=Paper=
{{Paper
|id=Vol-1498/HAICTA_2015_paper68
|storemode=property
|title=Tomato Fruit (Lycopersicum esculentum Mill) Maturity Study Based on Sensorial Analysis and Instrumented Color Determination
|pdfUrl=https://ceur-ws.org/Vol-1498/HAICTA_2015_paper68.pdf
|volume=Vol-1498
|dblpUrl=https://dblp.org/rec/conf/haicta/AlmeidaF15
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==Tomato Fruit (Lycopersicum esculentum Mill) Maturity Study Based on Sensorial Analysis and Instrumented Color Determination==
https://ceur-ws.org/Vol-1498/HAICTA_2015_paper68.pdf
Tomato Fruit (Lycopersicum esculentum Mill) Maturity
Study Based on Sensorial Analysis and Instrumented
Color Determination
Celina de Almeida1, Inacio Maria Dal Fabbro2
1
PhD Eng, Consulting Engineer, Campinas, SP, Brazil, e-mail: celinalmeida@yahoo.com.br
2
PhD Eng, Professor, Faculty of Agricultural Engineering, State University of Campinas,
Campinas, SP, Brazil, e-mail: jinacio@feagri.unicamp.br
Abstract. Table tomatoes (Lycopersicum esculentum Mill) have been tested
during maturation process by carrying color determination by means of
instruments as well as trough sensorial analysis, aiming to stablish data
correlation between both methods. Recent picked testing fruits were selected
by taking into account an uniform physiological maturation considered
adequate for harvesting. Fruits were presented to a group of trained volunteers
and employing a non-structured scale. Instrumental readings were carried by
means of a “Macbeth” HUNTERLab equipment at five points selected on the
transversal fruit axis. Sensorial color determination did not present significant
difference (p ≤0.05) between the days 1, 3 and 5; 5 and 8; 10 and 12; and 12,
15, 17 and 19, however differences were noted between these groups. The
fruits showed moderated characteristic colors between the 10th and 12th day
and very characteristic colors from the 12th.
Keywords: Tomato fruits, fruit color, fruit maturation, sensorial analysis,
instrumental color determination.
1 Introduction
Tomato is considered the horticultural crop of major worldwide commercial interest.
As reported by the FAO (2014), world consumption of tomato in natura guarantees
the second place of importance. Tomato is cultivated in different zones of Brazil, in
all the seasons as well as in a variety of crop handling systems. These details promote
a high production, placing the country among the bigest tomato producers in the
world, as China, USA, Italy, Turkey, Spain, Egypt and Mexico (Cardoso et al 2010).
The total área devolted to tomato crop in Brazil reaches 66.418 hectares which
produces 4,146,466 metric tons a year, yielding 62.616 kg/ha. IBGE (2012 ).
Tomato is a climacteric and perishable fruit which requires adequate storage
conditions in order to delay ripening process, to minimize losses as well as to
increase shelf life (Brackmann et al., 2007). Only fruits meeting expected qualities by
the consumers will be considered for commercialization. Color is an important
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quality attribute which is close associated to maturity and together with shape, size,
firmness, bruising and defects will support consumer selection.
Fruit color perception is associated to some characteristics as the combination of
certain pigments. Small changes of fruit color are connected to certain factors as
maturity, exposition to radiant energy, size, burning, tanning, etc Little (1973).
As reported by Nickerson, apud Lozano (1977), color can be determined through
an appropriate system based on tonality, luminosity and on the chromaticity of our
sensations. Instead of describing them, MUNSELL developed a system which
stablished the three color dimensions and measuring each one of them by referring to
an appropriate scale.
As reported by Setser (1984), due to variation, the surface characteristics have to
be standardized before submission to color determining instrument. In case of non-
homogeneous distribution, the readings should be repeated in order to increase the
data reliability. Hobson et al (1983) reported an objective method to define
composition changes during maturation process by setting tomato fruits in a varying
degree of maturation. Initially, the authors restricted the test to a cultivar and used a
spectrophotometer of the HUNTER Lab system. Color has been measured during
fruit maturation after carrying sensorial analysis in a color sequence. The authors
conclusions referred to the applicability of the proposed method to other cultivars in
a varying maturation levels.
Thai, Shewfelt (1991) presente a physical analysis of tomato color by means of an
HUNTER Lab SYSTEM spectrophotometer calibrated with a rose pattern model.
Eight spaced readings have been carried out around the fruit equator and recorded in
software. The resulting mathematical model involving “C” (chromaticity) and “H”
(tonality) which hae been statistically analyzed. The authors verified that “L”, “H”
and “C” were correlated to sensorial color perception.
