Biochemical changes occurring in fresh green chilli pepper fruits (Capsicum annuum L. cv KA2) during storage in polymeric films at different temperatures were determined. Packaging films; Low Density Polyethylene (LDPE) 35μm, Polypropylene (PP) 80μm and LDPE micro perforated 31.75μm were used to store fruits at 4.3°C and 10°C for four weeks and at 26-34°C (ambient) for nine days. Biochemical analysis of the film-stored fruits for changes in ascorbic acid, total carotenoids, total phenols, soluble solids and titratable acidity were carried out before and after storage. Ascorbic acid in the fruits significantly (p<0.05) decreased at both low (4.3°C and 10°C) and ambient (26-32°C) storage temperatures. Carotenoids and titratable acidity increased at all the storage temperatures while total phenols decreased at low temperature but increased at ambient temperature. Soluble solids generally increased at low temperature but remained stable at ambient temperature. These results suggest that biochemical changes occur during the storage of chilli pepper fruits in polymeric films at both low and ambient storage temperatures. Article Citation: Edusei VO and Ofosu-Anim J. Biochemical changes in green chilli pepper fruits during storage in polymeric films. Journal of Research in Agriculture (2013) 2(2): 187-192. Full Text: http://www.jagri.info/documents/AG0050.pdf

1. Biochemical changes in green chilli pepper fruits during
storage in polymeric films
Keywords:
Chilli pepper, fruits, film, packaging, storage, temperature
ABSTRACT:
Biochemical changes occurring in fresh green chilli pepper fruits
(Capsicum annuum L. cv KA2) during storage in polymeric films at different
temperatures were determined. Packaging films; Low Density Polyethylene (LDPE)
35μm, Polypropylene (PP) 80µm and LDPE micro perforated 31.75μm were used to
store fruits at 4.3°C and 10°C for four weeks and at 26-34°C (ambient) for nine days.
Biochemical analysis of the film-stored fruits for changes in ascorbic acid, total
carotenoids, total phenols, soluble solids and titratable acidity were carried out
before and after storage. Ascorbic acid in the fruits significantly (p<0.05) decreased at
both low (4.3°C and 10°C) and ambient (26-32°C) storage temperatures. Carotenoids
and titratable acidity increased at all the storage temperatures while total phenols
decreased at low temperature but increased at ambient temperature. Soluble solids
generally increased at low temperature but remained stable at ambient temperature.
These results suggest that biochemical changes occur during the storage of chilli
pepper fruits in polymeric films at both low and ambient storage temperatures.
187-192 | JRA | 2013 | Vol 2 | No 2
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www.jagri.info
Journal of Research in
Agriculture
An International Scientific
Research Journal
Authors:
Edusei VO1
and
Ofosu-Anim J.2
Institution:
1. Department of Energy
Systems Engineering, School
of Engineering, Koforidua
Polytechnic. Ghana.
2. Department of Crop
Science, College of
Agriculture and Consumer
Sciences, University of
Ghana.
Corresponding author:
Edusei VO.
Email:
Web Address:
http://www.jagri.info/
documents/AG0050.pdf.
Dates:
Received: 02 Aug 2013 Accepted: 12 Aug 2013 Published: 10 Sep 2013
Article Citation:
Edusei VO and Ofosu-Anim J.
Biochemical changes in green chilli pepper fruits during storage in polymeric films.
Journal of Research in Agriculture (2013) 2(2): 187-192
Original Research
Journal of Research in Agriculture
JournalofResearchinAgriculture An International Scientific Research Journal

2. INTRODUCTION
Peppers are an important source of nutrient in the
human diet as they provide excellent supply of
carotenoids, ascorbic acid and phenolic compounds
which are important antioxidants (Marin et al., 2004).
Antioxidants are beneficial because of their protective
roles against multiple diseases such as cancer, anaemia,
diabetics and cardiovascular diseases. The antioxidants
perform their function by counteracting the oxidizing
effects on lipids by scavenging highly reactive oxygen
free radicals (Perucka and Materska, 2007). Levels of
these beneficial compounds or nutrients can vary by
genotype, growing conditions, maturity, handling and
storage conditions (Howard et al., 2000). Storage
condition has a vital role for the maintenance of the
quality of fruits and vegetables before sale and
consumption. Many compositional changes can occur
during storage of vegetables that influence their
appearance, texture and flavour and nutritional content.
