Sibel Fadıloğlu

Conversion of olive pomace oil to cocoa butter-like fat in a packed-bed enzyme reactor

Refined olive pomace oil (ROPO) was utilized as a source oil for production of cocoa butter-like fat. Immobilized sn-1,3 specific lipase catalyzed acidolysis of ROPO with palmitic (PA) and stearic (SA) acids was performed in a laboratory scale packed-bed reactor. Effect of reactor conditions on product formation was studied at various substrate mole ratios (ROPO:PA:SA; 1:1:1, 1:1:3, 1:3:3, 1:2:6), enzyme loads (10%, 20%, 40%), substrate flow rates (1.5, 4.5, 7.5, 15 ml/min) and solvent amounts (150, 400 ml). The highest yield (10.9% POP, 19.7% POS and 11.2% SOS) was obtained at 40% enzyme load, 1:2:6 substrate mole ratio, 45 degrees C, 7.5 ml/min substrate flow rate, 150 ml solvent and 3h reaction time. The melting profile and SFC of the product were comparable to those of CB. Polarized light microscope (PLM) images showed no drastic changes in polymorphic behavior between CB and product.

Kinetics of lipase-catalyzed hydrolysis of olive oil

Abstract Lipase-catalyzed hydrolysis of olive oil has been studied in the absence of added emulsifier. The kinetic analysis of the lipase-catalyzed hydrolysis reaction was found to be possible in this system. The amount of fatty acids produced was linearly proportional to the enzyme concentration of 0.1 mg protein ml−1. The specific enzyme activity was 2500 units mg−1 enzyme, at 37 °C in 25 mM phosphate buffer, pH 7.0, at 50% (v/v) olive oil concentration. The hydrolytic reaction obeys Michaelis-Menten kinetics with Vmax,app and Km,app of 3470 units mg−1 enzyme and 16.7% (v/v), respectively. Maximum activity was obtained at pH 7.0, at low buffer ionic strength, 25 mM and 37 °C. The enzyme was found to be inhibited by 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide and o-phthaldialdehyde in a biphasic manner. These results suggested that carboxyl groups and lysyl and cysteinyl residues might be involved in the catalytic site or substratebinding site of this enzyme.

Lipase production by Rhizopus oryzae growing on different carbon and nitrogen sources

Nitrogen and carbon sources influencing the growth and production of lipase by Rhizopus oryzae were studied. High yields of enzyme activity were obtained when proteose peptone was the nitrogen source in media with olive oil (MWO) and without olive oil (MWHO). Carbon sources increased lipase activity in MWHO but decreased it slightly in the presence of oil. Lipase activity was significantly (P < 0.5) higher in MWO than in MWHO. Biomass concentration was also higher in the presence of oil. Industrial by-products bran and whey have been used as efficient media for the production of lipase by R oryzae. © 1999 Society of Chemical Industry

Genetic programming approach to predict a model acidolysis system

This paper models acidolysis of triolein and palmitic acid under the catalysis of immobilized sn-1,3 specific lipase. A gene-expression programming (GEP), which is an extension to genetic programming (GP)-based model was developed for the prediction of the concentration of major reaction products of this reaction (1-palmitoyl-2,3-oleoyl-glycerol (POO), 1,3-dipalmitoyl-2-oleoyl-glycerol (POP) and triolein (OOO). Substrate ratio (SR), reaction temperature (T) and reaction time (t) were used as input parameters. The predicted models were able to predict the progress of the reactions with a mean standard error (MSE) of less than 1.0 and R of 0.978. Explicit formulation of proposed GEP models was also presented. Considerable good performance was achieved in modelling acidolysis reaction by using GEP. The predictions of proposed GEP models were compared to those of neural network (NN) modelling, and strictly good agreement was observed between the two predictions. Statistics and scatter plots indicate that the new GEP formulations can be an alternative to experimental models.