Borguini, R. G.; Silva, M.V. in 2005 determined texture, other physical properties
and color of Debora and Carmem tomato cultivars produced under organic as well as
under conventional agricultural practices. Sensorial analysis of these samples
indicated no difference for red tonality between both agricultural practices.
Instrumental color readings adopted the mathematical model for C (chromaticity) and
h (tonality). It was observed that L,h and C yielded good correlation for subjective
color.
Thai, Shewfelt (1991) reported an experimental evaluation of tomato color based
on the Shewfelt et al (1987) method adapted to red tomatoes. Volunteers were trained
to designate grades in a non-structured scale on a line of 150 mm of length, showing
an initial mark de 0 to 12, where 0 indicates no-red color, next to 75 mm indicating
light red color and 138 mm indicating total red color.
Borguini, R. G.; Silva, M.V. (2005) comments that the “h” parameter defined the
basic sample color and also represented the average sample tonality. The authors also
verified that as great as the color angle “h” it means that fruit color was close to the
yellow and as the small the angle the close to red was the color. It was also noted
non-significant difference of red color when compared the fruits produced by both
agricultural practices. Tomato shelf life is influenced by the maturation level at
which the fruits were harvested and stored.
604
2 Materials and Methods
2.1 Materials
In the experimental part of this research work the tests were carried with table
tomato Santa Clara cultivar I 5300. The choice of that cultivar was based on the
productivity reached in the area of Campinas, SP, Brazil. Tomatoes were direct
picked on the field during morning period. Physiological maturity level, uniformity,
free of bruising, as stated by the IFT (1981).
Difuse Reflectance Spectophotometer. Tomato color analysis carried during the
storage period was tested by a MACBET 1500 plus model in the Laboratory of the
Chemistry Institute at The State University of Campinas, SP, Brazil, where all the
instrumental fruit color determination were carried out. Spectophotometer readings
were transmitted to a software available in the instrument, where they were codified
and stored.
During reflectance measurement by the Hunter Spectrophotometer, the incident
light beam was reflected as a diffuse beam which was collected and measured by the
sphere as is displayed. The spectrophotometer emits a light beam which does not
inside perpendicularly onto the sample surface.
The spectrophotometer was developed by HUNTER in 1950 based on the Hering
Opponent-Process Theory. Color determination refers to red and green as well as
between yellow and blue. Three dimensional view representing the color
determination results, where 1) the dimension +a and –a refers to the chromaticity
red-green, 2) the dimension +b – b refers to the chromaticity yellow – blue,
meanwhile the dimension L measures luminosity.
Sample chromaticity was obtained through the equation:
C = (a2 +b2)1/2 (1)
which represents the hypotenuse of the rectangle triangle having “a” and “b” as sides, as
shown on Fig. 2. Tonality was obtained through the angle “H” obtained by
H=tg –1(a/b) (2)
The fruit total color variation is given by:
(ΔL2 +Δa2+Δb2)1/2 (3)
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Where ΔL, Δa and Δb stands for the reading differences between the first and the
second day of observation, as reported by Little (1982). Where c= chromaticity, -a to
+a = green to red color, -b to +b = blue to yellow color and H = tonality.
Fig. 2. Scheme for three dimensional color measurement.
2.2 Methods
Preliminary analyzis - Commercial classification. The commercial tomato
classification directed to “in natura” consume for the domestic market was based on
the Brazilian Program for the Horticulture Modernization – Tomato Classification
Norms, Horticulture Quality Center, CQH/CEAGESP.
Preliminary analyzis - Physical properties. Fruit dimensions were surveyed by
means of a caliper, by selecting a number of 24 individuals at random, taking into
consideration the fruit shape. Specific weight determination was based on the
Archimedes Principal as recommended by Mohsenin, N. N. (1965). The fruit was
placed in a 1000 ml beaker together with 500 ml of water avoiding contact between
fruit and the glass sides. The displaced water volume was calculated by means of
equation (4).
Pr=(Pf.DH2O/Pd) (4)
Where “Pf” – fruit weigth in grams - “DH2O” stands for water density given in g/cm3 -
“Pr” is the real specific weight in g/ml.
In order to determine the apparent weight it was employed a container with the
dimensions of 31x18x11 cm having a volume of 6138 cm3 which was filled with the
fruits in a natural way, i.e., without interference, without excess or missing fruit.
Tomato weight was calculated by the difference between the total weight and the
container weight, as indicated by the equation (5) as recommended by Mohsenin, N.
