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 pear-shaped fruits, characterized by either a thin, thick, smooth or rough skin, which depends on the variety involved. They belong to the group of stone fruits. The colour can be either green as ('Fuerte') or brownish red to black ('Hass'). The surrounding flesh has a white to green colour. In ripe condition, it has a sweet taste which resembles nuts. The inedible light brown stone in the center constitutes approx. 20% of the total fruit. The skin of the Ettinger variety is smooth green.

Avocados do not become soft or ripe enough on the tree. Therefore they are picked at the pre-climacteric stage when they are still firm. Depending on variety, they can be kept in this stage for up to several weeks. The older fruit, which generally are larger, ripen earlier than younger fruit. If avocados are picked too early they do not ripen properly and become wrinkly. During ripening, the water content decreases and the fat content increaes. Avocados contain significant quantities of oil; sometimes >30% of fresh weight depending on cultivar/maturity.

Avocados are highly pressure- and impact-sensitive and therefore adequate care must be taken during handling of the produce. The cold chain must be maintained, since the cargo will otherwise spoil rapidly. The major quality criteria of avocados used during grading are size, skin colour, blemishes, freedom from wounds, insect damage, spray residue and other contaminants on the skin. Avocados are chiefly intended for fresh consumption. They are amongst others used in salads, sauces and spreads.

Cooling and storage

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.

When chilling damaged, the flesh of the fruit goes brown, the skin shows sunken spots and is also going brown. Subsequently, the flesh becomes soft and breaks down around the stone. External chilling injury is generally initiated by temperatures of <3°C. However, with increasing maturity the fruit becomes less sensitive, and ripe fruit are less affected. Avocados have the lowest water content of all types of fruit.

During the voyage, controlling respiration processes (release of CO₂, water vapour, ethylene and heat) must be aimed at in such a way that the cargo is at the desired stage of ripeness upon reaching destination. Improper 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.