| Research Article |
Open Access |
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| Effect of Post Harvest Treatment on Stored Cherry Tomatoes |
| Maedeh Gharezi*, Neena Joshi and Elnaz Sadeghian |
| University of Agricultural Sciences, Bengaluru, India |
| *Corresponding author: |
Maedeh Gharezi
University of Agricultural
Sciences
Bengaluru, India
Tel: 00989133256104, 00919482230630
E-mail: mgharazi@yahoo.com |
|
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| Received June 27, 2011; Accepted August 11, 2012; Published August 17, 2012 |
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| Citation: Gharezi M, Joshi N, Sadeghian E (2012) Effect of Post Harvest
Treatment on Stored Cherry Tomatoes. J Nutr Food Sci 2:157. doi:10.4172/2155-9600.1000157 |
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| Copyright: © 2012 Gharezi M, et al. This is an open-access article distributed
under the terms of the Creative Commons Attribution License, which permits
unrestricted use, distribution, and reproduction in any medium, provided the
original author and source are credited. |
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| Abstract |
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| Cherry tomatoes are grown for its edible fruits, which can be consumed either fresh as a salad or after cooking as
snacks. Cherry tomato is a store house of antioxidants such as Lycopene, ascorbic acid and phenolics.The study was
conducted to undertake the effect of storage conditions on the post harvest quality of Cherry tomato cv. Marilee red
(Lycopersicon esculentum Mill) harvested at pink stages. The experiment consisted of three post harvest treatments
comprising fruits dipped in cold water for five minutes (control), fruits dipped in CaCl2 @ 2% and fruits dipped in
acetic acid @ 5%. Fruits imposed with post harvest treatments were stored at ambient (temperature 25°C ± 2 and
relative humidity approx. 75 ± 5%) and cold storage conditions (10°C ± 2). Physico-chemical changes recorded on 0,
2, 4, 6, 8, 10, 12, 14 days of storage. Lycopene, ascorbic acid and total sugar changes recorded on 0, 4, 9, 14 days
of storage. The data on physical characteristics (firmness, taste, juiciness, decay, colour, gloss, uniformity, shrivel)
were recorded. CaCl2 was the best treatment followed by control and acetic acid treatment. Significant differences
observed among the chemical parameters due to various post harvest treatments and storage conditions. CaCl2
had highest ascorbic acid, lycopene content and had lowest PLW, moisture content. Acetic acid had highest PLW,
titratable acidity, moisture content and lowest TSS, lycopene, total sugar content. Control had highest TSS, total
sugar content, lowest titratable acidity and ascorbic acid content at ambient and cold temperatures. TSS and acidity
contents increased rapidly initially, but started decreasing gradually afterwards in all storage treatment. CaCl2 was
found highly effective in controlling storage loss as well as in maintaining the quality of the produce during storage.
Although the ascorbic acid registered a decrease during storage, it could still contribute significantly towards the
dietary intakes. |
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| Keywords |
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| Cherry tomato; Post harvest; Physico-chemical; Acetic
acid; CaCl2 |
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| Introduction |
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| The tomato (Lycopersicon esculentum) is one of the most widely
consumed fresh vegetable in the industrialized world [1]. Botanically,
tomatoes are fruits (berry), but they are commonly referred to as
vegetable. Fresh-market tomatoes are a popular and versatile fruit
vegetable, making significant contributions to human nutrition
throughout the world for their content of sugars, acids, vitamins,
minerals, lycopene and other carotenoids, among other constituents
[2,3]. Being a climacteric and perishable vegetable, tomatoes have
a very short life span, usually 2-3 weeks. The small size snacking
tomatoes (cherry, grape types) contain high concentrations of sugars
and acids, major contributors to tomato flavor, and now comprise about
24% of retail sales of tomatoes in the U.S. [4]. Tomatoes are consumed
widely throughout the world and their consumption has recently been
demonstrated to possess health benefits because of its rich content
of phytonutrients [5,6]. Postharvest recommendations indicate that
tomatoes, including cherry tomatoes, should be stored at 10°C or
higher to avoid chilling injury [7,8] and even 10°C may be detrimental
to tomato flavor quality [9]. Cherry and grape tomatoes are sometimes
held at lower than recommended temperatures. Also cherry and grape
tomatoes are routinely used as components on fresh cut vegetable trays
under modified atmospheres, with expected shelf-life of 14-18 days at
5-10°C. A few studies have characterized changes in small tomatoes
stored at below recommended temperatures alone or in combination
with modified atmosphere packaging [10,11]. Different studies
explained that calcium chloride reduced post harvest decay, controlled
development of physiological disorders, improved quality and delayed
aging or ripening [12]. It improves the skin strength [13] making the
cell wall and tissues more resistant and less accessible to the enzymes
that are produced by fungi and bacteria, limiting infection while
controlling ripening, softening, storage breakdown, rotting and decay
at the same time [14-16]. According toz different studies, it improved the Ca+2 contents, lycopene contents, ascorbic acid contents, firmness
index [17,18] and reduced the disease index [19]. Bioregulators affect
fundamental processes of plant growth and development. |
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| Acetic acid (AA) is plant bioregulator belonging to the auxin group.
