The role of beta-carotene degradations in the development of
off-flavors in milk and milk products has not been established. The
purpose of this investigation was to study the oxidation of beta-carotene
and to identify volatile compounds arising from autoxidizing
beta-carotene.
Pure cyrstalline beta-carotene, mixed with Celite to accelerate
oxidation, was oxidized at 50°C by molecular oxygen in two different
systems. The peroxide value and loss of beta-carotene were measured
after controlled oxidation periods. In one system the maximum
peroxide value, 295 milliequivalents per 1,000 grams, occurred
after three hours of oxidation. In the other system the maximum
peroxide value, 586 milliequivalents per 1,000 grams, was observed
after six hours of oxidation. Approximately 80 percent of the beta-carotene
was decomposed within the first ten hours of oxidation.
Volatile compounds from autoxidizing beta-carotene were
collected by a cold-trap gas-entrainment technique. The collected compounds were subjected to gas-liquid chromatography and rapidscan
mass spectrometry, and the following compounds were identified:
n-pentane, ethyl ether, acetaldehyde, acetone, propanal,
methyl vinyl ketone, toluene, isobutanal, 2-octanone and acetic
acid. Compounds tentatively identified included diacetyl, 3-methyl-
2-pentanone, 4-methyl-3-pentan-2-one, 2-methylfuran, 1,3,3-trimethylcyclohexene,
rnethyl formate, butanone, 2-methyl-2-heptenal,
1, 3-dimethyl-2-ethylcyclohexane, 2-ethyl-2-hexenal, 2-formyl-3, 3-
dimethylcyclohexene, 1, 1, 3-trimethyl-2-n-propylcyclohexane, 2-
methyl-3-nonene and 3, 5, 5-trimethyl-4-(4'-butyl-3'-en-2'-onyl)
cyclohexa-1, 3-diene. A fraction possessing a strong "nutty" aroma
was tentatively identified as 2-methyl-2-heptenal. The volatile compounds
identified can be predicted as degradation products of beta-carotene
oxidation. / Graduation date: 1967
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/26796 |
| Date | 07 October 1966 |
| Creators | Chiba, Naoki |
| Contributors | Lindsay, Robert C. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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