Posts Tagged: Food Safety

Low food-safety risk at Northern California farmers markets

A new study by UC Davis researchers finds a low risk of contamination of foodborne pathogens on produce and meat at Northern California certified farmers markets, but still finds cause for some concern.

The study, published in the Journal of Food Protection, examined the prevalence of Salmonella on meat and produce, as well as the prevalence of generic E. coli on produce. Samples were taken from 44 certified Northern California farmers markets, including in the Sacramento region and Bay Area. Less than 2% (1.8%) of animal products sampled, including beef, pork and poultry, tested positive for Salmonella, while all produce samples tested negative. Slightly more than 30 percent (31.3%) of produce tested positive for generic E. coli. Generic E. coli is an indication of fecal contamination, but not all E. coli is harmful. This study didn't test for pathogenic E. coli.

“Based on this data, I think it's safe to consume meat and produce from farmers markets,” said lead author Alda Pires, a UC Cooperative Extension specialist and research scientist in the UC Davis School of Veterinary Medicine. “That's a low risk of contamination of foodborne pathogens, especially Salmonella.”

While the prevalence of generic E. coli may seem relatively high, the concentrations were low. Pires said that's especially so compared to previous studies of contamination at farmers markets elsewhere in the United States. The prevalence of Salmonella in meat sampled from Northern California farmers markets is also much lower than what previous studies have found in grocery stores.

Among the produce sampled, leafy greens had the highest prevalence of E. coli, followed by root vegetables.

Consumers should still be cautious

Consumers and farmers should still be aware that produce and meat were not free from contamination. Consumers need to make sure the foods they prepare from farmers markets follow the good hygiene practices recommended by Centers for Disease Control and Prevention. Consumers should also keep produce separate from meat to avoid cross-contamination. 

“The study raises awareness that it's not just very large farms that can have contamination,” said co-author Michele Jay-Russell, with the Western Center for Food Safety at UC Davis. “Farmers need to pay attention to everything they're doing, from planting to storage, to avoid contamination.”

While certified farmers markets are inspected for food hygiene, microbiological quality is not explored. Smaller farms, those making less than $25,000 a year, are also exempt from certain food-safety provisions of the U.S. Food and Drug Administration's Food Safety and Modernization Act. Foodborne illness costs the U.S. economy more than $15 billion annually.

Other co-authors include James Stover, Esther Kukielka, Viktoria Haghani, Peiman Aminabadi and Thais De Melo Ramos of UC Davis. Research support came from the U.S. Department of Agriculture.

 

Smoke and ash from wildfire may have lingering impacts in food production

A summer of smoke and ash in many parts of California has raised questions about the safety of produce growing on farms and in the garden, eggs laid by chickens who peck around in ash-laden areas, and remediation needed to safely and effectively grow food in the future.

UC Agriculture and Natural Resources brought together experts who have researched the effects of previous fires' fallout and studied soil contaminants to share their insight in a two-hour webinar now available on YouTube.

“The No. 1 health concern during a fire is smoke inhalation, and it's been well documented that wildfire smoke can negatively impact both the heart and the lungs,” said Claire O'Brien, a pharmacology and toxicology doctoral student at UC Davis. “However, the chemicals found in the smoke don't just stay in the air. They can deposit onto plants and into soil and water.”

Although every fire is unique, some generalizations can be drawn from research conducted following previous fires. UC Cooperative Extension food systems advisor Julia Van Soelen Kim detailed a study conducted following the October 2017 wildfires in Sonoma County and across the North Bay.

With the help of UC Master Gardener and community volunteers, the researchers collected over 200 samples of homegrown collard greens, lettuces, kale and chard that were exposed to wildfire smoke and ash. A subset of the samples were analyzed by a private laboratory.

 “There was very low concern about chemicals on produce,” Van Soelen Kim said. “No samples had detectable levels of lead, arsenic, mercury or chromium. And that's a huge sigh of relief.” However, analytical results vary by site, site history and by fire event, and few have pre-fire baseline data to compare with.

Van Soelen Kim said basic food-safety practices should be followed when preparing to eat food grown in a home garden, regardless of ash or smoke contamination.

“You should always wash your hands before and after harvesting, and wash your produce in running water to mitigate any kind of potential risk,” she said.

Are backyard chicken eggs safe to eat?

Another study outlined at the webinar used a similar process to determine whether there might be contaminants in the eggs laid by backyard poultry that live and feed in areas exposed to wildfire ash and smoke.

Scientists know from previous research that chickens exposed to lead in their environment can produce eggs with high lead content and that heavy metal content of ash from urban wildfires is higher than from rural wildfire.

