The reduction of both TA and firmness during postharvest
storage has been found in other sweet cherry cultivars
and is associated with acceleration of the ripening process,
being responsible for significant quality losses (Esti et al.2002; Usenik et al. 2008; Serrano et al. 2009). The effects
of edible coating decreasing acidity losses and softening
have been also found in chitosan- and alginate-coated
peaches (Li and Yu 2001; Maftoonazad et al. 2008), in
avocado coated with methylcellulose (Maftoonazad and
Ramaswamy 2005) and in sweet cherry coated with
Semperfresh (Yaman and Bayindirli 2002) or with A. vera
gel (Martínez-Romero et al. 2006). The effect of coating on
acidity retention could be a result of the lower respiration
rate found in coated fruits, since organic acids are substrates
for many reactions during aerobic respiration in plant cell.
On the other hand, retention of firmness in coated fruits
could be explained by delayed degradation of cell wall
components, especially water-insoluble and NaOH insoluble
pectins, due to the effect of the internal fruit atmosphere with
high CO2 and low O2 on decreasing the activity of the cell
wall hydrolases responsible for fruit softening (Valero and
Serrano 2010). Thus, the overall results show a delay in the
postharvest ripening/maturation process in alginate-coated
cherries, leading to maintenance of organoleptic and nutritive
quality parameters.