in your mouth. Another good one is Dapple Dandy, which is a little later.”

Flavor Grenade is a large fruit with oblong shape. The skin has a red blush on green background, and the flesh is a juicy yellow. Dapple Dandy has mottled pale green to yellow, red-spotted skin and red or pink juicy firm flesh.

About a dozen varieties of pluot are offered by Dave Wilson Nursery of Modesto, Zaiger’s exclusive licensee. Dave Wilson Nursery supplies bare root trees in the winter to retail nurseries across California. The best time to plant is early- to mid-winter.

At the UC Cooperative Extension Fair Oaks Horticulture Center in Sacramento, Master Gardeners are creatively planting and pruning pluots and other fruit trees to make them easier to harvest and take less space.

Phil Damewood, a former Sacramento County Master Gardener, prunes a fruit bush.
“We have fruit bushes at the horticulture center,” Ingels said. “It works out really well.”

Fruit bushes are standard or semi-dwarf trees kept small by periodic summer pruning. Fruit bushes can be managed without a ladder and multiple species and varieties can be grown in relatively small areas. When bare-root planted in the winter, the trees are headed to knee height. In late spring and again in the summer, new growth is cut in half. This pruning regimen continues until trees reach the desired height - usually two years. For the life of the tree, it is pruned to a size manageable from the ground.

“The main concern is keeping them tame,” Ingels said. “For pluots, there is just one dwarfing rootstock – Citation.”

Pluots, like plums, will also need a pollinizer of a different variety to ensure good fruit set. Most pluot varieties will pollinize another pluot variety. Another option is planting certain varieties of plum to pollinize the pluot.

At the Fair Oaks Horticulture Center, Master Gardeners are experimenting with a number of planting arrangements, such as planting two to four different trees in one hole. Trees grown in this close proximity combine to form a bush the approximate size of one tree grown alone. For more ambitious gardeners, fruit trees can also be carefully trained into an espalier or other design. For examples, see the Fair Oaks Horticulture Center website.

Posted on Thursday, August 9, 2012 at 8:00 AM

Discovery could deliver vintage flavor to a tomato near you

People often complain about grocery store tomatoes, saying they’re too hard and don’t have the flavor we remember from the days of old. And we thought we knew why - because the millions of tons of tomatoes harvested in the United States and beyond have to be picked before they’re fully ripe and juicy in order to survive being shipped long distances. What’s more, many shoppers store their tomatoes in the fridge, which destroys both their flavor and texture.

Ann Powell inspects tomatoes in UC Davis greenhouse.
But guess what? It’s not just how tomatoes are grown, harvested and stored that affect their flavor. A research team led by Ann Powell, a biochemist in the UC Davis Department of Plant Sciences, has discovered a gene mutation that diminishes a tomato’s flavor even if the fruit is picked ripe and stored well. The finding, which was reported in the June 29 issue of the journal Science, identifies a gene that was unknowingly bred out of modern cultivated tomatoes and plays a vital role in producing the sugars and aromas that make heirloom tomatoes so tasty.

The news is unexpected and encouraging, because now breeders have the genetic information they need to create modern varieties suited for large-scale harvest and shipping with all the flavor of more delicate heirloom varieties.

“Now that we know that some of the qualities that people value in heirloom tomatoes can be made available in other types of tomatoes, farmers can have access to more varieties of tomatoes that produce well and also have desirable color and flavor traits,” Powell said.

It takes awhile to breed a new tomato variety, so don’t expect to taste the results anytime soon. But Powell and her team’s discovery is a huge first step. Tomato lovers can also be grateful for C.M. Rick Tomato Genetics Resource Center at UC Davis, home to a vast collection of mutant and wild species of tomatoes which provides the genetic diversity scientists and breeders need to recapture the flavor of old.

You can read more about the study here.

You can access the Science article here.

You can learn more about the C.M. Rick Tomato Resource Center here.

