USING A SIMULTANEOUS FACTOR OPTIMIZATION APPROACH FOR THE DETECTION OF VOLATILES IN MILK BY DYNAMIC HEADSPACE GAS-CHROMATOGRAPHIC ANALYSIS

Optimum conditions for dynamic headspace capillary gas chromatography were investigated to obtain maximum volatile recovery from pasteurized milk. The simultaneous factor optimization approach used for establishing purge and trap conditions resulted in a method of high sensitivity and repeatability. Factors optimized were purging time, sample temperature, and sample volume. Simultaneous factor optimization not only allowed maximum recovery of volatiles but also allowed detection of factor combinations that resulted in trap breakthrough. A Tenax TA trap for volatile concentration was preferred to other combination traps. A midpolarity column coated with cyanopropyl phenyl poly(dimethylsiloxane) was found to provide better resolution than other stationary phases. Several volatiles consisting mainly of aldehydes, ketones, and alcohols were identified in good-quality milk. Poor-quality milk showed not only the presence of new volatiles including esters but also increased amounts of those already present.