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

In this work, descriptive analysis (DA) and consumer panels were conducted on "Hass" and "3-29-5" (GEM® ) avocados, grown in southern California. Both panels encompassed at least five time points across the 2019 harvest season. The DA panel identified and evaluated overall richness, creamy, smooth, watery, oily, sweet, bitter, umami, salty, astringent, buttery, nutty, and green. The texture attributes received the highest scores in both "Hass" and "3-29-5." Both varieties increased in richness, creaminess, and oiliness at harvests 5 and 6. The consumer panel found that "3-29-5" showed more changes in its eating experience over the season than "Hass," which agreed with dry weight data collected in a simultaneous analytical study. Correspondence analysis indicated that "Hass" samples had a consistent sensory profile over the harvest season, whereas "3-29-5" changed substantially, becoming more closely associated with a positive eating experience late in the harvest season. This is the first work to characterize avocado flavor over the harvest season using both trained and consumer sensory panels. PRACTICAL APPLICATION: Many aspects of avocado were found to have some impact on flavor, but textural properties were by far the most important in determining how well the fruit was liked. This information will be useful in future taste evaluations of avocado and the ongoing development of new avocado varieties.

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".

Starch-Flavor Complexation Applied to 2-Acetyl-1-pyrroline.

The pleasant popcorn-like smelling compound 2-acetyl-1-pyrroline (2AP) occurs naturally in many foods but is scarcely used as a flavoring agent due to its great instability. In this work, we evaluate the potential of high amylose corn starch to complex and stabilize 2AP. The methodology was first optimized using model compounds, 2-acetylpyridine and 2-acetyl-2-thiazoline, and then applied to 2AP. Complexes were successfully prepared and characterized using X-ray diffraction, gas chromatography, and differential scanning calorimetry. Loadings of up to 0.504 (±0.071)% 2AP were achieved, and storage studies showed that over half of the flavor was retained after 2 weeks at 0% relative humidity. To our knowledge, this is the first demonstration that 2AP can form amylose inclusion complexes and may lead to a method to effectively stabilize this labile aroma compound.

Flavor chemistry of lemon-lime carbonated beverages.

The most potent aroma-active components of Sprite (SP), Sierra Mist (SM), and 7UP (7UP) were identified. Aroma extracts were prepared by liquid­liquid continuous extraction/solvent-assisted flavor evaporation (LLCE/SAFE). Twenty-eight compounds were detected by gas chromatography­olfactometry (GC-O) with linalool (floral, lavender), octanal (pungent orange), and 2,3-dehydro-1,8-cineole (minty) determined to be predominant aroma compounds based on their high flavor dilution (FD) factors by aroma extract dilution analysis (AEDA). The data indicate that lemon-lime flavor is composed of a small number of compounds (22 at the most in SM), and only a subset of these may be important because many compounds were detected only at low FD factors. Predominant aroma compounds (23) were quantified using static headspace solid phase microextraction (SPME) combined with stable isotope dilution assays (SIDA). In contrast to FD factors, the calculated odor-activity values (OAVs) indicate that octanal and limonene make the greatest contribution to the overall aroma of lemon-lime carbonated beverages, followed by nonanal, decanal, linalool, 1,8-cineole, and geranyl acetate. The results demonstrate that lemon-lime carbonated beverages share many of the same compounds but the relative abundance of these compounds varies by brand.

Hydroxyquinolines with extended fluorophores: arrays for turn-on and ratiometric sensing of cations.

8-Hydroxyquinoline-based ligands with extended conjugated fluorophores were designed to provide turn-on and ratiometric signal output optimized for use in fluorescence-based sensor arrays, where the changes in blue and green channels of the RGB signal are used to distinguish between cationic analytes.