726 in Biosciences 7(9): 726-728, 2014
Trends
Trends in Biosciences 7 (9), 2014
Changes in Colour Value of Banana var. Grand Naine during Ripening
S.SHAHIR1 AND R.VISVANATHAN2
1
Department of Food and Agricultural Process Engineering
Post Harvest Technology Centre
Tamil Nadu Agricultural University, Coimbatore, India
email : [email protected]
2
ABSTRACT
Colour development is an important feature during ripening
which is used in determining the quality of fruit for marketing.
The peel colour is also been used to characterize the state of
ripeness of banana fruit. Moreover most retailers ask for
fruit at yellow colour. Hence it is important to quantify the
yellow colour developed during ripening. The maximum ‘L’
and ‘b’ value was found to 74.25 and 51.11 respectively on 4th
day. And decrease in both the values thereafter. This confirms
that the banana treated with ethylene gas attains the maximum
yellow colour on 4th day. The colour developed during ripening
was judged as more homogeneous.
Key words
Banana, Ripening, Ethylene, Colour values.
Fruits are classified as either climacteric or nonclimacteric based on the pattern of respiration and ethylene
biosynthesis during ripening. For climacteric fruits, the
respiration rate and ethylene formation are minimum at
maturity and raise dramatically to a climacteric peak, at the
onset of ripening, after which it declines (Tucker and
Grierson, 1987). Examples are banana, mango, sapota,
guava, etc.
Banana is chiefly eaten raw as a dessert fruit, because
in the ripe stage it is sweet and easily digestible. Kader,
1997 reported that ripening is the composite processes that
occur from the later stages of growth and development
through the early stages of senescence and that result in
characteristic aesthetic and/or food quality, as evidenced
by changes in composition, colour and texture or other
sensory attributes.
Von Loesecke, 1950 described the different stages of
ripening which relate to pigment changes within the peel
of banana. The visual descriptions for the different stages
are
(i) Green, (ii) Green with trace of yellow, (iii) Green
and yellow both occur, (iv) Yellow with trace of green, (v)
Green tip, i.e., when the fruit is full yellow except at the
extreme flower end (vi) Completely yellow colour (vii) Full
ripe, i.e., clear yellow with signs of dark marking (Flecking),
(viii) Flecked, i.e., markings well developed (blackening)
During ripening, colour development depends on
external conditions and is an important factor in determining
the quality of fruit for marketing (Hewage, et al., 1996;
Marriott and Palmer, 1980). Fruits undergo significant
textural and colour transformation as they pass through
ripening process. Generally, the colour conversion is from
dark green to pale green and then to slight yellow or orange
colour from unripe to ripe stage. The colour of banana
changes from green to yellow. This is due to chlorophyll
degradation, which subsequently reveals the yellow
carotenoid pigments (Marriott and Lancaster, 1983;
Seymour, et al., 1993; Stover and Simmonds, 1987). The
stage of colouration is an excellent indicator of the probable
composition of banana fruit. Lightness (‘L’) value,
greenness (‘a’) value and yellowness (‘b’) value was a
useful approach to determine the development of peel colour
of banana and could be a useful replacement of subjective
method of colour charts (Kajuna, 1998). Collin and Dalnic,
1991; Li, et al., 1997 reported that the colour of the peel
has often used as a rapid measurement to characterize the
state of ripeness of banana fruit. The most retailers prefer
fruit at yellow colour (Madrid and Lopez-Lee, 1996). It is
important to study the changes in colour value during the
ripening process and hence the objective is framed to study
the change in ‘L’, ‘a’ and ‘b’ values for banana var. Grand
Nine.
MATERIALS AND METHODS
The present study was conducted using Grand Naine
variety of banana. Bunches of banana fruits at full three
quarter grade, which means they were almost fully grown,
were harvested from the Orchard, Horticultural College
and Research Institute, Tamil Nadu Agricultural University,
Coimbatore. The bruised and diseased fruits were sorted
out manually. Only healthy and uniform sized fruits were
selected for the study. Mature and firm fruits were washed
in tap water to remove the latex, soil particles, floral remains
and other physical impurities. Then it was shade dried until
the surface moisture got evaporated.
Ripening of fruits:
The procedure involved in the ripening of fruits is
presented in Figure 1.
SHAHIR AND R.VISVANATHAN , et al., Changes in Colour Value of Banana var. Grand Naine during Ripening
727
A known weight (approximately 5 kg) of freshly
harvested unripe cleaned fruits was carefully placed on the
tray such that there was no superimposition of fruits. The
mass and volume of fruits and free volume left in the
chamber were recorded. Known quantity of ethrel and
NaOH was mixed to produce desired level of ethylene gas.
