Microbiological Aspects of Spontaneous Wort Fermentation in the Production of Lambic and Gueuze

Abstract

Lambic and Gueuze are special Belgian beers obtained by spontaneous fermentation. Micro organisms involved in this fermentation were counted and differentiated using several selective growth media. Micro-organisms were also isolated from samples of Lambic of different age and originating from different casks and brews and identified by classical tests. The following general pattern of microbial development was observed. After 3 to 7 days the fermentation started with the development of wort Enterobacteriaceae and strains of Kloeckera apicu/ata. These organisms were overgrown after 3 to 4 weeks by strains of Saccharomyces cerevisiae and S. bayanus. These were responsible for the main fermentation, lasting for 3 to 4 months. This was followed by a strong bacterial activity. This period was dominated by the growth of strains of Pediococcus cerevisiae. These reached their maximal numbers during the summer months and were responsible for a five fold increase in lactic acid concentration. In some casks they caused ropiness. After the main fermentation period Lambic is very sensitive to spoilage by acetic acid bacteria of the genus Acetomonas. The presence of air may be the determining factor for their development. After 8 months a new increase in yeast cells was noted. These belonged now mainly to the genus Brettanomyces bruxellensis and Br. lambicus. They caused a further slow decrease in residual extract and the appearance of special flavours. Oxidative yeasts of the genera Candida, Cryptococcus, Torulopsis and Pichia were also detected and may be responsible for the formation of a flim on the beer surface after the main fermentation.

The Impact of Simple Phenolic Compounds on Beer Aroma and Flavor

“…Long-term wood-aging has been carried through for certain specialty beer styles, such as lambic and Flanders red ales [35][36][37][38][39][40][41]. There has been a resurgence of barrel and wood-aging in recent decades, particularly among the craft brewing industry.…”

“…Many strains of brewer's yeast (Saccharomyces cerevisiae), as well as Brettanomyces sp., Lactobacillus, and Pediococcus are PAD+ [50][51][52][53][54]. These non-Saccharomyces genera of microbes are utilized in traditional sour beers of Belgium, and increasingly in other "wild" and sour beer styles popular in the craft brewing industry [36,37,[39][40][41]50]. PAD catalyzes the enzymatic decarboxylation of HCAs to their vinyl derivatives (see Figure 2).…”

“…Interestingly, they also contribute key organoleptic qualities to specialty beer styles including lambic, gueuze, Flanders red and brown ales, Berlinerweiss, and others [36,37,[39][40][41]50,[60][61][62][63]. They are increasingly utilized in other new "wild" ale styles in the craft brewing industry.…”

Non-Saccharomyces yeasts and their importance in the brewing industry. Part II

“…Po přibližně 3 týdnech, kdy koncentrace alkoholu dosáhne 3-4 %, je její růst zastaven a je nahrazena Saccharomyces spp. (Van Oevelen et al, 1977).…”

“…After approximately 3 weeks, when the alcohol content reaches 3-4 %, its growth ends and is replaced by Saccharomyces spp. (Van Oevelen et al, 1977).…”