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).