Characteristics of stirred low-fat yoghurt as affected by high pressure

Abstract

The effects of high pressure on the physicochemical, chemical, microbiological and sensory characteristics of stirred low-fat yoghurt were studied. Laboratory-made yoghurts were treated at high pressure (100-400 MPa) for 15 min at 20°C. No significant changes in pH and total organic acids were observed after pressuring the yoghurt. Pressures over 200 MPa prevented post-acidification of the yoghurt during chilled storage. Pressurized yoghurts exhibited higher viscosity and amino acid contents than did the untreated controls, and the differences were maintained after chilled storage. High-pressure treatments at 300 and 400 MPa reduced the number of viable cells of lactobacilli to below the legal minimum permitted in many countries. Significant differences in sensory characteristics between untreated and pressurized yoghurts (200-300 MPa) were detected after chilled storage.