Effect of High Pressure on Isomerization and Degradation of Lactose in Alkaline Media

The combined effects of temperature (60 °C) and high-pressure treatments (400 MPa for 3 h) on the isomerization−degradation of lactose (10%) in basic media were studied. The formation of isomeric disaccharides (lactulose and epilactose) and galactose decreased by the application of high pressure in aqueous sodium hydroxide 4 mM (pH 10.2) and 8 mM (pH 10.6), and sodium carbonate−bicarbonate buffer (pH 10.0). In addition, no substantial color development was observed in the sodium hydroxide systems for high and atmospheric pressure, whereas the application of high pressure led to a noticeable decrease of color development in the carbonate−bicarbonate system. Keywords: High pressure; lactose; isomerization; browning