Bioactive compounds recovered from apple pomace as ingredient in cider processing: monitoring of compounds during fermentation.

The apple pomace-industrial residue of apple beverages manufacture-presents 42-58% of the phenolic content of fresh fruit. As the phenolic composition influences the quality of ciders, it is very relevant to monitor the evolution of these compounds during the industrial process. Therefore, this research aim was to monitor the cider composition with the addition of phenolic extract from apple pomace during the fermentation. Two treatments, S1 (without extract) and S2 (with added extract), were evaluated during 15 days of fermentation. After 15 fermentation days, the sample S2 presented an increase of 23% in total phenolic compounds and 40% in flavonoids without harm to the fermentation kinetics. Concerning the evolution of monomeric phenolic compounds, the phenolic acids in S1 and S2 presented a similar trend during the fermentation period. Enzymatic hydrolysis reactions resulted in the chlorogenic acid content decreasing, in line with increased levels of caffeic acid. Phloridzin and quercetin glycosides content showed the greatest increase in S2. The final product S2 presented higher antioxidant activity and some sensorial characteristics (astringency, bitterness and colour) were accentuated. This work shows that phenolic compounds added were maintained during the process and it did not prejudice the fermentation reactions. Therefore, this is a good alternative to valorize apple pomace and improve the functional and sensorial quality of the cider.