Some changes can be desirable, while others can be
detrimental to the quality of the commodity (Kader,
1986; Maguire et al., 2004). Considerable efforts have
been made to determine changes occurring in the main
constituents during the storage of several agricultural
products and, as a result, significant progress has been
made in assessing and controlling nutritional quality
(Tonelli et al., 1981).
Storage temperature and packaging in polymeric
films are important storage conditions that have been
shown to affect biochemical composition. Ascorbic acid,
chlorophyll, thiamin (vitamin B1), and riboflavin
(vitamin B2) contents in bell peppers, green beans and
spinach have been shown to be affected after storage in
polymeric films at different temperature conditions
(Watada et al., 1987).
The objective of the study is to investigate some
compositional changes (ascorbic acid, total carotenoids,
total phenolic compounds, total soluble solids and
titratable acidity) that occur during the storage of KA2
chilli pepper fruits in polymeric films at different
temperatures.
MATERIALS AND METHODS
Fresh green chilli pepper fruits (KA2) were
obtained at their maturity stage (firm and mature green)
from a commercial farm in the Greater Accra Region of
Ghana and transported to the Food Processing and
Engineering laboratory of the Food Research Institute,
CSIR, Accra. Fruits were selected for the absence of
defects, washed with tap water and then with sodium
hypochlorite solution (150 ppm) for two minutes to
reduce the microbial load. They were then carefully
mopped with tissue paper to dry, weighed (70 g), packed
and sealed in three different types of plastic films as
treatments consisting of (i) Low Density Polyethylene
(LDPE) (18 cm x 20 cm x 35 μm), (ii) Polypropylene
(PP) (17.5 cm x 24 cm x 80 μm) and (iii)
microperforated LDPE (17.5 cm x 24 x 31.75 μm) bags.
Fruits were stored in a refrigerator (AKAI-RF-
ED14SR2G-China) at an average temperature of 4.3°C
and in a climatic chamber (BINDER KBF- GmbH,
Germany) at 10°C for four weeks and also at ambient
temperature (26-34°C) for nine days on a bench under a
shed in a completely randomized resign with three
replications. Data on ascorbic acid content, total
carotenoids, total phenolic compounds soluble solids and
titratable acidity were subjected to analysis of variance
(ANOVA) and means were compared using least
significant difference (LSD) at 5%.
Ascorbic acid
Ascorbic acid content was quantitatively
determined at the beginning and end of the storage
period using 2, 6-dichloroindophenol-dye method
(AOAC, 1990). 0.05 g 2, 6-dichloroindophenol dye was
dissolved in 100 cm3
of distilled water. Standard solution
of ascorbic acid was prepared by dissolving 0.2 g of pure
ascorbic acid in 1000 cm3
of distilled water. The
indophenol solution was titrated against 10 cm3
of the
188 Journal of Research in Agriculture (2013) 2(2): 187-192
Edusei and Ofosu-Anim, 2013

3. standard ascorbic acid solution in a conical flask until the
indophenol dye changed from violet to rose pink and the
average titre value was recorded. Chilli pepper, 10 g
fruit sample, was then macerated in 100 cm3
distilled
water using a commercial blender and filtered. Then
25 cm3
of 20% metaphosphoric acid was added to the
juice for stability and titrated with the standard
2, 6-dichloroindophenol solution until the colour
changed from violet to rose pink and the average titre
value was recorded. Ascorbic acid content of the juice
was determined on equivalent basis as follows:
Total carotenoids total phenolic compounds
The total carotenoids and total phenolic
compounds were determined by the chlorophyll II
determination (US10200H) method (PerkinElmer, Inc.
USA) using PerkinElmer Lamda 850 UV
Spectrophotometer. A one gram sub-sample pepper fruit
was ground using a mortar and pestle and the pigments
were extracted using 50 cm3
of 96% methanol. The
filtrate was sieved into a beaker using a cheese cloth and
the was volume recorded. The filtrate was poured into a
50 cm3
falcon tube and centrifuged at a spin of 2500 rpm
for 10 minutes. Total carotenoids were estimated by
taking the absorbance at 480 nm, 630 nm, 647 nm,
664 nm, 665 nm and 700 nm and expressed as g/100 g
fresh weight equivalent of total carotenoid and total
phenols.
