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

Abstract

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 aromaactive 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".

Sensory characterization of two California‐grown avocado varieties (Persea americana Mill.) over the harvest season by descriptive analysis and consumer tests

“…For the descriptive analysis (DA) and consumer panels, avocados were harvested near Saticoy, California on an approximately monthly basis between February and July 2019 (February 6, March 8, April 3, May 8, June 25, and July 29). The avocado orchard, storage, and ripening were described previously (Hausch et al, 2020). For sensory analysis, the avocados were surface sterilized with bleach, at a concentration of 25 mg sodium hypochlorite/L water (Lawton et al, 2020).…”

“…As with the DA panel, the research had exempt status granted by an IRB-SB board at UCR. Fruit were partially ethylene ripened at UCKREC as described previously (Hausch et al, 2020). They were then transported to the UCR campus (∼450 km) in cooled ice chests.…”

“…The avocado orchard, storage, and ripening were described previously (Hausch et al, 2020). For sensory analysis, the avocados were surface sterilized with bleach, at a concentration of 25 mg sodium hypochlorite/L water (Lawton et al, 2020).…”

“…Additionally, declines in nuttiness (from harvest 4) and astringency (from harvest 2) are observed. The dry weights of the avocados are shown in Table S2, which were collected in our corresponding analytical study (Hausch et al, 2020). The dry weights for both varieties increase over the harvest season, with statistical changes prominent in "3-29-5," as observed by a significantly higher dry weight at harvest 6 compared to harvest 4.…”

“…Further, by using separate panelists for the consumer and descriptive panels, the consumer panel will be more representative of the average consumer's perceptions. In a companion study by our lab, analytical measures were performed on "Hass" and "3-29-5" avocados over the harvest season to increase the knowledge on avocado flavor and relate aroma-active volatiles to the moisture and oil contents and fatty acid profile (Hausch et al, 2020). The fruit analyzed were from the same lots as those used in this study.…”