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Optimization of Temperature, Time, and Lactic Acid Concentration to Inactivate Lipoxygenase and Lipase and Preserve Phytase Activity in Barley (cv. Blenheim) During Soaking

¹SIK, The Swedish Institute for Food and Biotechnology-AB, P.O. Box 5401, S-402 29 Göteborg, Sweden. ²Chalmers University of Technology, Department of Food Science, P.O. Box 5401, S-402 29 Göteborg, Sweden. ³Corresponding author. Phone: +46 31 35 56 07. Fax: +46 31 83 37 82. E-mail: Annika.Rutgersson@sik.se.

A barley-soaking process was studied to find conditions that inactivate the prooxidative enzyme lipoxygenase and the lipolytic enzyme lipase but preserve phytase activity to develop possible procedures for production of barley products with potentially high mineral bioavailability and good oxidative stability. Lactic acid concentration, temperature, and soaking time were studied. The study was done using a multivariate experimental design. Lactic acid concentration varied between 0 and 1%, temperature varied between 45 and 70°C, and soaking time varied between 30 and 120 min. Although conditions under which lipoxygenase was inactivated were found, total inactivation of lipase was not obtained. Total lipoxygenase inactivation with <20% remaining lipase activity and >60% remaining phytase activity was reached after soaking in 1% lactic acid at suitable time-temperature combinations of 70–110 min and 53–58°C.