“We combined those two pieces of research with what we know that chickens do all day: they peck at the ground for hours on end,” said Todd Kelman, a veterinarian in the School of Veterinary Medicine at UC Davis. “That makes for a pretty good hypothesis that urban wildfire could pose a risk for the production of eggs and poultry that contain heavy metals.”

Kelman and his team put out a call for eggs from backyard poultry and received samples from 344 premises in fire-affected and non-fire-affected areas of California.

Surprisingly, egg samples that contained higher lead levels came from parts of the state that were not directly impacted by ash and smoke.

“Did our data support our hypothesis that proximity to urban wildfire is a driving source for lead in eggs of backyard poultry? The answer is not so much,” Kelman said. “So, is it safe to eat eggs from your backyard poultry? We can't give you a definitive answer to that question. But we do suggest you assess your risk and reduce the risk of contamination.”

Practices that reduce the risk include keeping chickens off the ground, using a chicken feeder that prevents spillage onto the ground and making calcium readily available, for example in the form of oyster shells, because calcium can prevent the absorption of lead. Making sure that chickens are provided uncontaminated water is also an important part of risk reduction.

For confirmation on the safety backyard chickens and their eggs, lab tests for eggs are available for $60 from the California Animal Health and Food Safety Laboratory at UC Davis, or chickens may be submitted to CAHFS for necropsy.

Are soils safe for growing food after a fire?

Fire effects on soil is another consideration in burned areas, said UC Cooperative Extension urban agriculture advisor Rob Bennaton.

“Fires heat topsoil layers. They reduce the amount of living micro-organisms at the site of the burn, and also affect organic matter and nutrients. Ash deposits over time may make soils more alkaline,” he said. “As a result of these combined factors, there are temporary changes in nutrient levels and the capacity for soils to exchange nutrients for optimal plant growth and nutrition.”

With proper land care and management, soils can be remediated over time.

“It won't happen overnight. Soils were developed over millions of years,” he said.

Some ways to improve safety when gardening in fire-affected areas including keeping the soil covered with wood chips or other landscape mulch to reduce airborne soil dust. Use drip irrigation to prevent up splash onto the undersides of growing vegetables. Promote good drainage, especially at the bottom of slopes to prevent the concentration of contaminants.

Lab tests are often needed to determine the soils' post-fire characteristics. “Don't guess, but test,” Bennaton said.

The UC Master Gardener Program can provide technical assistance to help home gardeners find resources for home soil testing, he said.

Additional resources and information shared during the webinar include: 

Post-fire soil resources and soil testing information

• UCCE publication on Soils in Urban Agriculture with soil testing & sampling information
• The UC ANR Healthy Soils Website, which has many resources worth reviewing.
• Tips for Interpreting Soil Analysis
• UC Master Gardener of Sonoma County 2018 workshop video “Effects of fire on soil”

Post-fire food safety

• Research on produce safety and backyard chicken egg safety after the 2017 wildfires in California is available on this web page. To view a past webinar recording with these research findings, click this link.
• Poultry wildfire resources from the UC Davis School of Veterinary Medicine:
• Best Practices for Produce Safety After Fire
• Understanding Risk: A community guide for assessing the potential health impacts of locally grown produce exposed to urban wildfire smoke

Firewise and sustainable home landscaping design in the defensible space zone

• Visit the UC Master Gardener Program of Sonoma County firewise landscaping web page.
• For a recent firewise & sustainable design and maintenance video by the Resilient Landscapes Coalition.

Impact of smoke & ash on plants

• UC Berkeley Botanical Garden blog post on "The Effects of smoke and ash on plants" 

Study finds 82 percent of avocado oil rancid or mixed with other oils

Consumer demand is rising for all things avocado, including oil made from the fruit. Avocado oil is a great source of vitamins, minerals and the type of fats associated with reducing the risk of heart disease, stroke and diabetes. But according to new research from food science experts at the University of California, Davis, the vast majority of avocado oil sold in the U.S. is of poor quality, mislabeled or adulterated with other oils.

In the country's first extensive study of commercial avocado oil quality and purity, UC Davis researchers report that at least 82% of test samples were either stale before expiration date or mixed with other oils. In three cases, bottles labeled as “pure” or “extra virgin” avocado oil contained near 100 percent soybean oil, an oil commonly used in processed foods that's much less expensive to produce.

“I was surprised some of the samples didn't contain any avocado oil,” said Selina Wang, UC Cooperative Extension specialist in the UC Davis Department of Food Science and Technology, who led the study recently published in the journal Food Control.“Most people who buy avocado oil are interested in the health benefits, as well as the mild, fresh flavor, and are willing to pay more for the product. But because there are no standards to determine if an avocado oil is of the quality and purity advertised, no one is regulating false or misleading labels. These findings highlight the urgent need for standards to protect consumers and establish a level playing field to support the continuing growth of the avocado oil industry.”

