Acta agriculturae Slovenica, 87 - 2, september 2006 str. 235 - 243 
Agrovoc descriptors: lycopersicon esculentum, tomatoes, quality, storage, 
temperature, storage losses, weight, colour 
 
Agris category code: Q04, J11 
 
COBISS Code 1.01 
 
Comparative study of quality changes in tomato cv. 'Malike' 
(Lycopersicon esculentum Mill.) whilst stored at different 
temperatures 
 
Dragan ŽNIDARČIČ
1
, Tomaž POŽRL
2
  
 
Received June 26, 2006; accepted August 18, 2006. 
Delo je prispelo 26. junija 2006; sprejeto 18. avgusta 2006. 
 
ABSTRACT 
 
The objective of this study was to compare the effects of storage conditions on the 
indeterminate tomatoes (Lycopersicon esculentum Mill.) cv. 'Malike'. Fruits were stored at 5 
o
C and 10 
o
C for up to 28 days; to extend their post-harvest life and maintain fruit quality 
parameters. The weight loss, soluble solids, titrable acidity and skin colour components of the 
fruits were recorded weekly. The weight loss of tomatoes was almost linear at both storage 
temperatures. Fruits stored at 10 
o
C lost weight faster than those stored at 5 
o
C. Storage at 
lower temperature tended to increase tomato longevity. At the end of the storage period the 
fruits stored at 5 
o
C experienced a weight loss of 13.6 % (after 28 days), while those stored at 
10 
o
C showed values of 14.2 % (after 21 days). Soluble solids increased slightly from 5.06 % 
to 6.92 % at 5 
o
C (during 28 days period) and from 5.06 % to 6.26 % at 10 
o
C (during 21 days 
period). There were only slight changes in soluble solids content during the stored period 
studied, as well as non-significant differences between the two temperatures. Changes of 
titrable acidity during storage were relatively small. After seven days the content of titrable 
acid started to decrease at both temperatures. There was no significant skin colour difference 
between the tomatoes maintained at different temperatures. 
 
Key words:  Lycopersicon esculentum, tomato, storage, temperature, weight loss, colour, 
chemical composition  
 
IZVLEČEK 
 
PRIMERJALNA ŠTUDIJA KVALITATIVNIH SPREMEMB PARADIŽNIKA CV. 'MALIKE' 
(Lycopersicon esculentum Mill.), SKLADIŠČENEGA PRI RAZLIČNIH TEMPERATURAH 
 
Cilj raziskave je bil primerjati, kako razmere skladiščenja vplivajo na indeterminantni 
paradižnik (Lycopersicon esculentum Mill.) cv. 'Malike'. Plodovi so bili skladiščeni 28 dni pri 
temperaturi 5 
o
C in 10 
o
C z namenom, da bi podaljšali trajnost plodov in hkrati obdržali 
njihovo kakovost. V enakih tedenskih intervali smo merili izgubo teže, vsebnost suhe snovi, 
vsebnost skupnih kislin in barvo kože plodov. Izguba teže je bila skoraj linearna pri obeh 
temperaturah. Plodovi, skladiščeni pri 10 
o
C, so težo izgubljali hitreje kot tisti, skladiščeni pri 5 
o
C. Ob skladiščenju pri nižji temperaturi se je pokazala težnja po podaljšanju življenjske dobe 
plodov. Na koncu poskusa smo ugotovili, da so plodovi skladiščeni pri 5 
o
C izgubili 13,6 % 
                                                 
1
 M. Sc. Agr., SI-1111 Ljubljana, Jamnikarjeva 101, P. O. Box 95, 
2
 M. Sc. Food. Tech., ibid, 

Acta agriculturae Slovenica, 87 - 2, september 2006 
 
236 
teže (po 28-ih dneh), medtem ko so tisti pri 10 
o
C izgubili 14,2 % teže (po 21-ih dneh). 
Vsebnost suhe snovi je počasi naraščala od 5,06 % do 6,92 % pri 5 
o
C (v obdobju 28 dni) in 
od 5,06 % do 6,26 % pri 10 
o
C (v obdobju 21 dni). Ugotovljena je bila majhna, statistično 
neznačilna razlika v suhi snovi paradižnikov med obema temperaturama. Spremembe 
skupnih kislin so bile med skladiščenjem relativno majhne. Po sedmih dneh so skupne kisline 
začele upadati pri obeh temperaturah. Med paradižniki, skladiščenimi pri različnih 
temperaturah, tudi ni bilo statistično značilnih razlik v obarvanosti kože. 
 
Ključne besede: Lycopersicon esculentum, paradižnik, skladiščenje, temperatura, izguba 
teže, barva, kemična sestava 
 
 
INTRODUCTION 
 
Tomato is one of the most widely used food crops in world vegetable economy 
(Chapagain and Wiesman, 2004). In Slovenia, tomato plants are being grown in 
almost every home garden as well as in commercial operations (Žnidarčič et al., 
2003). Tomato fruits still live and respire after harvesting, however their quality and 
appearance change during post-harvest handling. 
 