Plant bioregulators are organic compounds, either natural or synthetic
that modifies or control one or more specific physiological processes
within a plant. They can accelerate or retard the growth or maturation
rate or otherwise alter the behaviour of plants or their products [20,21].
Bioregulators are used to advance or delay fruit harvest by influencing
fruit maturation and ripening [22]. An increase in the storage life and
improvement of tomato fruit quality is really desirable and the initial
step required for ensuring successful marketing is to harvest the crop at
the optimum stage of maturity. Full red, vine-ripened tomatoes may be
ideal to meet the needs of a roadside stand, but totally wrong if the fruits
are destined for long distance shipment [23]. Extending the shelf life of
tomatoes is very important for domestic and export markets. Storage
at 13°C was more favorable as compared to 24°C for prolonged shelf
life and increasing vitamin C content of fruits [24]. Cherry tomatoes
are sold at a premium in many of the large retail stores in the country.
There is an interest in finding ways to improve the shelf life. Safe and
low cost methodologies that can extend the shelf life while at the same
time retain the quality under ambient as well as cold conditions need to be evaluated. Hence the present investigation was undertaken to study
the effect of pretreatment on shelf life, physico-chemical and sensory
characteristics. |
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| Materials and Methods |
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| For the experiments on storage study of fresh cherry tomato, 15 kg
of the variety Marliee Red were harvested from orchards at Namdhari
Seed Company, Bidadi, Karnataka and transported to laboratory. The
fruits were refrigerated (10°C) to cool, brought to the laboratory with
least damage and utmost care. Samples were assigned to the different
experimental test conditions. These conditions are described in
following paragraph. |
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| Storage study of fresh cherry tomato |
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| One hundred grams of tomato sample was filled in foam trays
measuring 12.5 x 12.5 cm. For each treatment there were 3 trays for
each day of observation and totally there were 36 trays. Thus, in all
108 trays were used for the entire study as there were two treatments
and control as indicated in Table 1. Cherry tomatoes were stored at i)
ambient conditions prevailing in the laboratory (temperature (25°C
± 2) and relative humidity around (50 ± 10%) ) and ii) a refrigerator
maintained at cold temperature (10°C ± 2), which had provision for
proper aeration and light, arranged side by side (Annexure). |
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Table 1: Description of replications in study on storage of pretreated fresh cherry
tomatoes (cv.Marilee red). |
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STORAGE DAYS |
TEMPRETURE (°C) |
RELATIVE HUMIDITY (%) |
MINIMUM |
MAXIMUM |
MINIMUM |
MAXIMUM |
1st day |
20 |
27 |
63 |
80 |
2nd day |
19 |
26 |
65 |
77 |
3rd day |
18 |
26 |
70 |
82 |
4th day |
18 |
27 |
68 |
79 |
5th day |
19 |
25 |
66 |
81 |
6th day |
18 |
25 |
70 |
82 |
7th day |
19 |
24 |
71 |
82 |
8th day |
19 |
25 |
68 |
79 |
9th day |
18 |
26 |
69 |
82 |
10th day |
20 |
26 |
70 |
81 |
11th day |
20 |
24 |
71 |
80 |
12th day |
19 |
24 |
72 |
78 |
13th day |
18 |
23 |
68 |
80 |
14th day |
17 |
24 |
68 |
79 |
15th day |
19 |
25 |
69 |
81 |
|
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| Annexure: Temperature and relative humidity recorded during storage of cherry
tomato under ambient condition. |
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| Pre treatments for storage of fresh tomato |
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| CaCl2 is often used for extending the shelf life of tomatoes [25]
and acetic acid is a known surface sanitizer. Therefore for studying the
shelf life of cherry tomato (cv. Marliee Red), 2% CaCl2, 5% acetic acid
solution and distilled water (control) were used. Samples were dipped for 5 min and wiped before storage at two temperatures (10°C and
ambient temperature). |
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| Thus, in this study the following pretreatments were used: |
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| T1- Fruits dipped in cold water for five minutes (Control) |
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| T2- Fruits dipped in CaCl2 @ 2% for five minutes |
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| T3- Fruits dipped in acetic acid @ 5% for five minutes |
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| Packaging system: After those treatments fruits were placed in
foam trays measuring 12.5 x 12.5 cm and wrapped with PVC film.
