- Author: Michael Hsu
Growers, UC Cooperative Extension researchers offer guidance on producing high-quality olives
Facing a deluge of lower-price products from Europe, the California olive oil industry is doubling down on its clear-cut competitive edge: the consistent and bona fide quality of its oil.
“Olive Production Manual for Oil,” a new book published by University of California Agriculture and Natural Resources, aims to help California olive growers maximize that advantage.
“It's a tough market to compete in, but I think the way to win for California is to compete on quality,” said book co-editor Selina Wang, a UC Cooperative Extension specialist in the UC Davis Department of Food Science and Technology. “The quality of California olive oil is unmatched, but you can't make good quality olive oil with bad fruit, so the goal is to get more fruit from the trees – and for the fruits to be high-quality fruit.”
The 273-page manual, available for purchase online, is the first of its kind in the U.S. While some parts of the book are specific to California (which grows nearly all of the olives for domestically produced olive oil), most of the material would be useful to producers in other states, Wang noted.
“Through our conversations with growers, it became clear to us that a manual like this – not a scientific publication but a manual that is easy to follow, written in language that is accessible, and with pictures and illustrations – would be really helpful to the growers,” she said.
Growth of California olive oil industry necessitated creation of manual
Aside from a book focused predominantly on table olives and another on organic olive production (by UCCE farm advisor emeritus Paul Vossen), there was no one-stop, comprehensive resource on the bookshelf for oil olive growers. The need for such a manual had become more acute as oil olives replaced table olives in California orchards during the last 20 years.
Whereas harvesting by hand was historically cost-prohibitive, the introduction of super-high-density planting systems in 1999 made oil olive production more economically feasible. Mechanical pruning and harvesting of new cultivars (Arbequina, Arbosana and Koroneiki) – specifically bred for these densely planted orchards – led to the rapid expansion of oil olives in the state. According to a U.S. Department of Agriculture report, California olive oil production jumped from 2 million pounds in 2006 to an average of 21 million pounds in 2021–23.
With about 37,000 acres of oil olives planted across California, the Olive Oil Commission of California saw the need to support the production of this manual. Championed by Dan Flynn, founder and executive director emeritus of the UC Davis Olive Center, Wang and co-editor Louise Ferguson outlined the contents of the book. They then sought out a mix of growers and industry professionals and UCCE advisors and specialists to write its chapters.
“Most of the information is data-based, from people who are working with the olives,” said Ferguson, a UC Cooperative Extension pomologist at UC Davis. “This is the first data-based olive oil production manual we've had.”
Manual infused with firsthand insights, practical recommendations
Hard-earned experience taught growers a valuable lesson that is conveyed in the book – the need to hand-prune. While mechanical pruning helps control the size of the trees, some hand-pruning is still required to allow light to filter to the leaves. Failing to do so leads to a dramatic decrease in yield.
“That happened in many of the orchards that were inexperienced in these new cultivars and new super-high-density planting systems,” Ferguson said.
She added that other key topics in the manual include irrigation management in a water-constrained state, nitrogen management, harvest timing and orchard site selection. Choosing a good spot for planting is crucial in this era of extreme climate volatility, Ferguson noted, as olive trees are significantly affected by temperature shocks in spring (fruit set) and fall (harvest).
For Wang, another overarching theme in the manual is the importance of testing. Testing the soil, water and leaves provides critical data that growers can use to adjust their inputs and production practices for optimal profitability.
“You may spend a couple hundred dollars on the lab work, but it will pay off, for sure – you're going to increase the health and productivity of your trees,” Wang explained. “Oil olive growers are paid based on the oil content in their fruit; you not only want to have a lot of fruit on the trees, you want to make sure that your fruit are accumulating oil.”
California oil olive growers, practices continue to evolve
Wang and Ferguson hope their book will help California producers compete more effectively in the global marketplace. Currently, about 90% of the olive oil consumed in the U.S. is imported from Mediterranean countries, due primarily to the lower price point. In that region, producers tend to harvest riper olives that produce oil at a greater volume but lesser quality.
