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Advisor(s)
Abstract(s)
The effects of spray-drying of the unicellular microalga Dunaliella salina on its B-carotene content
and geometric isomer composition have been studied. The efficacy of a range of synthetic and natural
antioxidants in preventing degradation of B-carotene has been determined. Losses of B-carotene
and isomerization were minimal during processing for both the control (no exogenous antioxidants)
and the samples containing butylated hydroxytoluene (BHT) and tert-butylhydroquinone (TBHQ).
However, the use of tocopherol-based antioxidants resulted in degradation of 52-72% of B-carotene
during the drying process. All dried powders of Dunaliella proved to be unstable during storage in
the presence of light and air, with B-carotene degraded according to a first-order kinetic model. Of
the antioxidants studied, only TBHQ was successful in significantly minimizing degradation
(degradation constants of 0.03 and 0.04 days-1, compared to 0.53 days-1 for the respective control).
For control powders and those with BHT added to the feed, the degradation constants were reduced
to values between 0.27 and 0.37 days-1 by restricting light and flushing with nitrogen; however,
storage in the dark alone had no effect. For more slowly degrading powders having TBHQ added to
the feed, it was clear that degradation of â-carotene was influenced by both light and oxygen. During
storage the 9-cis isomer of B-carotene was significantly more unstable than the all-trans form. TBHQ
was, however, successful in reducing relative losses of this isomer for samples stored in the dark.
The results suggest a dominant photodegradative mechanism for the loss of the 9-cis isomer of
B-carotene.
Description
Keywords
Antioxidants B-carotene Dunaliella salina Spray-drying
Pedagogical Context
Citation
ORSET, Sandra... [et al.] - Spray-Drying of the Microalga Dunaliella salina: Effects on B-Carotene Content and Isomer Composition. Journal of Agricultural and Food Chemistry. ISSN 0021-8561. Vol. 47, n.º 11 (1999), p. 4782-4790
Publisher
American Chemical Society