Olive leaves have been underutilized primarily due to limited awareness of their health benefits, overshadowed by the popularity of olives and olive oil in culinary traditions. There are many challenges in processing techniques, regulatory constraints, and limited research development and consumer awareness which also contribute to their infrautilization. In this article, we would like to dive deeper on the many reasons why revalorisation of olive leaves is crucial.
Have you ever wondered what happens to olive leaves after olive recollection and pruning? They remain in the field and olive mills!
Accounting for a staggering volume of biomass currently underutilised. Olive trees that are grown to produce table olives need to be pruned every year, whilst olive trees grown for olive oil need to be pruned every second year. It is estimated that a whopping 1.25 million tons of olive leaf biomass is produced annually in Spain alone, representing approximately 50% of the world’s total production. Most of the biomass generated from the pruning has traditionally been incorporated back to land, fed to livestock, or burned in field, contributing to greenhouse gas emissions and meaning that a valuable resource is largely underutilised. As such, these discarded olive leaves are starting to be recognised as a precious source of biomass.
Indeed, olive leaf biomass is rich in valuable bioactive compounds such as polyphenols, triterpenoids, essential oils, lipids, and lignocellulose, making it a potential asset in various industries including food, feed, chemical, nutraceutical, cosmetic, and pharmaceutical sectors. Collecting and finding the best valorisation route for a given batch of leaves is very challenging and something that has been rarely tried before.
OLEAF4VALUE is a 3-year collaborative EU-funded project (funded under the BBI-JU, now known as CBE-JU) which began in June 2021 and ends in July 2024. It brings together a consortium of 16 experienced partners dedicated to fully exploiting the potential of this underutilised biomass. The project uses enzymatic biotransformation and nanoencapsulation technologies to create tailored products for the specific end-user markets. The consortium includes entities from the entire value chain, encompassing the collection and supply of raw material, biorefining processes, post-extraction technologies, and bio analysis, market validation, and impact assessment, including sustainability.
The project’s primary goal is to provide a sustainable solution for the comprehensive valorisation of olive leaves, that is, finding the best final product for the given condition of the leaves. Factors like tree location, horticultural practices, tree type, and leaf origin within the tree (i.e. whether the leaves grew on older, low-hanging branches, or new growth near the tree crown) can impact on what compounds can be extracted and in which quantities from the leaves. The project aims to establish six new value chains that will introduce 24 bio-based and cost-effective products to the market. These products aim to create value across the entire chain, with a particular emphasis on the primary sector.
Notable compounds such as oleuropein, luteolin, and oleanolic acid found in olive leaf extracts are currently being investigated in the valorisation process. Examples of subsequent products include natural preservatives; treatments for certain health conditions such as diabetes; antioxidants for the food market; new feed additives to enhance animal health and reduce the use of antibiotics; and lastly, new building blocks and natural antioxidants for the chemical sector. Additionally, several bio-based compounds generated by the project show promising results as potential cosmetic ingredients, for example, offering protection against oxidative stress.