Eect of tyrosine on tyramine formation during beer fermentation
Â Maria Izquierdo-Pulido *, AbelMarine-Font, M. Carmen Vidal-Carou
Â Ácia, Avg. Joan XXIII, s/n, 08028 Barcelona, Spain Departament de Nutricio i Bromatologia-CeRTA, Facultat de Farma Received 8 August 1999;received in revised form 30 January 2000; accepted 30 January 2000
Abstract Changes in tyramine, in its precursor amino acid tyrosine, and in Pediococcus spp. were followed during54 beer fermentations. No statistical relationship between tyramine production and wort tyrosine levels was found, either between the amount of tyramine formed or the decreasein tyrosine through beer fermentation. However, tyramine formation signi®cantly correlated with Pediococcus spp. contamination (r=0.876; P0.05) R=À0.375 (P>0.05) R=À0.596(P>0.05)
Tyramine/decrease tyrosine R=0.358 (P>0.05) R=0.375 (P>0.05) R=0.457 (P>0.05)
Expressed as ®nal value found in beer minus initial value found in wort. Expressed asinitial value found in wort minus ®nal value found in beer. Mean and standard deviation.
To study relationships between tyramine formation and its precursor amino acid,correlation coecients were calculated between levels of tyrosine in wort and tyramine formation, and also between tyramine formation and tyrosine decrease during beer fermentation. Nostatistically signi®cant relationship was found between tyramine production and tyrosine decrease (r=0.096, P>0.05, n=54). In other words, a higher tyramine production was notrelated to a higher decrease in tyrosine. Although the correlation coecient between tyramine formation and the levels of tyrosine in wort was statistically signi®cant (r=À0.410; P