Posted on Tuesday, August 7, 2012 at 8:13 AM

Chicken salad recall put the spotlight on mysterious food pathogen, Listeria monocytogenes

The news this past week that nearly three tons of Trader Joe’s prepared barbeque chicken salad were recalled due to possible contamination by Listeria moncytogenes had me wondering anew about this mysterious foodborne pathogen. And today, seven tons of Garden Fresh prepared salads were also recalled.

I’ve spent precious minutes worrying about E. coli (ubiquitous, especially in poop) and Salmonella (the reason we must take care with raw eggs), but why doesn’t Listeria moncytogenes rank higher on my food-safety recognition meter?

A quick check of the U.S. Food and Drug Administration website showed that of 27 food recalls in July, 16 were related to Listeria monocytogenes. (One was linked to Staph bacteria, three to Salmonella and the rest to undeclared ingredients.)

Susan Algert, UC Cooperative Extension advisor in Santa Clara County, helped to fill me in. She is a nutrition, family and consumer sciences expert. Listeria monocytogenes is a ubiquitous soilborne bacteria found virtually everywhere.

The problem arises, Algert said, when the bacteria is spread by food handlers, farm equipment and food processing machines, then allowed to grow to levels that can cause illness.

“It can proliferate in the refrigerator if it’s not cold enough, under 40 °F,” Algert said, “and it will not be killed if food isn’t heated to over 140 °F.”

Perishable food should be disposed of after it has been sitting out for one hour. Photo by Bruce A. Stockwell.
According to FDA, Listeria monocytogenes is linked with a serious and sometimes fatal illness called listeriosis among society’s most vulnerable: young children, the frail or elderly, and people with weakened immune systems, such as due to organ transplants or AIDS. Listeriosis can also cause miscarriages and stillbirths among pregnant women. Healthy people may suffer from short-term symptoms such as severe fever, headaches, abdominal pain and diarrhea.

Safe food handling is key to preventing listeriosis, and all other foodborne illnesses, in people at greatest risk. This includes:

  • Washing hands before preparing food.
  • Thawing foods in the refrigerator — never at room temperature.
  • Keeping foods cold (< 40 °F) or heating them thoroughly (> 140 °F).
  • Disposing of perishable foods that have been left out for more than an hour.

“These measures are especially important at this time of year,” Algert said. “It’s warm. Dangerous bacteria in food will grow faster.”

(ANR has published guidelines for controlling Listeria monocytogenes in food packing operations.)

Algert noted that the symptoms of listeriosis can occur long after exposure, another reason why illnesses may not be linked to the bacteria.

“The incubation period is up to 70 days,” she said. “Many people get sick but don’t associate it with something they ate several weeks ago.”

While it was the chicken salad recall that hit the news, the recall actually involved all onions processed by Gill’s Onions of Oxnard, which supplies onions for processed salads and other foods. Other California products affected by the recall included Trader Joe’s salad dressings, butternut squash salad, and red quinoa and wheatberry salad. The Garden Fresh prepared salads also contained these onions.

The products were voluntarily recalled after FDA found Listeria monocytogenes in a random sample of diced yellow onions; the factory has been closed since July 17 pending an investigation. No illnesses have been linked to the possibly contaminated products.

“Gills Onions is committed to protecting public health and to executing this voluntary recall effectively and efficiently,” said Steve Gill, president of the company. “We are a multigenerational family business, and we work hard every day to earn the trust and confidence of customers and consumers who enjoy our high quality, healthy products.”

Anyone who has the recalled product should not consume it and destroy or discard it. Trader Joe’s said that it will provide full refunds.

Posted on Monday, August 6, 2012 at 10:39 AM
  • Author: Janet Byron

Farm to fork, and all that's in between

* - Updated 8/6/2012

As the local food movement scales up and consumers demand information about where their food comes from, more grocers and institutions are seeking wholesale access to local produce. To make the connection between producers and retail sellers, distribution networks are taking on an increasingly important role in the local food system. More and more, farmers are becoming part of values-based supply chains and  ‘food hubs’ to pool their product with that of other farmers and move food more easily to market and complete the chain from farm to fork (*). 

