Discrimination of Fruit Beer Based on Fingerprints by Static Headspace-Gas Chromatography-Ion Mobility Spectrometry

Fruit beer, a recognized special beer, is produced with fruit addition during fermentation, maturation, or the refermentation process. Volatile organic compounds of seven fruit beers were investigated using a gas chromatography-ion mobility spectrometry (GC-IMS) technique. A total of 38 compounds were identified, and volatiles in the seven beers differed greatly. The concentration of nonanal, methyl octanoate, ethyl 2-methylbutanoate, propyl hexanoate, and methyl 2-methylbutanoate was high, and the first two compounds were the characteristic volatiles in the pineapple beer. Apple beer had a higher concentration of butyl acetate, isobutyl acetate, methyl heptanoate, and butanal. Butyl acetate was the specific apple beer volatile. Peach beer showed a higher concentration of 3-methylbutanal, methional, phenylacetaldehyde, alpha-pinene as well as 2,3-diethyl 5-methylpyrazine, and the last was detected only in the peach beer. Ethyl heptanoate and maltol were abundant in the cranberry beer, whereas linalool, furaneol, and benzaldehyde were rich in the cherry beer, and benzaldehyde was the characteristic cherry beer volatile. Raspberry beer had abundant 3-pentanone, ethyl propanoate, and E-2-hexenol, whereas blueberry beer had abundant ethyl 2-hydroxypropanoate. Discrimination and classification of the seven fruit beers were effectively performed by the principal component analysis (PCA) method with good dispersion, and all groups had corresponding attribution areas in the PCA map. The cumulative contribution rate of the first two PCs was 60%. This study offers an approach for the analysis of the volatiles of fruit beers and could help in the verification of adulteration in fruit beers.