GALA, BRAEBURN, AND FUJI APPLES - MATURITY INDEXES AND QUALITY AFTER STORAGE

Changes in apple maturity indices and fruit quality were measured weekly at harvest and after storage for 'Gala' 'Braeburn,' and 'Fuji' apples. Fruits were evaluated on the day of harvest and after seven days at room temperature for internal ethylene concentration (IEC) skin color, firmness, starch index (SI), total soluble solids concentration (SSC) pH, and titratable acidity (TA). Color, firmness, SSC, and TA were again measured after 6, 12, 18, and 24 weeks for 'Gala' and 8, 18, 24, and 32 weeks for 'Braeburn' and 'Fuji' held in cold storage at 0 +/- 0.5C. Optimum harvest dates were determined retrospectively using consumer taste tests conducted approximately every four weeks for 'Gala' and every eight weeks for 'Braeburn' and 'Fuji.' Horticultural maturity of 'Gala' was attained 122 DAFB for long-term storage. On that date, St was highly variable, SSC was at 11 degrees Brix, and IEC averaged one ppm, but fruit color was not fully developed. I;ater-harvested fruit had the best eating quality after short-term storage in October and November. 'Braeburn' picked 168 and 175 DAFB had the best storage potential. SSC was the most obvious maturity index in 1991. Fruit harvested 154 DAFB was already capable of producing autocatalytic ethylene when ripened seven days at 20C. SI increased too late (175 DAFB) to be used as a predictor of harvest. Fruit harvested before 168 DAFB developed scald and later harvested fruit had very low sensory ratings after 24 weeks in storage. IEC in 'Fuji' fruit stayed at low levels and without autocatalytic production and therefore could not be used as a physiological predictor of maturity. Obvious indices were the starch index and hue value of the ground color. The former increased suddenly and the latter decreased by 173 DAFB. Only fruit picked 173 and 180 DAFB were free from scald and retained good sensory quality after eight months storage.