Transforming Olive Byproducts into Safe Food Ingredients: Research and Education to Ensure the Safety of Olive Leaf Powder as a Novel Food Ingredient

Commodities

• Fruits: olives
• Additional Plants: trees, other

Practices

• Crop Production: food processing, food product quality/safety, season extension

Olive trees are one of the most agronomically and ecologically sustainable crop trees in the Western U.S.: low pest pressure and low nutrient needs mean low inputs; low to no water needs. They are a viable permanent crop on small/family farms, particularly in multi-cropping systems or in conjunction with pasturing.

Olive growers in the Western U.S. produce mainly olive oil. The big problem they face is intense pricing competition from very large foreign producers of cheap olive oil. Western U.S. olive growers need novel products to make olive growing more economically sustainable.

PI Caceu (olive grower) and TA Waite-Cusic (Professor of Food Safety and Quality Systems at Oregon State University) will evaluate the efficacy of olive leaf drying methods to inactivate Salmonella enterica, to determine their suitability as process preventive controls. The targeted drying process was previously optimized (in WSARE project FW25-004) to maximize the retention of polyphenols in the dried olive leaf material. However, the effectiveness of the drying process on microbial safety was not evaluated in FW25-004. Therefore, the proposed project will build on top of FW25-004. A validated safety process will position dried olive leaf to meet the safety expectations of food, beverage, and supplement manufacturers.

Working with olive leaf up-cycles a byproduct of the pruning of olive trees, which extends the season from a fall harvest (of olives for olive oil) to a year-round harvest of olive leaves for dried olive leaf, increasing olive growers' economic sustainability.

The research findings will be submitted for publication in a peer-reviewed journal. TA Waite-Cusic will prepare and present a poster or oral presentation at a relevant stakeholder event (e.g., OSU Small Farms Conference). The data will also be disseminated to the olive growing community with help from the leading growers' associations in the Western region.

The proposed project has multilayered objectives:

(1) Crop processing sustainability. The project seeks to identify a washing and drying process that is simple, energy efficient (low temperature oven drying), cost effective (little to no inputs), and therefore highly sustainable, to prepare a dried olive leaf powder. It is very important that the process retains the highest levels of polyphenols and that it is effective at ensuring the microbial safety of the end product. Only thus can a dried olive leaf powder enter the marketplace positioned to meet the safety requirements of food, beverage, and supplement manufacturers. TA Waite-Cusic's research will provide the data needed to determine the proper process.

(2) Nutritional value of the dried olive leaf powder. The Linus Pauling Institute will conduct measurements of the total phenolic content in samples of dried olive leaf in order to confirm that the washing and drying process identified by TA Waite-Cusic is also most effective at the retention of polyphenols from the olive leaf. Polyphenols (or phenolic compounds) are molecules with strong antioxidant and anti-inflammatory activity that have been linked to health maintenance in humans.

(3) Agronomic sustainability, increased by the up-cycling of a by-product. The project's focus is on olive leaf, not on olives (the fruit) or olive oil. That is because scientific literature shows that olive leaves have similar and sometimes higher levels of polyphenols (depending on olive varietal, time of harvest, etc.) than olives or olive oil. Entire olive branches are pruned each year in order to maintain the 'open vase' shape of the trees that is best for the health of the olive tree (air flow) and best for production of olives (thanks to light penetration inside the olive tree's canopy). The project's research elevates the by-product of yearly pruning into a product that can be marketed as a standalone product (e.g., olive leaf as a substitute for green tea) or as a polyphenol-rich ingredient for food, beverage, or supplement manufacturers.

(4) Agronomic and economic sustainability, increased by season extension. U.S. olive growers primarily produce olive oil. The olives are harvested and milled in the fall (October-November), during a very brief season. Working with olive leaf, on the other hand, can happen at any time of the year because olive trees are evergreen and olive leaves are always available to be harvested and processed. This would extend the season to one that is year-round.

(5) Economic sustainability, increased by product diversification. The dried olive leaf powder is a novel product for U.S. olive growers. The powder could be marketed as a standalone food product or as a functional ingredient to be used in other food and beverage products to impart polyphenols. Produced in addition to olive oil, the dried olive leaf powder expands and diversifies olive growers' product lineup, which can only be beneficial for their economic sustainability.

(6) Educational outreach. The project's educational objective is to submit the project's findings for publication in an open-access, peer-reviewed journal such as Journal of Food Protection, and to present the project's findings at an educational outreach event such as the Small Farms Conference at Oregon State University. This annual conference brings together over 1,000 participants, mainly farmers and food and beverage producers. The project's findings will also be disseminated to olive growers via the leading olive growers' associations in the Western U.S., Olea Project (Oregon) and American Olive Oil Producers Association (AOOPA, a national organization based in California).