TASTE RECOGNITION THRESHOLD CONCENTRATIONS OF STYRENE IN OIL-IN-WATEREMULSIONS AND YOGURTS

Taste recognition threshold concentrations (TRTC) of styrene were dete rmined in samples of oil-in-water emulsions (30-300 g kg-1 oil) and yo ghurts (1-30 g kg-1 fat), spiked with styrene. The observed TRTC incre ased linearly with increasing fat content and ranged from 0.3 to 2.1 m g kg-1 for the emulsions and from 36 to 171 mug kg-1 for the yoghurts. Styrene equilibrium partition coefficients between emulsions and thei r respective vapour phases were determined. The concentrations of styr ene in the continuous aqueous phase of the emulsions and yoghurts were calculated at the TRTC. The styrene concentrations in the continuous phase had constant values of about 15 mug kg-1 indicating that percept ion of styrene for oil-in-water emulsions is determined by the aqueous phase of the emulsion. The concentrations of styrene in the vapour ph ases above the emulsions and yoghurts were also calculated and were fo und to be constant at the TRTC. This relationship probably resulted fr om the equilibrium of distribution of styrene between the respective p hases. Commercial yoghurts packed in polystyrene beakers contained sty rene levels in the range 2-11 mug kg-1, much lower then the TRTC repor ted.