In contrast, California growers harvest earlier and produce oil that is higher quality (with more flavor and more antioxidants) and far exceeds accepted standards for “extra virgin olive oil.”
According to Wang, California olive oil mills have nearly maximized their efficiency, and the growth opportunity for the industry is in the orchards: to optimize practices to produce more fruit, and to plant more trees. Wang said the new manual can help on both fronts.
“Just like for other crops, focusing on quality – while increasing efficiency and productivity, and therefore profitability – is the name of the game,” she said.
Ferguson also stressed that knowledge continues to evolve and urged growers to reach out to the editors and chapter authors with their experiences.
“Most of the authors are in California and they're working,” she said. “So if you start to notice things that are different, or you want more information or something is not clear, the authors are available.”
The manual can be purchased at https://anrcatalog.ucanr.edu/Details.aspx?itemNo=3559.
/h3>/h3>/h3>/h3>- Author: Emily C. Dooley, UC Davis
Low-cost wine industry additive also improved feed efficiency and milk quality
Researchers at University of California, Davis, added fresh grape pomace left over from winemaking operations to alfalfa-based feed for dairy cows and found that methane emissions were reduced by 10% to 11%.
The preliminary findings could offer a low-cost sustainable pathway for vineyards to reduce waste while helping dairy operations maintain quality while cutting back on emissions of methane, which is a powerful greenhouse gas.
“This is the first time anybody has shown that this can work in California,” said Ermias Kebreab, an animal science professor and associate dean of global engagement at UC Davis. “You're reducing emissions, you're improving the quality and it may also reduce the cost of production.”
The pilot research project, which will be detailed in a paper later this year, also found that mixing in grape pomace improved feed efficiency and increased healthful fats, said Selina Wang, an associate professor of Cooperative Extension in small scale fruit and vegetable processing.
“We found that the feed with the additive of grape pomace changed the fatty acid composition of the milk and, in particular, increased the polyunsaturated fats, which are the main fats in grape pomace,” Wang said. “This suggests that supplementing the feed with an optimal fatty acid profile may have positive impact on the fatty acid profile of the milk and increase their health benefits.”
Symbiotic commodities?
In 2022, California was the leading dairy producer in the country, generating $10.40 billion in sales, while 90% of wine production came from the Golden State, with a market value of $5.54 billion.
Processing grapes for wine generates thousands of tons of waste in the form of grape pomace, which consists of leftover seeds, skins and stems. Dairy and livestock are responsible for more than half of the state's methane emissions, owed largely to cow burps.
They are the top two agricultural commodities in California, according to state production statistics, and reducing waste and emissions for both industries are key to the state meeting its climate goals.
Tannins for emission reductions
Wine grapes are high in fats and tannin, which is known to reduce methane emissions, so Kebreab sought to test if adding grape pomace to feed could have a positive effect while not adversely affecting production.
“It's a byproduct that's not being used much,” he said. “This is something that can be included in our efforts to try to reduce emissions.”
A mix of feed options
To do the research, scientists worked with Holstein dairy cows and gave the animals feed consisting of alfalfa, wheat, almond hulls, cottonseed and grain. After two weeks, the cows were split into three groups: A control group with no change in diet, another where the feed combination included 10% grape pomace and a third that received 15% grape pomace.
Every four weeks, the cow groups would change feed combinations.
They were fed twice daily by postdoctoral students and interns, and emissions were monitored daily. Milk production was documented in the morning and evening and milk samples were collected weekly to analyze for fat, protein, lactose and other measurements, which showed no differences between the control and other groups.
Methane and hydrogen emissions were reduced compared with the control group, suggesting that grape pomace reduced enteric emissions without affecting production.
“I think the dairy industry will be very interested in this,” Kebreab said. “Sometimes when you're using additives, they have palatability issues. With grape pomace, they absolutely love it.”
Next on the list is a trial with olive pomace and working to understand the mechanism that reduces emissions. “If we have a better understanding of the mechanisms, we can select the feed additive or a mix of feed additives to reduce dairy cattle emissions and make dairy milk healthier while making use of the agriculture byproducts,” Wang said. “There's a lot of room to grow in this space and we're excited about this work.”
