Enzymatisk nedbrytning av arabinoxylan och fytinsyra som metod för att öka utbytet och biotillgängligheten av näringsämnen i flytande havrebas

This project (Enzymatic degradation of arabinoxylan and phytic acid as a method to increase yield and bioavailability of nutrients in liquid oat base) evaluates the degradation of phytic acid, of the insoluble fraction from Oatly’s existing production process, with the aim of increasing available nutrients such as minerals and proteins. Previous studies have shown that phytic acid from this fraction is hard to disassemble and one possible theory is that the phytic acid is tightly bound to the fibers and hence hard to access. A fiber degrading enzyme, a xylanase, was studied for degradation of the fibers with 6 % dry weight. Three phytases were studied separately and in combination with the xylanase. The xylanase was expected to break up part of the fibers that the phytic acid is believed to be attached to, and the anticipation was that the degradation of the phytic acid would be more effective in the presence of xylanase. The optimal concentration of the xylanase Pentopan® Mono Conc. BG (16,1 µg/ml), which degrades the oat cell wall fiber arabinoxylan to oligosaccharides, was determined and combined with the determined optimal concentrations for the phytases Phytase® 5000 L (1,39 µg/ml) and Quantum™ TR 5000 L (1,60 µg/ml). The third phytase, Sternzym PHY 21097, was not further investigated since it did not show reasonable activity within the applicable time and temperature intervals. No apparent synergistic effect between the xylanase and the phytases could be determined with the optimized amounts of xylanase. However, a free phosphorous analysis showed a higher amount of free phosphorous with 100 times the optimized amount of the xylanase added. This indicates that more phytic acid had been degraded but which also resulted in xylose release. This result supports the hypothesis that the phytic acid is more easily degraded when the insoluble fibers have been detached and other treatments for the degradation of the fiber structure are recommended to further evaluate. The results showed that Phytase® 5000 L was a better alternative in terms of increasing available nutrients. 20 % of the iron content and 19 % of the proteins in the fiber material, after 120 minutes enzyme treatment in 60°C, were found in the fraction to be returned to Oatly’s process. On the other hand, the results from the free phosphorus analysis showed that more free phosphorus, which was used to evaluate the degradation of phytic acid, was obtained with Quantum™ TR 5000 L than with Phytase® 5000 L. A potential theory was that the Phytase® 5000 L only partially degrades phytic acid while Quantum™ TR 5000 L fully degrades phytic acid into inositol. A degradation of IP6 to IP4 is enough to decrease the binding strength of ions. A hydrolysis profile, an IP6 - IP1 analysis, could have confirmed this theory but was not performed within the project. An alternative treatment for the degradation of phytic acid that used germinated oat grains was studied in parallel in this project. The germination was expected to cause a lower amount of phytic acid and increase the amount of soluble minerals and proteins. However the opposite was shown since the amount of solvent minerals and proteins decreased with an increase in time of the germination