Effect of reduction of lactose in yogurts by addition of β-galactosidase enzyme on volatile compound profile and quality parameters

Abstract

A comparative study between reduced-lactose yogurts made with added b-galactosidase (E yogurts) and controls (C yogurts) was performed. The evolution of lactose content, pH, acidity and volatile compounds was measured during fermentation and storage at 5 °C. The hydrolysis percentages of lactose ranged from 75% to 78% in E yogurts and from 10% to 13% in C yogurts at the end of manufacture and stayed without changes throughout storage. There were no significant differences in pH and titratable acidity values among yogurts. A total of 22 volatile compounds were identified. The change in lactose level by the action of b-galactosidase influenced the production of some volatile compounds derived from this sugar.At the end of fermentation, minor differences in volatile composition were recorded among yogurt samples.During storage, acetaldehyde and diketone levels were always higher in hydrolysed yogurts than their respective controls.