Study on the effect of dry matter content on storability and eating quality of ‘Big bucks’ and ‘Cripps’ Red’ apples to facilitate better postharvest decision making.

The objective of this study was to determine how dry matter content (DMC) is related to fruit quality, consumer acceptance and eating quality.

DMC samples were collected from 12 ‘Bigbucks’ and ‘Cripps’ Red’ apple orchards starting 5 to 3 weeks before, until 2 weeks after commercial harvest in the Grabouw/Elgin region, South Africa. The samples were used to determine the variation in fruit DMC as affected by fruit differences, sampling date and tree and orchard effects. At commercial harvest the DMC and maturity analysis of fruit from each orchard were determined before start of storage. Post-storage fruit evaluations were done to determine the relationship between DMC, storability and eating quality.

Fruit samples collected at harvest from 12 ‘Bigbucks’ and ‘Cripps’ Red’ apple orchards showed a variation in mean fruit DMC between replicates, with individual fruit DMC showing a larger range of variation. The DMC also differed significantly between orchards. Top canopy fruit had significantly higher DMC than bottom canopy fruit. Fruit DMC at harvest proved to be a reliable predictor of total soluble solids (TSS) after cold storage for ‘Bigbucks’ and ‘Cripps’ Red’ apples. There was also a significant relationship between DMC and firmness at harvest and after cold storage for ‘Bigbucks’ apples. No clear relationship was found between DMC at harvest and disorder incidences after storage for both cultivars.

A high level of variation in DMC existed within orchards and between orchards. Although DMC changed over time leading up to commercial harvest in some orchards, it followed no consistent trend. An orchards’ harvest DMC could already be determined a few weeks before commercial harvest for ‘Cripps’ Red’ apples. The higher DMC in top canopy fruit could be an indication of the importance of good canopy management for increased DMC in fruit. DMC could be used as an indicator of firmness after storage for ‘Bigbucks’ as well as TSS after storage for both ‘Bigbucks’ and ‘Cripps’ Red’ apples, which could aid in marketing decisions. Higher DMC were associated with a higher sweet taste after shelf life for ‘Cripps’ Red’ apples. There were no other correlations between DMC and eating quality.

DMC differs between orchards and between canopy positions. It also seems to be a good indicator of fruit quality after storage, specifically TSS for ‘Cripps’ Red’, and firmness and TSS for ‘Bigbucks’. This could aid in decision making regarding which fruit should be stored for specific markets with high firmness and TSS requirements.