Effect of maturity and storage on quality of "Gala," "Braeburn," and "Fuji" apples

Graduation date: 1994In apples, the rapid changes occurring in fruit metabolism when approaching\ud maturity affect their quality at harvest and after storage. The interest in the newly\ud introduced cultivars, 'Gala', 'Braeburn' and 'Fuji' has initiated the following study\ud on maturity indices and storage in the conditions of the Pacific Northwest.\ud 'Gala', 'Braeburn' and 'Fuji' apples were sampled at weekly intervals from\ud 108 to 143 days after full bloom (DAFB), 133 to 189 DAFB and 138 to 187 DAFB,\ud respectively. Fruit color, firmness, soluble solids concentration (SSC), titratable\ud acidity (TA), pH, starch hydrolysis and internal ethylene were determined at\ud harvest. The same parameters except starch hydrolysis and internal ethylene were\ud measured on fruits after regular storage at 0 ± 0.5C, every 6 wks for 'Gala', and 8\ud wks for 'Braeburn' and 'Fuji'. Additionally, apples were evaluated for overall liking\ud (OL), firmness, sweetness, tartness and flavor intensities by a consumer taste panel\ud approximately every 4 wks for 'Gala' and every 8 wks for 'Braeburn' and 'Fuji',until\ud January, May and June, respectively.\ud A principal component analysis (PCA) showed that all the measured\ud maturity indices were important and the model could not be reduced.\ud All the maturity indices could be used in 'Gala' to determine that the\ud physiological maturity was attained 122 DAFB. Fruits harvested at that stage had\ud the highest storage potential (January) but their color was not fully developed,\ud whereas those harvested later had the best quality after short-term storage\ud (October-November).\ud Results of the sensory data and observation of fruit physiological disorders\ud such as scald and internal breakdown led to establish that only fruits picked 168 and\ud 175 DAFB had the best storage potential (April) for 'Braeburn'. SSC and hue\ud angle of the ground color were the most obvious parameters on which to predict\ud optimum harvest date in 1991. Internal ethylene showed the autocatalytic rise\ud earlier, 154 DAFB. Starch index increased 175 DAFB.\ud 'Fuji' fruits picked 173 and 180 DAFB were the only ones free from scald\ud and retaining good quality after 8 months storage. The only reliable indices at\ud harvest were the starch index and hue value of the ground color. 'Fuji' apples\ud produced low levels of ethylene.\ud A multivariate analysis of the data with 5 sensory descriptor variables\ud revealed that a taste panel could differentiate between maturity stages. The loss\ud of firmness and acidity occurring during maturation and in storage was well\ud perceived, but firmness was the only instrumental variable correlated to sensory\ud firmness. Additionally, changes in sweetness and in flavor not revealed by the\ud analytical data were described. OL, sweetness and flavor ratings were not rated\ud independently, but tartness and firmness were. Sweetness ratings contrasted those\ud of tartness and firmness