Flavour profiles and survival of starter cultures of yoghurt produced from high-pressure homogenized milk

Abstract

Volatile carbonyl compounds, organic acids and yoghurt bacteria counts were investigated in yoghurts made from ultra-high pressure homogenized milk. Yoghurts were manufactured from milk treated using ultra-high pressure homogenization at 200 or 300 MPa and at 30 °C or 40 °C, and compared with those produced from heat-treated milk with 3% added skim milk powder. To study the evolution of these parameters, samples were analysed after days 1, 14 and 28 of storage. Yoghurts from milk heat-treated or treated at 300 MPa had very similar profiles of organic acids and volatile compounds, as well as similar bacterial counts of both starter cultures. In comparison, yoghurts from milk treated at 200 MPa at either 30 °C or 40 °C gave different profiles, together with a sharp decrease in counts of lactobacilli. During storage, only slight differences in flavour compounds and yoghurt bacteria counts were detected, except in those samples from milk treated at 200 MPa.