chapter  4
30 Pages

An integrated MDGC-MS-olfactometry approach to aroma and flavor analysis

I. Introduction .................................................................................................. 82 II. Malodor/malflavor investigations............................................................ 83

A. Case study #1 — precursor oxidation in bottled drinking water ................................................................... 85

B. Case study #2 — aroma/flavor defect in plastic-wrapped cracker product ................................................. 88

C. Case study #3 — malflavor in powdered smoked meat flavor concentrate ...................................................................... 91

III. GC-O in aroma-flavor quality control ..................................................... 95 A. Case study #4 — vanilla-extract flavor quality:

A univariate approach ........................................................................ 95 1. Designing a QC method ............................................................ 96 2. Univariate vs. multivariate data analysis ............................... 97

B. Case study #5 — beer flavor quality: A multivariate approach................................................................................................ 97 1. Variability of beer flavor ............................................................ 97 2. Beer aroma comparison.............................................................. 97 3. Importance of the flavor panel ................................................. 98 4. Indirect aroma correlations........................................................ 99 5. Minimum aroma monitoring set .............................................. 99

6. Instrumental QC method......................................................... 100 7. Headspace collection ................................................................ 101 8. Multivariate data analysis ....................................................... 101 9. Sampling at fermentation ........................................................ 103 10. Flavor drift ................................................................................. 103

IV. Integrated MDGC-MS-O system design strategy ................................ 104 A. Case study #6 — wildflower honey: Aroma

character-defining compound isolation ......................................... 105 V. Summary ..................................................................................................... 108 Acknowledgments.............................................................................................. 108 References ............................................................................................................ 108

Recent years have seen the emergence of a number of innovative technologies for the investigation of aroma and flavor-quality issues for food, beverage, and consumer products. These have included, among others, e-nose [1], ms-nose [2], fast-GC [3], ion trap GC-MS [4], and 2D-GC-TOF [5]. Although each of these technologies has demonstrated some utility for limited applications, in our experience none of these has been as directly or widely effective as integrated multidimensional gas chromatography-mass spectrometry-olfactometry (i.e., MDGC-MS-O) for rapidly pinpointing and resolving problems related to aroma and flavor quality [6].