1. The study developed a color grade chart to classify the ripening stages of two mango varieties, Alphonso and Banganapalli, based on measurements of physio-chemical, internal and external color values, and textural characteristics throughout the ripening period. 2. Principal component analysis and hierarchical clustering classified the ripening period into five stages: unripe, early ripe, partially ripe, ripe, and overripe. 3. The color grade chart provides images and quality parameter values for each ripening stage, to allow non-destructive grading of mangoes for packing and processing industries.

1. Amirtha Ganesh P
Anantharaman G
Madan B
Tarun Kumar S
1

2.  Ripening period of mangoes into different stages
 To develop a colour grade chart for Indian Mangoes
 The Physio-chemical, Internal and External colour values and
textual characteristics were measured throughout the
ripening period of two varieties.
 Alphonso
 Banganapalli
 PCA along with Hierarchical clustering method were used and
the ripening period of mango fruits was classified into five
stages.
 Unripe
 early ripe
 partially ripe
 ripe
 over ripe
2

3.  A colour grade sheet was developed based on these stages
along with the physico-chemical, textural and color values of
both varities.
 The developed colour chart can be used as a useful rapid,
non-destructive grading tool at mango pack houses and
processing industries.
3

4.  Mango is an important tropical fruit having a worldwide
demand, India ranking first in production with 54.2%
contribution producing 14-16 million tonne yearly.
 The Indian varities, known for its strong aroma, intense peel
coloration, delicious taste and high nutritious value, are
 Alphonso
 Kesar
 Totapuri
 Banganapalli
 Dussehari
 Neelum
 Mangoes, being climacteric fruits, their ripening process
takes place immediately after harvest.
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5.  Mango pack houses require an easy
nondestructive tool to grade the fruits based
on ripening before packaging. The pulping
industry needs it to select the fruits at an
optimum ripening stage to get desired pulp
characteristics.
 The colour grade chart would fulfil the above
purposes, but at the same time it should
contain information about the quality
parameters like physico-chemical properties
and textural properties
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6.  These kind of colour charts were developed
purely based on the external appearance,
the internal changes were not considered
and moreover scientific way of classification
had not been employed.
 Hence the study was carried out with the
objective of classifying the ripening period
into different stages and develop a colour
grade chart for Alphonso and Banganapalli
mangoes.
6

7.  Mangoes were treated with ethylene for 24 h
and allowed for ripening. The quality factors
viz. TSS, external & internal colour values,
titrable acidity and textural parameters were
measured throughout the ripening period.
 These measured parameters were analysed
for its significance and PCA was used to
predict the total variability. Then the
ripening period was classified into five stages
with hierarchal clustering method.
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8. 1. Mango sample collection and preparation
2. Physicochemical properties
3. Textural and colour measurement
4. Statistical analysis
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9.  Raw Alphonso and Banganapalli mangoes were
collected from two different locations viz.
Krishnagiri at 20 days intervals.
 The mangoes after washing and shade drying for
30 min were treated with ethylene at 200 ppm
for 24 h at 20◦ C with 85 percent Relative
Humidity in the ripening chamber.
 After the treatment, the chamber was opened
to exude ethylene and the treated mangoes
were kept in the for regular analysis.
9

10.  Two batches of mangoes were made, one set for
imaging and another one for physico-chemical
analysis.
 From the second set, three fruits from each
varieties were taken randomly for
physiochemical analysis every day.
 The experiments were continued till the decay
of fruit. The decay stage was decided by visual
inspection when 50 percent of available fruits
for analysis reached the spoilage.
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11.  Homogenized mango pulp was obtained with
laboratory mixer to determine
1. Total Souble Solid (TSS)
2. Titrable Acidity.
 TSS was measured using a digital
refractometer and expressed as ◦Brix .
 Titrable Acidity was determined by titration
with 0.1 N NaOH and it was expressed as
grams citric acid equivalent/100g sample
(average considered).
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12.  The textural characteristics of the mangoes
were measured using the Texture - 4 mm
cylindrical probe(P/4) was used with 1 mm
s−1 pre-test speed, 0.1 mm s−1 test speed, 1
mm s−1 post-test speed, and 10 mm
penetration depth to obtain force
displacement curve.
12

13.  The maximum force required to pierce the peel
is called as peel strength(pointB).
 The slope between A and B point is called as
stiffness of the fruit.
 The mean force between C and D point is called
as flesh firmness.
 Textural values were measured at three points in
a mango and the average value was used.
 Colour coordinates were recorded both for
external and internal surface of the mango using
a Hunter LAB colour meter. The internal colour
was measured by cutting the fruit into two
halves along with the vertical axis.
13

