Assessment of fruit density as an indicator for internal browning susceptibility in Fuji apples

The objective of this project was to determine if fruit density can be used as a predictor of internal browning (IB) susceptibility in Fuji apples. Fruit density is pre-determined during the cell division phase and fruit with more cells are expected to be denser and more prone to IB, whereas fruit with fewer cells will be less dense and less prone to IB.

Fruit were harvested from orchards that have a previous history of IB disorders and the density of the fruit were measured at harvest using the mass and diameter of the fruit. The fruit were evaluated for IB disorders at the end of CA storage and correlations between IB and density were performed

The orchard with the most mature fruit exhibited the highest incidence of internal CO₂ damage, despite fruit from this orchard having the lowest density. This shows that fruit maturity is a more important factor compared to density when considering IB susceptibility in Fuji apples.

It was expected that denser fruit will be more prone to IB. However, results from this study proved the opposite of what was expected to be true; there was a negative correlation between density and IB incidence. This was because fruit from orchards with low density had advanced maturity and this resulted in high IB incidence despite the density being low.

Fruit density has an impact on the incidence of IB in Fuji. However, other factors such as maturity also influence IB incidence and so a holistic approach that looks at all the possible causative factors for IB should be adopted, both pre-and post-harvest.