Integrated bioprocess for the valorization of olive pomace: Production of dietetic structured lipids, FAME, emulsifiers, and phenolic extracts

Abstract: Virgin olive oil (VOO) is extracted from the olive fruit (Olea europaea L.) only by mechanical processes. After VOO extraction, the olive pomace (OP) still contains 3-4.5% of oil (w.b.), which can be solvent-extracted. This oil (olive pomace oil, OPO) presents similar composition to that of olive oil, and after refining, is used for human consumption. OP is also rich in bioactive phenolic compounds. The aim of this study was the efficient valorization of (i) olive pomace crude oil and (ii) deoiled olive pomace as source of phenolic compounds, by biocatalysis or other green technologies. High acidic crude OPOs (12-20% acidity) were used to produce (i) low-calorie structured lipids (SLs), or (ii) biodiesel (fatty acid methyl esters, FAME) and emulsifiers (monoacyglycerols, MAG) by methanolysis, using sn-1,3 regioselective immobilized lipases (Lipozyme RM IM and Lipozyme TL IM) as biocatalysts. SLs were obtained either by oil acidolysis with medium-chain fatty acids (C8:0 or C10:0) or interesterification with their ethyl esters (C8EE, C10EE), in batch or continuous plug-flow bioreactor. High SL (48–53%, 7h) and FAME yields (97%, 4h) and high operational stability of biocatalysts were observed even using high acidic crude oils. Deoiled industrial and monocultivar (Cobrançosa or Galega cultivars) OPs were submitted to ultra-sound treatment (15 min), followed by green-solvent (ethanol and/or water) extraction at 30 or 40°C, to recover phenolics. Higher phenolic content (72 mg GAE/g OP) and antioxidant activities (FRAP: 89.6 mg TROLOX/g; DPPH: 89.3 mg TROLOX/g) were observed in ethanol/water (1:1) extracts of Cobrançosa OPs. The phenolic profiles of Galega and Cobrançosa OPs, showed high hydroxytyrosol, oleuropein derivatives and luteolin contents, especially in Cobrançosa, which can explain the antioxidant activities.


Funding: This work was funded by FCT –Fundação para a Ciência e a Tecnologia, I.P., Portugal, under the scope of the project Linking Landscape, Environment, Agriculture and Food Research Centre (UIDP/04129/2020; UIDB/04129/2020)