Difference between revisions of "Grapefruit"

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(Harvesting and handling)
 
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{{Infobox_Fruit
 
{{Infobox_Fruit
 
| image                              = grapefruit.jpg
 
| image                              = grapefruit.jpg
| carrying temperature                = Generally 10°C to 15°C, dependent upon variety
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| carrying temperature                = Generally 12°C to 14°C, dependent upon variety
 
| highest freezing point              = -1,1°C
 
| highest freezing point              = -1,1°C
 
| acceptable product temp            = Max. 5°C above carrying temperature
 
| acceptable product temp            = Max. 5°C above carrying temperature
 
| Optimum humidity                    = 90%  
 
| Optimum humidity                    = 90%  
 
| Ventilation setting for containers  = 50 m³/hr   
 
| Ventilation setting for containers  = 50 m³/hr   
| Storage life                        = 1-2 months, dependent upon variety
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| Storage life                        = 6-8 weeks, dependent upon variety
 
| Climateric / non-climateric        = Non-Climacteric  
 
| Climateric / non-climateric        = Non-Climacteric  
 
| Ethylene production                = Very Low
 
| Ethylene production                = Very Low
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== Harvesting and handling ==
 
== Harvesting and handling ==
The grapefruit is a large, yellow-peeled, round citrus [[fruit]] weighing approximately 250 - 700 g. Its pulp is very juicy and has a refreshing, aromatic taste. The bitter taste is caused by the glycoside naringin; the amount of this bitter substance present varies according to variety and place of origin. Grapefruit from the tropics generally have a sweeter, less sharp flavour than those from cooler regions of cultivation. The "Ruby" and "Ruby red" varieties, for example, are red-fleshed, seedless fruits with a reddish tinge to the peel in parts (russeting) and a milder, sweeter flavour than other varieties. In international trade, they are two of the most important varieties.
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The grapefruit is a kind of berry with a leathery rind that is divided into segments. Each segment contains hundreds of individual juice vesicles that comprise the majority of the edible portion of the [[fruit]]. White and red pigmented cultivars are grown. Marsh is the predominant white cultivar. Ruby Red, Star Ruby, Henderson, Ray Ruby, and Flame are the most popular red pigmented varieties.<br><br>
<br><br>
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A high quality fresh-market grapefruit will have a turgid, smooth peel and be relatively blemish-free. The fruit should be elliptical and firm. An appropriate balance of SSC:TA within the edible portion should be achieved, and bitterness should be at a minimum.<br><br>
The degree of ripeness of citrus fruit is determined on the basis of three criteria:<br><br>
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Marketable fresh grapefruit generally range from size 23 (23 fruit/carton) through 56 (56 fruit/carton). Grade standards for fresh grapefruit rely on color-break, texture, peel blemishes, shape and firmness. In markets that emphasize processing, grapefruit must achieve a minimum juice content and SSC/TA ratio before harvest. Grapefruit are commonly packed, stored and shipped in 4/5 bushel [[cardboard]] cartons.<br><br>
* by the ripeness index: this is determined by the Brix value, which is a measure of the sugar/acid ratio of the [[fruit]].
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Grapefruit is a non-climacteric [[fruit]] and does not exhibit a classic ripening pattern of increased respiration and ethylene production.<br><br>
* by cutting at purchase: freshness is determined by cutting the fruit in half from the stem-end to the opposite end. If the fruit is withered at the stem-end, it must not be shipped.
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Degreening is necessary for marketing early-season fresh grapefruit in areas where night temperatures remain high. High RH of approx. 90% must be maintained to avoid softening and accentuation of existing peel injuries or blemishes.<br><br>
* by peel colour: the colour of the peel is not necessarily a reliable indicator of ripeness, but its surface gloss is.<br><br>
 
Fruit harvested early in the season may be 'degreened' by means of manufactured ethylene released into the room. The appropriate regime is dictated by cultivar and growing conditions. Ethylene treatment carries with it the disadvantage of hastening the death of green 'button' tissue, thereby predisposing the fruit to invasion by stem-end rot fungi.  
 
<br><br>
 
Fungicides are diphenyl, orthophenylphenol (OPP) and thiabendazole (TBZ). Diphenyl can be recognised from its naphthalene-like odour. The fungicides primarily prevent blue and green moulds, but they do impair flavour and indication of their use is mandatory.  
 
Waxing to prevent loss of aroma and weight is required because the washing process removes the natural wax layer. The film of wax sprayed onto the peel only partially seals the pores so that the fruits are still able to respire.
 
