Influence of clay and microtalc addition on the extraction yield and quality of extra virgin oil from Arauco cultivar

MASTIO, VALERIO; PIERANTOZZI, PIERLUIGI; MAESTRI, DAMIÁN; CASTELLANO, JUAN PABLO; BUFFA, ELINA; GENTILI, LUCIANA; CONTRERAS, CIBELES; TIVANI, MARTÍN; TORRES, MARIELA

Jaen

Simposio; Simposio; 3rd Yale International Symposium on Olive Oil and Health, IV International Congress on Olive Oil and Health; 2021

Universidad de Jaen- Universidad de Yale

In the last decades, the technological process of olive processing has undergone significant innovations aimed at increasing both the extraction yields and the chemical, sensory, and nutritional properties of virgin olive oils. In particular, in view of increasing oil yields, the positive effects of using processing aids are particularly important for pastes without adequate rheological properties for phase separation in malaxation, usually called difficult pastes. So, under these conditions, lower olive oil yields can be observed due to the high moisture content of the fruits. Several studies have reported the use, at pilot and/or industrial level, of physical adjuvants, such as talc, sodium chloride, enzymes, calcium carbonate or clay, to increase the oil yield in the pastes mentioned above. The aim of the present investigation was to assess the influence of microtalc and clay addition during the extraction process of extra virgin olive oil from cv. Arauco. Olives from Arauco cultivar were used in trials and were processed by adding: 0.3 g/100 g of technological adjuvant micronized talc (MT, T1), 0.15 g/100 g of MT combined with 0.15 g/100 g of adjuvant clay (MT+C; T2), 0.15 g/100 g of adjuvant clay (C; T3), 0.30 g/100 g of adjuvant clay (C; T4). In all the industrial trials previously described, an enzymatic solution (pectinase, 100 ppm) was also used, taking this as a control reference. The variation ranges for all adjuvants concentrations were chosen taking into account the recommendations of the respective manufacturers. All adjuvants were added at the beginning of malaxation. Routine quality analyses (Free acidity, oleic acid %; Peroxide value, meq O2/kg; Extinction coefficients, K270 and K232; Total tocopherols, α‐Tocopherol, ß‐Tocopherol and ɣ-‐Tocopherol mg/kg; Total phenols, mg/kg; Chlorophylls and Carotenoids, mg/kg; Induction time, h) and oil yield (fruits and olive pomace or ‘alperujo’) determination were also carried out to have a more complete quali-quantitative evaluation.As shown in Table 1, there are practically no significant differences in oil yield values among the treatments considered. However, T4 (clay 0,15%) showed a slight increase on this parameter with respect to the control treatment (T0). Regarding oil quality characteristics, no influence by either adjuvant was detected as oil components remained unaltered during the extraction process, indicating that these compounds only act physically on this process (Table 2). Considering the average analytical values obtained the oil was classed as “extra‐virgin” because the acidity, peroxide, K232, and K270 values, were within the limits stated by Regulation EEC/2568/91 and latter modifications of the European Community. In conclusion we can say that based on the results obtained, the addition of clays can be a valid practice to increase the quantity of oil extracted from the olive paste. However, more studies are necessary to investigate various aspects, such as dosage. Furthermore, the evaluation of other clay typologies could ensure a clearer overview.