Shelf life is defined as the period in which a product should maintain a predetermined 
level of quality under specified storage conditions (Shewfelt, 1986). A number of 
chemical and physical processes take place in vegetables during shelf storage. Also, 
quality of most fruits and vegetables is affected by water loss during storage, which 
depends on the temperature and relative humidity conditions (Perez et al., 2003). 
Hardenburg et al. (1986) mentioned, that storage under low temperature has been 
considered the most efficient method to maintain quality of most fruits and vegetables 
due to its effects on reducing respiration rate, transpiration, ethylene production, 
ripening, senescence and rot development. Temperature plays an important role in 
maintaining post-harvest quality of tomato fruits, too (Ball, 1997). The effect of 
storage temperature on physiochemical quality and quantity changes in tomatoes, 
varies with cultivar (Abou-Aziz et al., 1976), exposition time (Hobson, 1981) and 
harvesting conditions (Autio and Bramlage, 1986). 
 
Tomato can be stored at ambient temperature for a period of up to 7 days. It is 
generally agreed that for longer period ripe tomato can be stored at a temperature of 
10-15°C and 85-95 relative humidity (Shewfelt et al., 1987; Castro et al., 2005). At 
these temperatures chilling injury and ripening are minimal. However, careful 
handling of fruits during their storage is essential to avoid bruises and injuries. Decay 
organisms enter through such breaks in the skin. 
 
Correct temperature management is also important for the consumer. Tomato should 
not be stored in the refrigerator. Refrigerating a tomato will reduce its flavour by 
approximately 30% (Ressureccion and Shewfelt, 1985). Flavour quality of tomatoes is 
largely determined by the sugar (estimated by soluble solids content) and acid 
composition of the fruit (Moretti et al., 1998). For example, the cold temperature will 
convert the sugars to starch. It will also cause its firm texture to turn pulpy 
(Adegoroye et al., 1989; McDonald et al., 1999). 
 
Tomato colour is another important factor in the consumer preference of tomatoes 
(Thorne and Alvarez, 1982; Batu, 2003). The term colour is based on human 

ŽNIDARČIČ, D., POŽRL, T.: Comparative study of quality changes in tomato … 
 
 
237
perception of light and refers to one narrow band of the electromagnetic spectrum, 
called the visible spectrum (Hendry and Calkins, 1998). The colour of a ripe tomato is 
determined by the ratio of two pigments, lycopene and β-carotene (Hobson and 
Grierson, 1993). Colour can be commonly determined instrumentally because it gives 
more accurate information than other methods (Bakker et al., 1986). The most 
common instrument used is a colour differences meter and a model of the Minolta 
Chroma Meter (Anon, 1993). 
 
In Slovenia, very little research has been done to identify the optimum environmental 
conditions for extending post harvest life of tomatoes. Tomato has potential to be 
developed as an exported crop in Slovenia. Due to the long distance transportation, 
optimum temperature might be needed for storage life extension.  
 
During the 2005 season, study was conducted to evaluate the effectiveness of holding 
fresh tomato fruits in different storage temperatures of 5 
o
C and 10 
o
C to extend their 
post harvest life and maintain fruit quality parameters (weight loss, skin colour, 
soluble solids and titratable acidity). 
 
 
MATERIAL AND METHODS 
 
Tomato plants (Lycopersicon esculentum Mill.) used for the study were indeterminate tomato 
cv. 'Malike' (Clause Tezier). Plants were grown at the Experimental Station of the Biotechnical 
Faculty in Ljubljana in matted rows with 60 cm between rows, 40 cm on the row, and 1 m 
between plots. Transplants were planted in an open field in May. Standard agricultural 
practices were adopted uniformly according to crop requirements. Thirty of the tagged fruits 
per plot were harvested on the same day when they reached the middle-red ripe stage. 
Maturity of middle-red ripe stage fruit was determined in the field using subjective evaluations 
of fruit size, position on the plant, smoothness of fruit shoulder and by observation of locular 
development in some representative fruit (Kader and Morris, 1975). After harvest fruits were 
held overnight at about 10-15 
o
C and transported the following day to the Laboratory of plant 
food technology located at the Department of Food Science and Technology. Upon arrival at 
the laboratory, individual tomatoes were evaluated for initial quality. Only fruit free of apparent 
mechanical injuries, insect damage or disease were selected and placed on cardboard trays. 
The diameter of individual fruits were between 60 and 65 mm. 
 
