'Gala' is an apple cultivar with a distinctive aroma and flavor. 'Gala' storage season is short in regular atmosphere (RA). Controlled atmosphere (CA) extends 'Gala' storage but volatile production is reduced. 'Gala' odor-active aroma compounds were identified using Osme, a gas chromatography and olfactometry technique. Changes in aroma after RA and CA storage were characterized by Osme and descriptive sensory analysis (DSA).
Hexyl acetate, butyl acetate and 2-methylbutyl acetate were emitted in the largest amounts and were perceived with the strongest intensities, with "ripe apple", "solvent" and "fruity" descriptors. Production of hexyl acetate and butyl acetate after CA storage decreased significantly compared to apples stored in RA, along with perceived intensities. 2-Methylbutyl acetate only decreased in apples stored 20 weeks in CA. Other esters with an apple odor were butyl 2-methylbutyrate and hexyl 2-methylbutyrate.
Methyl 2-methylbutyrate, ethyl 2-methylbutyrate and propyl 2-methylbutyrate had sweet, fruity, and berry-like odors. Ester production after CA storage decreased at different rates. The non-ester compounds 4-allylanisole (anise) and 0-damascenone (grape juice) as well as an unidentified compound (watermelon), were perceived mostly from RA stored fruit. Other unidentified peaks had cucumber, mushroom, adhesive tape or skunk odors.
Comparison of mixtures of 'Gala' odor-active compounds in water with whole 'Gala' apples revealed that hexyl acetate, hexanal and butyl acetate were necessary to impart an apple odor. 2-Methylbutyl acetate and methyl 2-methylbutyrate also contributed to the least difference between mixture solutions and apples.
DSA of 'Gala' apples stored in RA and CA confirmed the general decrease in fruity aroma following CA storage. A floral descriptor was also significantly affected by CA storage. A musty note appeared in CA stored fruit, which may have corresponded to a garlic odorant peak detected during Osme. 'Gala' apples stored 16 weeks in CA followed by 4 weeks in RA emitted more volatiles than fruit stored 20 weeks in CA. The difference in volatile production was perceived by Osme analysis, and differences in overall fruity aroma between 16 and 20 weeks CA stored fruit were perceived only for whole fruit. There was no difference between those two types of storage for fruit flavor. / Graduation date: 1998
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/33826 |
| Date | 13 March 1998 |
| Creators | Plotto, Anne |
| Contributors | Mattheis, James P. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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