Abstract:

In this study, the effect of intermittent hot water (56 ℃) immersion for 2 min with temperature return in cold or
warm water (0, 5 and 20 ℃) after every 40 s continuous treatment on quality preservation of ‘Tarocco’ orange during three
sequential stages of logistics, namely cold quarantine (at 2 ℃, relative humidity (RH) 90%?95% for 21 days), simulated
transport (at 10 ℃, RH 60%?70% for 7 days) and shelf life (at 20 ℃, RH 60%?70% for 7 days). The results showed that
the intermittent heat treatments with different return temperatures could reduce the decay index of ‘Tarocco’ orange and
5 ℃ return temperature treatment had the least decay index among them. At the same time, this treatment could enhance
the activities of polyphenol oxidase (PPO), peroxidase (POD), superoxide dismutase (SOD), and cactalase (CAT) in fruit
peel towards the shelf life, and maintain color parameters (color index and Hue), firmness and nutritional attributes (the
contents of anthocyanins, total acid and soluble solids). Furthermore, 0 ℃ return temperature treatment induced maximum
temperature difference, followed by 5 ℃ return temperature treatment, and minimum temperature difference was obtained
by returning the temperature to 20 ℃. Conclusively, the suitable temperature variation promotes the quality preservation of
‘Tarocco’ oranges.

Key words: intermittent heat treatment, return temperature, ‘Tarocco&rsquo, orange, sensory quality, logistics