(Plate 1 and 2) |
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Plate 1: Storage of fresh cherry tomatoes subjected to specific pretreatments
(1) CaCl2 2%, (2) Acetic acid 5% and (3) Control. |
|
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Plate 2: Packaging material used in study of fresh cherry tomato (cv. Marliee
Red). |
|
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| Observations: Physico-chemical observations (Firmness, taste,
juiciness, decay, colour, gloss, uniformity, shrivel) were recorded on 0,
2, 4, 6, 8, 10, 12, 14 days of storage. For estimating lycopene, ascorbic
acid and total sugar content, samples were drawn on 0, 4, 9, 14 days of
storage as already explained. |
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| Analytical procedure |
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| Evaluation of quality characters [7]: Fruits were ranked for quality
parameters, from higher to lower descending order of acceptability.
Colour, flavor, taste, decay, gloss, firmness, uniformity, shrivels and
over-all acceptability of the fruit were determined by visual assessment
and grouped. Quality characters were determined by a panel of 5 semi
trained judges on a 5 point hedonic scale. |
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| Physiological loss in weight [26]: For determining the physiological
loss in weight, fruits were weighed before imposing the treatment
which served as the initial fruit weight. The loss in weight was recorded
at 7 days interval until 14 days which served as the final weight. The
physiological loss in weight was determined by the following formula
and expressed as percentage. |
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 |
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| Total soluble solids (TSS) [27]: Total soluble solids were
determined using hand refractometer 0-32 (°Brix) range A drop of juice
was used to record the TSS and values were expressed as °brix. |
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| Titratable acidity: A known volume of filtered juice was diluted
with a known volume of distilled water. An aliquot was taken from this sample and titrated with 0.1 N NaOH using phenolphthalein indicator.
The appearance of light pink colour was marked as the end point.
Acidity was computed and expressed as per cent citric acid. |
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 |
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| Milli-equivalent weight of citric acid = 0.06404 |
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| Ascorbic acid content: Ascorbic acid was estimated by indicator
method. This method is based on stoichiometric reduction of the dye
2,6- dichlorophenol indophenol by ascorbic acid into a colourless
compound. The filtration was conducted in the presence of acetic acid
and metaphosphoric acid. |
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| Lycopene content [28]: Lycopene was estimated by rapid method.
Lycopene was extracted in petroleum ether and the absorbance was
measured by using spectrophotometer at 503 nm using UV-VIS
spectrophotometer-Shimadzu. |
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| Estimation of moisture: Moisture was determined by taking
about 10 g of sample in petri dish and dried in an oven at 105°C till the
weight of the petri dish with its content was constant. Each time before
weighing, the petri dish was cooled in desiccators. Moisture content of
the sample was expressed in g/100g of sample. |
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 |
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| Estimation of total sugar by Phenol Sulphuric acid method [29]:
The intensity of colour developed by the reaction of phenol sulphuric
acid with total sugar was read at 490 nm in a colorimeter (Elico SL 164,
Spectrophotometer). |
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| Statistical analysis: The data pertaining to physiological and
biochemical parameters of the fruit were subjected to statistical analysis
of FCRD using analysis of variance (ANOVA) as per the procedure
given by Fischer (1960). The level of significance used in F test and ‘t’
test was p ≤ 0.05. Critical difference values were calculated wherever
the ‘F’ test was found significant. The data were subjected to Minitab
Statistical Software (Minitab Inc., USA). |
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| Results and Discussion |
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| Pre-packaging plays an important role in quality maintenance by
slowing down the biochemical changes and reducing the moisture loss,
thus increasing the shelf life of fresh produce [30]. The role of calcium
in the physiology of plant tissue is well established. Addition of calcium
rigidifies cell wall and obstructs enzymes such as polygalacturonase
from reaching active sites [25]. Calcium compounds have shown
promising results in the quality retention of fruits and vegetables
through maintenance of firmness and reducing the respiration rates [16].