14.  Initially anova was carried out to check the variability between
zones.
 Then all the observed data were analyzed with Pearson
correlation to find out the correlation between variables.
 Then PCA was carried outto predictthe variability. Since all the
observed data were describing variables and no predicting
variable was involved, cluster analysis would be more suitable
rather than PLS or discriminant analysis.
 Kaur and Kaur (2013) reported that hierarchical clustering could
be more suitable and efficient than K-means clustering for small
dataset and ripening might be explained better by hierarchical
clustering.
 Hence hierarchical clustering analysis using ward method was
carried out in order to group the whole data into 5 stages of
ripening.
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15.  Ripening process was faster in Alphonso and has researched
the decay stage on 19th day and Baganapalli on 23rd day
due to physiological variations between two varieties.
 The Anova result showed that, the changes in physico-
chemical, textural and colour properties between the
samples collected from two zones were highly non-
significant (P > 0.40) during ripening.
 It can be perceived that 75 percent of ripening had
reached within 10 days and contributed to the major
changes in all quality parameters.
 Thus the remaining ripening period did not have
significant influence on most of the physic-chemical and
textural properties.
15

16.  Changes in total soluble solids and titrable acidity of Alphonso and
Banganapalli is shown in the Fig. 2. Total soluble solids(TSS) was linearly
increasing up to 9th day from 7.7 ± 0.8 to 19.3 ± 0.1 ◦Brix and 7.5 ± 0.3
to 16.5 ± 0.2 ◦Brix for Alphonso and Banganapalli respectively.
 An increase of TSS could mainly be due to hydrolysis of starch into
soluble sugars such as sucrose, glucose and. After 9th day, only slight
variations were observed in TSS in both the fruit varieties, and Alphonso
had a TSS of 21.1 ◦Brix on 19th day and Banganapalli had 15.8 ◦Brix on
the 23rd day of ripening.
 Unlike TSS, titrable acidity (TA) was decreasing up to 16th day and after
that no significant change was observed in case of Alphonso.
 At the same time, decreasing trend was observed till decay in
Banganapalli.
 The rate of change in TA was observed to be higher for Alphonso than
Ban ganapalli.
 This might be due to physiological variation between varieties. The
titrable acidity of raw and fully ripened Alphonso was 0.019 ± 0.003 and
0.003 g/100 g of sample respectively and for Banganapallithe acidity
values were 0.007 ± 0.003 and 0.001 g/100 g of sample, respectively.
16

17. 17

18.  During ripening, the external colour of raw mango turned from
green to reddish yellow, which increased all hunter colour
coordinates(Le *,ae *,be *) during ripening.
 This was due to chlorophyll degradation, which subsequently
revealed the yellow carotenoid pigments.
 The changes in internal and external colour values are shown in
Fig. 3 and 4. Le * value increased from 49.21 ± 1.4 to 64.55 ±
0.86 and 51.70 ± 2.15 to 70.51 ± 2.75 for Alphonso and
Banganapalli respectively. ae * value increased from −9.8 ± 1.07
to 29.07 ± 0.83 and −10.95 ± 2.35 to 16.45 ± 2.40 while be *
increased from 32.46 ± 0.82 to 62.150 ± 1.38 and 27.74 ± 3.95 to
48.81 ± 4.12 for Alphonso and Banganapalli respectively.
 Lightness value, Li * for the inner surfaces of mango was
decreasing due to the internal colour turning from white to
yellow. But both internal ai * and bi * values followed the same
trend with the external a* and b* values. Li * value decreased
from 76.96 ± 1.48 to 56.38 ± 4.47 and from 91.24 ± 1.67 to 73.28
± 2.94 forAlphonso and Banganapalli respectively.
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19. 19

20. 20

21.  The typical force displacement curve
obtained for the mangoes is shown.
 Decreasing trend was found in all the three
parameters during ripening in both varieties.
Many researchers have reported about
reduction in fruit firmness for different
fruits.
 The reduction in fruit firmness was due to
alteration in cell wall structure by degrading
enzymes (e.g. polyglacteronase) and also by
degradation of starch and breakdown of
starch, cellulose and hemicellulose.
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22. 22

23.  During the first week of ripening, drastic
reduction was observed in all the three
parametersThe rate of decrease in the peel
strength, fruit stiffness and flesh firmness
reduced after 8th day. All these changes
substantiate that 75 percent of ripening
occurs within the 10 days.
 The maximum and minimum peel strength of
raw and ripened mango were 64.75 ± 3.72 N
and 5.79 ± 0.72 N for Alphonso and 70.72 ±
3.21 N and 6.82 ± 1.07 N for Banganapalli
respectively.
23

24.  The raw fruit had the higher stiffness of
18.56 ± 1.25 N and 14.65 ± 1.547 N and lower
stiffness were 1.18 ± 0.03 N and 2.05 ± 0.21
N for Alphonso and Banganapalli respectively.
 Significant difference in flesh firmness
between varieties were observed initially and
the values were 28.63 ± 0.97 N and 22.06 ±
1.12 N for Alphonso and Banganapalli
respectively. The final flesh firmness was
recorded as 0.87 ± 0.24 N and 0.83 ± 0.13 N
for Alphonso and Banganapalli respectively.
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25. 25

