compounds that are present in marc extract, but not anthocyanin
fraction, were responsible for the increased bitterness and astringency of the purees. It was demonstrated previously that the
addition of anthocyanin extract to wine had only minor effect on its
astringency and no effect on bitterness (Brossaud et al., 2001). The
changes of pH and the content of soluble solids may also influence
sensory quality of purees. For instance, reduced pH might cause an
increase in product acidity; however the relationships between pH
and sensory perception in a complex food matrix are rather
complicated and therefore in our case the reduction in pH by marc
extract, most likely, was too low (by 0.15e0.16 units) to provide any
significant changes in sensory characteristics. Regarding soluble
solids, higher content of sugars might increase product sweetness;
however, the effects of extract were not remarkable. Soluble solids
also contain other substances such as organic acids, and from this
point of view, the possibilities of complex interactions of sweet and
sour taste might play some role