Preliminary study of extraction of polysaccharides from pomace by high powered ultrasonic combined with enzymes
Red grape pomace can be an important source of polysaccharides, but currently they are little studied and even less with viable and environmental extraction processes (green extraction). These green techniques must be able to break the cell wall so that the compounds contained in the cells, including polysaccharides, are released and can have a great influence on extraction yields, the chemical structure of polysaccharides and applications in wines. Amongst the emerging green techniques most applied to the extraction of bioactive compounds, such as polysaccharides, high-power ultrasound (US) and enzyme-assisted extraction stand out. High power ultrasonic assisted extraction is based on the application of mechanical sound waves with frequencies between 20 kHz and 100 kHz inducing acoustic cavitation in a liquid medium, which causes fragmentation and formation of pores in the cells of the cell wall, and leads to increased extraction and diffusion of polysaccharides. While the use of enzymes causes the rupture of the cell walls, hydrolyzing them under optimal experimental conditions and releasing polysaccharides at lower temperatures, avoiding possible changes in the structure and bioactivity of the polysaccharides. Extraction combined with both techniques can increase the extraction yield of polysaccharides and/or reduce the extraction time. In this work, the variables of extractant liquid pH at three levels, US application time at three levels and application of enzymes before or after the US treatment on the polysaccharide extraction yield were studied. All the tests were carried out at 30 kHz, a red pomace/liquid ratio of 1.3 and with a dose of 0.6 ml/Hl of enzymes. In addition, the distribution of the molecular weights of the extracts obtained in the different tests was determined.
Acknowledgments: This research was funded by the Ministry of Science, Innovation and Universities from the Spanish Government and Feder Funds, grant number PID2021-123361OR-C22.
Issue: ICGWS 2023
1Instituto de Ciencias de la Vid y el Vino (Universidad de La Rioja, Gobierno de La Rioja, CSIC), Spain
2Instituto Tecnológico Agrario de Castilla y León (ITACyL), Spain