Influence of various post harvest treatments and storage conditions in
cherry tomato cv. Marilee Red was studied. The experiment consisted of
three post harvest treatments comprising fruits dipped in cold water for
five minutes (control), fruits dipped in CaCl2 @ 2% and fruits dipped
in acetic acid @ 5%. Fruits imposed with post harvest treatments
were stored at ambient (temperature 25°C ± 2 and relative humidity
approx. 75 ± 5%) and cold storage conditions (10°C ± 2). Observations
on various physico-chemical and quality changes during storage were
recorded at two or five day’s intervals for 14 days. The results obtained
from the investigation are presented in the following paragraphs. |
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| Physiological loss in weight (PLW) (%) |
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| Weight loss of fresh tomatoes is primarily due to transpiration and
respiration. Transpiration is a mechanism in which water is lost due
to differences in vapour pressure of water in the atmosphere and the
transpiring surface. Respiration causes a weight reduction because
a carbon atom is lost from the fruit each time a carbon-dioxide
molecule is produced from an absorbed oxygen molecule and evolved
into atmosphere [31]. Physiological loss of weight can influence the
economic returns. The data on physiological loss in weight as influenced
by post harvest treatments and the storage conditions are presented
in Figure 1 which indicated significant differences between both post
harvest treatments and storage conditions (p ≤ 0.05). It was observed in
general, that the PLW was lower under cold storage compared to ambient
storage in all the treatments. Among post harvest treatments, PLW was
lowest in CaCl2 treated samples (3.49%) which was significantly lower
over all other treatments under both cold (1.62%) and ambient (5.37%)
conditions at 7 days of storage. The next best treatment in terms of low
PLW was control. The PLW progressively increased with an increase
in the storage period, irrespective of the storage condition and the treatments. Among the treatments, PLW was maximum in acetic acid
treatments under both ambient and cold storage conditions at 7 and 14
days. In the present investigation, weight loss was significantly lower
in CaCl2 pretreatment under ambient and cold storage. This could be
attributed to the maintenance of high humidity in the microatmosphere
within the packages by the respiring fruits and due to low water vapour
transmission rates of packaging material [26]. Cold stored fruits had a
low weight loss due to temperature effects on vapour pressure difference
and increased water retention [32]. |
|
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|
Figure 1: Physiological loss in weight of cherry tomato (Marilee red) during
storage. |
|
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| Total soluble solids (°brix) |
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| Results on the effect of storage at ambient temperature on the total
soluble solids (TSS) are presented in Figure 2. It was observed that
significant differences existed between the post harvest treatments at all
stages of observation (0, 2, 4, 6, 8, 10, 12 and 14 days) (p ≤ 0.05). Among the post harvest treatments, mean TSS was lowest in acetic acid treated
(4.08%) followed by CaCl2 treated (4.76%) fruits. However, the control
(5.11%) fruits recorded highest TSS among all of them in ambient
temperature. Among the post harvest treatments, mean TSS was lowest
in acetic acid treated (4.33%) and followed by CaCl2 treated (4.46%)
fruit and the highest was in control (5.11%) in cold temperature. The
means of the results were subjected to student ‘t’ test. There were no
statistically significant differences between ambient temperature and
cold temperature. The total soluble solids acts as a rough index of the
amount of sugars present in fruits. It is the amount of sugar and soluble
minerals present in fruits and vegetables. Sugars constitute 80-85 per
cent of soluble solids. The total soluble solids increased during the
ripening due to degradation of polysaccharides to simple sugars thereby
causing a rise in TSS [30]. However, in the present study, control had
highest TSS in post harvest treatment, CaCl2 and acetic acid treatments
were lower than that of control samples treated with distilled water.
