2.3. Quantification of carotenoids
The lipid extracts from shrimp waste and tomatoes and the
commercial b-carotene were diluted with hexane, petroleum ether,
and ethanol, respectively, to a known volume, and the absorbance
of the appropriately diluted extract was measured at 470 (astaxanthin
and lycopene) and 450 (b-carotene) nm using a Beckman
Coulter DU 800 spectrophotometer (Beckman Coulter, Indianapolis,
USA). The carotenoid concentration was calculated using the
equation described by Britton (1995),