Indian Journal of Traditional Knowledge
Vol. 10(2), April 2011, pp. 375-379
Evaluation of self-life and organoleptic aspects of fruits stored in a modified
traditional earthen pot cool chamber
Murugan AM1, Ranjith Singh AJA1* & Vidhya, S2
1
Department of Advanced Zoology and Biotechnology Sri Paramakalyani College, Alwarkurichi 627 412, Tamil Nadu;
2
Department of Microbiology Srimath Andavan Arts and Science College, Thiruvanaikoil,
Trichirapalli 620 005, Tamil Nadu
E-mail: [email protected]
Received 17.11.2009; revised 09.04.2010
The efficacy of earthen pot cool chamber to store vegetables and fruits were studied using tomato, grapes and brinjal.
The quality retaining capacity in the products kept in earthen pot cool chamber was compared with other type of storage
system like refrigeration and room temperature. After 9 days of storage, physiological weight loss, changes in microbial,
nutrient (biochemical changes) and organoleptic value were evaluated. The products stored in earthen pot cool chamber
were fresh and less affected when compared to other storage systems. The study revealed that the earthen pot cool chamber
(EPCC) is a good storage system to keep the vegetables in fresh condition. It is an eco-friendly, energy saving and cost
effective alternative method to substitute refrigeration.
Keywords: Earthen pots, Pot cool chamber, Traditional storage, Traditional refrigeration
IPC Int. Cl.8: A01F25/00
Since the dawn of civilization, man has learnt the art
of developing earthenware utensils for food
preparations, eating and storage of food or
agricultural products. Earthenware cool chambers are
eco-friendly, non-toxic, less expensive, degradable
and are made up of readily available material that can
be used as an alternative to refrigerator to a great
extent in rural areas. Thereby power consumption,
pollutants particularly chlorofluorocarbon release and
other pollution load to the environment can be
reduced. Many researchers have given different
design to make double walled brick cool chambers1-5.
But it has it’s own merits and demerits. To overcome
these, an efficient earthen pot cool chamber (EPCC)
was designed to increase the shelf-life capacity6. In
the study, a double vessel EPCC was designed and
shelf-life capacity and preservation of organoleptic
value in fruits & vegetables (tomato, brinjal, and
grapes) were tested to evaluate the efficiency over of
the unit over refrigerator and room temperature.
present in the smaller vessel to keep the smaller vessel
intact inside the larger vessel (Fig. 1). In such a way
that a gap is present in between the vessels and water
should be poured between these two vessels. Water
present in the vessel plays a vital role in regulating
relative humidity and to maintain low temperature. In
EPCC, the humidity was 87–92% and temperature
was 5-6°C lesser than the room temperature. Relative
humidity and temperature at room condition were
60±2% and 29 ±1°C, respectively. But in the
refrigerator, the relative humidity and temperature
were 55% and 5±1°C. To test the efficacy of the
earthen pot cool chamber, three agro-products, viz.
tomato, grapes and brinjal were collected in a garden
fresh state from the farms in Alwarkurichi, South
Methodology
EPCC consists of two vessels, an outer and an inner
vessel; outer is larger and inner is smaller. Small inner
vessel can fit into the larger outer vessel; a lock is
__________
*Corresponding author
Fig. 1―Modified earthen pot cool chamber
Parts of cool chamber
INDIAN J TRADITIONAL KNOWLEDGE, VOL 10, No. 2, APRIL 2011
376
Tamilnadu. The samples collected were washed with
sterile water and packed in sterile plastic bags with
respiratory holes. The initial weights of the sample
were noted and were stored in three different types of
storage systems, viz. EPCC, refrigerator and room
(room temperature). In duration of every 48 hrs, the
physiological loss in weight, changes in organoleptic
characteristics, microbial load, protein and
carbohydrate level in the stored products were
monitored and recorded. The storage was extended to
nine days and the study parameters were recorded
regularly. Physiological loss of weight (PLW) was
calculated using the following formula:
PLW=
Initial weight-Final weight × 100
Initial weight
For total microbial load count, one gram of each
stored products were dissected out separately and
homogenate with 9 ml of sterile distilled water.
After serial dilution, the microbial load of bacterial
and fungal colonies was enumerated using nutrient
and potato dextrose agar medium respectively.
Carbohydrate content and protein content were
estimated using Anthrone and Lowry’s method,
respectively.
To
evaluate
the
organoleptic
characteristics viz., taste, texture, appearance and
flavour, the following scale was used (Table 1)
according to National Research Centre for Banana
(NRCB), Tiruchirapalli, Tamil Nadu.
Results and discussion
In the study, the efficacy of the EPCC to keep the
vegetables in good storage condition was evaluated
and was compared with other storage processes.
During the course of storage, changes in physiological
weight bacterial load, fungal presence, biochemical
factors and organoleptic characters were analyzed.