The reduction in the TSS of calcium treated cherry tomato fruit was
probably due to slowing down of respiration and metabolic activity,
hence retarding the ripening process. In this regard, the view of [33]
is noteworthy that the slower respiration also slows down the synthesis
and use of metabolites resulting in lower TSS due to the slower change
from carbohydrates to sugars. Dewanto et al. [34] stated that application
of calcium increased fruit calcium content and influenced several post
harvest treatment senescence changes involving free sugars, organic
acid, anthocyanin content and texture of fruits. |
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|
Figure 2: Total soluble solids content of cherry tomato (Marilee red) during
storage. |
|
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| Titratable acidity (%) |
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| The data on titratable acidity presented in Figure 3 indicated
significant differences (p ≤ 0.05) among the post harvest treatments at
all stages of observation (0, 2, 4, 6, 8, 10, 12 and 14 days of storage)
and (p ≤ 0.05). Acetic acid treated fruit recorded significantly higher
mean titratable acidity (0.39%) over all other treatments followed by CaCl2 treated (0.36%) fruit, control treatments had lowest titratable
acidity (0.33%) at ambient temperature of observation. Among the
treatments, significantly higher mean titratable acidity was recorded
in acetic acid treated (0.41%) fruit over all other treatments at cold
temperature. The next best treatment was CaCl2 treated (0.40%) fruit.
Significantly lower titratable acidity was recorded in control (0.40%)
fruits at cold temperature. The means of the values were subjected
to student ‘t’ tests to assess the effect of interaction between storage
temperature and pretreatment. There were statistically significant
differences between ambient temperature and cold temperature and
pre treatments. Acidity in fruits is an important factor in determining
maturity. Titratable acidity gives the total or potential acidity, rather
than indicating the number of free protons in any particular sample. It
is a measure of all aggregate acids and sum of all volatile and fixed acids.
In the present study, the titratable acidity of the cherry tomato fruits
differed significantly over the storage period. A gradual decline in the
titratable acidity was noticed by the end of storage period among the
cherry tomato fruits. The changes in organic acids during ripening have
been attributed to a rise in citrate and fall in malate, indicating a change
in metabolism of citrate [35] and reduction in the level of citric acid.
As Bhatnagar et al. [36] stated that during storage the fruit itself might
utilize the acid so that the acid in the fruits during storage periods
decreases. However, predietry fruits treated with acetic acid had higher
acidity throughout the period of study. |
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|
Figure 3: Titratable acidity content of cherry tomato (Marilee red) during
storage. |
|
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| Moisture content (%) |
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| The data on moisture content presented in Figure 4 indicated nonsignificant
differences in moisture content among the post harvest
treatments at all stages of observation (0, 2, 4, 6, 8,1 0, 12 and 14 days
of storage) at ambient temperature (p ≤ 0.05). Acetic acid treatment
recorded significantly higher mean moisture content (92.1%) over
all other treatments followed by control (91.9%), CaCl2 treatments had lowest mean moisture content (91.7%) at ambient temperature
of observation. Non-significant differences in moisture content were
observed among the post harvest treatments at all stages of observation
(0, 2, 4, 6, 8, 10, 12 and 14 days of storage) at cold temperature. Acetic
acid treated fruit recorded significantly higher mean moisture content
(91.9%) over all other treatments followed by control (91.7%), CaCl2
treatments had lowest moisture content (91.3%) at cold temperature.
