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United States Department of Agriculture

Agricultural Research Service

Research Project: MEASUREMENT SYSTEMS FOR DETERMINATION OF VITAMINS IN FOODS AND DIETARY SUPPLEMENTS

Location: Food Composition and Methods Development Lab

Title: A simplified 96-well method for the estimation of phenolic acids and antioxidant activity from eggplant pulp extracts using UV spectral scan data

Author
item Luthria, Devanand

Submitted to: Journal of Functional Foods
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 18, 2011
Publication Date: January 12, 2012
Citation: Luthria, D.L. 2012. A simplified 96-well method for the estimation of phenolic acids and antioxidant activity from eggplant pulp extracts using UV spectral scan data. Phytochemical Analysis. 4:238-242.

Interpretive Summary: This paper describes a simple 96-well rapid screening method for evaluation of antioxidant activity in eggplant pulp extracts. Seven different freeze-dried eggplant pulp samples belonging to different cultivars or grown under different environmental conditions along with single peel sample were selected as models to evaluate the applicability of the simple UV spectral method for estimating concentration of phenolic acids and antioxidant activity in different eggplant pulp extracts. HPLC results, simple UV spectral scan data, and quantification of antioxidant activity by FRAP assay in seven eggplant pulp extracts showed a strong correlation (R-squared greater than 0.9) between three methods. The data presented in this manuscript may be of interest for the researchers, food producers, and nutrition professionals.

Technical Abstract: Eggplant fruit is ranked amongst the top ten vegetables in terms of oxygen radical absorbance capacity due to its high phenolic acid content. The main objective of this study was to determine if a simple UV spectral analysis method can be used as a screening tool to estimate the amount of phenolic acid and the antioxidant capacity of eggplant pulp extracts. Calibration curves for different concentrations of 5-caffeoylquinic acid were developed from UV spectral data, HPLC analysis, and ferric reducing antioxidant power (FRAP) assays. Seven different freeze-dried eggplant pulp samples belonging to different cultivars or grown under different environmental conditions along with a single peel sample were selected as models to evaluate the applicability of the simple UV spectral method for estimating concentration of phenolic acids and antioxidant capacity in different eggplant pulp extracts. HPLC results, simple UV spectral scan data, and quantification of antioxidant capacity by FRAP assay in seven eggplant pulp extracts showed a strong correlation (R-squared greater than 0.9) between three methods. These results suggest that the spectral scan method can be used to predict the concentration of phenolic acids and the antioxidant capacity in eggplant pulp extracts without peels as peels are enriched in another class of phenolic compounds, namely anthocyanins, that impart color to the peels and also contribute towards antioxidant capacity. A simple and rapid 96-well UV spectral scan procedure can be used to predict the concentration of phenolic acids and antioxidant capacity in eggplant pulp extracts. This method can also be used as a quick screening tool to evaluate the influence of growing conditions on antioxidant capacity or phenolic acid content in eggplant pulp extracts.

Last Modified: 4/24/2014