Changes in the volatile composition of apple and apple/pear ciders affected by the different dilution rates in the continuous fermentation system

The research concentrated on the analysis of biochemical parameters and volatile composition of the ciders prepared from two Polish apple varieties (Gala and Idared) with and without addition of the pear juice (Konferencja). Ciders have been prepared in a continuous fermentation system using FS-V-A bioreactor with different dilution rates (ranging from 0.0050 h-1 to 0.2222 h-1).Volatilome of ciders has been analysed by the means of headspace solid-phase microextraction coupled with gas chromatography and mass spectrometry (HS-SPME-GCMS). Performed analyses have shown that apple variety, dilution rate of fermenting cider, as well as pear juice addition has significant influence on the composition of the acquired cider volatiles. Ciders fermented at a lower dilution rate were characterised by a higher concentration of compounds such as ethyl decanoate, phenylethyl alcohol, while a higher dilution rate resulted in higher concentration of 2-hexanal, ethyl hexanoate, pentyl octanoate and (Z, E)-farnesene. Pear addition increased concentration of (2E, 4Z)-deca-2,4-dienoate and ethyl octanoate in the ciders.