Enzyme Extraction of Phenolics from Skins Grape Skins (Vitis vinifera L.) and apples (Malus domestica) in relation to the Chemical Compositional
Special Symposium - Innovations in Food Technology (LMC Congress)
White BioTech & Related Processes (Food-2a)
Keywords: phenolics enzyme extraction, Visit vinifera L., Malus domestica, HPAEC-PAD, HPLC-DAD
Aims: To conduct a deep and detailed exploration of enzyme-assisted extraction of phenolics from berry and grape skins. The exploration will provide a ground base for understanding how the phenolics are bound to fruit skin cell wall polycarbohydrates-lignin matrix.
Hypotheses: a) Whether it is possible to extract and retain selectively the most potent antioxidants by novel physical and enzymatic treatments of the berry and grape skin.
b) Whether it is possible to modify enzymatically the phenolics to optimize their health potential
Practically there is sparse knowledge about the phenolics detailed locations, and how they are bound into the fruit skin polysaccharides matrix. Knowledge about skins composition is needed. As first attempt we used grapes and apples skins as model to understand the relation between skin cell walls polysaccharides and phenolics compounds. Such detailed compositional knowledge is a key issue to upgrade the wine making press residues or valorise the fruit skin for phenolics phytochemicals production as functional food additive. Polysaccharide composition of fruits skins cell walls are usually determined by measuring the monosaccharides released after hydrolysis with acid, alkaline, or enzyme. Chemical hydrolysis is simple, standardised, and an easily repeatable technique. By acid chemical hydrolysis, chromatographic data are simplified and interferences from undesired substances could be minimized. The cell wall polysaccharide composition (CWCP) data produced using acid chemical hydrolysis was helpful during extend enzyme assisted-extraction. Building CWCP reference helped comparing different enzymes under different conditions acting on different CWCP fruits materials.
For extend enzyme assisted-extraction selected commercial plant cell wall macerating enzymes were tested. The enzymes were Pectinex® BE Colour, Celluclast® 1.5 L FG, Vinozym® FCE G, Pectinex® BE Colour + Vinozym® FCE G (50:50), and Celluclast® 1.5 L FG + Vinozym® FCE G (50:50). These enzymes are already employed in the wine and juice industry. The enzyme were added to pulverized, lyophilized grape skin samples - of defined particle size - of Cabernet Sauvignon and Merlot grapes in a full factorial design template, where type of enzyme preparation, enzyme loading, reaction temperature, and time were systematically varied. The extent of polysaccharide hydrolysis was evaluated by assessing levels of total water soluble carbohydrates, and by monosaccharide quantification by HPAEC-PAD analysis. The extents of carbohydrate hydrolysis were then compared with the phenolic release pattern as measured by colorimetric quantification of total phenolics, and phenolic profiles by HPLC.
Presented Wednesday 19, 15:35 to 15:50, in session White BioTech & Related Processes (Food-2a).
