Laboratory‐scale optimization of olive oil extraction: Simultaneous addition of enzymes and microtalc improves the yield

Abstract

The aim of this work was to optimize olive oil extraction, at laboratory-scale (Abencor system), from fruits of "Cobrançosa" and "Galega Vulgar" Portuguese cultivars, either in the absence or in the presence of enzymes and natural microtalc. Using a Placket-Burman design to select significant variables followed by a central composite rotatable design (CCRD), Abencor operation conditions were optimized: no water addition in 30 min malaxation and 14% w/w water addition at 50°C in centrifugation. The combined effects of the concentrations of natural microtalc (MT: 0.04-0.46 w-%) and enzyme preparation (E: 0.003-0.117 w-%) added at the beginning of malaxation, on quality criteria, total phenols and chlorophyll pigments concentrations, and on oil extraction yield, were investigated using a CCRD. The results showed that the addition of both an enzyme preparation and natural microtalc could enhance olive oil yield (up to 34% for 0.4-0.5% of microtalc and 0.1% of enzymes for "Galega Vulgar") without any effect on quality of the obtained virgin olive oil.Practical applications: Abencor system is the most used laboratory-scale installation in olive oil technology to carry out trials that would be very difficult to perform at industrial scale. This study presents an optimization of the Abencor extraction process, as well as the optimization of extraction with two adjuvants, enzymes and natural microtalc, using two different cultivars. The effect of E and/or MT addition depend on the cultivar. However, an improvement in extractability was always found for both cultivars. This study shows that for "Cobrançosa" olives, considering both olive oil yield and economical aspects, the chosen conditions are 0.05-0.15% of microtalc in the absence of added enzymes. For "Galegar Vulgar" olives, the highest extractability is observed under the presence of enzyme preparation amount higher than 0.10% and microtalc amount of 0.4-0.5%.

Bioactive Compounds of Portuguese Virgin Olive Oils Discriminate Cultivar and Ripening Stage

“…Olive oils were extracted in a laboratory Abencor equipment, under previously optimized conditions [34]. The olives were crushed with a hammer mill equipped with a 4 mm sieve at 3000 rpm.…”

“…Malaxation of the pastes was performed at 28-30 °C for 30 min and centrifugation at 3500 rpm (3 min). After centrifugation, the olive oil was separated by settling in a graduated cylinder; water traces were removed with anhydrous sodium sulfate, filtered through a cellulose filter and stored in amber glass bottles at 4 °C until analysis [34].…”

High resolution melting analysis of DNA microsatellites in olive pastes and virgin olive oils obtained by talc addition

“…Food grade micronized talc (hydrated magnesium silicate) is a physical coadjuvant widely used in the olive milling process . At doses of 0.5–2% on dry fruit weight, talc improves the structure of olive paste and reduces the emulsions , with positive effects on oil yield . Other outcomes are a decrease of α‐tocopherol content coupled with slight oil discoloration , and an increase of both the level of phenolic compounds and oxidative stability .…”

Has the use of talc an effect on yield and extra virgin olive oil quality?

“…The studies in the literature do not report a clear and unequivocal influence of MNT addition to olive paste during malaxation on the oxidative and hydrolytic degradation of the obtained extra virgin olive oil. In particular, most studies carried out on different olive cultivars report that talc addition to olive paste during malaxation did not influence the final amount of free fatty acids . Similarly, Ranalli et al did not find a significant effect of MNT on oil from de‐stoned olives.…”

“…When comparing talc and calcium carbonate, Espínola et al and Moya et al showed that MNT offers a lower extraction efficacy than calcium carbonate at identical particle size and dosage conditions; moreover, Moya et al reported that low concentrations are preferable to high concentrations and that small particle size is preferable to large particle size, though increasing particle size seemed to negatively influence oil extraction more than increasing coadjuvant addition. Peres et al observed that the addition of blends of MNT and enzymes during malaxation had different effects on the extraction yield depending on the cultivar used. In particular, for Cobrançosa olives, a maximum of 24% yield increase, compared with the results obtained in the absence of coadjuvants, was attained when 0.05–0.15% MNT was used, without the need for enzyme addition.…”