Banana fruits were exposed to ethylene concentration of
100 ppm for 24 h in a cooling chamber maintained at 20°C
and 95 per cent relative humidity. Change in colour values
were observed during the ripening process daily.
Colour is calibrated by fixing the defined colours like
white and black tiles on the colour flex meter. Calibration
is performed through necessary changes in the sample.
The skin of the fruit was peeled off and it was placed on
the colour flex meter and it was then covered with a black
cylindrical cup to prevent the reflection of light.
Measurement of colour was done as per the above principle
by determining ‘L’, ‘a’ and ‘b’ values.
Harvesting of fruits
Changes in colour values (‘L’, ‘a’, ‘b’) during
ripening for the period of seven days were presented in
Fig.2. It can be observed from the Fig.2, that the lightness
value (‘L’ value) and yellowness (‘b’ value) increased
during the ripening for the period of seven days. This might
be due to the chlorophyll degradation, which subsequently
reveals the yellow carotenoid pigments (Marriott and
Lancaster, 1983; Seymour, et al., 1993; Stover and
Simmonds, 1987). Lightness and yellowness value
increased up to the 4th day and then it starts decreasing.
Cleaning
Checking the maturity indices
RESULT AND DISCUSSION
Ethylene treatment
Ripening
Ripened fruits
Fig. 1. Process flow chart for ripening of fruits
Colour measurements:
Colour flex meter (Model: 45o/0o, M/s Hunter Lab,
Reston, Virginia, USA) was used for the measurement of
colour. It works on the principle of collecting the light and
measures energy from the sample reflected across the entire
visible spectrum. The meter uses filters and the
mathematical models rely on “standard observer curves”
that define the amount of red, green, and blue primary lights
required to match a series of colours across the visible
spectrum. The mathematical model used is called as Hunter
model. It provides reading in terms of L, a, and b. where L
indicates whiteness and darkness. Chromatic portion of
the solids is defined by: a (red), -a (green), b (yellow), and
-b (blue). These data may be sensed from the sensor (colour
flex 45o/0o ) and it is supported with Universal Software
(V4.10) software package. It produces functions that
define hue and chroma. “L, “a and “b value represents the
deviations of the individual values of the raw sample from
the respective values of the fully ripe sample.
Fig. 2. Changes in lightness (‘L’), greenness (‘a’) and
yellowness (‘b’) value during ripening of banana
fruit
This might be due to the development of brown flecks
over the peel which leads to the reduction of ‘L’ and ‘b’
values. Yellowness value follows the same trend as that of
the lightness value. Similar results of yellow colour
development on 4th day and later brown spots were observed
by Salvador, et al., 2007 on ripening the banana fruits. The
greenness value of banana fruit increased from negative
side to positive side. This confirms the de-greening of
banana peel. Similar results were reported by Boudhrioua,
et al., 2002 for banana fruits ripened at 20oC, the greenness
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Trends in Biosciences 7 (9), 2014
value was also increased rapidly during the ripening period.
A steep raise in total colour difference value of 18.92 was
observed on 3rd day of ripening.
LITERATURE CITED
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Collin, M.N. and Dalnic, R. 1991. Evolution de quelques critères
physico-chimiques de la banane plantain (cultivar Orishele) au
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Hewage, K., Wainwright, H. and Wijeratnam, R. 1996. Quantitative
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Fig. 3. Changes in total colour difference value during
ripening of banana fruit
value ‘a’ increased rapidly from –10 ± 3 (green) to 5 ± 2
(red).
Total colour difference is the measure of deviation of
individual colour values. From the Fig.3 it is observed that
the total colour difference increase steeply up to 3rd day
and starts decreasing on the 4th day. This indicates the less
deviation in colour value after third day of ripening of banana
fruit. This might be due to the increasing ‘L’ value up to
the 4th day of ripening. From 4th to 5th day, the lightness and
the yellowness value starts decreasing due to the formation
of brown flecks over the peel. This reflects in the total
colour difference value as decreasing trend from 3rd to 4th
day (Fig.3). These changes during ripening period (loss of
greenness, increase in redness and yellowness) occurred
as a result of the breakdown of the chlorophyll in the peel.
Similar results were reported for banana ripening at different
temperatures for different storage period by Chen and
Ramaswamy, 2002.
The change in colour value was observed when the
banana fruits are treated with ethylene gas. During ripening,
the maximum ‘L’ and ‘b’ value of 74.25 and 51.11
respectively was obtained on 4th day of ripening. Greenness
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Recieved on 18-03-2014
Accepted on 28-03-2014