ANTIOXIDANT PROPERTIES OF THREE

SELECTED HERBS AND THE

ENHANCEMENT

EFFECTS OF DRYING TREATMENTS

Assist. Prof. Eric Chan Wei Chiang

Overview

Thermal treatments used in food preparation and

processing is widely considered to degrade

biomolecules and reduce any bioactive properties

However, our recent work on the antioxidant

properties (AOP) of leaves of selected herbs

showed that three displayed enhancement

effects of thermal and non-thermal drying

treatments.

The herbs studied were Etlingera elatior (Torch

ginger), Morus alba (Mulberry) and Thunbergia

laurifolia (Blue trumpet vine).

Antioxidant assays and drying

treatments

Assessment of Antioxidant

Properties

Total phenolic content (TPC)

DPPH Radical Scavenging

(AEAC)

Ferric reducing power (FRP)

Drying treatments

Microwave drying

Oven drying

Sun-drying

Air drying

Freeze drying

Microwave-drying enhanced

the AOP of T. laurifolia leaves

with 34% increase in TPC

and 67% increase in AEAC

as confirmed by the half-leaf

test.

A likely cause for the

increase in antioxidant

activity following microwave-

drying was was the release

of bound phenolic

compounds, brought about

by the breakdown of cellular

constituents

Another possible explanation

is the rapid inactivation of

polyphenol oxidase (PPO)

activity in samples due to

microwave irradiation

Thunbergia laurifolia

Morus alba

Leaves of M. alba responded positively to Microwave-drying, Oven-

drying and Freeze-drying.

The increase in antioxidant properties is likely due to the release of

bound phenolic compounds.

Furthermore, the oxidative enzymes in M. alba was not activated by

oven drying as observed in T. laurifolia.

Freeze-drying enhanced the

AOP of leaves of E. elatior

The antioxidants within the

leaves were not heat stable

The HPLC chromatogram of

freeze-dried leaves of E.

elatior showed greater

amounts of minor compounds

than fresh leaves

Etligera elatior

Overlay of chromatograms

showed greater amounts of

minor compounds in freeze-

dried than fresh leaves.

Other research capabilities

Bioassay guided isolation of

phytochemicals for

NMR and MS

Synthesis of carboxymethyl cellulose

Encapsulation of nutraceuticals

Other research capabilities

The MSc. student behind it all

Yuen Ping’s research

team

Lainey Audrey Hui Qi

Alice Pang Kwok Meng

Monash Science Symposium

Thank youCheck out my blog here:

http://www.scoop.it/u/eric-chan-wei-chiang