Bioactive compounds and antioxidant attribute of carambola (Averrhoa carambola L.) fruit as affected by cultivars and ripening stages
Study on bioactive compounds and antioxidant activity was conducted on three different carambola cultivars (B2, B17 and B10) planted in Malaysia and the best cultivars in terms of antioxidant potential was selected and evaluatedat different ripening stages. Carambola fruits were analyzed for asco...
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| Main Author: | |
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| Format: | Thesis |
| Language: | English |
| Published: |
2013
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| Online Access: | http://psasir.upm.edu.my/id/eprint/67699/1/FSTM%202013%2034%20IR.pdf http://psasir.upm.edu.my/id/eprint/67699/ |
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| Summary: | Study on bioactive compounds and antioxidant activity was conducted on three
different carambola cultivars (B2, B17 and B10) planted in Malaysia and the best
cultivars in terms of antioxidant potential was selected and evaluatedat different
ripening stages. Carambola fruits were analyzed for ascorbic acid(AA), total
phenolic compound (TPC), total flavonoid content (TFC), total carotenoid content
(TCC), beta-carotene (β-carotene), tocopherols (alpha,α;beta,β;gamma,γ and delta,δ)
and sugars (glucose, fructose and sucrose). Free radical scavenging activity using
2,2-diphenyl-2-picrylhydrazyl assay (DPPH) and β–carotene-linoleic acid model
(BCLAM) assays were performed to evaluate their antioxidant activities. Results of
the study showed thatthere is no significant difference in AA content between cv. B2
and cv. B17. Among the cultivars, cv. B17 was found to contain significantly
(P<0.05) higher TPC, sugars, β–carotene and β-tocopherol levels while cv. B10 only
had significantly (P<0.05) higher content of γ– and δ-tocopherols. However, cv. B10
and cv. B17 did not show any significant difference in TCC, TFC, β-carotene and α-
tocopherol content. The study showed that each cultivar had their own advantages in
terms of bioactive compounds that could contribute to antioxidant activity. As
expected, cv. B10 and cv. B17 exhibited significantly (P<0.05) higher antioxidant
activity than that of cv. B2 for both DPPH and BCLAM assays. However, BCLAM
result showed that cv. B17 had the highest antioxidant activity among the
cultivars.Pearson’s correlation and Partial Least Square (PLS) were used to identify
the linkbetween antioxidant activity and bioactive compounds.Carambola cv. B17
had been selected forquantifying the bioactive compounds and antioxidant activity
changes at different ripening stages. Carambola cv. B17 was tagged at fruit set stage
and harvested at week 9,10,11,12 and 13. Ascorbic acid, TCC and sugar composition
were significantly (P<0.05) increased while TPC, TFC and β-carotene exerted the
reverse trend during ripening. Tocopherols homologue changes were varied where α–
and β–tocopherols levels wereincreased until week 12 before decreased in week 13.
On the contrary, γ– and δ–tocopherolslevels were significantly (P<0.05) decreased
during ripening. Fruitsharvested at a later ripening stage allow for the synthesis and
accumulation of bioactive compounds,thus explained the increasing trend. On the other hand, decreased trend in the bioactive compounds are probably due to their
functions as precursor compounds. Antioxidant activities of the samples were
significantly (P<0.05) decreased as measured by DPPH and BCLAM
assays.Multivariate analysis revealed clear separations between the ripening
stagescaused bytransitional changes in bioactive compounds and antioxidant activity
during fruit ripening. In conclusion, bioactives compound and antioxidant activity
were cultivar- and ripening stage-dependent. Carambola fruit cv. B17 was found to
be the best cultivar in terms of antioxidant potential and should be harvestedat week
9 to get its full benefit of antioxidant property. |
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