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

摘要

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 nonsignificant 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. (C) 2015 Elsevier Ltd. All rights reserved.