PRESERVATION OF RAW-MILK WITH CO2 - SENSORY EVALUATION OF HEAT-PROCESSED MILKS

The effect of CO2 on the growth of psychrotrophic milk spoilage organi sms was studied, both in raw fresh milk and in pure cultures of three species of Pseudomonas growing in sterilised milk. Changes of sensory properties of CO2-treated samples after heat treatment were also analy sed. Inhibition of psychrotrophic growth at 7-degrees-C in milk treate d with CO2 to a pH 6.2 or 6.0 was impaired by a gradual reduction of t he CO2 content during storage. Growth inhibition was considerably impr oved by pH adjustment at 24-h intervals. Sensory analysis showed signi ficant differences between non-acidified and acidified samples after h eat treatment at 75-degrees-C for 20 s or 110-degrees-C for 5 min. No sensory differences were found between non-acidified and acidified mil ks degassed before heat treatment.