TRIKALA, Greece – The olive tree is woven into Greece’s life since time immemorial, with its cultivation in the country stretching back to deepest antiquity. So much so that its image has become a symbol for the country and its traditions, of a traditional way of life. Nevertheless, a team of Greek scientists has set itself a task of finding new uses for this most ancient of crops, transforming the huge quantities of olive waste produced each year into a source of protein for animal feed.
The Athens-Macedonian News Agency (ANA-MPA) spoke with Professor of Entomology at the University of Thessaly, Christos G. Athanassiou, who is conducting related research at the Laboratory of Entomology and Agricultural Zoology, within the Department of Agriculture, Crop Production and Rural Environment. His team is investigating how olive by-products can be utilised by means of a particular insect to produce animal feed and soil improvers.
The photos were provided to the Athens-Macedonian News Agency (AMNA) by the two university researchers.
“Huge quantities of organic waste are produced in Greece every year, most of which remain unused and end up in landfills. The agriculture industry, one of the key pillars of the Greek economy, contributes significantly to this problem as it generates great volumes of discarded matter for which no productive use is found. Such agricultural waste includes peel and vegetables remnants, grain and rice husks, stems, fruit remains and many more. Among these, the byproducts of olive cultivation are a particularly improtant category,” Athanasiou explained.
The research is being carried out as part of the European PRIMA programme and the OLIWA project (OLIve Waste – https://www.oliwa-project.xyz/). According to the initial findings, as outlined by Professor Athanassiou, two-phase olive pomace can account for up to 50% of the larvae’s diet when combined with other residues. By contrast, olive leaves and branches removed during the cleaning process do not appear to support the insect’s development, as higher proportions of these materials result in lower body weight and slower growth. These findings are only the beginning. Over the three-year duration of the OLIWA project, the researchers will also investigate three-phase olive pomace, olive mill wastewater and the role of phenolic compounds in insect development, with the aim of developing a comprehensive model for utilising olive industry by-products through insects.
The research is being conducted by Professor Athanassiou and doctoral researcher Panagiota Soulioti, who continue to explore new ways of making use of olive by-products.
The photos were provided to the Athens-Macedonian News Agency (AMNA) by the two university researchers.
Globally, more than 3.5 million tonnes of olive by-products are estimated to be generated each year, according to the two researchers, while in Greece the figure stands at approximately 1.3 million tonnes. The main by-product is olive pomace, which is produced either through two-phase processing, with a moisture content that can reach 60–70%, or through three-phase processing, which results in a considerably lower moisture content. The three-phase method also generates a liquid residue known as olive mill wastewater, one of the most difficult waste streams to manage in the olive oil industry. In addition, leaves and small branches are removed when the olives are cleaned before crushing, adding another type of residue to the overall waste stream.
Olive by-products are rich in dietary fibre, fats and phenolic compounds. However, their uncontrolled disposal into the environment poses serious risks, as phenols and tannins can contaminate soil and aquatic ecosystems. At the same time, valuable nutrients that could otherwise be recovered and put to use are lost.
The photos were provided to the Athens-Macedonian News Agency (AMNA) by the two university researchers.
The researchers conclude by emphasising:
“In recent years, both industry and the scientific community, at national, European and international level, have been seeking new solutions for managing the ever-increasing volumes of organic waste. In this context, insects have emerged as an unexpected but highly promising ally. Their ability to convert organic residues into useful biomass has attracted the interest of researchers and companies seeking sustainable and cost-effective methods of valorising agri-industrial by-products. Among the species studied, the black soldier fly, Hermetia illucens (Diptera: Stratiomyidae), stands out for its ability to convert organic residues into products with high added value.”