Independent Research Proposal
Redika Ardi Kusuma / F301404-URSEP
Effect of Electrical Treatment on Antioxidant Contents in Red
CabbageIntroductionThe results of various epidemiological studies
have shown a strong correlation between vegetable consumption and a
reduced occurrence of chronic diseases, such as cancer (Kotake-Nara
et al., 2001) and cardiovascular diseases (Jacob,Periago, Bohm,
& Berruezo, 2008). Fruit and vegetables contain numerous
different secondary plant compounds, many of which possess
antioxidant properties. Based on the chemical structure, secondary
plant compounds such as phenolic compounds have a free binding
character and may protect against free radical reactions (Bazzano
et al., 2002).
Secondary plant compounds (e.g. phenolic compounds) assume a
wide range of function in plants. They play important roles in the
interaction of plants with their environment (Evers, 1994) and
regulate stress situations (Schreiner, 2005). Biotic stress and
environmental stress cause stress in plants, which respond with an
accumulation of various phytochemicals, e.g. phenolic compounds
(Huyskens-Keil, 2009).
Most of the previous research results showed that electricity
can stimulate physiological processes in plants. Pulsed electric
fields may activate as well plant stimulus. Gachovska et al. (2010)
treated red cabbage by pulsed electric field (2.5 kV/cm electric
field strength) and found that it can enhanced total anthocyanin
extraction in water from red cabbage by 2.15 times. In further
studies, direct-electric-current (DC) give enrichment effect on
secondary plant compounds and antioxidant activity in harvested
tomato and sweet potato (Dannehl, 2011 & Hironaka, 2012).
However, information on changes in phenolic compounds and
antioxidant activity in red cabbage as affected by small electric
currents are scanty. Therefore, in the present study the effect of
different intermittend-direct-electrical-currents (IDC) on phenolic
compounds and antioxidant activity was investigated in different
morphological compartments of red cabbage.Research Objectives
The main objective of this study, therefore, was to investigate
the effects of different DC and different treatment times on
phenolic compounds and antioxidant activity in harvested red
cabbage. With this step, it might be possible to integrate
electrical treatments in postharvest processes, in order to
increase health-promoting phytochemicals of vegetables.Literature
ReviewSecondary compounds are complex chemicals made by plants that
are not essential to the life of the plant. They are thought to be
produced primarily as pesticides and anti-grazing agents, but they
also used as pigments, hormones and chemical agents that can attack
other plants (alleleopathy).
Previous studies elicited that phenolic compound from plant
foods could signicantly contribute to their antioxidant capacity
(Zielinska et al., 2008). In Wiczkowski study (2014), total
anthocyanin concentration is positively and signicantly correlated
(P < 0.05) with the antioxidant capacity of all varieties of red
cabbage studied. The results indicated that anthocyanins occurring
in plants of red cabbage were responsible for their antioxidant
capacity. So that, the antioxidant capacity of raw and processed
cabbages was highly correlated with their contents of
polyphenolics.
The general application of electric current which is used to
enhance the quantity of functional food ingredients is pulsed
electric elds (PEF). However, it has to be considered that a high
electrical eld (35 kV cm-1) and pulse duration of 1015 ms leads to
irreversible damage of the cell membrane. On the other hand,
applied electrical eld strength of 0.6 kV cm-1 induced stress
reactions, resulting in reversible cell permeability (Zimmermann,
Pilwat, & Riemann, 1974).
Dannehl (2011) report that the aplication of weak electric
current, different DC treatments, increased the total phenol
content in harvested tomatoes. After an adaptation time of 2 h, the
maximum contents of lycopene (122.4%), -carotene (140.4%), total
phenol (120.0%), and antioxidant activity (126.5%) were attained
with a DC treatment of 500 mA for 15 min. The same effects of weak
direct electric current were observed in radish during growth
(Dannehl, 2009). Methodology
Plant Material and Experimental SetupCommercially bulbs of red
cabbages (Brassica oleracea) as experimental materials will be
purchased from a local supermarket (Genowan, Okinawa). A simplied
prototype to purge red cabbages, combined with the opportunity to
apply DC in postharvest processes, will developed. Red cabbage will
be immersed in a 0.1% NaCl solution for 2 min and subsequently
treated with 0, 10, 20, 30, 40, 50, 100, 200 and 300 mA (DC) for 5
min in a parallel copper plate. Total phenols and antioxidant
activity will be measuredExtraction of Total Phenol Content
Three replications of each dried sample of red gabbage were used
for the analysis of total phenol content and each extraction was
determined in duplicate. The samples will be extracted following
the method by Connor, Luby, and Tong (2002) using acetic acetone
(50% distilled water, 49.5% acetone, and 0.5% pure acetic acid;
v,v,v). The extracts will be used to analyse the total phenol
content, as well as antioxidant activity in red gabbage.
Determination of the Total Phenol Content
The procedure described by Slinkard and Singleton (1977) with
some modications will be followed to determine the total phenol
content in red cabbage.
Antioxidant Capacity AssaysThe red cabbage extracts, which will
be prepared for the determination of the total phenol content, will
be used to analyse the antioxidant activity. The presence of
antioxidants in the red cabbage extracts will be monitored using
the Trolox equivalent antioxidant activity (TEAC) assay and will be
measured spectrophotometrically
Statistical AnalysisThe effects of DC on secondary plant
compounds in red cabbage will be evaluated using analysis of
variance (ANOVA) with Statistical Package for Social Sciences
(SPSS). A multifactorial analysis of the variance will be used to
answer the question whether DC or the application time had a
greater impact on the anthocyanin and total phenol content, as well
as antioxidant activity in the red cabbage.TimelineTable 1 The
estimated research timeline
TaskMont of
45678
Research preparation
Research data collection
Analysis and data processing
Writing Manuscript
Final Report
References
Bazzano, L. A., Ogden, L. G., Loria, et al. (2002). Fruit and
vegetable intake and risk of cardiovascular disease in US adults:
The rst National Health and Nutrition Examination Survey
Epidemiologic Followup Study. American Journal of Clinical
Nutrition, 76(1), 9399.Connor, A. M., Luby, J. J., & Tong, C.
B. S. (2002). Variability in antioxidant activity in blueberry and
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of the American Society for Horticultural Science, 127(2),
238244
Dannehl, D., Huyskens-Keil, S., Eichholz, I., etc. (2009).
Effects of intermittent direct-electric-current (IDC) on
polyphenols and antioxidant activity in radish (Raphanus sativus
L.) during growth. Journal of Applied Botany
Dannehl, D., Huyskens-Keil, S., Eichholz, I., etc. (2011).
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