Assessing the development of internal disorders in pome fruit with X-ray CT before, during and after controlled atmosphere storage and shelf life

This study examined the use of X-ray computed tomography (CT) for the early detection of physiological disorders in pome fruit during controlled atmosphere (CA) storage and shelf life. The CT images of healthy and disordered ‘Braeburn’ apples, ‘Golden Delicious’ apples and ‘Conference’ pears were evaluated. ‘Braeburn’ apple (n = 80) were scanned with CT before and during browning-inducing CA conditions (0.5 °C, 1.5 kPa O2, 5 kPa CO2) and subsequent shelf life. ‘Conference’ pears (n = 70) were scanned following regular air storage that induced freezing injury (−2 °C) and additional CA storage (−0.6 °C, 3 kPa O2, <0.7 kPa CO2) and subsequent shelf life. ‘Golden Delicious’ apples (n = 60) were scanned after CA storage (1 °C, 1 kPa O2, 3 kPa CO2) and after 35 days of shelf life. The causes of postharvest losses after CA storage and shelf life were core browning, flesh browning and bitter pit for ‘Braeburn’, ‘Conference’ and ‘Golden Delicious’, respectively. After CA storage, the mean greyscale value (MGV) of CT images was higher in healthy ‘Braeburn’ and ‘Golden Delicious’ apples compared to those that appeared externally healthy but later developed a disorder during shelf life. The MGV decreased during storage and shelf life in affected ‘Braeburn’ and ‘Golden Delicious’ apples, whereas no change occurred during shelf life for healthy ‘Golden Delicious’ apples, and ‘Braeburn’ apples stored for 17 weeks. No difference in the MGV was found between healthy and disordered ‘Conference’ pears. For ‘Braeburn’, voids associated with core browning did not develop until fruit were removed from CA storage and subsequently kept in shelf life for at least seven days. Results of this study indicate that the MGV of CT images can be used to indicate ‘Braeburn’ and ‘Golden Delicious’ apple fruit marketability after CA storage before shelf life.