Mechanism Of Expression Research Articles

Cell disruption pre-treatments towards an effective recovery of oil from Yarrowia lipolytica oleaginous yeast

The aim of this work was to evaluate the efficiency of different cell disruption techniques on oil extraction from Y. lipolytica oleaginous yeast. The techniques tested were mechanical expression (ME), moderate pulsed electric field assisted mechanical expression (MPEF-ME), high pulsed electric fields (HPEF), high voltage electrical discharges (HVED), ultrasound (US), and high-pressure homogenization (HPH). The impact of each cell disruption technique on fatty acid composition was investigated. Results show that the most efficient technique for Y. lipolytica disruption was HPH leading to the obtaining of 83.8 ± 4.8% oil extraction yield, compared to only 19.8 ± 0.5% for the control, without any pre-treatment. In terms of fatty acid composition, HVED induced significant changes in almost all the analyzed fatty acids, while US was the softest technique. HPH, ME, and MPEF-ME induced changes in the content of some fatty acids.

Gas assisted mechanical expression (GAME) for the selective recovery of lipophilic and hydrophilic compounds from olive kernel

This work is devoted to valorize olive kernel; a by-product produced during olive oil extraction process. For this purpose, aqueous liquid solid extraction (LSE), mechanical expression (ME), supercritical CO2 (SC-CO2) and gas assisted mechanical expression (GAME), processes were compared when applied separately or consequently (ME + GAME), in terms of total phenolic compound (TPC) and oil recovery yields. Results showed that although the high extraction yields of TPC using LSE (61.4 ± 1.3%), the extraction process is economically not viable. However, it was demonstrated that applying ME (1 h at 30 MPa) followed by GAME (1 h at 30 MPa ME and 10 MPa SC-CO2 pressures) allowed recovering extracts enriched with TPC (≈50% yield) and oil (≈80% yield), respectively. Recovered phenolic compounds and oil were then identified using liquid and gas chromatography – mass spectrometry, showing no degradation and high oil quality compared to commercial virgin oil.

Gas assisted mechanical expression (GAME) as a promising technology for oil and phenolic compound recovery from tiger nuts

Abstract The aim of this work was to investigate the potential of gas assisted mechanical expression (GAME) process as an innovative technology for oil extraction and polyphenol recovery from tiger nuts. GAME process was first studied by varying the supercritical carbon dioxide (SC-CO2) and the mechanical expression (ME) pressures (10–30 MPa), then was compared to separate processes applied alone, using either SC-CO2 or ME. The results showed that the better conditions for GAME were found using 20 MPa for SC-CO2 and 30 MPa for ME. Under these conditions, 50% of oil was released from tiger nuts after 10 min extraction, compared to only 10% and 20% when using SC-CO2 and ME separately at 20 and 30 MPa pressures, respectively. In addition to the faster extraction of oil using GAME process, the obtained results showed that this oil contains higher amount of polyphenols than that obtained using either SC-CO2 or ME. These molecules were extracted and identified using ultra performance liquid chromatography–high resolution mass spectrometry (UPLC–HRMS). Polyphenol profiles showed that GAME process led to the maximum polyphenol's recovery with 57 compounds, followed by SC-CO2 with 48 compounds, and ME process with only 27 compounds, concurring with the trends observed for total phenolic compounds. Although non-significant differences were observed in oil recovery after applying GAME or SC-CO2 alone, scanning electron microscopy (SEM) images revealed that GAME had a higher impact on cell structure, which can facilitate the release of important valuable compounds. All of these results pave the way towards the industrialization of GAME process as an innovative and alternative technology for enhanced oil extraction, thus replacing the conventional processes. Industrial relevance The increasing need in application of more efficient extraction processes in full correspondence with green extraction concept has led to deeper interest in new non-conventional methods that can reduce the extraction time, process temperature and consumption of toxic solvents (i.e. hexane). For instance, gas assisted mechanical expression (GAME) technology may constitute a useful tool for food industry as it allows to improve oil recovery and the amount of bioactive compounds (polyphenols) from tiger nuts, compared to supercritical fluid extraction and conventional methodologies (mechanical expression and hexane extraction) thus avoiding the use of toxic solvents.

Analysis of Combined Electroosmotic Dewatering and Mechanical Expression Operation for Enhancement of Dewatering

This article presents an efficient approach for the analysis of combined electroosmotic dewatering (EOD) and mechanical expression (ME) using the Terzaghi-Voigt combined model by considering creep deformation of the material. The EOD-ME process enhances dewatering because it combines the advantage of electroosmosis and mechanical dewatering, resulting in reduced void ratio compared to individual operation. The basic differential equation based on the model is solved analytically by assuming that both an electroosmotic pressure gradient E pg and a modified consolidation coefficient C e of the material are constant, resulting in the equation of solid compressive pressure in the material as a function of time and position. The analysis also leads to the equation of the average consolidation ratio U c, which is a measure of the progress of dewatering; this equation can describe well the empirical results under various conditions. The proposed approach can clearly explain the relationship of the driving forces of individual mode of operation. The large water content of semisolid bentonite–water mixture can effectively be reduced by the EOD-ME combined operation analyzed in this research.