The total weight of tomato, grapes and brinjal
decreased due to physiological stress when stored for
long period. The weight of the three products was
recorded before keeping them in storage units. After
storage, weight changes due to physiological stress
were noted on 3rd, 5th, 7th and 9th days, respectively
(Table 2). After 9 days of storage in the earthen pot
cool chamber, the physiological loss in weight was
5.3% for grapes, 7.5% for tomato and 1.69% for
brinjal. But, in refrigerator, the physiological loss in
weight was 10% for grapes, 10% for tomato and
2.35% for brinjal, where as in room storage, the
physiological loss in weight was higher than
refrigerator and EPCC. The efficiency of EPCC to
reduce the physiological loss in weight was due to
minimum stress. Stress leads to loss of membrane
integrity, leakage, loss of permutation changes in
enzyme activity7. The mechanical stress leads to loss
of quality during post harvest period. The ethylene
stress widely initiate ripening of fruits in storage8. In
EPCC, there is less pathological stress and the
evaporation process is minimum. But, in refrigerator,
Table 1―Table showing evaluation scale for organoleptic qualities
Scale
5
4
3
2
1
Skin colour
Appearance
Flavour
Texture
Tasted & odour
Overall quality
Expected
Very attractive
Attractive
Good
Fair in appearance
Poor
Excellent
Very acceptable
Good
Poor
Poor
Very hard
Hard
Soft
Very soft
Too Soft
Excellent
Quite acceptable
Good
Fair
Poor
Excellent
Quite acceptable
Good
Fair
Poor
Table 2―Changes in the total weight of different agro-products after
Nature of
storage
Samples
Room
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
Refrig-erator
EPCC
1st day
14.0
13.3
3.66
15.0
12.2
3.23
15.0
13.3
3.6
Weight changes (gm) during storage intervals (days)
3rd day
5th. day
7th day
13.8 (1.42)
13.2 (0.75)
3.65(0)
14.8 (1.33)
12.1 (0.81)
3.22 (0.30)
14.8 (1.33)
13.20 (0.15)
3.6(0)
13.0 (7.14)
12.9 (3.07)
3.63
14.6 (2.66)
11.7 (4.09)
3.19 (1.23)
14.7 (2.00)
12.9 (3.00)
3.6(0)
12.5 (10.71)
12.5 (6.01)
3.59
13.9 (7.33)
11.5 (5.7)
3.16 (2.16)
14.4 (4.00)
12.5 (6.00)
3.6(0)
9th day
Final percentage
loss in weight
12.11 (13.57)
11.3 (15.03)
3.56 (2.33)
13.5 (10.1)
11.0 (10.0)
3.15 (2.35)
14.2 (5.3)
12.3 (7.51)
3.5 (2.77)
13.57
15.03
2.73
10.0
10.1
2.35
5.3
7.51
1.69
MURUGAN et al.: EVALUATION OF SELF-LIFE AND ORGANOLEPTIC ASPECTS OF FRUITS
there was an increase in physiological loss of weight
due to mechanical stress, water stress, freezing or
chilling injury. Freezing injury had been reported to
reduce the physiological weight loss9.
The distribution of total heterotrophic bacterial and
fungal population in the stored products on the first
day and ninth day after storage showed marked
variation (Tables 3 & 4). The bacterial and fungal
load was analyzed in grapes, tomato and brinjal in all
the three storage systems. Bacterial invasion into the
storage products may be due to injured tissue, natural
opening and wounds. Many bacteria enter through
wounds producing soft rot in fruits and vegetables10.
The main reason for highest bacterial and fungal
count in the vegetable kept at room temperature was
because of the fact that room environment is a good
medium for the dispersion of microorganisms. The
reason for higher microbial load in refrigerator was
due to mechanical stress, chilling injury, ethylene
stress, which leads to the ooze out of nutrients, which
provide a better growth medium for the organisms.
The reason for low growth of fungi is due to low
relative humidity. The increase in fungal load in the
EPCC stored products may be due to high relative
humidity in the chamber. The reason for low growth
377
of bacteria in EPCC stored product was due to
efficient temperature maintenance in EPCC and it did
not support the growth of mesophilic as well as
pychrophillic microorganism. Also, the domination of
fungal growth suppresses the growth of bacteria due
to antibiosis. The carbohydrate and protein content of
the three stored products were recorded before and
after storage (Tables 5 & 6). The carbohydrate and
protein content of all three samples was reduced much
in room temperature than in refrigerator and EPCC
due to less physiological changes in the sample, less
microbial activity and low mechanical stresses in
EPCC. Retaining of water and moderate temperature
prevents glucose oxidation11. Post harvest diseases
also bring about a substantial decrease in the sugar
content of the fruit12.
