Avocados

Infobox on Avocados
Example of Avocados
Freshness facts
Optimum carrying temperature	4,0°C to 4,5°C (Booth 1, Lula) 5,5°C (Ettinger) 5,0°C to 8,0°C (Fuerte/Hass) 10,0°C to 13°C (Fuchs, Pollock, Waldin)
Highest freezing point	-0,9°C/-1,6°C
Acceptable product temp. at loading into containers	Max. 2°C above carrying temperature
Optimum humidity	85 to 90%
Ventilation setting for containers	60 m³/hr
Storage life	4 to 8 weeks (Booth 1, Lula), 2 to 3 weeks (Ettinger, Fuerte, Hass), 2 weeks (Fuchs, Pollock, Waldin)
Climacteric / non-climacteric	Climacteric
Ethylene production	High
Ethylene sensitivity	High
Modified / controlled atmosphere	3%-10% CO2; 2%-5% O2
Potential benefits	Moderate
Availability
Australia South Africa South America	February - August October - April January - April

Avocados

Harvesting and handling

Avocados are stone fruit. Depending on the variety, the elongated, pear-shaped fruits have a thin, thick, smooth or rough skin, which may be green ('Fuerte') or brownish-red to black ('Hass') and encloses the whitish to green flesh. Their flavour is sweetish to nutty. The light brown stone is as large as a walnut. It constitutes approx. 20% of the total fruit and is inedible. The Ettinger variety has a smooth green skin.

Avocados do not become soft or ripe enough to eat on the tree, so they are picked at the pre-climacteric stage while firm. They can be kept in this stage for up to several weeks, depending on cultivar. The older fruit, which generally are larger, will ripen earlier than younger fruit.

Avocados picked too early do not ripen properly and become wrinkly. During ripening, the water content falls and the fat content rises. Avocados are one of the few fruit that contain significant quantities of oil; sometimes >30% of fresh weight depending on cultivar and maturity.

Avocados are highly pressure- and impact-sensitive and appropriate care must therefore, be taken during cargo handling. The cold chain must at all costs be maintained, since the cargo will otherwise spoil rapidly.

For avocado, the major quality criteria used during grading are size, skin colour, freedom from wounds, blemishes, insect damage, spray residue and other contaminants on the skin.

Avocados are mainly intended for fresh consumption. They are used for the production of salads, sauces and spreads, for example.

Cooling and storage

Avocados require particular temperature, humidity/moisture and ventilation conditions. Ripening and softening can be delayed by pre-cooling the fruit immediately after harvest and placing them in ethylene-free storage at optimum temperature.

Optimum storage conditions vary by cultivar, growing conditions, time in the season (maturity) and length of storage required. However, in general, unripe avocados should be stored at 5°C to 12°C with RH of 95%. Optimum storage temperatures for ‘Has’ are 5°C to 7°C for early season fruit and 4°C to 5,5°C for late season fruit. After 3 to 4 weeks storage, ‘Hass’ fruit quality is reduced, and storing fruit for >6 weeks remains a challenge.

In the event of chilling damage, the flesh of the fruit goes brown and the skin exhibits sunken spots while also going brown. The flesh subsequently becomes soft and breaks down around the stone. External chilling injury is generally induced by temperatures of <3°C. However, fruit becomes less sensitive with increasing maturity, and ripe fruit are less affected.

Of all types of fruit, avocados have the lowest water content.

Care of the cargo during the voyage must be aimed at controlling respiration processes (release of CO2, water vapour, ethylene and heat) in such a way that the cargo is at the desired stage of ripeness on reaching its destination. Inadequate ventilation may result in fermentation and rotting of the cargo as a result of increased CO2 levels and inadequate supply of atmospheric oxygen.

After transit, ethylene may be used to stimulate (uniform) ripening, as for bananas.

Mixed Loads

Do not ship with ethylene-producing commodities. Avocados have a very slight, pleasant odour and do not therefore affect other products except for pineapples.

Cautions

Oxygen below 1% can cause off-flavours and flesh browning. Carbon dioxide above 15% can cause skin browning and off-flavours. Varietal differences in sensitivity to low O2 and high CO2 may be expected.

Storage disorders

Alternaria rot, Anthracnose, Bacterial soft rot, Blotch, Blue mould, Chilling injury, Fusarium, Phytophthora, Rhizopus rot, Rind discoloration, Scab, Sooty blotch, Stem end rot.