Guest speaker for the Monash Science Symposium 2016. Slides describe how we should not assume that food processing reduces the amount of phytochemicals present.

1. ENHANCEMENT OF BIOACTIVE
PROPERTIES OF FRUITS, HERBS
AND SPICES AFTER PROCESSING
Associate Professor Eric Chan Wei Chiang

2. About myself
 Full-blooded
Monash alumni
 Still a young
researcher
 Enjoy making
friends

3. Previous Monash Science
Symposium

4. Things I hope to address in
this talk
 Convince you that raw food does not
mean good food
 My own research journey
 Some thoughts about the future

5. Raw foods
 There is a whole movement propagating
the virtues of raw foods and it is the
subject of multiple books
 Benefits include better retention of
nutrients and phytochemicals
 Heat is widely perceived to degrade
nutrients and phytochemicals – until
today some still hold this as gospel

6. Phytochemicals
 Phytochemicals are plant secondary
metabolite that confer health benefits
 The most widely studied group of
phytochemicals are the polyphenols
 A few notable examples include resveratrol
from grapes that prevent heart disease and
xanthones, potent antioxidants from
mangosteen and mangoes

7. Effects of heat
 Heat decreases the stability of
phytochemicals but may not affect the
overall bioactive properties.
 Some phytochemicals are more stable
than others even within the same group
e.g. flavonoids
 They occur in a matrix and may be
protected from thermal degradation

8. Effects of heat
 Heat may release additional phenolic
compounds
 Heat inactivates polyphenol oxidase an
enzyme present in many plants which
oxidizes phenols
 Polyphenol oxidase converts green tea in
to black tea but it also reduces its
antioxidant capacity

9. My research journey
 It is very important to ask good research
questions
 During my undergraduate honours
research I asked:
 Would it be ok to just dry leaves in the
microwave?
 Would heat degrade the antioxidants?
 I moved on to other bioactive properties
but these questions drove my research
for a good period of time.

10. 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

11. 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.

12. 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

13. Overlay of chromatograms
showed greater amounts of
minor compounds in freeze-
dried than fresh leaves.

14. Spices: Antioxidant
 Clove and cardamom
showed an increase in total
phenolic content and
radical scavenging after
thermal treatment
 Phenolics were leached by
water used by boiling and
blanching to different
degrees in different herbs
 Heat treatment releases
bound phenolics but is
offset by thermal
degradation and leaching

15. Spices: Anti-tyrosinase
 Cinnamon and cumin had the highest tyrosinase
inhibition with potential to be applied in skin-
whitening
 In most cases, heating does not affect tyrosinase
inhibition
 Tyrosinase inhibition often attributed to phenolic
compounds but the type of phenols is more
important than quantity

16. Spices: Anti-tyrosinase
 Cinnamon and cumin had the highest tyrosinase
inhibition with potential to be applied in skin-
whitening
 In most cases, heating does not affect tyrosinase
inhibition
 Tyrosinase inhibition often attributed to phenolic
compounds but the type of phenols is more
important than quantity

17. Spices: Antibacteria
 Clove showed broad-spectrum antibacterial activity
against all six bacteria
 Cooking had a variable effect on antibacterial activity
 Interestingly, cinnamon only inhibited Gram-negative E.
coli after cooking

18. Fruits
 Reviewed the effects of drying on the
bioactive properties properties of fruits
for a chapter in a book
 Fruits are often eaten raw so it is very
interesting to see how drying affects its
properties
 True enough, a review of literature
showed that heating and drying had
variable effects but it is also possible to
observe enhancement

19. Elderberries
 Kruger et al. 2015 reported additional
DPPH radical scavengers being released
by elderberries after drying

20. Thoughts about the future
 It is getting harder to get research grants but
more and more journals are adopting the pay to
publish model even prestigious ones by Elsevier
and Nature Publishing
 Research has evolved as follows
 2000: Journals went online
 2005: Impact factor becomes important
 2010: Impact factor segregated into quartiles
 2015: Pay to win
 What would 2020 bring? Would journals be
obsolete rendering impact factor meaningless?
Would Donald Trump bring about the end of
civilization?

21. Thoughts about the future
 It is impossible to tell what the future
may bring
 Research niches may dry up
 Therefore it is important to keep asking
good research questions even if it means
venturing into the unknown

22. Venturing into the unknown
 Moving out of your niche can be very rewarding
 Winning the Top 5 in Elsevier's Green Chemistry
Challenge allowed me to bring my students to
Berlin

23. Thank you
Slides and publications can be downloaded here:
www.slideshare.net/ChanEWC
https://www.researchgate.net/profile/Eric_Chan14