Typescript, etc. / Digitized by Kansas State University Libraries

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'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

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Master of Science

The distribution of total phenolics, antioxidant capacity, monomeric anthocyanin, and ascorbic acid contents in the peel and flesh of Red Delicious, Granny Smith, and Fuji apples during a six-month storage period were determined. In addition, the effect of 1-MCP (1-Methyl cyclopropene) on these parameters of the edible portion of apples during storage was also investigated. Two different assays were employed to determine antioxidant activities: the spectrofluorometric-based Oxygen Radical absorbing Capacity (ORAC) and the spectrophotometric-based Ferric Reducing Antioxidant Power (FRAP). Total phenolics were measured using the Folin-Ciocalteau method. A determination of monomeric anthocyanin content was also performed using the pH-differential method for Red Delicious and Fuji apples. Antioxidant activity was predominantly observed in the aqueous fraction and was attributed to polyphenolics. Antioxidant activities were highest in the peel, with Red Delicious peel having the highest values, presumably due to anthocyanin pigments. At zero time month storage, the ORAC, FRAP, total phenolics, and total monomeric anthocyanin contents of Red Delicious peel were: 37.7 μmol T.E./g, 62.7 μmol T.E./g, 6.63 mg/g GAE, and 26.4 mg/100g, respectively. The three tested cultivars were significantly different with respect to ORAC, FRAP, total phenolics, and monomeric anthocyanin contents. 1-MCP treatment did not have a significant influence on antioxidant activities and monomeric anthocyanin contents of the three cultivars during storage. Storage did not have significant influence on ORAC values of the edible portion of apple, however it had significant influence on the FRAP values. The contribution of ascorbic acid to the total antioxidant capacity was small. / Graduation date: 2003