Industrial trials on coadjuvants for olive oil extraction Original Research Article

Industrial scale experiments were performed in an olive oil production factory to assess the effect of different physical acting coadjuvants on oil extraction and oil quality. Up to 120,000 kg olives were processed. Talc and calcium carbonate, with different particle sizes, were assayed at concentrations ranging from 0.3% to 1% by weight. Both coadjuvant types are food grade and are recognized as food additives by EU regulations (E-170 as calcium carbonate and E-553b as talc). Industrial trials were performed at room temperature with no added water, thus avoiding volatile compound loss and hydrosoluble compound content decrease. As a consequence, the obtained oils were more aromatic and their positive attributes more intense, in comparison to other olive oils produced in different operational conditions. In addition, energy requirements were decreased (releasing a lesser amount of carbon dioxide into the atmosphere) and water uptake was kept to a minimum. Results show that the use of coadjuvants improves the oil extraction yield. The extraction efficacy, defined as the percentage of initial oil that is extracted, increased by 2% by using carbonate in comparison to experiments performed without any coadjuvant, with 91.53% of oil content in the olives being extracted. For the same particle size, calcium carbonate was found to extract a greater oil amount than talc. For a single coadjuvant, the extraction yield decreased as the particle size increased. The best results, in terms of oil extraction yield, were obtained when using 0.3% calcium carbonate. Considering oil quality, no influence by either coadjuvant was detected as oil components remained unaltered during the extraction process. The sensorial evaluation gave the same result for all olive oils, no matter if a coadjuvant was used or not, indicating that these compounds only act physically on the oil extraction process.