Experimental investigation of processing parameters and effects of degumming, neutralization and bleaching on lampante virgin olive oil's quality

Various Strategies for the Immobilization of a Phospholipase C from Bacillus cereus for the Modulation of Its Biochemical Properties

In this study, the effect of various immobilization methods on the biochemical properties of phospholipase C (PLC) from Bacillus cereus obtained from the oily soil located in Sfax, Tunisia, was described. Different supports were checked: octyl sepharose, glyoxyl agarose in the presence of N-acetyl cysteine, and Q-sepharose. In the immobilization by hydrophobic adsorption, a hyperactivation of the PLCBc was obtained with a fold of around 2 times. The recovery activity after immobilization on Q-sepharose and glyoxyl agarose in the presence of N-acetyl cysteine was 80% and 58%, respectively. Furthermore, the biochemical characterization showed an important improvement in the three immobilized enzymes. The performance of the various immobilized PLCBc was compared with the soluble enzyme. The derivatives acquired using Q-sepharose, octyl sepharose, and glyoxyl agarose were stable at 50 °C, 60 °C, and 70 °C. Nevertheless, the three derivatives were more stable in a large range of pH than the soluble enzyme. The three derivatives and the free enzyme were stable in 50% (v/v) ethanol, hexane, methanol, and acetone. The glyoxyl agarose derivative showed high long-term storage at 4 °C, with an activity of 60% after 19 days. These results suggest the sustainable biotechnological application of the developed immobilized enzyme.

Optimization using response surface methodology of phospholipase C production from Bacillus cereus suitable for soybean oil degumming

This work deals with the optimization of an extracellular phospholipase C production by Bacillus cereus (PLCBc) using Response Surface Methodology (RMS) and Box-Behnken design. In fact, after optimization, a maximum phospholipase activity (51 U/ml) was obtained after 6 h of cultivation on tryptone (10 g/L), yeast extract (10 g/L), NaCl (8.125 g/L), pH 7.5 with initial OD (0.15). The PLCBc activity, esteemed by the model (51 U) was very approximate to activity gutted experimentally (50 U). The PLCBc can be considered as thermoactive phospholipase since it showed a maximal activity of 50 U/mL at 60 °C using egg yolk or egg phosphatidylcholine (PC) as substrate. In addition, the enzyme was active at pH 7 and is stable after incubation at 55 °C for 30 min. The application of B. cereus phospholipase C in soybean oil degumming was investigated. Our results showed that when using enzymatic degumming, the residual phosphorus decrease more than with water degumming, indeed, it passes from 718 ppm in soybean crude oil to 100 ppm and 52 ppm by degumming using water and enzymatic process, respectively. The diacylgycerol (DAG) yield showed an increase of 1.2% with enzymatic degumming compared to soybean crude oil. This makes our enzyme a potential candidate for food industrial applications such as enzymatic degumming of vegetable oils.

Kinetics and Thermodynamics of β-Carotene Adsorption onto Acid-Activated Clays Modified by Zero Valent Iron

The adsorption of β-carotene from crude palm oil onto acid-activated clay and clay modified by zero valent iron (ZVI) was investigated in this work. Spectroscopic studies including FTIR, XRD, and SEM were used for its characterization. The adsorption characteristics such as kinetics, mechanism, isotherms, and thermodynamics of β-carotene were studied. The kinetic data were analyzed using the pseudo-first-order kinetic equation, pseudo-second-order kinetic equation, and intraparticle diffusion model. The pseudo-second-order kinetic model is the only one that describes the experimental data well (R2 ≥ 0.969). The chemical analysis of bulk clay showed that the predominant oxides are Al2O3 (57.91 wt%), Fe2O3 (32.54 wt%), SiO2 (3.09 wt%), K2O (2.37 wt%), and CaO2 (1.73 wt%). The adsorption capacity increases with an increase in temperature. The equilibrium data were described better by the Freundlich model for all clays. To determine the best fit kinetic model for each system, three error analysis methods, namely, chi-square (χ2), residual mean squared error (RMSE), and mean percent error (%APE) were used to evaluate the data. A thermodynamic study demonstrated that β-carotene adsorption is spontaneous, endothermic, and an entropy driven process for both forms of clay.

Olive Mill Wastewater: From a Pollutant to Green Fuels, Agricultural Water Source, and Bio-Fertilizer. Part 2: Water Recovery

Water shortage is a very concerning issue in the Mediterranean region, menacing the viability of the agriculture sector and in some countries, population wellbeing. At the same time, liquid effluent volumes generated from agro-food industries in general and olive oil industry in particular, are quite huge. Thus, the main aim of this work is to suggest a sustainable solution for the management of olive mill wastewaters (OMWW) with possible reuse in irrigation. This work is a part of a series of papers valorizing all the outputs of a three-phase system of oil mills. It deals with recovery, by condensation, of water from both OMWW and OMWW-impregnated biomasses (sawdust and wood chips), during a convective drying operation (air velocity: 1 m/s and air temperature: 50 °C). The experimental results showed that the water yield recovery reaches about 95%. The condensate waters have low electrical conductivity and salinities but also acidic pH values and slightly high chemical oxygen demand (COD) values. However, they could be returned suitable for reuse in agriculture after additional low-cost treatment.

The effect of temperature on rice oil bleaching to reduce oxidation and loss in bioactive compounds

Refining conditions are very important to obtain high-quality rice oil. This work aimed at evaluating the effect of bleaching temperature in chemical and physical refining processes to avoid losses in γ-oryzanol and carotenoids. In addition, the aspects related to rancidity were investigated. Samples of degummed oil (obtained by a physical procedure) and of neutralized oil (obtained by a chemical procedure) were provided by a local industry. The oils were bleached at 80, 95 and 110 °C using 1% (w w-1) activated earth. The temperature of 95 °C was the best in relation to oxidative stability. The γ-oryzanol and carotenoids were better preserved through physical refining than by the chemical procedure by about 64 and 84%, respectively. However, the oxidation indicators were high for the oil bleached by the physical procedure, indicating that bleaching without prior neutralization is viable, but it is necessary to obtain an industrial crude oil with less oxidation.