Effect of Plastic and Paper Effect of Plastic and Paper Packaging on Tomato Fruits Packaging on Tomato Fruits

Stored at Different Stored at Different Temperatures and High Relative Temperatures and High Relative

HumidityHumidity

I. Chemical Properties, Quality I. Chemical Properties, Quality Attributes and Shelf LifeAttributes and Shelf Life

International Symposium on Greenhouses, Environmental Controls and In-house Mechanization for Crop Production

in the Tropics and Sub-Tropics.

Equatorial Hill Resort, Cameron HighlandsPahang, Malaysia.June 15-17, 2004

By:Abdullah A. Alsadon1,

Abdullah M. Alhamdan2

Mahmoud A. Obied1

1 Department of Plant Production and 2 Dept. of Agric. Engn.,

College of Agric., King Saud University,

P.O. Box 2460, Riyadh 11451, Saudi Arabia

INTRODUCTIONINTRODUCTION

Hydroponic vegetable production is expanding in Saudi Arabia.

Tomato is among the most important vegetable crops worldwide including Saudi Arabia.

Availability of tomato in the market year round - by green houses- is important for farmers as well as for consumers.

Storage temperature, relative humidity and packaging influence fruit quality and shelf life.

Objectives:Objectives:

1. To study the influence of two plastic and paper packages on quality, chemical attributes and shelf life of hydroponically grown tomato fruits.

2. To study the influence of storage conditions (5, 15, and 25˚C at high relative humidity (97%) on fruit quality.

Materials:

Cultivar: Red Gold (De Ruiter, Holland)

Seed were sown in JV7 pots.

Three weeks old seedlings were transferred to the greenhouse.

Materials and MethodsMaterials and Methods

Hydroponic growing system has been used in the Agricultural Research and Experiment Station at Dirab, near Riyadh, Saudi Arabia.

All cultural treatments were carried out as recommended.

Fig. 1. Hydroponically grown tomato plants showing fruits at the time of harvest (at stage 2 maturity as shown in the fruit at left)

Fig. 2. Tomato color chart corresponding to stages

of fruit maturity (Will, et al. 1998).

Average size tomato fruits were harvested at stage 2 (Breaker stage).

Two plastic packaging were used:

- Low Density Poly Ethylene (LDPE), 50 m,

- High Density Poly Ethylene (HDPE), 22 m,.

Paper packaging (Brown paper bags, 0.11mm thick) were also used.

Three growth champers were set at three storage temperatures (5, 15, and 25˚C).

Relative humidity were set at 97% in each champer using humidification and dehumidification system.

Humidifier

RelativeHumidity Controller

المرطاب

Hygrostat

Storage Unit

Dehumidifier

Temperature controller

Thermostat

EnvironmentalControl Unit

Fig. 3 Diagram and photo of relative humidity control system of the storage room

Methods:Methods:1. Fifteen tomato fruits were harvested at

breaker stage and placed inside each type of packaging.

2. Control treatment consisted of un-packaged fruits.

3. Fruits were labeled and divided into three replicates.

4. Another group of fruits were stored for six weeks for chemical analysis.

5. Plastic bags were sealed using thermal sealer.

6. Paper bags were sealed using stapler.7. Fruit characteristics were evaluated weekly.

Measured parameters:Measured parameters:

Weight loss, %. Fungal infection, %. Coloring

Chemical analysis (TSS, PH).

Storage period (shelf life).

RESULTS AND DISCUSSIONRESULTS AND DISCUSSION

Influence of storage conditions and packaging on:

Weight loss, %. Fungal infection, %. Coloring.. Chemical analysis (TSS, PH).

Significant weight loss occurred in fruits stored at 25˚C.

Highest weight loss occurred with prolonged storage time.

Lowest weight loss at 5˚C although not significantly different than at 15˚C.