The means of the results were subjected to student ‘t’ test. There were
statistically significant differences between ambient temperature and
cold temperature. |
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|
Figure 4: Moisture (%) content of cherry tomato (Marilee red) during storage. |
|
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| Ascorbic acid content (mg/100 g fr.wt) |
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| The data on ascorbic acid content presented in Figure 5 indicated
significant differences in ascorbic acid content among the post harvest
treatments at all stages of observation (0, 2, 4, 6, 8, 10, 12 and 14 days
of storage) at ambient and cold temperatures (p ≤ 0.05). Treatment
with CaCl2 recorded significantly higher mean ascorbic acid content
(21.84 mg/100 g) over all other treatments followed by acetic acid
treated (20.24 mg/100 g), control treatments had lowest ascorbic
acid content (17.88 mg/100 g) at ambient temperature. Pre-treatment
with CaCl2 recorded significantly higher ascorbic acid content (22.78
mg/100 g) over all other treatments followed by acetic acid treatment
(21.13 mg/100 g) and control (20.45 mg/100 g) at cold temperature. The
means of the results were subjected to student ‘t’ test among the storage
conditions, significantly higher ascorbic acid content were recorded at
ambient temperature compared to cold storage. An increase in ascorbic
acid content in fruit is thought to be an indication that the fruit is still in
the ripening stage, while a decrease indicates a senescent fruit [37]. In
addition, Miller and Evans [38] reported that phenolic substances have
been found to play a protective effect on the ascorbic acid. The presence of phenolics in the fruit cells may help to maintain the ascorbic acid
content. Tomatoes are rich source of ascorbic acid. The ascorbic acid
content of ripe tomato ranges from 15 mg to 23 mg/100 g fruit [35].
Ascorbic acid (vitamin C) content has been found to have a significant
role in the assimilation of iron obtained from other sources. It is
essential for the formation of normal teeth and bones. Preservation of
ascorbic acid content during storage is a difficult task since it undergoes
oxidation [39]. An increase in ascorbic acid content in fruit is thought
to be an indication that the fruit is still in the ripening stage, while a
decrease indicates a senescent fruit [40]. In the present investigation, the
ascorbic acid content of fruits was significantly influenced by various
post harvest treatments and storage conditions. Ascorbic acid contents
significantly decreased during storage. It was also observed that fruits
treated with calcium chloride showed the highest ascorbic acid content
followed by that of simply packed fruits. Among all treatments, control
showed lowest ascorbic acid contents. Subbiah and Perumal [17] also
observed higher ascorbic acid values in tomatoes that were treated with
CaCl2 when compared to untreated samples. According to them, CaCl2
pretreatments in high carbon dioxide atmosphere affect the ripening
rate, delaying ascorbic acid production. Loss of ascorbic acid in cold
stored tomatoes was significantly slower than air stored tomatoes.
Tasdelen and Bayindirli [32] found similar results in ascorbic content
during storage of tomatoes. |
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|
Figure 5: Ascorbic acid content of cherry tomato (Marilee red) during storage. |
|
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| Lycopene content (mg/100 g. fr. wt)0 |
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| Lycopene is the pigment principally responsible for the
characteristic deep red colour of ripe tomato fruits. It is the most
abundant carotenoid in ripe tomatoes, comprising approximately 80 to
90 per cent of the pigments present [41]. Normally, tomatoes contain
about 3 to 5 mg lycopene per 100 g of fruit [42,43]. Lycopene exists as small globules, in the chromoplasts which are suspended in the
tomato pulp throughout the fruit. Lycopene is an efficient antioxidant
and quenches highly reactive singlet oxygen radicals and acts as a
preventive agent for cancer [44]. Lycopene needs to be protected from
excessive heat and extreme pH conditions, exposure to light, oxygen
and lipid degrading enzymes in order to prevent its oxidation and
isomerization [45]. The data on lycopene content presented in Figure
6 indicates significant differences in lycopene content among the post
harvest treatments at all stages of observation (0, 2, 4, 6, 8, 10, 12 and 14
days of storage) at ambient temperature (p ≤ 0.05). Pretreated tomatoes
with CaCl2 recorded significantly higher lycopene content (3.82 mg/100
g) over all other treatments followed by control (3.79 mg/100 g), acetic
acid treatments had lowest mean lycopene content (3.60 mg/100 g) at
ambient temperature. Significant differences in lycopene content was
observed among the post harvest treatments at all stages of observation
(0, 2, 4, 6, 8, 10, 12 and 14 days of storage) at cold temperature (p ≤
0.05). CaCl2 treated fruit recorded significantly higher lycopene content
(3.94 mg/100 g) over all other treatments followed by control (3.90
mg/100 g), while those treated with acetic acid had lowest lycopene
content (3.87 mg/100 g) at cold temperature. The means of the results
were subjected to student ‘t’ test among the storage conditions, cold
storage recorded significantly higher lycopene content compared to
ambient temperature. In the present investigation, tomato fruits showed
a significant increase in lycopene content during the storage period.