The research was supported by the California Dairy Research Foundation.
This article was first published on the UC Davis news site.
/h3>/h3>/h3>/h3>
- Author: Tiffany Dobbyn, UC Davis
Researchers identify key markers to help professional retail buyers choose authentic products
Avocado oil has become a popular choice for many people in recent years because of its heart-healthy benefits and versatility in cooking. However, not all avocado oil products on store shelves are created equal. Some products are labeled as “pure” avocado oil when they contain other oils or additives. No enforceable standards defining the chemical and physical characteristics of avocado oil exist yet.
Researchers at the University of California, Davis, analyzed samples of 36 private label avocado oil products and graded them based on quality and purity. Private label products are made by a third-party processor and sold under a grocery store or retailer brand label. Their findings, published in the journal Food Control, show that 31% of the samples tested were pure, and 36% were of advertised quality. Quality refers to whether the oil is fresh or has gone bad due to aging, heat or light exposure. For purity, researchers measured fatty acids, sterols and other components that differentiate avocado oil from other oils.
The study included oils purchased from 19 retailers in the U.S. and Canada with various price points. They found that lower-priced oils were more likely to be tainted with other oils.
“We found that low-cost products indicate a higher probability for adulteration, but high cost didn't guarantee purity or quality,” said Selina Wang, associate professor of Cooperative Extension in the Department of Food Science and Technology. She and Hilary Green, a postdoctoral researcher at UC Davis, co-authored the paper.
Researchers also identified certain chemical markers in avocado oil that professional retail buyers can use to make more informed decisions when it comes to choosing suppliers. This way, consumers can feel confident about the products they buy.
This is the second comprehensive study conducted by UC Davis researchers on the quality of avocado oil sold in the U.S. The first study released in 2020 found that many of the test samples were of poor quality, mislabeled or adulterated with other oils.
“This study demonstrates that although progress is being made in standard development since our first market study in 2020, there are still issues with purity in avocado oil and these issues extend significantly into private label oils,” Wang said.
Avocado oil standards
Since the release of the first UC Davis study, Wang said there's been a coordinated effort by researchers, industry leaders and government agencies to establish enforceable standards. The Avocado Oil Expert Group was formed in collaboration with the American Oil Chemists' Society to discuss potential standards and future research projects.
Wang's research group has been studying how natural factors like different types of avocados, harvest times, geographic origins and processing methods could affect the chemical composition of avocado oil. They want to create standards that will accommodate natural variations while detecting any adulterations.
Wang hopes that the study's findings will contribute to the establishment of standards that benefit both consumers and avocado oil producers who want to compete in a fair market.
“I'm very optimistic for the future of the avocado oil industry,” Wang said. “It's a high-value product with high consumer demand, similar to what I saw with olive oil 10 years ago. Olive oil quality and purity have improved significantly, which is where I see avocado oil going, if we can establish fair standards and eliminate fraudulent products.”
/h3>/h3>- Author: Pamela Kan-Rice
Barman named UCCE IPM advisor in Imperial County
Apurba Barman joined UC Cooperative Extension as low desert integrated pest management advisor on Jan. 11, 2021. He will be headquartered at the UCCE Imperial County office, which adjoins the UC Desert Research and Extension Center in Holtville.
"I am very excited for my new role as an IPM advisor based in Southern California and for the opportunity to serve one of the most important vegetable production regions in the state,” Barman said. “The diversity and intensity of crop production in this region demand targeted research to solve pest management issues and effective extension programs to reach diverse clientele. I feel prepared for this job with my experience and passion to serve the community.”
Barman earned a bachelor's degree at Assam Agricultural University in India, and master's degrees in Indiana and at Texas Tech University, Lubbock. In 2011, he completed a doctorate degree at Texas A&M University in College Station, where he developed a research program to understand the extent of damage and management of thrips in the Texas High Plains region.
Barman comes to UC Cooperative Extension from the University of Georgia, where he led a whitefly monitoring and management progress across cropping systems in the southern region the state.
