Abstract:

In this study, the effect of hot water treatments under varying conditions temperature and time (at 48, 52 and
56 ℃ for 1 and 2 min, respectively) in maintaining the quality of ‘Tarocco’ orange was evaluated during subsequent cold
storage (at 3 ℃ and relative humidity (RH) of 90%?95% for 21 days), simulated transportation (at 10 ℃ and 60%?70%
RH for 7 days), and shelf life (at 20 ℃ and 60%?70% RH for 7 days). The results showed that some appropriate hot
treatments could significantly mitigate the negative influences of temperature shifts in logistics and enhance the activities
of antioxidant enzymes in fruit peel, such as polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD),
and cactalase (CAT), which remained at high levels. At the same time, hot water treatment (HWT) also had positive effects
on color (including citrus color index and Hue), firmness and quality attributes (anthocyanins content, total acid and soluble
solids content). Nevertheless, treatment at temperatures higher than 56 ℃ caused irreversible thermal damage to orange
and temperature shifts in logistics accelerated fruit decay. Collectively, our results showed that the preservative effect of
treatment with hot water for 2 min at 52 ℃ was the best.

Key words: hot water treatment, ‘Tarocco&rsquo, orange, antioxidant enzymes, logistics