Heat treated orange juice, both pasteurized and concentrate, are being increasingly
consumed in the U.S. Orange juice is primarily heat treated to increase its shelf life, by
curbing the growth of microorganisms; and to inactivate pectin methylesterase, which
demethylates pectin and leads to cloud loss in the juice. However, because of heat
processing, orange juice undergoes undesirable flavor changes that decrease its
acceptability to consumers.
The objectives of this study were to differentiate between fresh frozen and heat
treated orange juice employing descriptive analysis, and to determine by Osme, a gas
chromatography-olfactometry (GCO) method, odor active volatiles that were either
lacking or created in the heat treated juice. The second objective was to determine how
changes in the odor-active volatile profile of heat treated orange juice, relates to changes
in the aroma and flavor intensities of the samples as assessed by descriptive analysis.
Through descriptive analysis, the panel was successful in significantly (p<0.05)
separating the fresh, pasteurized, and concentrate samples. Orange, orange peel, sweet,
and grassy descriptors were found to be important for fresh aroma and flavor, while
cooked, yam, metallic, tamarind, green bean and artificial orange descriptors were higher
in heat treated samples.
Using Osme, it was possible to separate fresh frozen from heat treated orange
juice, on the basis of their aroma profiles. Fresh frozen samples show a higher
concentration of peaks tentatively identified as gamma-butyrolactone, citral, nonanal,
carvone, perillaldehyde, carvyl propinate, valencene, and other unidentified peaks
possessing descriptors such as floral, lime, citrus, pine, bamboo leaf, metallic, and vinyl.
Pasteurized samples show a larger concentration of peaks tentatively identified as
hexanol, octanol, nerol / carveol, myrcene, 2-octanone, p-cymene, terpenen-4-ol, betacitronellol,
and other unidentified peaks with descriptors such as cilantro, vinyl, melon,
mushroom, and metallic.
Descriptors such as orange, orange peel, sweet, grapefruit, and grassy are more
pronounced in the fresh samples and are similar to the odor descriptors of Osme peaks
higher in the fresh samples. Descriptors such as cooked, artificial orange, yam, metallic,
tamarind, and green bean are higher in the pasteurized samples, and are similar to the
odor descriptors of peaks higher in these samples. / Graduation date: 1999
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27658 |
| Date | 08 June 1998 |
| Creators | Shah, Rohan |
| Contributors | McDaniel, Mina R. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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