Articles
Effect of precooling in reducing chilling injury of ‘Midknight’ and ‘Valencia Late’ Valencia oranges during cold storage
Article number
1466_17
Pages
129 – 138
Language
English
Abstract
Pre-cooling is an important postharvest treatment for citrus fruit exported under phytosanitary cold-treatment methods; however, cultivar-specific responses are little characterized.
This study investigated the effects of container shipment (CS) and specialized refrigerated vessel (SRV) pre-cooling methods on the physicochemical quality, antioxidant responses, chilling injury (CI), and marketability of ‘Valencia Late’ and ‘Midknight’ oranges stored at 2°C. SRV fruit were hydrocooled to 3°C surface temperature before storage, while CS fruit were precooled using tap water and stored at 2°C for 42 days.
SRV increased juice retention maintained titratable acidity (TA), and moderated increases in maturity index (MI), particularly in ‘Valencia Late’, under cold storage conditions.
Antioxidant responses revealed that SRV improved preservation of the total antioxidant capacity during long-term storage, whereas CS caused an early but unsustainable buildup of antioxidants.
Chilling injury incidence was highest in ‘Valencia Late’ under CS (100%), whereas ‘Midknight’ showed greater chilling tolerance than ‘Valencia Late’, with CI incidence of 60-70% but maintained 100% marketability under both precooling treatments.
Overall, SRV pre-cooling enhanced chilling tolerance by stabilizing metabolic activity and reducing oxidative stress, particularly in the more susceptible ‘Valencia Late’, while ‘Midknight’ displayed greater chilling tolerance, with CI symptoms observed but without compromising marketability, maintaining 100% marketability under both precooling treatments.
These findings emphasize the need to combine pre-cooling techniques with cultivar selection to improve citrus export quality.
This study investigated the effects of container shipment (CS) and specialized refrigerated vessel (SRV) pre-cooling methods on the physicochemical quality, antioxidant responses, chilling injury (CI), and marketability of ‘Valencia Late’ and ‘Midknight’ oranges stored at 2°C. SRV fruit were hydrocooled to 3°C surface temperature before storage, while CS fruit were precooled using tap water and stored at 2°C for 42 days.
SRV increased juice retention maintained titratable acidity (TA), and moderated increases in maturity index (MI), particularly in ‘Valencia Late’, under cold storage conditions.
Antioxidant responses revealed that SRV improved preservation of the total antioxidant capacity during long-term storage, whereas CS caused an early but unsustainable buildup of antioxidants.
Chilling injury incidence was highest in ‘Valencia Late’ under CS (100%), whereas ‘Midknight’ showed greater chilling tolerance than ‘Valencia Late’, with CI incidence of 60-70% but maintained 100% marketability under both precooling treatments.
Overall, SRV pre-cooling enhanced chilling tolerance by stabilizing metabolic activity and reducing oxidative stress, particularly in the more susceptible ‘Valencia Late’, while ‘Midknight’ displayed greater chilling tolerance, with CI symptoms observed but without compromising marketability, maintaining 100% marketability under both precooling treatments.
These findings emphasize the need to combine pre-cooling techniques with cultivar selection to improve citrus export quality.
Publication
Authors
N.S. Khoza, N. Khanyile, S. Shezi
Keywords
pre-cooling, cold storage, chilling injury, antioxidant activity, citrus quality
Online Articles (74)