Volume 74, 15 November 2015, Pages 680–688
Highlights
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- Residues of Hibiscus sabdariffa L. are rich in dietary fiber (DF) and antioxidants.
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- Effect of re-extraction on DF and antioxidants of the residue was analyzed using RSM.
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- Even after 3 re-extraction steps, the residues are richer in DF and antioxidants.
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- Residues possessed better antioxidant fibers than fruit pomace and peel fiber.
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- These residues can be potential source of DF and antioxidants for food industry.
Abstract
Effect of re-extraction and drying temperature on the antioxidant capacity and dietary fibers of Hibiscus sabdariffa
L. calyces residues were studied using response surface methodology
with respect to 3 factors Doehlert experimental design. Mathematical
models were obtained for the effect of re-extraction parameters on
ascorbic acid, TPC, TFC, ABTS, SDF, and SDF/IDF ratio. The suitability
of each response model was judged using the average absolute deviation
method and the calculation of the Bias factors. No significant
difference was observed for the total dietary fiber content among
different samples. Soluble dietary fibers in the residues varied from 47
to 216 g kg−1 dry matter. Insoluble dietary fiber
represented more than 75% of total dietary fibers. Samples exhibited
high scavenging activity of ABTS cation radical (TEAC ranging from 2.488
to 9.416 mMeq. Trolox) and DPPH free radical with IC50 values ranging from 0.915 to 0.062 mg mL−1. TEAC and IC50 values were correlated to TPC and TFC. The study indicated that H. sabdariffa
L. calyces residues can be a potential source of additive/ingredient
for the food industry and the re-extraction at lower temperatures
further improves the dietary fiber composition of the residue.
Graphical abstract
Keywords
- Hibiscus sabdariffa L.;
- Re-extraction;
- Ascorbic acid;
- Antioxidant activity;
- Dietary fibers;
- RSM
- Corresponding author. Tel.:
+91 471 2515348; fax: +91 471 2495050.
Copyright © 2015 Elsevier B.V. All rights reserved.
