Methanol extracts from seven species of Indonesian seaweeds were evaluated for their anti-oxidant activities in a fish oil emulsion system. The system was incubated at 50 ∞ C for 3 and 24 h, in the presence of ferrous ion as a catalyst. Peroxide value (POV), ferrous ion chelating effect in the oil emulsion system and ferrous ion binding effect in methanol extracts were determined as oxidation markers. In the presence of ferrous ion catalyst, all of the methanol extracts from seaweeds showed significantly lower POV of the emulsion than the control, and the extract from Caulerpa sertularoides had the strongest anti-oxidant activity. The highest chelation on ferrous ion was also found in the extract from C. sertularoides and it was significantly different compared to the other methanol extracts both in 3 and 24 h incubation. Methanol extracts from seaweeds had excellent ferrous ion binding effect; however, their ability decreased in the fish oil emulsion system.KEY WORDS: anti-oxidant, chelating effect, Fe 2 + + + + , methanol extract, oxidation, peroxide value, seaweed.
This experiment was carried out to study the mineral contents and profiles of several Indonesian green, brown, and red seaweeds, and to evaluate the solubilities of Ca and Mg as a#ected by boiling in di#erent solutions (water, +ῌ sodium chloride and *./ῌ acetic acid). The macromineral profiles were dominated by Ca, K, Na and Mg. The trace minerals Cu, Fe and Zn were found at low concentrations. Boiling in water and *./ῌ acetic acid significantly increased the solubilities of Ca and Mg (pῌ*.*/), whereas boiling in +ῌ sodium chloride resulted in varying solubilities of Ca and Mg. Mainly soluble Ca was found in both low (MWῌ+*,***) and high (MW῍,**,***) molecular weight fractions, whereas soluble Mg was found in the high (MW῍,**,***) molecular weight fraction.
Impacts of extraction conditions on lipid and carotenoid yields from hepatopancreas of Pacific white shrimp (Litopenaeus vannamei) were investigated. Among single solvents (acetone, isopropanol and hexane) and their mixtures, a mixture of hexane and isopropanol (50:50, v/v) rendered lipids with the highest carotenoid yield (336.40 mg/kg hepatopancreas) with the extraction yield of 18.22% (w/w hepatopancreas) (P < 0.05). The use of hepatopancreas to solvent ratio of 1.0:4.5 (w/v) and three repetitions showed the highest carotenoid yield (363.94 mg/kg hepatopancreas) with the extraction yield of 18.08% (w/w hepatopancreas). Astaxanthin, astaxanthin diester and canthaxanthin were the major carotenoids found in lipids. When astaxanthin (2 mg/g lipid) was added into lipid, the oxidation was lowered, in comparison with the control during the storage at 30C for 10 days as indicated by lower ρ-anisidine value. Fourier transform infrared spectra study also revealed that triglyceride in lipids underwent oxidation to a lower degree when astaxanthin was incorporated.
PRACTICAL APPLICATIONSShrimp hepatopancreas, a by-product from shrimp-processing industries, is one of the important sources of lipids and natural carotenoids, which are susceptible to oxidation. Their changes are associated with development of off-odor and loss in nutritive value. The recovery of lipid and carotenoid from hepatopancreas by an appropriate means would increase the revenue for shrimp-processing industries. Additionally, those value-added products could serve as the excellent source of nutrients as well as bioactive compounds.
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