Optimising cold storage to boost antioxidants and anthocyanins in blood oranges

Blood oranges get their name from their deep red flesh and the antioxidant pigment that their skin contains. Studies have shown that blood oranges (Citrus sinensis L. Osbeck) contain beneficial compounds including anthocyanins and other flavonoids, polyphenols, hydroxycinnamic acids, and ascorbic acid, which offer health benefits through antioxidant activity.

 

Commonly grown in Italy and Spain, blood oranges have been reported to develop high anthocyanin levels in the flesh across a wide temperature range in the specific regions of Valencia (Spain), and Sicily (Italy) which have a Mediterranean climate. However, in subtropical or tropical regions, such as Sao Paulo (Brazil) or Florida (USA), blood oranges contain low or negligible anthocyanin concentrations at commercial maturity, which limits their economic potential. In addition, in tropical or subtropical regions, storing blood oranges at ambient temperatures or on the tree beyond commercial maturity can degrade bioactive compounds and rapidly shorten shelf life due to water loss, increased respiration, senescence, and fungal decay.

 

Storing blood oranges in cold storage helps to maintain fruit quality, reduce the respiration rate and decay. Therefore, researchers at the University of Florida evaluated the potential of different postharvest temperatures (6, 8, 10, and 12°C) to determine the most suitable storage temperature for ‘Budd Blood’ blood orange fruit.

 

The researchers found that storage temperatures ranging from 6 to 12°C significantly improve anthocyanin accumulation, phytochemical content, and antioxidant activity in ‘Budd Blood’ blood orange. More specifically, storage temperatures of 10–12°C resulted in the highest increases in anthocyanin, phenolic content, and antioxidant activity over the 60-day storage period. Storing blood oranges at 6–8 °C was most effective for preserving fruit firmness, minimising weight loss, and maintaining sugar content.

 

These findings offer valuable insights into the potential of optimised postharvest storage as a simple strategy to enhance the health benefits and visual appeal of blood oranges grown in tropical and subtropical climates.

 

For more information, the complete study is published in open access in Food Chemistry Advances.

 

 

Source

Habibi, Fariborz, et al. “Postharvest storage temperature strategies affect anthocyanin levels, total phenolic content, antioxidant activity, chemical attributes of juice, and physical qualities of blood orange fruit.” Food Chemistry Advances 4 (2024): 100722. https://doi.org/10.1016/j.focha.2024.100722