(492k) Solid Phase Microextraction as a Convenient Method for Analysis of Volatiles in Commercial Whey Protein Preparations

Whey proteins are recovered from cheese whey as functional food ingredients. However, many volatile compounds could remain in the powdered whey protein preparations or be generated during processing or storage. These volatiles may cause undesirable flavors when the protein ingredients are used in foods, and novel strategies are needed to remove these compounds for improved product quality. Complete analyses of flavor profiles may require stringent and labor intensive extraction/distillation conditions and thus may not be suitable for developing novel processes where many parameters are to be screened and many products are to be assayed. In this work, solid phase microextraction (SPME) was evaluated as possible methods for quick and reliable assays suitable for process development. Two SPME fibers were studied: divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) and carboxen/polydimethylsiloxane (CAR/PDMS). Vials containing whey protein isolate or concentrate powders were incubated in a water bath at 50 or 60 ºC for 30 min. The SPME fiber was then inserted in the headspace of the vial for durations of 5-20 min. After adsorption, the fiber was used for GC/MS analyses. Nine peaks were consistently observed under the studied conditions. Eight out of 9 peaks reached adsorption equilibria after 15 min, as judged from the peak heights. The observations were in coincidence with nine compounds consistently detected by the extraction/distillation approach. This work showed that the SPME may be a simple method to analyze flavor profiles of whey protein preparations for fast evaluation of process parameters during technology development.