Elimination of Lipid Hydrolysis in Aqueous Suspensions of Oat Flour

Abstract

Aqueous suspensions of oat flour were studied to investigate the possibilities of eliminating the development of rancidity due to lipid hydrolysis. The hydrolysis was efficiently eliminated by immersing dry-milled flour in slightly alkaline water. Only a slight in pH was needed (pH 8-9) at the beginning of the soaking to prevent almost completely the hydrolysis of triglycerides, which under similar conditions, but in water without pH adjustment, led to free fatty acid content of up to 36% of the total lipids. In the alkaline suspensions the selective loss of linoleic acid from polar lipids, observed in a water slurry, was also very efficiently reduced. The hydrolysis of triglycerides was also diminished at acidic pH values (below pH 6) increasingly with reducing pH, although the same efficiency of inhibition as at alkaline pH was not reached. It was concluded that wet processes can be used for the preparation of non-deteriorated oat products by including simple pH adjustments in the process.