Olive fruit processing method entailing stone removal and dehydration to obtain olive oils and flours with enhanced content of bioactive substances: Quantitative characterization of two promising products

OLMO-GARCÍA, LUCÍA; FERNÁNDEZ-GUTIÉRREZ, ALBERTO; MONASTERIO, ROMINA P.; CARRASCO-PANCORBO, ALEGRÍA; SANCHEZ- ARÉVALO, CARMEN MARÍA

Valladolid

Congreso; XXII Reunión de la Sociedad Española de Química Analítica (SEQA); 2019

Sociedad Española de Química Analítica (SEQA)

Virgin olive oil (VOO) is still produced using, essentially, the same principle implemented by Romans, which involves huge simultaneous waste generation (mainly olive pomace and mill wastewater). Over the last decades, the interest in looking for a cost-efficient, technically feasible and environmentally sound solution for the residues generated from olive oil industry has considerably increased. One of the innovative proposed strategies consists on performing a stone removal treatment from clean olives, followed by a dehydration process and a cold press. This procedure drives to two products: 1) an olive oil with numerous potential uses which could certainly meet the increasing demand for high-quality oils (with a very high content of bioactive compounds); and 2) a pulp pellet that can be converted into ?olive flour? by grinding and which is expected to contain high levels of fiber and bioactive compounds, fulfilling the criteria to act as a potential ingredient in functional food. Carrying out the chemical characterization of both products is essential to estimate its industrial viability and to check the advantages that the novel processing method could bring to the VOO sector.Thus, the main objective of the present work was to accomplish the comprehensive qualitative and quantitative characterization of the metabolic profiles of the olive oils and flours obtained by means of the described processing method and to evaluate the effect of the dehydration temperature on the composition of the resulting products.Fresh fruits from Lechin de Granada cv. were harvested, conditioned (washing and size-sorting) and subsequently, they were stoned and dehydrated at four different temperatures (35, 55, 75 and 100 ºC). Afterwards, dry pulp was pressed with a screw press to obtain olive oil and defatted pulp separately. Finally, the obtained oils were filtered through a paper filter to remove solid particles and the stoned, dehydrated and defatted pulp was grinded to obtain ?olive flour?. Additionally, ?conventional? VOO was obtained through an Abencor® laboratory oil mill (two-phase system), in order to facilitate the comparison with the new ones.The prepared samples were analyzed by means a powerful LC-MS multi-class method capable of determining around 60 metabolites belonging to different chemical classes (phenolic compounds, pentacyclic trirterpenes and tocopherols) within the same run [1]. Both the flours and the new oils presented considerable amounts of olive fruit metabolites that are usually absent from VOOs. In addition, qualitative and quantitative differences were found among VOOs and oils produced using different dehydration temperatures probably due to the inhibition of some enzymes (e.g. β-glucosidase and polyphenoloxidase) caused by the temperature increase or the absence of water during the processing.In general terms, all the evaluated chemical families were found at higher concentration levels in samples produced from fruits dehydrated at 100ºC. The oils obtained in these conditions were also richer than the conventional VOO in terms of most of the determined metabolites except for phenolic acids and aldehydes, three minor secoiridoids and the aglycone flavonoids.