Testing domestic and imported brands  

Wang and Hilary Green, a Ph.D. candidate in Wang's lab, analyzed various chemical parameters of 22 domestic and imported avocado oil samples, which included all the brands they could find in local stores and online. Wang and Green received a $25,000 grant from Dipasa USA, part of the Dipasa Group, a sesame-seed and avocado-oil processor and supplier based in Mexico.

“In addition to testing commercial brands, we also bought avocados and extracted our own oil in the lab, so we would know, chemically, what pure avocado oil looks like,” Wang said.

Test samples included oils of various prices, some labeled extra virgin or refined. Virgin oil is supposed to be extracted from fresh fruit using only mechanical means, and refined oil is processed with heat or chemicals to remove any flaws.

Fifteen of the samples were oxidized before the expiration date. Oil loses its flavor and health benefits when it oxidizes, which happens over time and when exposed to too much light, heat or air. Six samples were mixed with large amounts of other oils, including sunflower, safflower and soybean oil.

Only two brands produced samples that were pure and non-oxidized. Those were Chosen Foods and Marianne's Avocado Oil, both refined avocado oils made in Mexico. Among the virgin grades, CalPure produced in California was pure and fresher than the other samples in the same grade.

A push for standards

Ensuring quality is important for consumers, retailers, producers and people throughout the avocado oil industry. Retailers want to sell quality products, shoppers want to get their money's worth and honest producers want to keep fraudulent and low-quality oil out of the marketplace.

But since avocado oil is relatively new on the scene, the Food and Drug Administration (FDA) has not yet adopted “standards of identity,” which are basic food standards designed to protect consumers from being cheated by inferior products or confused by misleading labels. Over the last 80 years, the FDA has issued standards of identity for hundreds of products, like whiskey, chocolate, juices and mayonnaise. Without standards, the FDA has no means to regulate avocado oil quality and authenticity.

Avocado oil isn't the only product without enforceable standards. Honey, spices and ground coffee are other common examples. Foods that fetch a higher price are especially ripe for manipulating, especially when adulterations can be too subtle to detect outside a lab.

Wang is working to develop faster, better and cheaper chemical methods to detect adulteration so bulk buyers can test avocado oil before selling it. She is also evaluating more samples, performing shelf-life studies to see how time and storage affects quality, and encouraging FDA officials to establish reasonable standards for avocado oil.

Wang has experience collaborating with industry and the FDA. Ten years ago, she analyzed the quality and purity of extra virgin olive oil and discovered that most of what was being sold in the U.S. was actually a much lower grade. Her research sparked a cascade of responses that led California to establish one of the world's most stringent standards for different grades of olive oil. The FDA is working with importers and domestic producers to develop standards of identity for olive oil.

“Consumers seeking the health benefits of avocado oil deserve to get what they think they are buying,” Wang said. “Working together with the industry, we can establish standards and make sure customers are getting high-quality, authentic avocado oil and the companies are competing on a level playing field.”

Tips for consumers

• The flavor of virgin avocado oil can differ by varieties and region. In general, authentic, fresh, virgin avocado oil tastes grassy, buttery and a little bit like mushrooms.
• Virgin avocado oil should be green in color, whereas refined avocado oil is light yellow and almost clear due to pigments removed during refining.
• Even good oil becomes rancid with time. It's important to purchase a reasonable size that can be finished before the oil oxidizes. Store the oil away from light and heat. A cool, dark cabinet is a good choice, rather than next to the stove.  
• How do you know if the oil is rancid? It starts to smell stale, sort of like play dough.
• When possible, choose an oil that's closest to the harvest/production time to ensure maximum freshness. The “best before date” is not always a reliable indicator of quality.

Summer safety: Tips to avoid foodborne and heat illnesses

Happy summer! It's time to get the barbecue grilling and the pool party started. To keep your summer healthy and fun, UC ANR offers some important safety tips.

Food safety

Food poisoning is a serious health threat in the United States, especially during the hot summer months. According to the Centers for Disease Control and Prevention (CDC), 1 in 6 Americans suffer from a foodborne illness each year, resulting in thousands of hospitalizations and 3,000 deaths. 

Both the CDC and U.S. Department of Agriculture (USDA) suggest four key rules to follow to stay food safe:

• Clean: Clean kitchen surfaces, utensils, and hands with soap and water while preparing food. Wash fresh fruits and vegetables thoroughly under running water.
• Separate: Separate raw meats from other foods by using different cutting boards. And be sure to keep raw meat, poultry, seafood and eggs away from other items in your refrigerator.
• Cook: Cook foods to the right temperature; be sure to check internal temperature by using a food thermometer.
• Chill: Chill raw and prepared foods promptly.

