Delta Absorbance Meter As a Means to Predict and Reduce Incidence of Browning Disorders

The Delta Absorbance Meter measures the chlorophyll in fruit and has been suggested as a valuable, non-destructive indicator of fruit maturity. Delta absorbance (ΔA) values were measured on ‘Olympic’ Asian pears, ‘Pink Lady’ apples and ‘Granny Smith’ apples for their rate of success in predicting and reducing the incidence of two browning reactions: internal breakdown and storage scald. Internal breakdown involves the browning of the fruit flesh in mature fruit, while storage scald is a browning reaction that occurs in the peel of stored, immature fruit. There was not a clear value that determined if an ‘Olympic’ Asian pear had internal breakdown. An early harvest found that a ΔA value of below 0.6 indicated that fruit had internal breakdown, yet a second harvest one week later was not as effective. For the apple cultivars, ΔA values were measured weekly pre-storage, during September and October, to establish if a clear relationship could be found between ΔA value and storage scald. The two apple cultivars were also assessed for other maturity measurements, such as their starch pattern index. Results of ‘Pink Lady’ and ‘Granny Smith’ apples were inconclusive. For each, the ΔA pre-storage value did not equate to the ΔA post-storage value, nor was there a clear, predictive relationship with that measurement and the percentage of scald on fruit. However, both apple cultivars appeared to lose their scald susceptibility at a starch-pattern index of 4. The Delta Absorbance Meter was determined to be unable to derive a direct link between ΔA values and browning in either ‘Olympic’ Asian pears, ‘Pink Lady’ apples or ‘Granny Smith’ apples.