26.  The Pearson correlation matrix of quality parameters for
Alphonso and Banganapalli is given in Table 1 and 2.
Correlation behavior was found as similar for both
varieties.
 Le ∗ value had a high positive correlation(r > 0.90) with ae
∗, be * and TSS values and high negative correlation(r > −
0.90) with the textural characteristics.
 ae ∗ value had a high positive correlation(r > 0.90) with be
*, TSS and internal colour coordinates(ai *,bi *) and high
negative correlation(r > −0.90) with Li *, acidity and
textural properties.
 Except Li * the rest of the colour coordinates had shown
positive correlation between each other. From these
observations, it could be concluded that colour
coordinates and TSS were inversely correlated with
textural characteristics and acidity for Alphonso than
Banganapalli.
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27. 27

28.  The total variations occurring during the
ripening period are explained in the PCA
score graph and the variation between the
variables are shown in the PCA loading. PC1
represent 92 percent and 95 percent, PC2
represent 5 percent and 2 percent of total
variations occurring during ripening of
Alphonso and Banganapalli respectively.
 From the PCA loading graph, it could be
noticed that the peel strength can be
explained better by PC1 than PC2 and on the
contrary PC2 explains more about the colour
values ae *, be *.
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29.  Changes in acidity during ripening had
followed the same pattern in both varieties
and PC1 is sufficient to explain variation. It
was found that the changes in the textural
characteristics could be explained more with
PC1. But both PC1 and PC2 had an important
role to explain the total variation in internal
and external colour values since they were
dispersed over the PCA plot.
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30.  It was found that principal component and
hierarchical cluster analysis were capable of
differentiating radish slices to select hurdle
technologies. From the cluster analysis the
ripening period was grouped into five
clusters, encircled and denoted in alphapates
.Those five clusters represent five stages viz.
unripe, early ripe, partially ripe, ripe, over
ripe/decay during ripening.
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31.  The firsttwo stages can be grouped as pre-
climacteric phase, the second two stages as
climacteric and the last stage as senescence
phase. In case of Alphonso,firstfour days were
grouped to befirst stage,then5thand 6th days as
2nd stage, then 7th to 11th day as third stage,
then 12th to 17th day as fourth stage and finally
the 18th & 19th day as fifth stage.
 In case of Banganapalli, first six days were
grouped as first stage, then 7th and 8th days as
2nd stage, then 9th to 12th day as third stage
followed by fourth stage lied between 13th to
18th day and finally 19th to 23rd day as fifth
stage.
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32.  Clear differences between clusters were observed
(Fig. 6a)inAlphonso and it substantiates the distinct
changes in physic-chemical parameters in phased
manner during ripening. At the same time no clear
demarcation between the stages could be found in
Banganapalli(Fig. 7a).
 This may be due to the fluctuation in the changes in
physico-chemical parameters during ripening. In both
varieties,the second stage existed too short stint(only
for two days). The decay or over ripen stage existed
for a short period for Alphonso and it existed for 5
days for Banganapalli. This may be due to slow
ripening and physiological variation between the
varieties.
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33. 33

34. 34

35. 35

36. 36

37. 37

38. 38

39.  The colour grade chart was developed with a
comprehensive scientific approach using internal
as well as external quality parameters.
 The colour grade chart was prepared with five
ripening stages and is shown in for Alphonso and
Banganapalli based on the five clusters.
 These five stages were named as unripe, early
ripe, partially ripe, ripe and over ripe or decay
and categorized into three phases viz. pre-
climacteric, climacteric and senescence.
39

40. 40

41.  Images of mangoes of each stage were given in
colour chart along with the corresponding
ripening period.
 In addition to this information, Internal and
external quality parameters for the
corresponding ripening stage were given.
 This colour grade chart may be used as a
reference for quick classification based on the
external colour appearance of mango fruits in
the mango pack houses.
 For the export of fresh whole mango, the first
and second stage would be more suitable for
long and short distance respectively. For the
pulping industry, the fourth stage would be most
suitable to get good quality finished product.
41

42. 42

43. 43

44.  Scientific way of classification of the ripening
period of Indian mangoes into different stages
were carried out for the mango varieties viz.
Alphonso and Banganapalli.
 The colour grade charts were developed and the
entire ripening period were classified into five
stages viz. unripe, early ripe, partially ripe, ripe,
over ripe/decay using PCA and hierarchical
cluster analysis.
 The optimum stage suggested for fresh produce
packaging is stage 1 and 2 and for pulping is
stage 4.
44

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Starch breakdown and changes in amylase activity
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bananas. Acta Hortic. 269, 133–140. Anonymous.
2014. DGCIS annaul .
2. Boudhrioua, N., Giampaoli, P., Bonazzi, C., 2003.
Changes in aromatic components of banana during
ripening and air-drying. LWT-Food Sci. Technol. 36,
633–642. Boudhrioua, N., Michon, C., Cuvelier, G.,
Bonazzi, C., 2002. Influence of ripeness and air
temperature on changes in banana texture during
drying. J. Food Eng. 55, 115–121.
3. Camps, C., 2010. Non destructive measurement of
tomato quality by portable near infrared
spectroscopy. [French]. Revue Suisse de Viticulture.
Arboricult. et Horticult. 42, 298–303
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