<br><br>
 
Grapefruit are mainly eaten fresh as a very popular breakfast fruit, but they are also used in the production of juices, marmalades, salads etc. Because of its impact- and pressure-sensitivity, the fruit has to be handled with appropriate care. A high quality fresh-market grapefruit will have a turgid, smooth peel and be relatively blemish-free. The fruit should be elliptical and firm, and bitterness should be at a minimum.
 
  
 
== Cooling and storage ==  
 
== Cooling and storage ==  
 
The selection of a proper temperature for storing grapefruit should be based on pre-harvest factors - including weather during growth, tree condition, and orchard treatments - as well as ripeness of the fruit, postharvest handling, and length of proposed storage.  
 
The selection of a proper temperature for storing grapefruit should be based on pre-harvest factors - including weather during growth, tree condition, and orchard treatments - as well as ripeness of the fruit, postharvest handling, and length of proposed storage.  
 
<br><br>
 
<br><br>
Storage and transport temperatures differ considerably in their specific details according to variety and country of origin and are stated as different in the literature. For this reason, it is imperative that the specific travel temperature be indicated in writing by the consignor. The cargo should be pre-cooled prior to loading. California and Arizona grapefruits store best (4-6 weeks) at 14° to 15°C and Florida/Texas grapefruit at 10°C. Israeli and South African grapefruit are to be kept at 10°C to 12°C, at which they have a PSL of 10-16 weeks.
+
Storage and transport temperatures differ considerably in their specific details according to variety and country of origin. Hence, it is imperative that the specific carrying temperature be indicated in writing by the consignor. The cargo should be pre-cooled prior to loading. California and Arizona grapefruits store best (4-6 weeks) at 14° to 15°C and Florida/Texas grapefruit at 10°C. Israeli and South African grapefruit are to be kept at 10°C to 12°C, at which they have a PSL of 10-16 weeks.
 
<br><br>
 
<br><br>
 
Coating grapefruit with high shine water waxes reduces the incidence of chilling injury and may permit slightly lower carrying temperatures (approx. 8°C) to reduce fruit respiration and minimise postharvest pitting which is a peel disorder that affects waxed grapefruit stored at higher temperatures. Pitting associated with postharvest pitting is targeted to areas of the peel surrounding the oil glands, whereas pitting associated with chilling injury is not targeted to oil glands.  
 
Coating grapefruit with high shine water waxes reduces the incidence of chilling injury and may permit slightly lower carrying temperatures (approx. 8°C) to reduce fruit respiration and minimise postharvest pitting which is a peel disorder that affects waxed grapefruit stored at higher temperatures. Pitting associated with postharvest pitting is targeted to areas of the peel surrounding the oil glands, whereas pitting associated with chilling injury is not targeted to oil glands.  
 
<br><br>
 
<br><br>
Chilling damage is manifested in citrus fruits in particular by spots on the peel (brown dots on the peel), accompanied by a bitter taste and unpleasant odour, rot and cell wall collapse. The glossiness of the peel is lost and the albedo layer (inner layer of the peel), which is normally white, turns a dark colour. When the fruit is divided up, the segments, which have a low juice content, break up and the whole fruit is glassy and soft. The severity of the chilling damage is determined not only by the extent to which the temperature has fallen beneath the limit, but also by the length of exposure to this temperature. In grapefruit there is a risk of chilling damage at temperatures below 6°C.
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Significant warming of refrigerated fruit results in condensation and spoilage, and very high temperatures render the grapefruit highly impact-sensitive and susceptible to mould. Fresh air ventilation is important as citrus fruit can start to ferment within a few hours due to anaerobic respiration (resulting in total loss of the fruit). If fresh air ventilation is insufficient, storage damage may occur, implicating a bitter flavour and peel scab.<br><br>
<br><br>
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In areas infested with a number of tropical fruit flies, cold treatment is an approved quarantine treatment. However, grapefruit must first be preconditioned at 10 to 15 °C to increase resistance to chilling injury. After 1 week, temperatures can be reduced to 0.6 to 2.2 °C for 2-3 weeks. In areas of low fly infestation, a less stringent temp/duration schedule can be used.<br><br>
Excessively rapid warming of refrigerated fruit results in condensation and spoilage, and excessively high temperatures render the grapefruit highly impact-sensitive and susceptible to mould. The addition of fresh air is extremely important as citrus fruit can start to ferment within a few hours due to anaerobic respiration (resulting in total loss of the fruit). If ventilation is inadequate, storage damage may occur, taking the form of a bitter flavour and peel scab.
 
