UC Food Safety
University of California
UC Food Safety

UC Food Blog

Postharvest technology is something of a mystery

A field of strawberries.
Postharvest technology. Hmmm. What does that even mean to you?  Like most people, you’ve probably never thought about it, but it actually affects you every day. At least whenever you eat fruits and vegetables, and let’s face it, we all need to be eating more fruits and vegetables. 

Working at the Postharvest Technology Center, I often think about how to spread our mission of how to reduce postharvest losses and improve the quality, safety and marketability of fresh horticultural products. Part of doing this is educating consumers about making good choices so they have a better experience eating fruits and vegetables. And, if consumers have a better experience with fruits and vegetables, we eat more of them. If we can create demand at the consumer end, it will trickle through to the people that handle your produce: processors, retailers, distributors, carriers, marketers, shippers and finally growers.

I spoke with Jim Thompson, who wrote “From the Farm to Your Table: A Consumer’s Guide to Fresh Fruits and Vegetables” along with Adel Kader, two distinguished experts in the field of postharvest technology. Thompson said they wrote the publication knowing that, “For most consumers, it’s kind of a mystery what influences the quality of their produce. This publication answers some of the questions of how to make good choices at the market and at home.”

Thompson adds, “There are many things that can steal quality from produce. And it starts at the farm.” 

The type of cultivar the farmer chooses to plant and what kind of soil, temperature and light conditions, irrigation and fertilization practices at the farm affect flavor and nutritional quality. When the product was harvested, how it was handled prior to arrival at your market, and how your market stores the product all influence the quality of your produce. 

You certainly know which market in town has the best produce section, and it’s important to you. In fact, according to the 2011 National Grocers Association Consumer Survey Report, “Consumers say they are keeping health a priority—and 91 percent regard a stellar produce department as a ‘very important’ factor in where they buy groceries. This is precisely the same percentage as a year ago, which represented a dramatic five-point jump from the 86% level of two years ago.  While the recession may have withered wallets, it hasn’t hurt consumers’ resolve on this measure.”

If you’d like to learn more about how you can make the most of your fresh fruit and vegetable experiences, the Postharvest Technology Center is offering a 40 percent discount (making it only $4.20!) on “From the Farm to Your Table” through the end of September 2012. And as long as you’re there, our other consumer publication, the poster “Storing Fresh Fruits and Vegetables for Better Taste” (just $1) would be a lovely addition to your refrigerator! 

Please contact us at (530) 754-4326 or postharvest2@plantsciences.ucdavis.edu  if you’re interested in ordering multiple copies for a nutrition, health or cooking class or you can purchase them through our online bookstore.

Posted on Tuesday, August 28, 2012 at 11:08 AM

Food safety for the backyard garden

We're used to hearing news about food safety issues in the commercial food supply; from spinach to cantaloupes, consumers keep a watchful eye to make sure that the food they bring home from the market is safe for their families. But how much thought do you give to the safety of the fruits and vegetables from your backyard?

Many home gardeners assume that just because the food came from their own backyard it is safe. But that's not always the case.

The free UC ANR publication Food Safety in Your Home Vegetable Garden is a terrific guide to reducing the risk of contaminating the food grown in your garden. From clean hands, tools, and water to the careful use of compost and manures, you'll find easy-to-follow tips on how to keep your garden's bounty safe from planting to harvest.  An extensive list of online resources, including many other related UC ANR free publications, is included.

This publication is also available in Spanish - La seguridad alimentaria en su huerto familiar.

Posted on Tuesday, August 14, 2012 at 10:39 AM

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

First storyPrevious 5 stories  |  Next 5 stories | Last story

 
E-mail
 

Site Creation date 6/1/2009
Webmaster for site:  Zann Gates

Webmaster Email: zgates@ucdavis.edu