(1) Weight Loss:(1) Weight Loss:

Fig.(4) Effect of storage temperatures on weight loss of tomato fruits

0

2

4

6

8

10

12

14

16

18

1 2 3 4 5

Storage period (weeks)

We

igh

t lo

ss

(%

)

5 C

15 C

25 C

b

a a a

a

a

a

a

bb

b

b b

b

c

Best storage temperature was 15˚C since weight loss was less and chilling injury was avoided.

Highest weight loss was in unpacked fruits.

Lowest weight loss was in LDPE and HDPE packed fruits at all storage periods.

Fig. (5) Effect of types of packaging on weight loss of tomato fruits

0

2

4

6

8

10

12

1 2 3 4 5

Storage period (weeks)

We

igh

t lo

ss

(%

)

PELD

PEHD

Paper

Controla

aa

a a

a

a

b

bb

bb

b

b

cc

cc cc

Alternaria spp., Fusarium spp., Rhizopus spp., Stemphylius spp.

(2) Fungal infection:

Fruits were infected by one or more of the following fungus groups:

Similar findings (Sommer et al., 2002) indicated that the first three fungus groups generally infest tomato fruits during storage.

Fig. 6 Symptoms of fungal infection on tomato fruits stored in LDPE package at 25 C and 97 % RH after two weeks of storage.

The highest and significant fungal infection occurred on fruits stored at 25˚C.

Fungal infection were the same for fruits stored at 5 or 15˚C except at the fifth and six week of storage.

Fungal infection increased as storage period increased.

Best storage temperature were 15˚C since no significant difference in fungal infection with 5˚C and it did expose fruits to chilling injury as 5˚C.

Fig (7) Effect of storage temperatures on fungi infection

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6

Storage period (weeks)

Fu

ng

i in

fec

tio

n (

%)

5

15

25

a a

aa

aa

aa

b b b b bb

bb

b

b

Highest infection occurred in fruits packed in both plastic packaging.

Unpacked fruits were less infected with fungal diseases followed by paper packed at all storage periods.

Generally, fungal infection intensity correlated Generally, fungal infection intensity correlated with fruit color change as fruit mature.with fruit color change as fruit mature.

As fruits mature, the rate of infection increase.As fruits mature, the rate of infection increase.

Fig (8) Effect of types of packaging on fungi infection

0

10

20

30

40

50

60

70

80

90

100

1 2 3 4 5 6

Storage period (weeks)

Fu

ng

i in

fec

tio

n (

%)

PELD

PEHD

Paper

Control

c

b

a

b

a

a

a a

c

a

aa

a

a

a

aa

b

bb

b

b

c

c

))33 ( (Fruit ColoringFruit Coloring:: Storage at 15˚C accelerated fruit color

change compared to storage at 5 or 25˚C.

Storage at both 5˚C and 25˚C delayed fruit color change.

No significant differences between plastic packaging. They both resulted in slowing fruit color change.

Unpacked fruits and paper packed fruits had a speedy color change.

Fig (9) Effect of storage temperatures on tomato color degree

0

1

2

3

4

5

6

7

8

1 2 3 4 5 6

Storage period (week)

co

lor

de

gre

e

5

15

25b

b b

b

c

b b b b b b

b

a

aa

aa

a

Fig (10) Effect of types of packaging on tomato color degree

0

1

2

3

4

5

6

7

1 2 3 4 5 6

Storage period (week)

Co

lor

de

gre

e

PELD

PEHD

Paper

Controlb

aa

aa

aa

a a a a

a a

b b bbb

b

b bb bb

))44 ( (Chemical Analysis (Chemical Analysis (PH and TSS)H and TSS)

No significant influence of storage temperature or type of packaging on TSS at all storage periods.

TSS ranged from 5.33 to 7.00

Table (1) Interaction effects of storage temperatures and types of packaging on total soluble solid (TSS) of tomato fruits.

