Comparative analysis of the aroma profile of pineapple beers brewed with juice added at different times

Pineapple juice was added at three different points in the brewing process, (i) wort, (ii) toward the end of fermentation and (iii) at the beginning of maturation. The physicochemical properties, taste and aroma of the three fruit beers was compared to a control beer without addition of pineapple juice. The beers analysed using an electronic nose (E-nose), headspace solid phase micro-extraction gas chromatography-mass spectrometry (HS-SPME-GC-MS) and headspace gas chromatography-ion mobility spectrometry (HS-GC-IMS). Of the three fruit beers, esters characteristic of pineapple aroma was found in the beer produced with juice added late during primary fermentation. Further, the abundance of esters - isoamyl acetate, ethyl butyrate, ethyl acetate, ethyl hexanoate and phenethyl acetate - was higher. Sensory analysis showed the beer produced from the addition of juice late in fermentation had a superior aroma and was the most preferred in sensory testing. These results provide technical support for process optimisation and for improving the aroma of fruit beers.