3.5. Sugar and acid balance in strawberries at the moment of
consumption.
As would be expected given the aforementioned higher sugar levels when
fruit were transferred to 20 ºC for 1 day, TSS content was higher in LTC
than in LTA and exceeded values found in SLC following two days of
storage at 20 ºC (Table 1). In LTA strawberries, maximum TSS levels are
found during day 1. Following 2 days at 20 ºC, there is a pronounced
decrease in TSS that does not occur in LTC (data not shown). As can be
seen in Table 1, titratable acidity values which are expressed as % of
citric acid, decreased in strawberries previously stored at LT, with
this decrease being higher in LTC than in LTA. The present results
indicate that elevated CO2 reduced organic acid content
and increased the total sugar to acid ratio, reflecting lowered sourness
in the strawberry. As can be seen in Table 4, ‘Mara des Bois’
accumulates high levels of TSS during the DR stage. Although high TSS
may also correlate with a high risk of fungal disease, fruit is
considered to have a richer flavour when it has a good balance of sugars
and organic acids, with the sugar/acid balance largely depending on the
maturity degree (Schwieterman et al., 2013; Basson et al., 2010; Fait et
al., 2008; Jouquand et al., 2008). The highest sugar/acid ratio was
found in DR with values similar to those found in
CO2-treated fruit, being these previously scored as the
most highly in sweetness and sensory evaluations (data not shown).