The Effect of Pre-Fermentative Thermo-Maceration and Apple Pomace Addition on Phenolic Content and Volatile Profile of Hard Cider

The aim of this study was to investigate the effects of thermo-maceration and apple pomace addition on phenolic compound extraction during cider fermentation and on the volatile profile of the final product. Jonagold apples were milled, and the juice was divided into four groups: (1) Control: no apple pomace or thermo-maceration; (2) Control TM: thermo-maceration only; (3) CiderAP: apple pomace addition only; and (4) CiderAPTM: apple pomace addition combined with thermo-maceration. Apple pomace was added at 50% of the average pomace weight created during milling, and thermo-maceration consisted of heating the juice to 60 °C for 1 h prior to fermentation. Ciders were fermented at 20 ± 1 °C for 14 days. CiderAP and CiderAPTM showed higher total phenolic content (TPC) and antioxidant activity than the control treatments. The volatile profile was also modified, with CiderAPTM showing the highest phenylethyl alcohol concentration and esters exhibiting compound-specific responses. Statistical analysis showed that only apple pomace addition significantly increased TPC and antioxidant activity, while both apple pomace addition and thermo-maceration affected the volatile profile. Under the conditions evaluated, thermo-maceration did not increase TPC or antioxidant activity beyond the effect of apple pomace addition but did modify the volatile profile of the ciders. Further research should evaluate different thermo-maceration temperatures and durations to determine its potential application in cider production. The findings of this study provide valuable insights for cider makers on the valorization of apple pomace and potential use of thermo-maceration in cider production.