Posts Tagged: food safety
E. coli and Salmonella are rare in wild birds, Campylobacter more common
Concerns over foodborne risk from birds may not be as severe as once thought by produce farmers, according to research from the University of California, Davis, that found low instances of E. coli and Salmonella prevalence.
While the research found that the risk is often low, it varies depending on species. Birds like starlings that flock in large numbers and forage on the ground near cattle are more likely to spread pathogenic bacteria to crops like lettuce, spinach and broccoli, according to a study of food safety risk and bird pathogens from the University of California Davis. In contrast, insect-eating species were less likely to carry pathogens.
The findings, published in the journal Ecological Applications, suggest that current practice of removing bird habitats around produce growers' farms over concerns the animals could bring foodborne pathogens into their fields may not solve the problem.
“Farmers are increasingly concerned that birds may be spreading foodborne diseases to their crops,” said Daniel Karp, the senior author on the study and an assistant professor in the UC Davis Department of Wildlife, Fish and Conservation Biology. “Yet not all bird species are equally risky.”
Only one foodborne disease outbreak in produce has been conclusively traced to birds: a Campylobacter outbreak in peas from Alaska. While the bacteria can cause diarrhea and other foodborne illness in humans, it's less of a concern to growers than E. coli and Salmonella, which have been responsible for multiple outbreaks across the nation.
In this study, researchers compiled more than 11,000 bacteria tests of wild bird feces and found that Campylobacter was detected in 8 percent of samples. But pathogenic E. Coli and Salmonella were only found in very rare cases (less than 0.5%).
In addition to the bacteria tests, researchers conducted roughly 1,500 bird surveys across 350 fresh produce fields in Western states and collected more than 1,200 fecal samples from fields. They then modeled the prevalence of pathogens in feces, interactions with crops, and the likelihood of different bird species to defecate on crops to determine risk.
Insect-eating birds pose lower risk
Based on the data, insect-eating birds, such as swallows, present a lower risk, while birds that flock near livestock, such as blackbirds and starlings, are more likely to transmit pathogens.
The data can help the agricultural industry determine risk and take action, such as separating produce crops from cattle lands. They also don't need to treat all birds the same.
“Maybe farmers don't need to be quite as concerned about all types of birds,” Karp said. “Our data suggest that some of the pest-eating birds that can really benefit crop production may not be so risky from a food-safety perspective.”
Removing habitat can backfire
This study and the authors' prior work indicate that removing habitat around farms may actually benefit the species that pose more risk and harm the beneficial, pest-eating ones that are less risky to food safety. This is because many prolific insect-eaters may visit crop fields to eat pests but need nearby natural habitats to survive. In contrast, many of the bird species that most commonly carry foodborne pathogens readily thrive on both cattle farms and produce farms without natural habitat nearby.
Insect-eating birds that forage in the tree canopy pose minimal threat because they are less likely to carry foodborne pathogens and come into direct contact with produce. They can also be valuable parts of the ecosystem, particularly if they eat pests that can harm crops. Installing bird boxes could attract the pest-eaters, as well as help with conservation efforts.
“We basically didn't know which birds were problematic,” said lead author Olivia Smith, a postdoctoral researcher at Michigan State University who was at University of Georgia when the paper was written. “I think this is a good step forward for the field.”
Additional co-authoring institutions include James Cook University, UC Berkeley, UC Riverside, University of Kentucky, University of Texas, Virginia Polytechnic Institute and State University, Washington State University, BioEpAr, The Nature Conservancy and Van Andel Institute.
The research was funded by the United States Department of Agriculture and the National Science Foundation./h3>/h3>/h3>/h2>
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.
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.
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.
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.
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 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.