Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
Division of Agriculture and Natural Resources
University of California
Division of Agriculture and Natural Resources

Posts Tagged: Food Safety

UC SAREP webinars help farmers, ranchers pivot to direct sales during pandemic

Partnering for California
Ciara and Michael Shapiro of AM Ranch in Penn Valley were able to pivot to online sales during the pandemic. (Photo courtesy AM Ranch)

The COVID-19 pandemic hit farmers hard. Supply chains were disrupted and even non-traditional agritourism revenue streams such as hay mazes and on-farm events had to be canceled due to shelter-in-place mandates.

On the other hand, demand for local farm products skyrocketed, and thus many farmers and ranchers needed a quick pivot strategy and a set of new skills.

UC Sustainable Agriculture Research and Education Program (SAREP) was well-positioned to support this shift toward direct sales, pulling in trusted community partners and experienced farmers and ranchers to put together a comprehensive webinar series, “Agritourism and Direct Sales: Best Practices in COVID Times and Beyond”.

AM Ranch has been able to weather the pandemic by focusing on online marketing.

Funded by a USDA Farmers Market Promotion Program (FMPP) grant, the webinar series is part of a three-year project, Strengthening California Local Food Networks with Agritourism and Direct Sales, which provides trainings and technical assistance to farmers and ranchers on how to diversify their revenue streams. 

The strength of the series, which includes eight webinars that were recorded earlier this year and are available online, lies in the collaborations among the UC SAREP Agritourism Program, UCCE, community groups, and farmers and ranchers.

The series features a range of speakers, including representatives from community organizations, technical experts, academic researchers, and farmers – all coming together to build resilience and adaptability for small-farming operations and the agritourism industry across California during the pandemic and after.

“It's great to collaborate with other organizations and regions, to learn from each other and to broaden our networks, as we are all working to create more resilient and sustainable food systems,” said Carmen Snyder, executive director of Sonoma County Farm Trails, one of the nonprofit partners on this project.

And because of those strong partnerships, the webinar topics reflected the on-the-ground needs facing agricultural producers.

In one webinar, Emmettt Hopkins of Foggy River Farm discussed how online ordering proved to be a boon for their farm stand sales. (Image courtesy Foggy River Farm)

“COVID initially dramatically affected farmers' restaurant contracts, with many losing more than 80% of their accounts overnight,” Snyder said. “CSAs [Community Supported Agriculture], on the other hand, couldn't keep up with the demand, and all of our CSA members were full and had wait lists for the first time ever. Producers pivoted by creating more online stores, including pick-up and delivery options. It was a challenge for them to navigate the new technology and platforms.”

Unsurprisingly, two of the more popular webinars were “Online Sales Options and Methods” and “Safe, Healthy and Successful Farm Stands”.

The “Online Sales Options and Methods” webinar, a partnership with the Community Alliance with Family Farmers (CAFF), provided an overview of several e-commerce marketing and online sales strategies that farmers can implement to diversify their revenue pathways and reach new customers. CAFF stressed the importance of farmers enhancing their resiliency through e-commerce.

The webinar also featured Ciara Shapiro, the owner of AM Ranch in Penn Valley, who shared her experience with online marketing and how it helped her and her husband survive the pandemic when the restaurants and farmers markets they sold to shut down. This personal and informative webinar demonstrated the effectiveness of online sales and marketing, while highlighting available resources from groups like CAFF.

The “Safe, Healthy and Successful Farm Stands” webinar was aimed at farms of all sizes and organizations that operate or advise agricultural operations using farm stands as a form of revenue. The webinar provided an outline of the rules and regulations that farm stand operators needed to follow during COVID – as well as during business-as-usual times.

High interest in Petaluma Bounty's annual plant sale fundraiser helped drive increased engagement. (Photo courtesy Petaluma Bounty)
It featured two guest speakers who run successful farm stands: Emmett Hopkins, the owner of Foggy River Farm in Sonoma County and Reyna Yagi, the farm manager at Petaluma Bounty Farm. They shared their experiences during COVID and how they had to pivot to remain profitable and accessible within state guidelines.

Both farmers saw an increase in farm stand business during the pandemic, which Yagi attributed to the “traffic storm of people” who attended their annual plant sale fundraiser and came to participate in new farm outdoor activities and volunteer opportunities. Yagi also noted the growing number of low-income individuals who were unable to access fresh produce during the pandemic.

The speakers' shared experiences running successful farm stands gave audience members tangible examples and real-time information on how to incorporate farm stands into their businesses.

Carmen Snyder of Sonoma County Farm Trails, which helped circulate the recorded webinars to their network of farmers and ranchers, remarked: “These webinars were extremely helpful for local producers, to get clarity on best pandemic practices during these challenging times and to learn how other producers are adapting and navigating the circumstances.” 

Posted on Thursday, September 2, 2021 at 8:46 AM
  • Author: Rachael Callahan
  • Author: Cooper Limon
Focus Area Tags: Agriculture, Economic Development, Food, Innovation

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.”

Always wash your hands before and after harvesting, and wash your produce in running water to mitigate a potential risk. (Photo: Evett Kilmartin)

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.

Keeping chicken feed off the ground and providing clean water are two ways to reduce the risk of contaminated eggs. (Photo: USDA)

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.

