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