New reports released by the UC Sustainable Agriculture Research and Education Program (SAREP) show that, while food hubs help close the gap in distribution efforts, farmers should invest carefully. UC SAREP has created a Farmer Toolkit for those interested in taking part in a food hub.

“We wanted to suggest some questions farmers should consider before getting involved with an enterprise,” said Gail Feenstra, academic coordinator at UC SAREP (*). 

Photo by David Matheson Photography, courtesy of Veritable Vegetable

“When food hubs are working,” Feenstra said, “the farmer gets a higher price for their product, and everybody along the supply chain benefits. Consumers get the satisfaction of knowing where their food comes from, and the food is good quality” (*).   

But the challenges of food hubs are steep. While food hubs often succeed at keeping the social and environmental values of their products front and center (that they are organic, local, or grown by family farmers, to name a few values), business plans for long-term success are not always part of the planning process (*).

Traditional distribution centers that have been the standard in produce distribution are incredibly well established compared to young food hubs. In researching existing distribution networks, “we found that there are really long-standing partnerships amongst distributors,” says Feenstra. “They go back decades and generations.” 

For farmers looking to keep their social and environmental values embedded in their products, abandoning traditional distribution networks may not be the way to succeed.  Rather, “creative partnerships between conventional players and more alternative folks may be a better model. In cases where you can create cooperative of growers in which they own the process and they’ve got good management, it’s a slow build up, it can’t happen overnight. But they can succeed,” Feenstra said.

The farmer toolkit is meant to give farmers a better sense of how to make that success happen and how to bring the value of sustainably produced food into the supply chain. 

The farmer toolkit and more information on values-based supply chains can be found at the UC SAREP Web site.

Attached Files
Farmer Toolkit
Posted on Tuesday, July 31, 2012 at 8:32 AM

Foodborne illnesses and the 100K Genome Project

Bart Weimer
An ambitious effort to sequence the genomes of 100,000 infectious microorganisms and speed diagnosis of foodborne illnesses has been launched by the University of California, Davis, Agilent Technologies, and the U.S. Food and Drug Administration.

Bart Weimer, professor in the UC Davis School of Veterinary Medicine, serves as director of the 100K Genome Project and co-director of the recently established BGI@UC Davis facility, where the sequencing will be done. Other collaborators include the U.S. Centers for Disease Control and Prevention and the U.S. Department of Agriculture.

The new five-year microbial pathogen project focuses on making the food supply safer for consumers. The group will build a free, public database including sequence information for each pathogen's genome — the complete collection of its hereditary information. The database will contain the genomes of important foodborne pathogens including Salmonella, Listeria, and E. coli, as well as the most common foodborne and waterborne viruses that sicken people and animals.

The project will provide a roadmap for developing tests to identify pathogens and help trace their origins more quickly. The new genome database also will enable scientists to make discoveries that can be used to develop new methods for controlling disease-causing bacteria in the food chain.

"This landmark project will revolutionize our basic understanding of these disease-causing microorganisms," said Harris Lewin, vice chancellor for research at UC Davis.

The sequencing project is critically important for tackling the continuing outbreaks of often-deadly foodborne diseases around the world. In the United States alone, foodborne diseases annually sicken 48 million people and kill 3,000, according to the CDC.

"The lack of information about food-related bacterial genomes is hindering the research community's ability to improve the safety and security of the world food supply," Weimer said.  "The data provided by the 100K Genome Project will make diagnostic tests quicker, more reliable, more accurate and more cost-effective."

"We see this project as a way to improve quality of life for a great many people, while minimizing a major business risk for food producers and distributors," said Mike McMullen, president of Agilent’s Chemical Analysis Group.

A consumer-focused article about the project is available on the FDA website.

(This article was condensed from a UC Davis news release. Read the full press release and watch a video of Bart Weimer giving an overview of the project.)

Posted on Thursday, July 26, 2012 at 9:20 AM

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