Inactivation of lipase by carbon dioxide under atmospheric pressure

Abstract Lipase exposed to CO 2 (under atmospheric pressure) treatment at different pH and temperature conditions showed a decrease in enzyme activity. Inactivation was found to be highest as the temperature increased from 20 to 50 °C at initial pH 7.15. About 84% of the initial activity of the enzyme is lost at initial pH 7.15 and 50 °C. The faster drop in pH and enzyme activity occurred within 5 min. Without CO 2 , no significant change ( P >0.05) was observed in activity at the highest temperature (50 °C). The pH drop and loss in enzyme activity were higher at initial pH 8.20. No changes in enzyme activity and pH were observed when nitrogen gas was applied instead of CO 2 . Studies using gel electrophoresis showed no differences in protein patterns between CO 2 -treated and non-treated control. After 6 weeks of frozen storage, no changes in pH and activity were observed for CO 2 -treated lipase solution.

Effect of the addition of a cocoa butter-like fat enzymatically produced from olive pomace oil on the oxidative stability of cocoa butter.

A cocoa butter (CB)-like fat was produced in a packed bed enzyme reactor using sn-1,3 specific lipase, and its blends with CB were prepared at different ratios (CB: CB-like fat; 100: 0, 90: 10, 80: 20, 70: 30, 60: 40, 50: 50, 0: 100). The oxidation kinetics of CB: CB-like fat blends was studied by differential scanning calorimeter (DSC). Samples were heated in DSC at different temperatures (130, 140, 150, 160 degrees C) under 100 mL/min oxygen. From DSC exotherms, oxidation induction times (OIT) were determined and used for the assessment of the oxidative stabilities of the blends. Oxidation kinetics parameters (activation energy, E(a); preexponential factor, Z; and oxidation rate constant, k) were calculated. In general, it has been observed that above 110 degrees C increasing the ratio of CB-like fat in the blend increased the k value with increasing temperature. It has been observed that for all blends the increase in k value with temperature was significant (P < 0.05). Increasing CB-like fat ratio in the blend decreased the content of major TAGs (1,3-dipalmitoyl-2-oleoyl-glycerol [POP]; 1[3]-palmitoyl-3[1]stearoyl-2-oleoyl-glycerol [POS]; 1,3-distearoyl-2-oleoyl-glycerol [SOS]), and decreased the oxidative stability of the blends.

Reduction of Free Fatty Acid Content of Olive-Pomace Oil by Enzymatic Glycerolysis

The enzymatic glycerolysis of free fatty acids in olive-pomace oil was carried out by immobilised Candida antarctica lipase. The effects of time, molecular sieve, enzyme concentration and reaction temperature on free fatty acids content were investigated. The initial acidity of the olive-pomace oil (32%) was reduced to 2.36% in the presence of 750 mg of molecular sieve in the reaction mixture. The effectiveness of glycerolysis was directly related to the amount of molecular sieve present. As the amount of molecular sieve increased, the conversion of free fatty acids also increased at a defined time. In the absence of molecular sieve, the esterification reaction forced to reverse reaction that is the hydrolysis. The greater conversion of free fatty acids into glycerides was observed at an enzyme concentration of 27.2 mg/mL within 60 min. ANOVA showed that the effects of temperature on fatty acid content was significant (p < 0.05). Results obtained from non-linear regression analysis indicated that reaction order was 1.3 for fatty acid reduction in the olive-pomace oil. Calculated activation energy for fatty acid reduction was 32.89 kJ/mol.

Valorization of Olive Pomace Oil with Enzymatic Synthesis of 2-Monoacylglycerol

2-Monoacylglycerols (2-MAG) with a high content of oleic acid at sn-2 position was synthesized by enzymatic ethanolysis of refined olive pomace oil, which is a byproduct of olive oil processing. Six lipases from different microbial sources were used in the synthesis of 2-MAG. Immobilized lipase from Candida antarctica gave the highest product yield among the selected lipases. Response surface methodology was applied to optimize reaction conditions; time (4 to 10 h), temperature (45 to 60 °C), enzyme load (10 to 18 wt%), and ethanol:oil molar ratio (30:1 to 60:1). The predicted highest 2-MAG yield (84.83%) was obtained at 45 °C using 10 (wt%) enzyme load and 50:1 ethanol:oil molar ratio for 5 h reaction time. Experiments to confirm the predicted results at optimum conditions presented a 2-MAG yield of 82.54%. The purification yield (g 2-MAG extracted/100 g of total product) was 80.10 and 69.00 for solvent extraction and low-temperature crystallization, respectively. The purity of the synthesized 2-MAG was found to be higher than 96%.