Fruit from both cultivars was also found by the panelists to
become progressively less tart as storage progressed. The decrease
in tartness during storage was likely due to increases in SSC/TA
that occurred during storage as a consequence of loss in TA (both
varieties) and a gain in SSC (‘W. Murcott’). The loss in acidity during storage is a consequence of the respiratory activity of the fruit
and has been often reported to occur in citrus (Davis et al., 1973;
Echeverria and Ismail, 1987; Purvis, 1983). Marcilla et al. (2009)
reported in a recent paper on the storage of ‘Clemenules’ mandarins that the level of TA was closely related to flavor, with the
decline in acidity being associated with the development of poor
flavor. At least in the case of ‘Owari’ it seems unlikely that the loss
of acidity had a negative influence on flavor given the relatively
low SSC/TA values throughout the storage period and, in fact, the
loss in acidity may have benefited flavor. Obenland et al. (2009)
reported that sensory panelists increasingly liked navel oranges as TA declined and SSC/TA rose during navel orange maturation and
that the increase in likability did not plateau until SSC/TA values
of 18 or more were reached. Also, results from a consumer sensory
evaluation suggested that ‘Owari’ mandarins were highly liked by
consumers until SSC/TA reached 15 or more (Campbell et al., 2008).
As ‘W. Murcott’ had much higher SSC/TA values than ‘Owari’ and
exceeded 15 after 7 weeks of storage, it is possible that the loss of
acidity had some role in the decline in flavor quality in this cultivar,
although this cannot be conclusively determined.