Potential Use of Crude Oils from Spent Coffee Grounds or Olive Pomace for the Production of MLM-Type Structured Lipids Catalysed by Commercial Immobilised Rhizomucor miehei Lipase

Low calorie triacylglycerols (TAG) presenting medium-chain fatty acids (M) at positions sn-1,3 and long-chain fatty acids (L) at position sn-2 are known as MLM. This study aims at the production of MLM by acidolysis of crude oils extracted from spent coffee grounds and olive pomace with medium-chain caprylic (C8:0) or capric (C10:0) acids, or by interesterification of these oils with ethyl caprylate (C8EE) or ethyl caprate (C10EE), in solvent-free media, catalysed by the commercial immobilized lipase from Rhizomucor miehei (Lipozyme RM IM, Novozymes A/S, Denmark). Reactions were carried out in solvent-free media with a substrate molar ratio TAG/M (or TAG/EE) of 1:2, 50 ºC and 5% w/w enzyme content. The highest yields of new TAG from spent coffee grounds oil were achieved after 7 h acidolysis, yielding 71.3% and 70.1% of new TAG containing C8:0 or C10:0, respectively. With the olive pomace oil, the yields were lower: 57.8% and 61.6% of new TAG containing C8:0 or C10:0, respectively. After 7h interesterification with spent coffee grounds oil and C8EE or C10EE, 73.2 % and 70.3 %, of new TAG were observed, respectively. With the olive pomace oil, after 7 h interesterification, the yields of new TAG containing C8EE or C10EE were 48.8% and 55.4%, respectively. In addition, Lipozyme RM IM showed high operational stability along 13 consecutive batches of 7 h duration each. This strategy opens a new market to added value products based on crude oils from spent coffee grounds or olive pomace.