Fruits were randomly divided in two lots and stored for 28 days at 80-85 relative humidity to 
simulate a commercial storehouse situation. The first lot was stored at 5 
o
C and the second 
one at 10 
o
C. The temperature of storage rooms were controlled using a single point 
thermostat. Relative humidity inside the cold chambers was manually measured daily using 
wet bulbs/dry bulbs device and was maintained by spraying water when necessary. 
 
The tomatoes were analysed five times during storage from October 10
th
 to November 9
th
 
2005. All measurements were done in triplicate. Weight loss, skin colour, soluble solids and 
titratable acidity, were examined every seven days. 
 
Weight loss was evaluated by the difference in fruit weight on the first day of the experiment 
and each sampling. The weight of fruits was recorded using a Mettler balance model Toledo 
PB 602. 
 
Skin colour was measured on three points of the fruit surface; on the shoulder, at the equator, 
and at the base. Colour was measured using a portable Minolta Chroma Meter (Minolta 200b) 
with LCH model calibrated with standard white plate (CY=93.8, x=0.3164, y=0.3208). Colour 
was expressed in coordinates L, a and b. Three readings from each fruit were averaged prior 
to data analysis. 
 

Acta agriculturae Slovenica, 87 - 2, september 2006 
 
238 
Soluble solids concentration (Brix was noted in percentage) of the expressed juice was 
determined using a hand-held Atago PR1 refractometer (brix range 0–32% at 20 °C). 
 
A 10 ml sample was used for determination of acidity by titrating with 0.1 M NaOH. Titratable 
acidity was calculated as g/l citric acid.  
 
The data from all evaluations were subjected to multifactor ANOVA (Statgraphics) to compare 
quality parameters and storage time. Fisher’s least significant difference (LSD) was used to 
discriminate among the means. 
 
 
RESULTS AND DISCUSSION 
 
The tomatoes stored at 5 
o
C and those stored at 10 
o
C differed from the freshly 
harvested tomatoes in the intensity of measured parameters. The storage life of 
tomatoes was determined as 21 days at 10 
o
C, after that time the peel of the fruits was 
turning brown and fruits began to decay. However, from the second group, storage 
life of tomatoes at 5 
o
C was 28 days. 
 
Weight change was related to temperature and storage time. Post-harvest weight 
change in vegetables is usually due to loss of water through transpiration. This loss of 
water can lead to wilting and shrivelling, which both reduce market value and 
consumer acceptability (Ball, 1997). Weight loss of tomato was almost linear at both 
the storage temperatures (Figure 1). As expected, fruits stored at 10 
o
C lost weight 
faster than those stored at 5 
o
C. The intensity of weight loss during storage in the first 
week did not differ between the different temperatures. In both cases the weight loss 
increased more rapidly after seven days. At the end of the storage period the fruits 
stored at 5 
o
C experienced a weight loss of 13.6 % (after 28 days), while those stored 
at 10 
o
C showed values of 14.2 % (after 21 days). Lower temperature can also prevent 
weight loss.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 1: Changes in weight loss (%) in tomato cv. 'Malike' stored in different 
temperature conditions. Vertical lines represent standard errors of the 
means. 
 
0
2
4
6
8
10
12
14
16
18
0 7 14 21 28
Days in storage
Weight loss (%)
5 °C
10 °C

ŽNIDARČIČ, D., POŽRL, T.: Comparative study of quality changes in tomato … 
 
 
239
The fruit's content of soluble solids remained relatively constant during the post-
harvest period up to 21 days (Figure 2). Soluble solids increased slightly from 5.06 % 
to 6.92 % at 5 
o
C (during the 28 day period) and from 5.06 % to 6.26 % at 10 
o
C 
(during the 21 day period). Although soluble solids content was slightly higher in 
fruits at 10 
o
C than in fruits from the other group no statistical significant differences 
for the two temperatures were found. At every stage of storage time, except at the 
initial storage period, the soluble solids content in fruits at 10 
o
C was always slightly 
greater than that found in the fruits at 5 
o
C. From the qualitative point of view, 
however, the soluble solids concentration reached an absolute maximum at the end of 
the storage period. According Salunkha et al. (1974), the increment of soluble solids 
is caused by the biosynthesis processes or degradation of polysaccharides during 
maturity.  
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Figure 2: Changes in soluble solids (%) in tomato cv. 'Malike' stored in different 
temperature conditions. Vertical lines represent standard errors of the 
means. 
 
