HARVESTING, HANDLING AND PACKAGING OF TABLE GRAPES FOR EXPORT

HARVESTING

 Standards of grape maturity  Sugar level (sweetness)  Acid level (acidity taste)  Colour of the berries  White cultivars: Green, amber, yellow  Red cultivars: Pink, light red, dark red  Black: Black is only option  Sugar:acid ratio (20:1-35:1)

Sugar levels

   International standards for USA, Europe, UK, Far East (developed countries)   Minimum sugar levels (degrees Brix)  15.5-17.5 degrees Brix Sugar:Acid ratio  20:1 to 25:1 Cultivar differences are very great Standards are different for various cultivars

Refractometer

 Instrument that measures degrees Brix  Helpful instrument to determine the ripeness levels of the grapes  Planning essential for the start of harvest  Client may discard the fruit if minimum sugar levels are not adhered to

Specialised and expensive instrument that needs careful handling, cleaning and regular calibration with distilled water Vital instrument for any grape grower

GREEN Sultana/Kishmish

Grape colour (white)

AMBER Sultana/Kishmish YELLOW Sultana/Kishmish

PIENK Crimson Seedless

Grape colour (red)

RED Crimson Seedless DARK RED Crimson Seedless

AUTUMN ROYAL

Grape colour (black)

MIDNIGHT BEAUTY

Local market versus Export market

  What are the differences??

Why should we think differently about the two?

 Time between harvest and selling in local market is 1-2 days  Time between harvest and selling in export market is 7-30 days 

FRESHNESS or SHELF LIFE or KEEPING QUALITY

Local market sales

IDEAL SITUATION

  To retain peak condition, harvested grapes must be transported as quickly as possible to a facility where it can be cooled rapidly to reduce its field heat This fast cooling should be followed by storage at a constant temperature (0-1 degree Celsius), high humidity (90-98%), suitable air movement and atmospheric composition.

MIND SET FOR EXPORT

   What are the main challenges we face to increase the shelf life of the grapes?

TWO MAIN CHALLENGES

 

Decrease temperature as fast as possible after picking Maintain humidity as high as possible as soon as possible after picking

Large commercial exportation in USA, SA, Chile, Australia  Storage at 0-1 degree Celsius after fast cooling  90-98% Relative Humidity

Modern packing facilities -cooling -hygiene -handling

Modern cooling and transport facilities

Importance of temperature

Maintaining the cold chain

Maintaining the cold chain

Understanding the grape

  Extremely important to know what happens to the bunches after they have been harvested, because then we know what we can do to prevent fast deterioration of the fruit.

Remember:  Grapes do not ripen after harvest like some other fruit (bananas, pears), it only deteriorates   Aim of post harvest treatments are to limit the rate of deterioration High temperature cause water loss and low humidity will increase the rate of deterioration after picking will from the stems and berries, and this

Symptoms of water loss

   1-2% weight loss of bunch will have negative effects on berry firmness and stem colour 3-5% weight loss of bunch will cause serious deterioration  Bunch discoloration (browning)    Drying of bunch stems Loose berries Loss of berry firmness This deterioration is permanent and will cause rejection of the fruit by the market

Symptoms of water loss Stem browning due to delays before cooling

32°C/80% Relative Humidity + 6 days at 0°C/80%RH

Symptoms of water loss Stem browning Loss of berry firmness

Loose berries Browning

Good storage conditions

  Break in cold chain can increase risk of decay and disease development  Botrytis rot biggest problem Surface and sub-surface browning of berries can develop in sensitive cultivars

Internal browning Grapes before harvest Deterioration as browning after storage

Botrytis decay Grey mould

Physical bruising Sun burn

Effects of water loss

No cooling + bad storage <10 days Proper cooling + storage 130 days

Realities for Afghan growers

 We do not have all the specialized equipment and facilities as the developed countries  We do not have cultivars with good natural shelf life  BUT:  What are we going to do to get our grapes in the best possible condition for export?