Barman can be reached at (209) 285-9810 and akbarman@ucanr.edu. His Twitter handle is @Ento_Barman.
Tian joins UCCE as viticulture advisor in Kern County
Tian Tian has been named the UC Cooperative Extension viticulture advisor in Kern County, beginning Jan. 4, 2021. Tian previously served as a graduate research assistant at Oregon State University in Corvallis, where she conducted experiments and statistical analyses of data sets while completing her doctoral degree.
“I feel very excited to join UC Cooperative Extension and be part of this collaborative group,” Tian said. “I look forward to working with local growers and industry to improve management practices in the vineyard and increase the profit margin of table grape production.”
Tian earned a master's degree at California State University, Fresno, and a bachelor's degree at Northwest Agriculture and Forestry University, China, both in viticulture and enology. For several years she worked in industry, including an internship at E. & J. Gallo Winery in Modesto and as the assistant vineyard manager at Berryessa Gap Vineyard in Winters.
Tian's doctoral research focused on development of better guidelines for vineyard nitrogen management for growers in the Willamette Valley. She and the research team evaluated the influences of vineyard nitrogen on vine productivity, fruit composition and wine characteristics in chardonnay and pinot noir.
Tian can be reached at titian@ucanr.edu. Her Twitter handle is @TianUcce.
Garay named social media strategist
Dora Garay joined UC ANR as a social media strategist on Jan. 19. She brings over 15 years of communications experience, most recently serving as the digital marketing specialist at Everett Community College in Washington, where she managed more than 20 college-wide social media accounts and conducted innovative marketing campaigns in both English and Spanish.
Garay has a track record of engaging and empowering communities through her effective communications strategies and social media expertise. Along with more than a decade of working with digital media, her experience includes producing news and education segments for Univision, a top-rated television network.
Garay earned a bachelor of arts in political science at UC Berkeley and a Master of Communication in Digital Media at University of Washington.
She will be based in the UC ANR building in Davis and can be reached at dgaray@ucanr.edu and (510) 630-5622. Her Twitter handle is @DoraliciaGaray.
Flavell remains interim director of Sierra Foothill REC
An internal search to fill the director position at Sierra Foothills REC was conducted during November-December 2020. Unfortunately, no applications were received. UCANR leadership and UC Livestock & Natural Resources academics are exploring options to provide sustained leadership for SFREC.
In the meantime, SFREC superintendent Dustin Flavell will continue to oversee the center. Flavell has served as interim director since September, when Jeremy James left UC ANR to become department chair of Natural Resources at Cal Poly San Luis Obispo.
DOE honors Sanchez for carbon removal research
The U.S. Department of Energy (DOE) granted a Secretary of Energy Achievement Award to a team including UC assistant Cooperative Extension specialist Daniel Sanchez and Ph.D. candidate Bodie Cabiyo in the Department of Environmental Science, Policy, and Management at UC Berkeley.
Sanchez and Cabiyo's team "Getting to Neutral Carbon Emissions" was selected for their outstanding service and research contributions, both to the agency's mission and the benefit of the nation, in greenhouse gas emissions reduction scholarship.
The team's final report, titled “Getting to Neutral: Options for Negative Carbon Emissions in California,” provides a comprehensive study of technologies that remove carbon dioxide from the atmosphere. It offers frameworks for developing public policy and legislative action based on scientific data to help California achieve carbon neutrality by 2045 or sooner. Sanchez and Cabiyo contributed research to help estimate the amount of forest biomass that can be used in negative emission pathways, as a result of managing 1 million acres of forest each year. They used economically driven models to identify the most cost-efficient forest management strategies for the team's Forest Carbon Plan goals.
The award is one of the highest internal, non-monetary recognitions that DOE employees and contractors can receive.
Mitchell receives No-Till Innovator Research & Education award
Jeffrey Mitchell, UC Cooperative Extension specialist, received the No-Till Innovator Research & Education award for his commitment to the advancement of no-till farming systems.
