Articles
EFFECT OF COOLING RATE ON KIWIFRUIT FIRMNESS AND ROT INCIDENCE IN SUBSEQUENT STORAGE
Article number
1079_38
Pages
313 – 318
Language
English
Abstract
Temperature management is critical in maintaining quality and extending market life of Hayward kiwifruit in the supply chain.
In industry, harvested kiwifruit are pre-cooled using the forced draft cooling method to remove field heat.
Removal of field heat reduces the rate of deterioration as fruit metabolism and growth of spoilage microorganisms are both lowered.
Usually, rapid cooling is recommended to extend fruit storability and quality.
This study investigates the change in kiwifruit firmness during storage as influenced by cooling profile to the storage temperature.
Commercially produced Hayward kiwifruit (Actinidia deliciosa) were either directly cooled (3 d) or gradually cooled (2 weeks) to storage temperature of 0°C and subsequently stored for up to 25 weeks.
Fruit firmness and respiration rate measurements were conducted every 2 to 3 weeks across the storage period.
Fruit that were cooled in 3 d had higher proportion of unmarketable fruit after 120 d of storage in comparison to fruit that were cooled in 2 weeks.
After 40 d of storage, fruit cooled in 3 d displayed a more rapid average softening rate.
An increase in respiration rate was observed in rapidly cooled fruit after 120 d, possibly due to the stress caused by chilling injury.
Higher incidence of rotten fruit was found in fruit that were cooled in 2 weeks.
This study suggests that gradual cooling allows kiwifruit to acclimatise to future low temperature storage conditions, implying that rapid cooling to storage temperature may not essentially improve the marketable life.
On the other hand, gradual cooling increases the risk of rot development, possibly enabling the spoilage microorganism to advanced development initially.
Controlled gradual cooling of fruit is impractical with the large harvest volumes of industry.
Hence, there is a need to find an optimal cooling rate which removes field heat as applicable to industry.
In industry, harvested kiwifruit are pre-cooled using the forced draft cooling method to remove field heat.
Removal of field heat reduces the rate of deterioration as fruit metabolism and growth of spoilage microorganisms are both lowered.
Usually, rapid cooling is recommended to extend fruit storability and quality.
This study investigates the change in kiwifruit firmness during storage as influenced by cooling profile to the storage temperature.
Commercially produced Hayward kiwifruit (Actinidia deliciosa) were either directly cooled (3 d) or gradually cooled (2 weeks) to storage temperature of 0°C and subsequently stored for up to 25 weeks.
Fruit firmness and respiration rate measurements were conducted every 2 to 3 weeks across the storage period.
Fruit that were cooled in 3 d had higher proportion of unmarketable fruit after 120 d of storage in comparison to fruit that were cooled in 2 weeks.
After 40 d of storage, fruit cooled in 3 d displayed a more rapid average softening rate.
An increase in respiration rate was observed in rapidly cooled fruit after 120 d, possibly due to the stress caused by chilling injury.
Higher incidence of rotten fruit was found in fruit that were cooled in 2 weeks.
This study suggests that gradual cooling allows kiwifruit to acclimatise to future low temperature storage conditions, implying that rapid cooling to storage temperature may not essentially improve the marketable life.
On the other hand, gradual cooling increases the risk of rot development, possibly enabling the spoilage microorganism to advanced development initially.
Controlled gradual cooling of fruit is impractical with the large harvest volumes of industry.
Hence, there is a need to find an optimal cooling rate which removes field heat as applicable to industry.
Publication
Authors
J.M. Zhao, J.E. Bronlund , A.R. East
Keywords
Actinidia deliciosa, ‘Hayward’, direct cooling, gradual cooling, softening
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