Actions to prevent deterioration

 Before picking  Vineyard management that produced healthy grapes  Bird damage  Good cluster formation (low compaction)  Bee/wasp/other insects damage  Physical damage  Phytosanitary control of diseases (powdery mildew, Botrytis)

Bird damage Wasps/bees

Bird control

Bags Netting

Sun burn Physical blemishes

Berry split/cracking and sun spots

Compact bunch damages easily Loose bunch with less risk of damage during transport

Diseases Powdery mildew

Severe mealy bug infestation of clusters

Actions to prevent deterioration

 During picking   Boxes for picking must be clean Clean harvesting scissors for picking        Clean hands Harvest during cool part of the day (<25°C) Handle fruit carefully Pack only one layer of grapes in box Put soft materials at bottom of box Pick bunches of mostly similar maturity and berry size (uniformity) Transport as quickly as possible to working area

Harvesting equipment

Harvesting scissors Cluster preparation and cleaning scissors

“Clamping” the cluster Wrong way of handling fruit Multi layers in picking boxes Dirty basket

Correct way of handling fruit Support cluster at bottom Soft material in bottom to prevent bruising Single layer of fruit in picking box

Pick grapes of similar maturity Even maturity Uneven maturity

Transport grapes from the field to pack house as quickly as possible

Actions to prevent deterioration

 During handling of clusters in pack house  Work hygienic (clean hands, area of working, equipment)   Trimming the bad parts of the cluster     Rot Bird damage Physical damage, undesirable berries Remove undesirable parts that will make packaging difficult Careful handling of the cluster     Limit touching the berries No damage by the scissors to other berries, disease later Handle the bunch by the stem only Work softly with the bunch when picking it up and putting it down

Careful handling of clusters

Actions to prevent deterioration

 During packing the fruit in boxes for export  Packing only one layer of bunches, no stacking of bunches on top of another      Hygienic area and equipment Always clean your hands Boxes must be clean Packaging material must be clean Height of grapes in the box may never be higher than the height of the box

Packaging procedures

SO2 pad

Types of packaging

Paper bags Panets Plastic carry bags Loose Sponge (loose)

Strength of boxes to prevent pressure on clusters below

Practical approaches to Afghanistan limitations

  Our limitations are:  Lack of cultivars with good natural shelf life   Shindokghani Taifi     Delays between picking and packing shed Lack of proper cooling facilities and during transport after picking Lack of proper control of humidity Lack of proper packaging materials TRY TO LIMIT THE HANDLING OF THE GRAPES TO AS LITTLE AS POSSIBLE

Field preparation and packing

Cooling options

Straw house for packing and storage Evaporative cooling by wetting the sides during the day and thereby creating lower temperatures inside as well as increased humidity

Transport options

Creating air flow for bulk loads

Transport options

Creating air flow through the load Stacking the boxes inside with space for air flow

Packaging options

     Rice straw/dry grasses as liners in the bottom of boxes to limit physical damage No “pressure” of grapes between boxes The use of plastic/polyethylene liners inside the boxes are the only probable means of ensuring less water loss during transport  But: Can result in “sweating” of grapes Open truck transport of grapes without humidity protection is extremely risky  Good airflow in the shipment will increase the rate of water loss of the berries and stems Use of plastic liner will also decrease physical damage of the fruit in the wooden/carton box  Physical damage=juice=fast deterioration (rot)

Loose packaging

Bagged packaging

Summary

        We do not have the modern advantages, accept it Pick the fruit during the coolest part of the day (early morning) Pick the grapes carefully and only pack as one layer before trimming and cleaning Work in a shaded place (straw house) Store the grapes well ventilated with good humidity Cover the grapes inside the boxes with plastic liner to limit water loss Get the grapes to the market as quickly as possible Be inventive in your efforts to keep the grapes cool and as humid as possible