Chemical Characterization of Two California-Grown Avocado Varieties ( Persea americana Mill.) over the Harvest Season with an Emphasis on Sensory-Directed Flavor Analysis.

The research objective was to characterize avocado's aroma-active volatiles and use information about its overall composition, such as lipid profile, to discuss likely biosynthetic origins. To achieve this, two varieties, "Hass" and "3-29-5" (GEM), were evaluated during their commercial harvest period for dry weight, moisture content (freeze-drying), oil content (Soxhlet extraction), fatty acid composition, and aroma profile. Solvent-assisted flavor evaporation and aroma extract dilution analysis were performed on aroma extracts. Oleic acid (>50%) was the prominent fatty acid in the oil of both varieties. The majority of the aroma-active compounds in avocado are lipid-derived. The most notable compounds are 1-octen-3-one (mushroom) with a flavor dilution factor as high as 8192, hexanal (grassy), ( Z )-4-decenal, an unknown, and ( E,E )-2,4-nonadienal. Over the mid-to-late harvest season, a decline in hexanal and an increase in octanal were observed. In contrast to "Hass", the hexanal content was relatively stable in "3-29-5".