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acid

Total 313.0 198.1 409.7 243.7 278.2 187.2

acid

Total 313.0 198.1 409.7 243.7 278.2 187.2

Wort contains various nucleic acids and their degradation products. MacWilliam (1968) reported that 5.7-6.4% of the total wort nitrogen consisted of purines and of this 33% was free adenine and guanine, the remainder being adenosine and guano-sine. During mashing nucleases are active, liberating ribosides and phosphate. Higher temperature mashes are associated with reduced concentrations of free purines. This author concluded that there were no reports of pyrimidines occurring in worts. However, Chen et al. (1973) produced data indicating the presence of both. Total concentrations of nucleic acids in worts were given as being of the order of 280330 mgl 1. More nucleic acids arose when the mashing temperature was 60°C, as opposed to 40 or 70°C. Of this approximately 10-20% disappeared during fermentation, although there was considerable variation between individual components (Table 2.9).

Worts of 10.5°Plato contain 25-30 mgl 1 ammonia (Lie et al., 1974). Traces (usually less than 10 mgl *) of various amines may also be detected, including methylamine, dimethylamine, ethylamine, butylamine, amylamine, tyramine, hor-denine and choline. Certain amines have been implicated in the hygiene-related issue of'biogenic amines' (see Section 8.1.5.2). Reportedly, only choline is utilised to any great extent during fermentation (MacWilliam, 1968).

Table 2.7b Amino acid contents of worts (mg 100 ml ') produced at various mashing temperatures and green beers from lager fermentations performed at 11-16°C (from Chen et al., 1973).

Mashing

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