N. (1965), as
Pap=(m/Vr) (5)
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Where “m” is the product mass in g, “Pap” is the aparente specific weight in g/ml,
“Vr” is the container volume in ml.
After determining the real and apparent weight, the porosity was obtained by
equation (6) from Mohsenin, N. N. (1965).
P=(1-Pap/Pr)x100 (6)
Where “P” is the porosity in %, “Pap” is the apparent specific weight in g/ml and
“Pr” is the real specific weight in g/ml.
Preliminary analyzis - Sensorial analysis judges selection. Judges training took
place in the three weeks preceding the experimental phase. Initially 30 individuals
including men and woman have been invited as volunteer judges. Individual’s acuity
have been evaluated following FARNSWORTH MUSELL – 100 - HUE (1957)
recommendation for color description. Following that preliminary test, 23 individuals
having normal vision for color were selected. In the next step individuals were
selected for discriminative ability for color, judgment reliability and consensus with
the remaining individuals. Significant differences were noted between individuals.
A non-structured scale of 9 cm of length based on the IFT (1981) was anchored at
the ends ranging from “nothing” (for totally green fruit) to “well characterized” (for
totally intense red tomato). During the test the judge is supposed to mark the
identified color on the line.
Selection tests have been set by including 05 fruits for each judge with three
replications each, from which the F test was carried for the Analysis of Variance,
where P varying from (Fcalculated ≤ 0,30) ≥ 0,05 is the probability of acceptance of the
difference between judges, concluding that significant difference between judges did
not occur. Based on that, nine judges have been selected, (Banzatto e Kronka, 1989).
Experimental analyzis. - Sensorial analyzis for color. A set of 20 tomatoes a day
randomly selected from the initial group was used as recommended by Gormley,
Keppel (1976) and presented to nine judges previously selected. Each judge carried
individual evaluation of the samples checking his perception on the scale as
explained before.
Color tests were carried out under the day ilumination which Windows were
facing the north direction and iluminated with fluoresecent light as recommended by
FARNSWORTH MUSELL 100 HUE (1957).
Experimental analyzis. - Color Instrumental Analysis. Following, after the
sensorial tests the 20 individuals were analyzed through the diffuse reflectance
spectrophotometer, using an observation angle of 100, in the CRIIS configuration, D
illuminant and L,a,b patterns. A number of five readings were carried out on each
fruit surface. The HUNTER Lab, system was used as recommended by Litle (1982).
Experimental analyzis. - Statistical analyzis. The statistical analysis was carried
primarily to verify the differences between the parameters under consideration, i.e.,
L, a, b, c, DE as well as the sensorial analysis through the analysis of variance and
Tuckey test at 5%. (Banzatto and Kronka, 1989).
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3 Results and Discussion
3.1 Commercial Classification
Lycopersicum esculentum Mill, Santa Clara I 5300 cultivar exhibits an outstanding
productivity and used for “in natura” consumption. Cultivar characteristics included
oblong and bilocular fruit, indeterminate growing plant with 110 days (summer) of
productive cycle, cultivated with anf average number of twenty thousand plants per
hectare. Seeds germinate in 5 days and harvesting takes place in 100 to 110 days
after seeding. That variety is tolerant to Fusarium oxysporum 1 e 2, Verticillium
dahliai, Verticillium abloatrum and Stemphylum.
Fruits were harvested at the physiologically developing point showing uniform
green color, homogeneous size and free of bruising, being classified as:
- Group “I” – Fruits present the longitudinal diameter larger than the transversal
one.
- Class “big” – Fruits present a minimum diameter of 62 mm.
- Type “Extra” – The summation of defects did not exceed 7% of the total
number of analyzed fruits.
3.2 Physical Properties
Table 1. Presents the average values of Real Specific Weight, Aparent Specific Weight,
porosity, Size as well the respective standard deviation of the fruits included in the analysis.
real specific apparent specific porosity size average real specific
weight(g/cm3) weight (g/cm3) (%) values (cm) weight (g/cm3)
obliqúe distance
Average 0.957 0.550 43.60 6.61 6.81
3.3 Instrumental and Sensorial Analysis.
Table 02 presents average values of the sensorial and instrumental determinations for
the color parameter during the maturation period. Table 03 displays the analysis of
variance results.
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Table 2. Sensorial and color analysis daily average results of 20 fruits.
