Extracts from rhizomes (Lotus roots) knot (LRK) and whole rhizomes (LR) were investigated for their antioxidative capacity in
comparison with commonly used antioxidants from plant material. Radical scavenging activity was measured spectrophotometrically
using the stable radicals 1-diphenyl-2-picrylhydrazyl and 2,20
-azino(3-ethylbenzothioazolino-6-sulfonate), and
measured by electron spin resonance (ESR) trapping of the transient carbon-centered 1-hydroxyethyl radical (generated in a Fenton-type
reaction). Efficiencies as chain-breaking antioxidants were evaluated by electrochemical measurement of oxygen consumption
rate in a peroxidating methyl linoleate emulsion. LRK exhibited high antioxidative capacity, as measured by each of four
different methods. LR, however, only showed a significantly high scavenging activity for small carbon-centered radicals, as measured
by the ESR method. Total phenol content in the plant extract correlated with the antioxidant capacity, except for the
scavenging of carbon-centered radical. Lotus rhizomes knot, as a waste from food production, will be a potential material for
extracting antioxidants. # 2002 Elsevier Science Ltd. All rights reserved.