  
 
== Mixed loads ==  
 
== Mixed loads ==  

Latest revision as of 16:24, 1 November 2017

Infobox on Grapefruit
Example of Grapefruit
Grapefruit.jpg
Freshness facts
Optimum carrying temperature Generally 12°C to 14°C, dependent upon variety
Highest freezing point -1,1°C
Acceptable product temp. at loading into containers Max. 5°C above carrying temperature
Optimum humidity 90%
Ventilation setting for containers 50 m³/hr
Storage life 6-8 weeks, dependent upon variety
Climacteric / non-climacteric Non-Climacteric
Ethylene production Very Low
Ethylene sensitivity Moderate
Modified / controlled atmosphere 5%-10% CO2; 3%-10% O2
Potential benefits Although some benefit of increased firmness and delayed senescence can be gained from controlled atmosphere storage, commercial use of controlled atmosphere storage for grapefruit is very limited or non-existent.
Availability
Australia/New Zealand
South Africa
South America
USA

May - October
April - September
October - June

Grapefruit

Harvesting and handling

The grapefruit is a kind of berry with a leathery rind that is divided into segments. Each segment contains hundreds of individual juice vesicles that comprise the majority of the edible portion of the fruit. White and red pigmented cultivars are grown. Marsh is the predominant white cultivar. Ruby Red, Star Ruby, Henderson, Ray Ruby, and Flame are the most popular red pigmented varieties.

A high quality fresh-market grapefruit will have a turgid, smooth peel and be relatively blemish-free. The fruit should be elliptical and firm. An appropriate balance of SSC:TA within the edible portion should be achieved, and bitterness should be at a minimum.

Marketable fresh grapefruit generally range from size 23 (23 fruit/carton) through 56 (56 fruit/carton). Grade standards for fresh grapefruit rely on color-break, texture, peel blemishes, shape and firmness. In markets that emphasize processing, grapefruit must achieve a minimum juice content and SSC/TA ratio before harvest. Grapefruit are commonly packed, stored and shipped in 4/5 bushel cardboard cartons.

Grapefruit is a non-climacteric fruit and does not exhibit a classic ripening pattern of increased respiration and ethylene production.

Degreening is necessary for marketing early-season fresh grapefruit in areas where night temperatures remain high. High RH of approx. 90% must be maintained to avoid softening and accentuation of existing peel injuries or blemishes.

Cooling and storage

The selection of a proper temperature for storing grapefruit should be based on pre-harvest factors - including weather during growth, tree condition, and orchard treatments - as well as ripeness of the fruit, postharvest handling, and length of proposed storage.

Storage and transport temperatures differ considerably in their specific details according to variety and country of origin. Hence, it is imperative that the specific carrying temperature be indicated in writing by the consignor. The cargo should be pre-cooled prior to loading. California and Arizona grapefruits store best (4-6 weeks) at 14° to 15°C and Florida/Texas grapefruit at 10°C. Israeli and South African grapefruit are to be kept at 10°C to 12°C, at which they have a PSL of 10-16 weeks.

Coating grapefruit with high shine water waxes reduces the incidence of chilling injury and may permit slightly lower carrying temperatures (approx. 8°C) to reduce fruit respiration and minimise postharvest pitting which is a peel disorder that affects waxed grapefruit stored at higher temperatures. Pitting associated with postharvest pitting is targeted to areas of the peel surrounding the oil glands, whereas pitting associated with chilling injury is not targeted to oil glands.

Significant warming of refrigerated fruit results in condensation and spoilage, and very high temperatures render the grapefruit highly impact-sensitive and susceptible to mould. Fresh air ventilation is important as citrus fruit can start to ferment within a few hours due to anaerobic respiration (resulting in total loss of the fruit). If fresh air ventilation is insufficient, storage damage may occur, implicating a bitter flavour and peel scab.

In areas infested with a number of tropical fruit flies, cold treatment is an approved quarantine treatment. However, grapefruit must first be preconditioned at 10 to 15 °C to increase resistance to chilling injury. After 1 week, temperatures can be reduced to 0.6 to 2.2 °C for 2-3 weeks. In areas of low fly infestation, a less stringent temp/duration schedule can be used.

Mixed loads

Grapefruits can be shipped in mixed loads but they are chilling sensitive and so should (generally) not be kept below 10°C for long shipments.

Cautions

O2 below 3% can cause off-flavours. CO2 greater than 10% may cause off-flavours and areas of scald like damage on the rind. Grapefruits are chilling sensitive and their sensitivity may vary with variety, growing area and maturity.

Storage disorders

Alternaria rot, Anthracnose, Aspergillus rot, Black mould rot, Black pit, Black spot, Blue mould, Brown rot, Canker, Chilling injury, Cottonry rot, Degreening, Fusarium, Green mould rot, Grey mould rot, Insect damage, Melanose, Rind discoloration, Scab, Scald, Senescent breakdown, Sooty blotch, Sooty mould, Stem end rot.