Chlorophyll degradation and increased lycopene synthesis results in
the characteristic colour development during ripening in tomatoes
[46]. Cherry tomatoes treated with acetic acid significantly delayed the
lycopene biosynthesis. This can be attributed to delay in ripening due to
reduced respiration rate. Similar results have been reported by Nguyen
[47], and Causse et al. [48] Brandt et al. [49] in tomato. |
| |
|
Figure 6: Lycopene content of cherry tomato (Marilee red) during storage. |
|
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| Total sugar |
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| Significant differences in total sugar content were observed among the post harvest treatments at all stages of observation (0, 2, 4, 6, 8, 10,
12 and 14 days of storage) at ambient temperature (p ≤ 0.05). Control
recorded significantly higher mean total sugar content (5.10 mg/100 g)
over all other treatments followed by CaCl2 (4.51 mg/100 g), acetic acid
treatments had lowest total sugar content (4.34 mg/100 g) at ambient
temperature of observation (Figure 7). Significant differences in total
sugar content were observed among the post harvest treatments at 0,
2, 4, 6, 8, 10, 12 and 14 days of storage at cold temperature (p ≤ 0.05).
Control recorded significantly higher total sugar content (5.29 mg/100
g) over all other treatments followed by CaCl2 (4.67 mg/100 g) and
acetic acid treatments (4.44 mg/100 g) at cold temperature. Among
the storage conditions, cold storage recorded significantly higher total
sugar content compared to ambient temperature. |
| |
|
Figure 7: Total sugar content of cherry tomato (Marilee red) during storage. |
|
| |
| The means of the results were subjected to student ‘t’ test among
the storage conditions, cold storage recorded significantly higher
total sugar content compared to ambient temperature. The metabolic
breakdown of organic acid into carbon dioxide and polysaccharides
into water soluble sugar might be a reason for an increase in the sugar
content. The findings of [50] also indicated that starch is completely
hydrolyzed into soluble sugar such as glucose, fructose and sucrose as
ripening progresses. Their result of sugar content in cherry tomato is in
agreement with present findings. |
| |
| Physical characteristics |
| |
| The data on physical characteristics (firmness, taste, juiciness,
decay, colour, gloss, uniformity, shrivel) are presented in Tables 2, 3
and 4. For these characteristics there were no significant differences
between the three pretreatments of cherry tomatoes. The means of
the results were subjected to student 't’ test. CaCl2 was best treatment
followed by control and acetic acid treatment. |
| |
|
Table 2: Effect of post harvest calcium chloride treatment on keeping quality of
cherry tomato (Marilee red). |
|
| |
|
Table 3: Effect of post harvest acetic acid treatment on keeping quality of cherry
tomato (Marilee red). |
|
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|
Table 4: Keeping quality cherry tomato (Marilee red) subjected to no pretreatment. |
|
| |
| Shrinkage: Shrinkage is one of the indications of deterioration,
degrading the quality and reducing the quantity. In the present study
shrinkage occurred in all samples both treated as well as un-treated and
those stored at different temperatures. The effect of temperature showed
clearly that at lower temperature the shrinkage is less while it became
more at ambient temperature. However, treated samples showed less
shrinkage as compared to un-treated sample. This indicates that with
treatment, tomatoes can be stored at a bit higher temperature which is energy saving. Although samples stored at higher temperature showed
more shrinkage, but still the treated sample exhibited less shrinkage as
compared to un-treated [51]. |
| |
| Firmness: The most important factor next to visual appearance
in tomato quality is firmness which is closely associated with ripeness
stage. Most consumers prefer firm fruits which do not lose too much
juice when sliced and which do not have tough skins. Firmness affects
susceptibility of tomatoes to physical damage and consequently their
shipping ability [50]. The textural quality of tomatoes is influenced by
skin toughness, flesh firmness, and internal fruit structure which vary
greatly among cultivars. |
| |
| All fruit softened progressively during storage, firmness of tomato
was influenced by temperature and storage time. Firmness decreased
during storage at both temperatures. Treatment with CaCl2 resulted
in higher firmness compared to others. Calcium dips retarded the
metabolism as indicated by the slow ripening rate. Calcium chloride
improves the firmness of tomato fruits. All the treatments delayed
ripening and improved the storage life and quality significantly. |
| |
| Flavour: Flavour is a combination of taste and aroma sensations.