Total Soluble Solids
Total soluble solids were determined before and
after storage by taking representative juice of each
sample onto the glass of a handheld refractometer
(RB 32 Hanna Instruments). The refractometer readings
were recorded from the internal scale through viewing in
the eyepiece at room temperature (Mitcham et al., 1996).
Titratable Acidity
Fifty (50) grams of the pepper fruits were
macerated in 50 cm3
of distilled water and filtered. Ten
(10) cubic centimeters of the juice were diluted with
100 cm3
of distilled water and titrated against
0.1MNaOH using phenolphthalein as indicator. The
volume (in cubic centimeters) of NaOH required was
used to calculate the Titratable acidity (TA). The TA was
expressed as percent citric acid and was calculated as
follows:
[Acid milliequivalent (meq) factor for the predominant
organic acid (citric) in pepper fruit] (Mitcham et al.,
1996)
RESULTS AND DISCUSSION
Ascorbic acid
In general, there were decreases in ascorbic acid
(AsA) content at all storage temperatures compared to
the initial ascorbic acid content (Tables 1 and 2). The
decrease was significantly (p<0.05) low in fruits packed
in polyethylene (PE) film at 10°C than at 4.3°C. There
were 4% reduction at 4.3°C and 56% loss at 10°C after
28 days of storage in the PE packed fruits (Table 1). At
ambient (26-34°C) storage temperature, there was 24%
average reduction in AsA content after nine days of
storage with the fruits in microperforated film having
significantly (p<0.05) low reduction in As levels.
(Table 2). Adisa (1986) observed that, fruits and
vegetables generally show a gradual decrease in AsA
content as the storage temperature or duration increases.
Wang (1977) also reported that storage for six days in
CO2-enriched atmospheres resulted in a reduction in AsA
content of sweet pepper kept at 13°C. Therefore, the
reduced O2 level coupled with the elevated CO2 level as
a result of passive modified atmosphere in the packaging
films might have caused the reduction in AsA content.
Lee and Kader, (2000) suggested that temperature
management after harvest is an important factor to retain
the vitamin C (ascorbic acid) content of fruits and
vegetables and AsA losses increase at high temperatures
and with long storage periods.
Journal of Research in Agriculture (2013) 2(2): 187-192 189
Edusei and Ofosu-Anim, 2013
TA= ml NaOH x M (NaOH) x acid meq. Factor x 100
Average Titre value of pure Ascorbic Acid Weight of pure Ascorbic Acid
Weight of Ascorbic Acid in Fresh Pepper Average Titre value of Pepper juice
=

4. Total carotenoids
Generally, there was increase in total carotenoids
at the end of the storage periods. The average total
carotenoids in the film-packed chilli pepper fruits
recorded 15% and 21% increase at 4.3°C and 10°C
respectively (Table 1), while that at ambient (26-34°C)
storage temperature increased by 7.5% (Table 2).
Carotenoid biosynthesis or chlorophyll degradation can
cause the disappearance of chlorophylls and the
appearance of carotenoids leading to increased
accumulation or increased appearance of carotenoids.
Carrillo-Lopez and Yahia (2009), reported that content
of some carotenoids can increase from zero to high levels
in a few days as a consequence of maturation and
ripening. Adequate modified atmospheres (MA) and
controlled atmospheres (CA), especially atmospheres
with low concentrations of oxygen, are known to
maintain carotenoids and reduce their losses (Yahia,
2009).
Total phenols
The average total phenols in the film-packed
fruits decreased at 4.3°C and 10°C after 28 days while
there was slight increase at 26-34°C after 9 days (Tables
1 and 2). The synthesis of phenolic compounds occurs
during storage (Yang et al., 2011). However, when the
storage time is prolonged, the oxidization of phenolic
compounds becomes the major trend and phenolic
compounds decrease in cell (Yang et al., 2011, Toor and
Savage, 2006). A decrease of polyphenols were observed
in bell pepper, in which about 50% of polyphenols were
lost after 30 days of storage at 3°C (Fratianni et al.,
2010).
