The olive oil industry generates approximately 30 million cubic meters of mill waste each season. The most solid part of this waste is pomace, which is a major source of concern due to its capacity to pollute and affect soil balance. Although the pomace’s richness in organic compounds is what makes it a pollutant in the first place, these bioactive compounds are mainly phenols and triterpenes, which have a high antioxidant potential and thus significant health benefits.
A research team from the University of Córdoba has recently evaluated the phenols and other bioactive compounds from the extraction of olive oil pomace in 43 olive varieties for three consecutive seasons. This is the first study to evaluate the role played by olive variety in the phenolic profile of the pomace, taking into account a large variety of cultivars and a time span greater than a single season.
The scientists discovered that olive variety is the main factor determining what types of antioxidants their pomace contains, and classified the cultivars into three different groups based on these concentrations: one containing higher concentrations of oleuropein and ligustroside; one with higher concentrations of oleacein and oleocanthal; and finally, a group that had minor compounds, such as certain flavonoids and triterpenic acids.
Clarifying the bioactive composition of various olive varieties marks a decisive step forward from considering the pomace a waste product to its employment as a by-product from which to extract phenols that can be used in the pharmaceutical or cosmetical industries, as well as in food enrichments or animal feed, due to their significant health benefits. Moreover, extracting these compounds from the pomace makes it less pollutant for the environment.
“From the point of view of the recovery of these pomaces, the industry may know that if an area tends to be used for the picual variety, for example, the pomace generated will contain certain phenols, so one knows which phenols can be extracted from it,” explained study co-senior author Feliciano Priego a professor of Analytical Chemistry at the University of Córdoba.
“The high number of varieties analyzed, and having continued the study over three seasons, renders this work highly valuable,” added another senior author, Concepción Muñoz, a professor from the same department. “Thanks to Córdoba’s World Bank of Olive Germplasm, we can have varieties cultivated under the same agronomic and climatic conditions, thus allowing it possible to compare them.”
The study is published in the journal Food Chemistry.