Mitchell, who is based at Kearney Agricultural Research and Extension Center, has been a pioneer in design, research, knowledge generation and extension in conservation cropping systems in California. With his dedication, these conservation cropping systems are now beginning to be gradually adopted in the state and are receiving much attention from growers, extension, industry, educational institutions, state and federal government agencies, and non-governmental agencies, says Anil Shrestha, chair of the department of Viticulture and Enology at Fresno State University.
Initially, Mitchell established the UC Conservation Tillage Workgroup that was primarily focused on no-till systems. Later, he expanded the workgroup and established the Conservation Agriculture Systems Initiative (CASI) group with a broader conservation systems approach. CASI won the No-Till Innovator Award in 2018.
Mitchell expanded his work to vegetable crops and is among the first in the U.S. to work on these systems combined with precision irrigation technology. Mitchell organizes the CASI Workgroup Field Days and Demonstrations at the UC West Side Research and Extension Center.
An important part of Mitchell's research and education efforts has emphasized evaluations of the impacts and tradeoffs that reduced disturbance tillage and cover cropping have on soil and cropping system function.
Based on a long-term study dating to 1999, Mitchell worked with a team that documented that no-till and cover crop practices in sorghum, cotton, corn, wheat and tomato could not only maintain productivity, but also greatly impact a number of important soil quality indicators — including higher soil carbon and nitrogen, aggregation and infiltration. This work has documented that significant positive changes have occurred even in the arid, irrigated soils in the San Joaquin Valley.
Wang honored for olive research
Selina Wang, research director at the UC Davis Olive Center and UC Cooperative Extension specialist in the UC Davis Department of Food Science and Technology, recently received the Olive Wellness Institute's inaugural award for achievement in olive science research.
Wang joined the Olive Center as a postdoctoral researcher in 2010 and became research director in 2011, leading the center's research efforts in olive oil quality, authenticity and standardization. She took on her Cooperative Extension duties in 2018. “I still do the work I've been doing with olives and olive oil, but now I cover all the crops that are important for California,” she said.
Research from the Olive Center contributed to the scientific basis for the establishment of California grade and labeling standards for olive oil, refined-olive oil and olive-pomace oil. Under the standards, producers of greater than 5,000 gallons per year must test every lot of oil for quality, thereby instilling confidence in consumers.
Wang said she looks forward to continued research on maximizing quality, health benefits, yield and sustainability — in the field and in processing. “We've made a tremendous amount of progress in the past decade, and there's more work to be done, especially in response to climate change,” she said. “I will continue extension with the growers and processors and education with the students at UC Davis who are the future leaders.”
Dan Flynn, the recently retired Olive Center director, nominated Wang for the award. “Dr. Wang stands among the very best people I have worked with,” he said. “Her independent and significant research achievement, skill at attracting financial backing and resources, ability to inspire students, robust work ethic, dedication to the public interest and exceptional interpersonal skills place her among the noteworthy olive scientists globally.” – UC Davis News and Media Relations
Khan elected to national hydrologic science board
Safeeq Khan, assistant UC Cooperative Extension specialist for water and watershed sciences based at UC Merced, has been elected to the board of directors for the Consortium of Universities for the Advancement of Hydrologic Science, Inc. (CUAHSI).
Sponsored by the National Science Foundation, CUAHSI is a non-profit organization with a mission to serve the interdisciplinary water science community in promoting and expanding formal and informal educational opportunities.
Gosliner to serve on Farm to School Working Group subcommittee
Gosliner was recommended to participate in the Health Systems Data subcommittee because of her experience in measuring impact for food systems projects.
As a subcommittee member, Gosliner will help create a unified vision for the future of farm to school in California. The group will meet January 2021 through October 2021, culminating in the publishing of a “Roadmap to Success” for California's farm to school movement.
“Our state leaders recognize the need to transform our food system into one that is climate-smart, equitable, resilient, reflective of all of California's diverse cultures, and accessible to all,” said Ross and Siebel Newsom. “We know school nutrition is a key element of this transformation, and a recent $10m budget allocation from Governor Newsom shows the state is making a serious effort to expand its impact.”
- Author: Diane Nelson
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.