Synthesis of Dietetic Structured Lipids from Spent Coffee Grounds Crude Oil Catalyzed by Commercial Immobilized Lipases and Immobilized Rhizopus oryzae Lipase on Biochar and Hybrid Support

The aim of this study was the valorization of coffee industry residues, namely spent coffee grounds (SCG) as a source of oil, and silverskin (CS) as a source of both oil and biomass, under the concept of the circular economy. Therefore, crude oil from SCG was used to produce low-calorie structured lipids (SL) for food and pharmaceutical industries, and CS to produce biochar by pyrolysis for biotechnological uses. SL were obtained by acidolysis with caprylic or capric acid, or interesterification with ethyl caprylate or ethyl caprate, in solvent-free media, catalyzed by immobilized sn-1,3 regioselective lipases. Silverskin biochar (BIO) was directly used as enzyme carrier or to produce hybrid organic-silica (HB) supports for enzyme immobilization. Rhizopus oryzae lipase (ROL) immobilized on Amberlite (AMB), silica (SIL), BIO or HB, and the commercial immobilized Thermomyces lanuginosus (Lipozyme TL IM) and Rhizomucor miehei (Lipozyme RM IM) lipases were tested. Lipozyme RM IM showed better results in SL production than Lipozyme TLIM or ROL on BIO, SIL or HB. About 90% triacylglycerol conversion was attained after 7 h acidolysis or interesterification. Lipozyme RM IM was more stable in interesterification (80% and 65% activity with ethyl caprylate or ethyl caprate) than in acidolysis (first-order decay) after 10 reuses.

Enzymatic preparation of structured TAG containing conjugated linoleic acid (CLA) at solvent-free

Rice bran oil extracted by the water-enzymatic method was placed at a temperature of −5 °C for 8 h. Light-phase rice bran oil with an iodine value of 112.13 ± 0.21 g I2/100 g oil was separated by cryogenic freezing centrifugation. Lipozyme RM IM transesterified light-phase rice bran oil and conjugated linoleic acid (CLA) under supercritical system CO2 (SC-CO2). The optimal reaction conditions for transesterification of CLA and rice bran oil in SC-CO2 were determined as follows: the Lipozyme RM IM dosage was 9%, and the RBO/CLA molar ratio was 1:3, the reaction temperature was 55 °C, stirring speed was 300 rpm, and transesterification time was 20 h, the CLA conversion rate can reach 42.1%.

Rhizomucor miehei Lipase Supported on Inorganic Solids, as Biocatalyst for the Synthesis of Biofuels: Improving the Experimental Conditions by Response Surface Methodology

Two inorganic solids have been evaluated as supports of Lipozyme RM IM, a Rhizomucor miehei lipase immobilized on a macroporous anion exchange resin, in order to improve its application as a biocatalyst in the synthesis of biofuels. The experimental conditions have been optimized to get the selective transesterification of sunflower oil, by using a multi-factorial design based on the response surface methodology (RSM). In this way, the effects of several reaction parameters on the selective ethanolysis of triglycerides to produce Ecodiesel, a biodiesel-like biofuel constitute by one mole of monoglyceride (MG) and two moles of fatty acid ethyl ester (FAEE), have been evaluated. Thus, it was obtained that a 6:1 oil/ethanol molar ratio, 0.215 g of biocatalyst supported in silica-gel (0.015 g Lipase/0.2 g silica-gel), 50 µL of 10 N NaOH, together with previous optimized reaction parameters, 35 °C reaction temperature and 120 min of reaction time, gave the best results (conversions around 70%; selectivity around 65%; kinematic viscosities about 9.3 mm2/s) in the reaction studied. Besides, Lipozyme RM IM, supported on silica-gel, biocatalyst exhibited a very good stability, remaining its activity even after 15 cycles.