Storage temp.(°C)

Type ofpackage

Storage period (weeks)

1 2 3 4 5 6

5

PELD 6.70 b 6.50 a 6.00 bc 6.00 a 6.15 a 6.50 a

PEHD 6.50 b 6.25 ac 6.50 a 6.00 a 6.33 a 6.50 a

Paper 7.00 a 6.42 ab 6.50 a 5.33 b 5.58 b 5.75 c

Control 6.00 c 6.42 ab 5.50 d 6.25 a 6.17 a 6.00 b

15

PELD 6.33 bc 6.25 ac 5.83 c 5.33 b - -

PEHD 6.17 c 6.33 ac 6.00 bc - - -

Paper 6.17 c 6.17 bc 6.13 bc 5.83 a 6.08 a -

Control 6.00 c 6.33 ac 6.25 ab 6.00 a 5.58 b 5.50 d

25

PELD 6.42 bc - - - - -

PEHD 6.33 bc 6.33 ac 5.33 d - - -

Paper 6.42 bc 6.25 ac - - - -

Control 7.00 a 6.08 c 5.83 c - - -

Values having the same alphabetical letter in common do not significantly differ, using the revised L.S. D. test at 0.05 level. -Fruits deteriorated and discarded.

Similarly, No significant influence of storage temperature or type of packaging on PH.

Generally, PH increased as temperature increased and as storage period increased.

Highest PH recorded in HDPE packed fruits stored at 15˚C.

Table (2) Interaction effects of temperatures and types of packaging on

PH of tomato fruits.

Storage temp.(°C)

Type ofpackage

Storage period (weeks)

1 2 3 4 5 6

5

PELD 3.84 f 4.07 cde 4.20 c 4.21 ab 4.12 cd 4.30 ab

PEHD 3.82 f 4.07 cde 4.13 d 4.22 ab 4.70 a 4.38 ab

Paper 3.90 ef 4.06 cde 4.11 de 4.12 bc 4.09 d 3.37 b

Control 3.88 ef 3.98 e 3.99 g 3.99 c 4.12 cd 4.23 ab a

15

PELD 4.30 b 4.13 bc 4.04 fg 4.28 a - -

PEHD 4.93 a 4.14 bc 4.08 def - - -

Paper 3.94 de 4.05 cde 4.11 de 4.32 a 4.20 bc -

Control 3.81 f 4.03 de 4.07 ef 4.22 ab 4.26 b 4.84 a

25

PELD 4.14 c - - - - -

PEHD 4.18 c 4.19 ab - - - -

Paper 4.03 d 4.28 a 4.38 a - - -

Control 3.94 de 4.10 bcd 4.26 b - - -

Values having the same alphabetical letter in common do not significantly differ, using the revised L.S. D. test at 0.05 level.

ConclusionConclusion

1. Highest weight loss occurred in unpacked fruits stored at 25 or 15 ˚C.

2. Although storage at 15 ˚C resulted in speeding of fruit coloring, it is generally recommended for storing tomato fruit to avoid chilling injury, maintain fruit weight, maintain longer shelf life and minimize fungal infection.

3. No significant differences between the two plastic packaging on fruit traits. They both resulted in slowing of fruit color.

4. Unpacked and paper packed fruits resulted in speeding color change and reducing shelf life.

5. Storage at 5˚C and use of both plastic packaging resulted in significant delay in fruit color.

ConclusionConclusion....

6. Generally, TSS was highest in fruits stored at 5 or 15 ˚C with no significant differences between packaging materials.

7. Under the conditions of this study, it is recommended to use both plastic packages for short term storage (2 weeks) and paper packaging for longer periods (up to 5 weeks).

8. It is important to consider the influence of temperature and type of packaging when storing tomato fruits.

ConclusionConclusion....

This study was made possible by:

1- Grant from Saudi Arabian Basic Industries Company (SABIC).

2- Cooperation of Agricultural Research Center of the College of Food and Agricultural Sciences.

Acknowledgement

Thank You for Your Kind Thank You for Your Kind AttentionAttention