Changes of titrable acidity during storage were relatively small (Figure 3). The 
quantity of titrable acidity content of fruits at the time of storage varied similarly for 
both temperatures. During the storage the acidity was increasing slightly in the first 
seven days.  During  this  period  the  content of titrable acid increased by 0.08 g/l (at 
5 
o
C) and by 0.07 g/l (at 10 
o
C) on average per day. Afterward the content of titrable 
acid started to decrease at both temperatures. The decrease of titrable acidity after 
seven days was almost linear in all cases although the rate of decrease was slightly 
higher in fruits at the 10 
o
C than at the 5 
o
C. At the end of the storage period there 
were no significant differences among acidity at both temperatures. These results 
agreed with those from Castro et al. (2005) presenting an acidity decrease with 
maturity evolution. Will at al. (1981) showed, that amount of organic acid usually 
decrease during maturity, because they are substrate of respiration. The decrease in 
titrable acidity after seven days coincided with a better score for sensory evaluation of 
stored fruits (data not shown). 
0
1
2
3
4
5
6
7
8
0 7 14 21 28
Days in storage
Soluble solids (%)
5 °C
10 °C

Acta agriculturae Slovenica, 87 - 2, september 2006 
 
240 
0
1
2
3
4
5
6
7
0 7 14 21 28
Days in storage
Titratable acidity (g/l)
5 °C
10 °C
 
 
Figure 3: Changes in titrable acidity (g/l) in tomato cv. 'Malike' stored in different 
temperature conditions. Vertical lines represent standard errors of the 
means. 
 
The colour components (a, b, L) of fruit did not significant vary among particular 
temperature groups (Table 1). The colour changed in fruit corresponds to a fall in 
chlorophyll and an increase in carotenoid synthesis (Pretel et al., 1995), reflecting the 
transformation of chloroplasts to chromoplasts (Leshem et al., 1993). The colour 
development rate of tomatoes increased with increase in maturity (Batu, 2003). 
 
The colour development in fruits was similar at both temperatures. But on the 
contrary the colour components changes during the storage period. The colour value a 
which characterised the red colouring of the fruits (Auerswald et al., 1999), continued 
to increase clearly by 6.3 (at 5 
o
C) and by 6.6 (at 10 
o
C) during the first 21 days. 
Carotenes and xanthophylls contained in tomato, especially lycopene oxidize during 
the storage, gradually changed colour from bright red to dark brown. Our data is in 
accordance with Iwahashi et al. (1999). However, after 21 days all fruits reached their 
maximum red colour and although the fruits at the lower temperature tended to be less 
red than the fruits at the higher temperature, these differences were not significant. 
 
Up to the first seven days, the b parameter, which shows yellow discoluration (Artes 
et al., 1999) remained initially unchanged at both temperatures. Fruit stored at 5 
o
C 
changed b value more slowly. However, after 21 days fruits reached their minimum of 
b value at both temperatures.  
 
Luminance L measured changed rapidly at both temperatures over the first seven days 
of storage and remained at the same value after that. The intensity of luminance loss 
during storage in the first week slightly differed between the temperatures. L value 
was slightly higher in fruits at 10 
o
C than in fruits at 5 
o
C. According Hardenburg et 
al. (1986), storage under lower temperature reduces enzimatyc activities and the loss 
of luminance, resulting from normal ripening and storage process.  
 

ŽNIDARČIČ, D., POŽRL, T.: Comparative study of quality changes in tomato … 
 
 
241
Table 1: Changes in colour components in tomato cv. 'Malike' stored in different 
temperature conditions 
 
Colour components 
a b L 
Storage 
days 
5 
o
C 10 
o
C 5 
o
C 10 
o
C 5 
o
C 10 
o
C 
0  15.4 a 15.4 a 13.9 a 13.9 a 33.5 a 33.5 a 
7  17.8 b 18.6 b 13.6 a 13.7 a 31.6 b 32.2 b 
14  19.7 c 20.8 c 13.0 b 12.4 b 31.4 b 31.8 b 
21  21.7 d 22.0 d 12.6 c 11.9 c 31.3 b 31.5 b 
28  22.3 d -  12.9 b -  31.2 b -  
*Means within the same column followed by the same small letters are not 
significantly different (level of significance 5%)  
 
 
CONCLUSIONS 
 
The final results generally coincided with our anticipated results. 'Malike' tomato 
fruits were submitted to different storage temperatures and evaluated for their quality. 
The following conclusions could be drawn: 
- weight loss of tomato fruit is closely related with the temperature; 
- tomato fruit stored at lower temperatures have an acceptable weight loss; 
- tomato fruit stored at lower temperature had more stability and greater storage life 
than fruit stored at higher temperature; 
- where fruit is sold on a weight basis, loss of water means economic loss. 
Additionally, water loss reduces visual quality; 
- the content of soluble solids progressively increased with storage at both 
temperatures, but earlier at 10 
o
C; 
- the quantity of titratable acids, expressed as citric acid, slightly increased in both 
temperatures in the first seven days. Tomato fruits became less acidic after 14 days 
of storage. The relationship of titrable acidity content and temperature during the 
storage period of tomato fruits on higher and lower temperature was generally 
similar; 
- the red colour appearence of tomato fruit was influenced by time of the 
development. 
 
 
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