This study evaluated the effects of different covering materials on the quality and storage life of Sultana Seedless grapes. Grapes were covered with polypropylene cross-stitch (PK), Lifepack (LP), Mogul (MG), or transparent polyethylene (PE) for about one month before harvesting. The covered grapes were then stored for up to 120 days. The MG covering maintained higher berry removal force compared to others. While all materials maintained quality for 90 days, PK showed some deterioration by 120 days. Combining on-vine covering with cold storage allowed grapes to be stored for 4 months while maintaining shape though losing some flavor and crunchiness over time.

1. EFFECT OF DIFFERENTEFFECT OF DIFFERENT
COVERING MATERIALS USED ATCOVERING MATERIALS USED AT
PRE-HARVEST STAGE ONPRE-HARVEST STAGE ON
QUALITY AND STORAGE LIFE OFQUALITY AND STORAGE LIFE OF
SULTANA SEEDLESS GRAPESSULTANA SEEDLESS GRAPES
Assoc. Prof. Fatih ŞEN1
Aşkın ALTUN1
, MSc
Metin KESGİN2
Yüksel SAVAŞ2
1
Ege University, Faculty of Agriculture, Department of
Horticulture, İzmir-TURKEY
2
Viticulture Research Station, Manisa-TURKEY
35th World Congress of Vine and
Wine
19th June 2012, İzmir-TURKEY

2. INTRODUCTION
Grape is one of the most produced and well-known
fruit crop all around the world
68 M
tonnes
4.2 M tonnes
Source: FAOSTAT,

3. Table grapes
are mostly
exported to
Russian
Federation
followed by
Germany,
Ukraine and
Bulgaria..
In the Aegean Region
Sultana Seedless
variety has been
widely cultivated for
both table and raisin
production. Nearly
1.5 million tonnes
of grapes is being
produced in the
Aegean provinces.
Source: Aegean Exporters

4. In the region, Sultana Seedless prices are at
the lowest level when the supply peaks for the
fresh market.
In November table grape
prices are about 10-30%
higher than the prices in
September.

5. Thus supplying Sultana Seedless grapes for longer
periods is needed for exportexport and domestic markets.
There are two convenient solutions:
On-vine storageCold storage

6. In recent years, producers delay harvest time by
covering vines with various covering materials.
Polypropylene cross-stitch is the common covering
material in the Aegean Region.

7. AIM OF THE
RESEARCH
The research work was carried out with different
covers to examine their effects on grape quality
and storage life.
Additionally, the effect of delayed harvest on fresh
table grapes was assessed as continued with cold
storage.

8. Material and Method
The study was conducted on grapes cv.
‘Sultana Seedless’ in vineyard of Viticulture
Research Station located in Manisa province
between 2009 and 2011.

9. Cultural treatments were performed as recommended
for the table grapes.
Covering materials were covered on vines in the first
week of September in both years.

11. Polypropylene cross-
stitch (PK)
•made of polypropylene,
•white coloured,
•fabric covering material
Lifepack (LP)
•has three layers
•water-resistant
•8% UV additive top layer

12. Mogul (MG)
•made of polypropylene
•white coloured,
•light transmittance: 70%
•3% UV additive
Transparent polyethylene
(PE)
•made of polypropylene
•transparent coloured
•light transmittance: 95%
•3% UV additive

13. Grapes under cover
were harvested nearly
one month after than
those maturing under
open conditions.
Harvested grapes were
placed in plastic boxes and
later packaged into bags
before pre-cooling.

14. Packaged
grapes
E.U.Z.F. Storage Unit
Pre-cooling
24h, -0.5°C %95 RH
Storage
(-0.5 ± 0.5°C %90-95
Placing SO2-generating
pads and closing off PE
bags

15. In the first year, the grapes were kept for 90 days
and in the second year for 120 days in storage.
Grapes were sampled at harvest, and on 60th,
and 90th days and in the second year also on
the 120th day of storage.

16. Quality parameters analyzed
Berry removal force: Penetrometer (Somyf tec, N)
Color: Minolta colorimeter (CIE-L*, a*, b*)
Total soluble solids (TSS, %)
Titratable acidity (TA, g tartaric acid/100ml),
(Karaçalı, 2009)
Maturity index
Sensory analysis
Decay incidence (Anonymous, 1996)

18. Temperature and Humidity
Under cover tempature and relative humidity was measured
and saved with data loggers.

19. Results and Discussion
Berry Removal Force
• MG covering material has given higher results than others.
• After 90 days berry removal forces began to decrease.

20. Colour
Effects of covering materials on colour values seemed
similar in both years of the study.
PK, 90th day
LP, 90th day
MG, 90th day
PE, 90th day

21. Total soluble solids (%)
• Non significant in the first year.
• In the second year PE was found enhancing TSS compared
to other covering materials.

22. Titratable acidity (TA)
• In the first year, no significant effect on TA.
• PK has given higher results than others.
• At the end of the storage, TA has a decrease trend
comparing to pre-storage results.

23. Maturity Index
• Limited changes in the first year.
• PE has showed higher results in all cover materials in the
second year.

24. Sensory analysis
• Higher scores resulted from good looking.
• Low flavour and crunchiness values.

25. No SO2 damage, odor or taste has been observed during
cold storage phase.

26. Decay incidence
LP, 90th
day
PE, 90th
day
MG, 90th day

27. Moderate deterioration observed in grapes covered with
PK covering material on the 120th day of storage.
PK, 120th day

28. Stem Browning
M
G
P
E
PLP

29. Using dual release SO2-generating pads and
convenient pre-cooling and storage conditions
were effective in non-existence of stem browning.

30. CONCLUSIO
NGrapes can be stored for 4 months
successfully with the combination of covering
materials (1 month) and cold storage (3 months).
After 120 days of storage grapes seem good in
shape but not in flavour and crunchiness.
There are not prominent differences in effects of
covering materials on berry colour.

31. PE covering material is not recommended
because of causing damages on grapevine
leaves.
MG covering material can be preferred
because of yielding higher berry removal force
values.

32. Teşekkürler
Thank
You
Merci
Danke schön Grazie
Gracias