The UC Master Gardener Program can provide technical assistance to help home gardeners find resources for home soil testing. (Photo: USDA)

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

Post-fire food safety

Firewise and sustainable home landscaping design in the defensible space zone

Impact of smoke & ash on plants

[This article was first published Nov. 3, 2020]

Posted on Tuesday, July 13, 2021 at 8:17 AM
Tags: ash (1), food safety (84), Julia Van Soelen Kim (2), Rob Bennaton (4), smoke (2), Todd Kelman (1), wildfire (184)
Focus Area Tags: Food, Yard & Garden

Using vegetation barriers to reduce transmission of foodborne pathogens from livestock operations to fresh produce fields

Approximately 48 million people are sickened by foodborne illnesses leading to 128,000 hospitalizations and 3,000 deaths every year, according to the CDC estimates. A foodborne disease outbreak occurs when two or more people get the same illness from the same contaminated food or drink. Since most foodborne disease outbreaks can be traced back to contaminated fruits and vegetables, especially leafy greens, the disease burden has been a topic of concern for the agricultural industry and the public. Bacterial pathogens like Escherichia coli (E. coli), salmonella and campylobacter are among the common causes of the reported foodborne disease outbreaks.

How can we prevent foodborne pathogens from contaminating fruits and vegetables?

Before we can explore answers to the question of preventative measures, we must step back and ask a similarly important question: How do these foodborne pathogens contaminate the fresh produce to begin with? Understanding the different ways in which contamination occurs is imperative in exploring effective prevention measures and solutions.

So, how do foodborne pathogens like salmonella and E. coli get into our fruits and vegetables and why is there an increase in the observed foodborne disease outbreaks? Well, we can loosely attribute the general public's rejuvenated interest in consumption of fresh produce grown with sustainable or organic methods as a plausible explanation for the observed increase in foodborne disease outbreaks.  

Integration of livestock and crop production as a sustainable farming practice has been speculated to be a significant contributor to the increasing numbers of outbreaks, with some research studies affirming the speculation. One such research study, conducted by North Carolina State University, showed that there was indeed significant transmission from animal operations to the fresh produce on sustainable farms. In general, contamination of fresh produce by foodborne pathogens can occur through multiple pathways including the following:

  • Environmental sources such as contaminated runoff surface water
  • Insect transmission and air transmission due to proximity of farm animals to fresh produce
  • Contaminated manure and water irrigation systems
  • Improper food handling

Some of these foodborne pathogens are resistant to antibiotics, which means that even a small case of food poisoning could become fatal, hence the need to find mitigation strategies against foodborne disease outbreaks. One solution that has been proposed is using vegetation barriers to reduce transmission of foodborne pathogens like E. coli and Salmonella on sustainable farms.

Use of vegetation barriers to mitigate transmission of foodborne pathogens on sustainable farms

Vegetative barriers are narrow and parallel strips of stiff and dense vegetation planted on or close to the contour of slopes or across concentrated flow areas. Vegetative barriers slow down runoff water and even filter it out to some extent. They also loosen and improve the soil, which allows for more water retention in the ground. Since foodborne pathogens like E. coli and salmonella can contaminate fresh produce through wind transmission and through runoff surface water from animal farms, planting vegetation barriers can effectively reduce flow of runoff water and act as a wind barrier that traps spray droplets from animal operations, intercepting foodborne pathogens and preventing them from reaching fresh produce farms.

A recent study from North Carolina State University showed evidence of decreased rates of contamination of fresh produce by foodborne pathogens, specifically E. coli and salmonella, from animal operations when vegetation barriers were employed. For this study, a five-layer vegetative barrier (31x49 m) was constructed between a dairy farm, a poultry farm, and a nearby fresh produce farm. Fresh produce, animal fecal excrement and environment samples were collected during the next 15 months and tested for the level of salmonella and E. coli contamination.

The NC State results showed that only 18% of the total E. coli and salmonella samples isolated were present in the fresh produce after installation of the vegetative barriers. Their results confirmed the effectiveness of using vegetative barriers to reduce foodborne pathogen transmission.

It is important to note, however, that while vegetative barriers might be a good measure for lowering transmission by wind and runoff surface water, other transmission pathways like using contaminated manure and improper food handling can still lead to contamination regardless of whether vegetative barriers are present or not. In such scenarios, other mitigation measures are vital. 



Posted on Wednesday, June 30, 2021 at 2:40 AM
Tags: food safety (84)
Focus Area Tags: Agriculture, Food, Health

Low food-safety risk at Northern California farmers markets

“Based on this data, I think it’s safe to consume meat and produce from farmers markets,” said lead author Alda Pires. Photo by Karin Higgins UCD

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.


Posted on Monday, November 16, 2020 at 1:22 PM
  • Author: Amy Quinton
Focus Area Tags: Food

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

Avocados hang on a tree at UC South Coast Research & Extension Center. “Consumers seeking the health benefits of avocado oil deserve to get what they think they are buying,” says Selina Wang.

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 Wang.
“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.
Posted on Monday, June 15, 2020 at 5:38 PM
Tags: Avocado (12), food safety (84), nutrition (205), Selina Wang (1)
Focus Area Tags: Food

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