Seasonal variations in peel colour in relation to fruit development of grapefruit (Citrus paradisi Macf.)

Table 1 Peel Colour properties (L*, a*, b*, C* and h0) of grapefruit at different periods of fruit development.

Days After Fruit

L*

a*

b*

Chroma (C*)

Hue angle (h°)

Set (DAFS)

90

44.32±1.09c

-6.53±0.00e

19.67±0.39d

20.73±0.37e

108.39±0.33a

120

49.40±0.81b

-6.12±0.80e

22.88±0.39c

23.70±0.59d

104.89±1.63a

150

50.02±0.38b

0.24±0.04d

24.69±0.02b

24.69±0.02d

89.29±0.08b

180

55.12±0.65a

10.95±1.21c

25.27±0.41b

27.57±0.82c

66.71±2.02c

210

56.94±0.73a

14.93±1.27b

28.91±0.94a

32.56±1.39b

62.81±1.32d

240

57.20±0.28a

20.82±0.09a

28.69±0.64a

35.45±0.57a

53.99±0.52e

LSD (0.05)

2.45

2.67

1.76

2.33

3.74

CV (%)

9.42

189.99

13.59

19.59

26.80

LSD indicates the least significant difference test at p<0.05. Values are means ± SE and with a common letter are not

significantly different at 5% level. CV indicates coefficient of variation.

Fruit colour parameters (L*, a*, b*, C* and h°)

(positive) values, although masked at the beginning

Changes in colour are an important factor which

by the green colour of chlorophylls (coordinate a*)

determines the fruit quality (Kaur et al. , 2013). Use

and continued to increase until the mid of November

of Hunter Lab is non destructive determination of

at 210 DAFS and showed yellowish tinge. The loss of

fruit colour for reliable harvest index in grapefruit.

green colour with advancement of fruit maturation

A gradual change in fruit colour from dark green to

mayȱbeȱattributedȱtoȱdecreasedȱchlorophyllȱcontentȱ

pinkish-yellow was observed with the advancement

as reported by Deka et al. , (2006) in Khasi mandarin

of maturity towards ripening. The change in skin

and Ram et al. , (2005) in Kinnow mandarin. A non-

colour towards fruit maturation is shown by the

significantȱchangesȱaboutȱtheȱvalueȱofȱL*ȱfromȱ180-

overallȱsignificantȱincreasesȱinȱtheȱL*,ȱa*,ȱb*,ȱC*ȱandȱ

240 DAFS and from 210-240 DAFS for the value of

decreases in hue angle (h°) values of fruit peel (Table

b*ȱwasȱobserved.ȱButȱa*ȱvalueȱchangedȱsignificantlyȱ

1). The greater change in rind colour of fruit was

with season till the last date of sampling at 240 DAFS.

observed from 90 DAFS to 180 DAFS for values of

Similar results observed by Rosalizan et al. , (2010) in

L*(44.32±1.09 to 55.12±0.65), a*(-6.53±0 to 10.95±1.21)

Morinda citrifolia.

and b*(19.67±0.34 to 25.27±0.41). Thereafter, a

The chroma values (C*) were increased from

complete colour development stage was noticed at

minimum of 20.73±0.37 at 90 DAFS to the maximum

210 DAFS with values of L*, a* and b* were recorded

value of 35.45±0.57 at 240 DAFS. Similarly, the other

56.94±0.73, 14.93±1.27 and 28.91±0.94, respectively.

important colour parameter in grapefruit is hue

The increase in a* coordinate, which represents the

angle,ȱwhichȱisȱtheȱattributeȱofȱperceivedȱcolour.ȱItȱ

gradual loss of greenness and appearance of pinkish-

was recorded that the hue angle values decreased

yellow tinge on fruits during mid November at 210

continuously from 90 DAFS to the maturity of fruit

DAFS. Similar results were recorded by Machado

at 240 DAFS and the colour of the fruit was recorded

et al. , (2011) in grapefruit, who reported that peel

between yellow to red region in a colour wheel of

colour varied from yellow to pinkish. Calorimetric

360°. Similarly in Mosambi, Ladaniya and Mohalle

coordinate b* always remained within yellow

(2011) reported that hue angle (h°) declined with

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