Day sensorial color color color color color color
color “a” “c” “H” “L” “b” “ΔE”
1 1.5 -5.11 21.97 103.52 49.46 21.33 54.11
3 1.33 -4.54 21.41 102.17 49.13 20.73 53.51
5 2.03 2.98 21.56 96.72 47.16 21.02 51.72
8 3.86 6.06 23.23 76.1 42.29 21.24 50.39
10 5.5 7.98 23.76 67.38 42.02 20.94 47.62
12 6.67 15.11 25.71 53.1 40.22 19.74 47.28
15 7.54 16.24 23.97 45.4 38.09 17.73 45.04
17 7.85 17.96 25.41 45 37.75 17.88 45.47
19 8.22 20.03 26.09 40.33 36.74 17.59 45.39
Table 3. Analysis of Variance (ANOVA) results for the variables considered during the fruit
maturation period.
P>F C.V. R2 average
Sensorial color 0.0001 40.42 0.63 5.05
Color “a” 0.0001 57.11 0.83 7.83
Color “c” 0.0001 9.66 0.37 23.66
Color “H” 0.0001 16.82 0.82 70.34
Color “ΔE” 0.0063 121.33 0.12 11.78
Color “L” 0.0001 13.62 0.39 41.94
Color “b” 0.0151 18.2 0.11 19.34
C.V. – Coefficient of variation; P>F – level of significance; R2 – Coefficient of correlation. data
univariate analysis (ANOVA)
The ANOVA for color indicates the occurrence of differences between the samples
at p≤0.05. Tukey test was carried for multiple comparisons between the averages.
The values exhibiting the same letters do not present significant difference between
them at 5% of significance.
609
Table 3. Tukey test results are presented on Table 03 for each studied parameter during the
maturation period
Sensorial color determination did not present significant difference (p≤0.05) between
the days 1, 3 and 5; 5 and 8; 10 and 12; and 12, 15, 17 and 19, however differences
were noted between these groups. The fruits showed moderated characteristic colors
between the 10th and 12th day and very characteristic colors from the 12th.
Table 4. Tukey test results for color “a” during the maturation period.
The fruits included in the same maturation level did not show significant (p≤0.05)
for the parameter “a”, i.e., green – red color. Encountered maturation levels were
composed of the days 19, 17 and 15; 17, 15 and 12; 10 and 8; 5, 3 and 1, however
significant difference (p≤0.05) between the groups did occur, but with some
similarities between the last two groups.
Parameter “c” for color, reveals the chromaticity of the tomato samples during
maturation. Significant difference (p≤0.05) was not noted between the days 19, 17,
15, 12 and 10; 17, 15, 10 and 8; 10, 8, 5, 3 and 1. These results also show some
similarities between the three maturation levels with increasing chromaticity from the
17th maturation day on.
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Table 5. Tukey test results for color “H” during maturation period
The “H” parameter for color characterizes the fruit tonality during the maturation
period and significant difference (p≤0.05) between the days 1, 3 and 5; 8 and 10; 12,
15 and 17 and 15, 17 and 19 were noted, but differences occurred between these
groups. These results reveal four levels of tonality decrease during maturation period.
The two last maturation levels presented some chromaticity similarities in the
transition and lower chromaticity from the 17th of maturation.
The “ΔE” parameter represents the total fruit color variation during the maturation
period. Tukey test results for color “L” during maturation period. No significant
differences (p≤0.05) were noted during the maturation, excepting in the 8th and in
the last five days of maturation. It means that the parameter under consideration
cannot be taken into account as an important parameter.
Parameter “L” reveals fruit luminosity during the maturation period. Luminosity
did not present significant difference (p≤0.05) between the days of 1, 3, 5 and 8; 5, 8
and 10; 8,10 and 12; and 10, 12, 15, 17 and 19.
Results indicate that fruit luminosity did not show any differences in the five first
days. After the 10th day of maturation significant differences between fruits reffering
to luminosity.
Three luminosity levels have been noted, in which the most intense occurred in the
first day of maturation. Luminosity exhibits decaying and not well differentiable
levels.
As reported by Borguini, R. G.; Silva, M.V. (2005), according to the above
presented classification, as the fruit presents a higher chroma which occurs after the
15th maturation day, the analyzed fruits were noted to be in the initial chromaticity
level and no differences were found between the Carmen and Debora cultivars. Raffo
et al. evaluated cereja tomato type, Maomi F1 cultivar growing in green houses in
Italy, obtaining a chroma value of 15.6.
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4 Conclusions
Based on what it has been exposed before it can be concluded that it was possible
to determine the parameter color for tomatoes of ” Santa Clara” I5000 variety by
means of sensorial, as well as instrumented analysis. Both methods generated reliable
results as well as a statistically interpreted maturation level. The chromaticity
between red and green colors, i.e. the color “a” and the color “H’, i.e. the tonality, are
the parameters which present the best well defined color as function maturation time.
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