Here are some additional tips from the USDA. Be sure to check out the CDC's comprehensive food safety website, which also has materials in both Spanish and English. For food safety tips in real time, follow USDA Food Safety on Twitter.

Summer also means more outside grilling, which can pose unique food safety concerns. Before firing up the barbecue, check out these five easy tips from UC Davis.

Before you take off on a road trip, camping adventure or boating excursion, don't forget to consider food safety. You'll need to plan ahead and invest in a good cooler.

Remember, warns the USDA, don't let food sit out for more than one hour in temperatures above 90 degrees F. And discard any food left out more than two hours; after only one hour in temperatures above 90 degrees F.

If there are any doubts about how long the food was out, it is best to throw it out!

Get more food safety tips for traveling from the USDA.

Avoid heat illness

“Summer can be a time for fun and relaxation, but in warm climates, we need to stay aware of the signs of heat illness and help keep our family members and co-workers safe,” says Brian Oatman, director of Risk & Safety Services at UC ANR.

“UC ANR provides comprehensive resources on our website, but it's designed around California requirements for workplace safety.” But, Oatman notes, much of the information applies.

“The training and basic guidance – drink water, take a rest when you are feeling any symptoms and having a shaded area available – are useful for anyone at any time.”

To increase your awareness of heat illness symptoms – and to learn more about prevention – Oatman suggests a few resources.

“Our Heat Illness Prevention page has many resources, including links for training, heat illness prevention plans, and links to other sites. One of the external sites for heat illness that I recommend is the Cal/OSHA site, which spells out the basic requirements for heat illness prevention in the workplace. It's also available in Spanish." 

For those on the go, Oatman also recommends the National Institute for Occupational Safety and Health (NIOSH) mobile heat safety app.

 

Summer safety tips

Happy Fourth of July! It's time to get the barbecue grilling and the pool party started. To keep your summer healthy and fun, UC ANR offers some important safety tips.

Food safety

Food poisoning is a serious health threat in the United States, especially during the hot summer months. According to the Centers for Disease Control and Prevention (CDC), 1 in 6 Americans suffer from a foodborne illness each year, resulting in thousands of hospitalizations and 3,000 deaths. 

Both the CDC and USDA suggest four key rules to follow to keep food safe:

• Clean: Clean kitchen surfaces, utensils, and hands with soap and water while preparing food. Wash fresh fruits and vegetables thoroughly under running water.
• Separate: Separate raw meats from other foods by using different cutting boards. And be sure to keep raw meat, poultry, seafood and eggs away from other items in your refrigerator.
• Cook: Cook foods to the right temperature; be sure to check internal temperature by using a food thermometer.
• Chill: Chill raw and prepared foods promptly.

Here are some additional tips from the USDA. Be sure to check out the CDC's comprehensive food safety website, which also has materials in both Spanish and English. For food safety tips in real time, follow USDA Food Safety on Twitter.

Summer also means more outside grilling, which can pose unique food safety concerns. Before firing up the barbeque, check out these five easy tips from UC Davis.

Handling food safety on the road 

Before you take off on a road trip, camping adventure or boating excursion, don't forget to consider food safety. You'll need to plan ahead and invest in a good cooler.

Remember, warns the USDA, don't let food sit out for more than 1 hour in temperatures above 90 degrees F. And discard any food left out more than 2 hours; after only 1 hour in temperatures above 90 degrees F.

If there are any doubts about how long the food was out, it is best to throw it out!

Be sure to bring plenty of water, too, to stay well-hydrated.

Get more food safety tips for traveling from the USDA.

 

Avoid heat illness

“Summer can be a time for fun and relaxation, but in warm climates, we need to stay aware of the signs of heat illness and help keep our family members and co-workers safe,” says Brian Oatman, Director of Risk & Safety Services at UC ANR.

“UC ANR provides comprehensive resources on our website, but it's designed around California requirements for workplace safety.” But, Oatman notes, much of the information applies.

The training and basic guidance – drink water, take a rest when you are feeling any symptoms and having a shaded area available – are useful for anyone at any time.

To increase your awareness of heat illness symptoms – and to learn more about prevention – Oatman suggests a few resources.

“Our Heat Illness Prevention page has many resources, including links for training, heat illness prevention plans, and links to other sites. One of the external sites for heat illness that I recommend is the Cal/OSHA site, which spells out the basic requirements for heat illness prevention in the workplace. It's also available in Spanish." 

For those on the go, Oatman also suggests the National Institute for Occupational Safety and Health (NIOSH) mobile heat safety app.

Have a great (and safe) summer! 

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