The four tastes, sweet, sour, salty, and bitter are perceived by certain
regions of the tongue, while volatiles are perceived by the olfactory
nerve endings of the nose [52]. Tomato flavour involves perception
of the tastes and aromas of many chemical constituents. Sugars, acids
and their interactions are important to sweetness, sourness, and overall
flavour intensity in tomatoes [53]. The characteristic tomato flavour,
thus, is produced by the complex interaction of the volatile and nonvolatile
components [54,55]. High sugars and relatively high acids are
required for best flavour. High acids and low sugars will produce a tart
tomato while high sugars and low acids will result in a bland taste.
When both sugars and acids are low, the result is a tasteless, insipid
tomato. In the present study highest flavour score was observed in
the fruits treated with CaCl2 followed by control. This may be due
differential ripening resulting in better sugar to acid ratio which
determines taste [56]. Progressive deterioration in flavour score were
observed throughout the period of storage. Differences were seen in the
different pretreatments and storage conditions. Prolonged packaging
sometimes led to the anaerobic respiration causing the formation of
ethanol and aldehydes contributing to undesirable aroma [57]. Aromas
have important influence on food preferences [58] and as these scores
are the result of decision of panel of judges, the loss of volatiles may
have led to the lower flavour scores. |
| |
| Colour: External colour of tomatoes is the result of both flesh and
skin colours. A pink tomato has a colourless skin and red flesh while a red
tomato has a yellow skin and red flesh. Fruits of some tomato genotypes
have pink, purple, orange, dark yellow, light yellow, yellow with pink
end, and other colours. However, most consumers prefer the deep,
uniform red-coloured tomatoes. In the present study highest colour
score was observed in the fruits treated with CaCl2 followed by control.
Colour is an indicator of tomato ripeness stage. Several subjective
rating scales and colour charts have been developed for classifying
ripeness, included in the U.S. Standards [59]. Objective methods of
tomato colour evaluation include light reflectance measurement [60]
and light transmittance techniques [36,61]. |
| |
| Shelf life: Organoleptic evaluation in the present study in terms of
colour, aroma and texture differed significantly between the different
post harvest treatments and storage conditions over the storage period.
Organoleptic scoring was high for fruits stored in CaCl2. However, the
fruits kept in cold storage suffered chilling injury at the end of storage
period, with a reduction in the firmness and aroma. But, the fruits
packed and kept in cold storage had a reduced chilling injury. A better
avoidance of chilling injury was observed in cold stored CaCl2 fruits.
The fruits maintained a better aroma and texture and delay in colour
development was observed. This is in conformity with the studies of
Nirupama et al. [62] and Speirs et al. [57] in tomatoes, Smith and Reyes
[63] in celery, Escalona et al. [64] in kohlrabi. Extension of shelf life by
CaCl2 has also been observed by many workers viz., Hong and Gross
[65] and Tasdelen and Bayindirli [32] in tomato, Lizana et al. [66] in
mangoes. |
| |
| Conclusion |
| |
| The obtained results indicated that acetic acid, calcium chloride
and control play a very effective role in controlling the weight loss,
shrinkage, colour, flavor, firmness percentage and other compositional
changes such as titratable acidity, total soluble solids, total sugars, total
lycopene, ascorbic acid and moisture content of cherry tomatoes stored
at both ambient and cold temperature. Calcium chloride treatment had
delayed the ripening process more effectively and with a minimum quality loss, as compared to the control sample which had greater
compositional changes with maximum quality loss during storage at
ambient temperature. The shelf life of cherry tomato could be extended
more than 15 days without excessive deterioration in quality by treating
the fruits with calcium chloride. Among all the tested treatments,
calcium chloride treatment benefits storage life capacity and maintains
quality characteristics as compared to the fruits of control set. Thus it
may be concluded that the post harvest chemical treatments selected
for the present study have the potential to extend the shelf life of tomato
while retaining its nutritional quality. |
| |
| Acknowledgements |
| |
| Authors are thankful to Dr Kamal G. Nath, Dr Gopalakrishna Rao and K.M
Indiresh for their valuable suggestions and kind help during the research period and
to Food Science & Nutrition Department, University of G.K.V.K , U.A.S, Bangalore,
India for providing necessary facilities for carrying out this work. |
| |
|
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