Lemon oil quality is affected by numerous factors including lemon variety, climate, soil type, extraction method, etc.. Therefore, quality largely depends upon the lemons' origin, and aroma profiles of oils obtained throughout the world have potential to vary considerably. This research was conducted to identify differences in the aroma profiles of lemon oil samples from a variety of sources (Argentina, Brazil, California coast, California desert, Spain, South Africa). Two sensory methods commonly used to identify such differences are descriptive analysis and gas chromatography/olfactometry (GCO). A trained sensory panel identified significant differences (p<0.05) in the aroma profiles of the nine tested lemon oils in terms of overall intensity, peel, lime, orange, and sweet aromas. While descriptive analysis is useful in identifying perceived product differences, it does not provide information regarding the chemical components responsible for product differences. GCO is an effective method for identifying a flavor system's important odorants and their odor quality, but there are numerous methods by which it may be performed. Two different GCO methods, Osme and aroma extract dilution analysis with flavor dilution (FD) factors, were used to analyze cold-pressed lemon oil, and results obtained from each method were compared. Conclusions drawn from each method regarding the most critical odorants were slightly different, and better agreement among subjects was found to be present with Osme. Upon concluding that Osme provides a less variable method of identifying critical odorants, the relationship between Osme and descriptive analysis data was examined to determine if samples were characterized similarly by both sensory methods. Considerable agreement between methods was evident. In addition, neral, geranial, limonene, linalool, and gamma-terpinene were identified as important base contributors to lemon oil aroma. / Graduation date: 1998