Recommendations for Maintaining Post-Harvest Quality
Reference: Carlos H Crisosto, Elizabeth J Mitcham, Adel A Kader
Department of Pomology, University of California, Davis, CA 95616
Green Olives: Size and colour – even pale green with a minimum of whitish spots (lenticels) through a straw colour. An olive is considered mature if it exudes a characteristic white juice when squeezed.
Black Olives: Colour, removal force, fruits when this stage about 3-4 months after the green stage.
Green Olives: Colour, freedom from mechanical damage, shrivelling, surface blemishes, scale and other insect injury, and decay. These olives are processed according to the California black-ripe style or Spanish green style canned olives.
Black Olives: Colour, freedom from defects, oil content (12 to 25% depending on cultivar). These are processed (Greek or Italian style) or used for oil extraction.
5 – 7.5oC (41 – 45.5oF), temperatures below 5oC (41oF) cause chilling injury of fresh olives.
Optimum Relative Humidity
Rates of Respiration
|Range (ml CO2/kg.hr)
To calculate heat production multiply ml CO2/kg.hr by 440 to get Btu/ton/day or by 122 to get kcal/metric ton/day
Rates of Ethylene Production
Less than 0.1 (green olives) or 0.5 (black olives) plethylene/kg.hr at 20°C (68°F)
Responses to Ethylene
Olives produce very little ethylene but are moderately sensitive to ethylene action above 1 pm (loss of green colour and flesh firmness).
Responses to Controlled Atmospheres (CA)
Optimum CA 2 - 3% O2 + 0 – 1% CO2; delays senescence and softening for up to 12 weeks at 5oC (41oF) or 9 weeks at 7.5oC (45.5oF).
O2 below 2% can cause off-flavours.
CO2 greater than 5% may increase the severity of chilling injury if olives are kept below 7.5oC (45.5oF).
Note: The above information is for fresh green olives; fresh black olives should be processed as soon after harvest as possible.
Chilling Injury (CI): can be a major cause of deterioration if fresh olives are stored before processing for longer than 2 weeks at 0oC (32°F), 5 weeks at 2°C (36oF), or 6 weeks at 3°C (38°F). Symptoms include internal browning that begins in the flesh around the pit and radiates outward toward the skin as time progresses. Skin browning indicates an advanced state and /or greater CI severity. The order of cultivar susceptibility to CI is Sevillano (most susceptible) – Ascolano – Manzanillo – Mission (least susceptible).
Nailhead: This disorder is characterised by surface pitting and spotting. It results from the death and collapse of epidermal cells, which create air pockets underneath the fruit skin. Symptoms are observed on olives kept at 10°C (50°F) for 6 weeks or longer or 7.5°C (45.5°F) for 12 weeks or longer.
Carbon Dioxide Injury: Symptoms (internal browning and increased decay incidence and severity), result from exposure to more than 5% CO2 for longer than 4 weeks.
Post-harvest diseases occur if the olives have been chilled (exposed to temperatures below 5oC (41°F), mechanically damaged, not cooled promptly to the optimum temperature range of 5 - 7.5°C (41 - 45.5°F), or exposed to undesirable atmospheres (above 5% CO2 and/or below 2% O2).
||Olea europaea ssp.europaea
Refrigerated Container / Coolroom Recommendations
Optimum Product Temperature
|5.0 - 10.0° C
|Temperature set point for
|Air Delivery Control =
||5.0 - 6.0°C
||Return Air Control =
||6.0 - 7.0°C
|Ventilation ( Air Exchange) Settings for
|6m (20') Container =
||30 m/h = 20 cfm
||12m (40') Containers=
||60 m/h = 35 cfm
|Fresh Air Exchange
|Acceptable product Temperature at loading into container=
||4.5 - 10.0°
|Storage Time (days)
||Humidity % RH
||Freezing Point C
||Storage Time Ambient (~20C)
|28 - 42
||85 - 90
||Affected by Odour of
||Water Loss rate (% /week)
||Compatibility with Ice
Controlled Atmosphere, Respiration
|Benefit of Controlled or Modified Atmosphere
||Fair, (+21 days)
|Controlled Atmosphere Conditions
||Carbon Dioxide %
|2 - 3
||0 - 1