The organoleptic characteristics were evaluated in
the stored products (Table 7). The results of
organoleptic values in grapes in room temperature,
refrigerator and EPCC were 51.0%, 58.0%, and
83.0%. For tomato, it was 60.5%, 63.7% and 75.0%
and for brinjal, it was 76.0%, 80.0% and 85.0%,
respectively. Retaining ability of organoleptic values
in EPCC was better when compared to the products
stored at room temperature and refrigerator. The
Table 3―Total heterotrophic bacterial load in the stored products
Nature of storage
Total heterotrophic bacterial population in different days ( x105 cfu/ gm )
1 day
3rd day
5th day
7th day
9th day
Sample
st
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
Room
Refrigerator
EPCC
4.5
3.5
30.5
15
1.6
20.5
15
1.0
―
25.9
54.3
69.8
14.8
15
40.8
14.8
13.8
23
68
105.5
158.9
14.6
39.3
103
14.7
20.5
56.9
158
188
TNTC
13.9
70.8
159
14.4
40
108
TNTC
TNTC
TNTC
13.5
190
TNTC
14.2
5.5
209.3
TNTC – Too Numerable Too Count
Table 4―Total fungal colonies in the stored products
Nature of storage
Sample
Total heterotrophic fungal population in different days(x103 cfu/ gm)
1 day
3rd day
5th day
7th day
9th day
st
Room
Refrigerator
EPCC
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
3
―
3.5
―
―
3.5
―
―
5.9
6.5
5.3
8.9
2.3
5.3
8.9
4.5
3.3
10.8
10.6
18
40.8
10
18
40.8
13
20
40.5
55
23.5
70.8
63
23.5
70.8
18.5
69
130.8
185
56.5
145.3
50
56.5
145.3
208.3
130.4
170.8
INDIAN J TRADITIONAL KNOWLEDGE, VOL 10, No. 2, APRIL 2011
378
Table 5―Changes in the carbohydrate content of the different stored products
Nature
storage
of Sample
Room
Refrigerator
EPCC
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
1st day
3rd day
205
37
48
208
40
43
210
36
50
201 (1.95)
34 (8.10)
47 (4.10)
205 (1.44)
37.5 (0.62)
42.5 (1.16)
207 (1.42)
34.4 (4.4)
49.5 (1.0)
Carbohydrate content (mg/g)
5th day
7th day
198 (3.41)
31.5 (14.86)
45 (6.25)
203 (2.40)
35 (12.5)
41.5 (3.48)
202 (3.80)
31. 5(12.5)
47 (6.0)
195 (4.87)
28 (24.32)
43.5 (9.37)
198 (4.80)
33 (17.5)
40 (6.97)
199 (5.23)
29 (19.44)
40 (20.0)
9th day
190 (7.31)
26.5 (28.37)
42 (12.5)
195 (6.25)
30.6 (23.5)
39.5 (8.13)
198 (5.71)
28 (22.22)
45.5 (11.0)
Table 6―Changes in the protein content of the different stored products during the different storage periods (percentage of loss is
given in parenthesis)
Nature of storage
Room
Refrigerator
EPCC
Sample
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
1st day
3rd day
Protein content (mg/g)
5th day
7th day
9th day
4.5
18.5
14.2
5
20
13.8
5.5
19
15.5
4.0 (11.11)
17 (8.10)
13.2 (7.04)
4.8 (4.00)
18 (10.0)
13.2 (4.34)
5.3 (5.45)
17 (10.52)
15.0 (3.22)
3.80 (15.5)
15.6 (15.67)
13.0 (8.45)
4.5 (10.0)
16.5 (17.50)
13.0 (5.79)
5 (9.09)
15.5 (18.42)
14.6 (5.22)
3.0 (33.33)
12.0 (35.13)
11.5 (19.01)
3.5 (30.0)
13.0 (35.0)
11.5 (16.66)
4.0 (27.27)
12.5 (36.68)
14.0 (9.67)
Table 7―Percentage changes in organoleptic qualities in the
stored products
Nature of stage
Sample
Percentage change in
organoleptic value after 9
days of storage
Room
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
Grapes
Tomato
Brinjal
56 (p)
60.5 (F)
76.0 (QA)
58 (F)
63.7 (Fair)
80.0 QA
83 (QA)
75.0 (QA)
85 (QA)
Refrigerator
EPCC
P – Poor; Q.A-Quite Acceptable; F-Fair
reasons for high organoleptic value in EPCC were
mainly because of the rise in relative humidity
(>70%) and fall in temperature from ambient
condition. The higher relative humidity retains the
water content of post-harvested sample. Because
water is an important factor in maintaining post
harvest quality, it helps to maintain pH inside the
storage area. Any change in pH results in water loss
and affect the appearance, texture and in some case
flavors. Water loss also affects the crispness and
trimness13. In room temperature, the humidity was
3.5 (22.22)
13.5 (27.02)
12.3 (13.38)
4.0 (20.0)
14.5 (32.5)
12.3 (10.86)
4.5 (18.18)
14.5 (23.68)
14.3 (7.74)
low and hence the water loss was high causing
marked changes in organoleptic value. In refrigerator,
dehydration process had taken placed, which lead to
water loss and hence the organoleptic value of
refrigerated food was affected and the product became
hard in texture. The loss of 5-10% moisture rendered
a wide range of products unstable14. Cool chamber
stored fruits and vegetables look fresh and taste better
than the ones stored at room temperature4. The
marketing ability of fruits and vegetables highly
depend upon freshness, high organoleptic value and
nutritive value, which can be highly maintained by
keeping them in EPCC when compared to refrigerator
and at room temperature. But the technology has
limitation for storing and pre-cooling the product in
bulk. Therefore, the commercial size cool chamber
has been planned to develop by using some other
technology.
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