high-pressure technlogies as promising ......high-pressure technlogies as promising green methods...
TRANSCRIPT
HIGH-PRESSURE TECHNLOGIES AS PROMISING GREEN METHODS FOR
EXTRACTION OF COCOA SHELLTanja Gagić 1, Stela Jokić 2, Željko Knez 1,3 and Mojca Škerget 1
1 Faculty of Chemistry and Chemical Engineering, University of Maribor, Smetanova 17, Maribor 2000, Slovenia; [email protected] (T.G.); [email protected] (Ž.K);
[email protected] (M.Š.)2 Faculty of Food Technology Osijek, Josip Juraj Strossmayer University of Osijek, Franje Kuhača 20, Osijek 31000, Croatia; [email protected] (S.J.);
3 Faculty of Medicine, University of Maribor, Taborska ulica 8, Maribor 2000, Slovenia
Cocoa shell represents a waste from the industrial production of cocoa and chocolate. However, it attracts a lot of attention because it is rich in valuable compounds. Re-use of cocoa shell won’t
increase only profitability and avoid environmental pollution, it could also found application in cosmetic, pharmaceutical and food industry due to its antioxidant, antimicrobial, anti-ageing, anti-radical
and anticarcinogenic properties. Different methods were used for extraction of cocoa shell, but the data related to the use of green separation techniques are limited in the literature. Therefore, the
aim of this work was to use both green-based and conventional extraction methods in order to compare results. Supercritical CO2 extraction was performed at pressures of 200 and 300 bar and at
temperatures 40, 60 and 80 ˚C. Subcritical water extraction was carried out in a batch reactor at temperatures of 170 ˚C and 220 ˚C. Soxhlet extraction with hexane and extraction with 50 %
acetone were also performed. Total phenol content, total proanthocyanidin content and antioxidant activity of extracts were determined. Besides phenolic compounds, some extracts contained high
amounts of theobromine, followed by caffeine and theophylline. Furthermore, subcritical water extracts were rich in sugars and their derivatives. Fatty acids were also obtained using supercritical
CO2 and Soxhlet extraction of cocoa shell and were analysed by gas chromatography.
INTRODUCTION EXPERIMENTAL METHODS
CONCLUSION AND FUTURE APPLICATIONSGreen-based method such as supercritical CO2 and subcritical water extraction showed more efficient
results than conventional methods. Supercritical CO2 and subcritical water extractions need shorter
extraction time and their extracts are free of hazardous solvents. Furthermore, subcritical water and
CO2 are environmentally friendly, low-cost and safe extraction solvents, which could be promising
alternative for recovery of bioactive compounds. Precisely, supercritical CO2 extraction showed high
efficiency for fat recovery, whereas subcritical water technology found application for extraction of
sugars, methylxanthines and phenolic compounds. Furthermore, the chemical composition of cocoa
shell implies that it could be used in food, cosmetic and pharmaceutical industries.
RESULTS
1,85
1,99
2,6
2,75
3,05
2,772,86
0
0,5
1
1,5
2
2,5
3
3,5
yie
ld o
f extr
act,
%
The yield of extracts obtained by supercritical CO2 extraction at different
conditions and Soxhlet extraction with hexane.
0
20
40
60
80
100
120
140
160
tota
l p
hen
ol co
nte
nt,
mg/(
g o
f extr
act)
Total phenol content in extracts obtained by subcritical water
extraction and extraction with 50 % acetone.
170˚C 30 min 220˚C 30 min
200 bar 300 bar
0
1
2
3
4
5
6
7
tota
l p
roan
tho
cyan
idin
co
nte
nt,
mg/(
g o
f extr
act)
Total proanthocyanidin content in extracts obtained by subcritical
water extraction and extraction with 50 % acetone.
170˚C 30 min 220˚C 30 min
200 bar 300 bar
Compounds extracted from cocoa shell
0
10
20
30
40
50
60
70
yie
ld o
f extr
acts
, %
The yield of cocoa shell extracts obtained by subcritical water
extraction and extraction with 50 % acetone.
170˚C 30 min 220˚C 30 min
200 bar 300 bar
0
20
40
60
80
100
An
tio
xid
an
t acti
vit
y, %
The antioxidant activity of extracts obtained by subcritical water
extraction and extraction with 50 % acetone.
170˚C 30 min 220˚C 30 min
200 bar 300 bar