Total soluble solids
Total soluble solids (TSS) increased in the film-
packed chilli pepper fruit at low temperature (4.3°C and
10°C) Polypropylene packed fruits at 10°C had
significantly (p<0.05) high TSS. However the levels
remained stable at ambient (26-34°C) temperature
190 Journal of Research in Agriculture (2013) 2(2): 187-192
Edusei and Ofosu-Anim, 2013
Table 2. Changes in ascorbic acid, total carotenoids, total phenols, total soluble solids and titratable
acidity in polymeric film-stored chilli pepper fruits after 9 days at 26-34°C
Storage
Condition
Ascorbic Acid
(mg/100gFW)
Total carotenoids
(g/100gFW)
Total phenols
(g/100gFW)
Total Soluble Solids
(%Brix)
Titratable acidity
(%)
Initial 6.9 0.074 0.029 2.0 0.78
26-34°C(Ambient)
PE 5.2 0.077 0.031 2.0 1.19
PP 4.8 0.094 0.038 2.0 1.07
MP 5.8 0.079 0.032 2.0 1.12
LSD(0.05) 0.1 0.001 0.001 - 0.05
PE, PP and MP represent polyethylene, polypropylene and microperforated polyethylene films, respectively
Table 1. Changes in ascorbic acid, total carotenoids and total phenols, soluble solute and titratable acidity in
polymeric film-stored chilli pepper fruits after 28 days at 4.3°C and 10°C.
Storage
Condition
Ascorbic Acid
(mg/100gFW)
Total carotenoids
(g/100gFW)
Total phenols
(g/100gFW)
Total Soluble Solids
(%Brix)
Titratable acidity
(%)
Initial 5.0 0.060 0.036 2.0 0.73
4.3°C
PE 4.8 0.085 0.034 2.8 1.21
PP 3.6 0.073 0.031 2.4 1.08
MP 3.2 0.051 0.022 3.0 1.45
10°C
PE 2.2 0.055 0.022 2.2 1.15
PP 4.8 0.072 0.042 3.2 1.12
MP 4.1 0.092 0.035 1.9 0.89
LSD(0.05) 0.1 0.000 0.000 0.1 0.01
PE, PP and MP represent polyethylene, polypropylene and microperforated polyethylene films, respectively

5. (Tables 1 and 2).Gonzalez-Aguilar and Tiznado (1993),
Ozden and Bayindirli (2002) have investigated changes
in TSS that occur during the storage of pepper and
observed increases.
Titratable acidity
Titratable acidity (TA) increased at the end of
storage period at both low and ambient temperatures
(Tables 1 and 2). Kays (1997) has observed that TA is
closely linked to the level of organic acids in fruits and
vegetables as organic acids exist as free acids, anions
(malate), combined as salt (potassium bitartarte) and
esters such as isopentyle acetate. Sourness is determined
by the concentrations of the predominant organic acids.
Fruits and vegetables with very low levels of organic
acids may therefore lack characteristic flavour (taste)
(Kader, 2008).
CONCLUSION
Storage of chilli pepper fruits in polymeric films
at low temperatures (4.3°C and 10°C) resulted in
increased levels of total carotenoids, total soluble solids
and titratable acidity while ascorbic acid and total phenol
levels slightly decreased. At ambient (26-34°C) storage
temperature there were increase in total carotenoids, total
phenols and titratable acidity. However, levels of
ascorbic acid and total phenols slightly decreased while
soluble solids remained stable in the chilli pepper fruits.
These results suggest that biochemical changes occur
during the storage of chilli pepper fruits in polymeric
films at both low and ambient storage temperatures.
Efforts can therefore be targeted at postharvest
management techniques that assure biochemical and for
that matter nutritional stability particularly in ascorbic
acid and in effect maintain the quality of the fruits.
ACKNOWLEDGEMENTS
The authors wish to thank Mr. Singh of Poly
Products Ghana Ltd and Dr. Mark Opoku-Adusei for
assistance in obtaining polypropylene and
microperforated polyethylene films respectively.
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