Dry Matter and Soluble Solids Concentrations in Apple Cultivars at Harvest and during Storage

Dry matter concentration (DMC) has been suggested as a new quality metric for apple fruit. In this study, we have investigated the effects of postharvest treatment with 1-methylcyclopropene (1-MCP) and storage type (air and CA) on the relationships between DMC and soluble solids concentrations (SSC).  ‘McIntosh’, ‘Honeycrisp’, ‘Red Delicious’, ‘Golden Delicious’, ‘Fuji’, ‘NY1’, ‘Jonagold’, and ‘NY2’ apples were harvested at two harvest dates with one week intervals, treated with 1-MCP and stored in air for 6 and 12 weeks, or CA for 12 and 24 weeks.  DMC, SSC and other quality factors were measured at harvest and on days 1 and 7 at 20 ^oC after removal from storage. The DMC ranged from 112 g kg^-1 to 163 g kg^-1 depending on cultivar. Regression analyses of SSC against DMC resulted in R² values of 0.744, and these did not increase substantially during storage. The significant increase in R² values during storage reported by others was not found in our study. Little effect of 1-MCP or storage type was detected. Overall, the results support the concept that SSC is closely associated with fruit DMC, but not that DMC at harvest can be used as a metric to predict SSC of fruit in storage.