Influence of oak chips geographical origin, toast level, dosage and aging time on volatile compounds of apple cider

The effects of different geographical origin, levels of toasting, dosage and the aging time of oak chips on volatile compounds released into ciders were studied. The oak chips tested were the same size and with three different toast levels (light, medium and heavy) from French, American and Chinese oak. The oak wood chips were immersed in identical ciders. Higher alcohols, acids and esters were determined by headspace (HS)-solid phase microextraction (SPME) and gas chromatography (GC)-mass spectrometry (MS), while oak-related aroma compounds including trans-and cis-oak lactones, guaiacol, 4-methylguaiacol, furfural, 5-methylfurfural, vanillin, eugenol and isoeugenol, were determined by liquid-liquid extraction by means of ultrasound and GC/MS selective ion monitoring (SIM). The results showed that there was little difference between the oak-related volatile compositions of ciders aged with French oak chips and those aged with American oak chips, but that there were obvious differences with Chinese oak chips. It was observed that oak chips, at medium toasting levels, released the highest concentrations of volatile components into the ciders. Most of the oak-related volatile aroma compounds extracted had an increase that depended on the oak chip dosage with the exception of guaiacol and furfural.