Cinnamic Acid as the Basis of a Medium for the Detection of Wild Yeasts

Abstract

Cinnamic acid (100 ug ml"') incorporated in a solid medium was found to inhibit the growth of brewing strains (Pof~) of yeast while permitting the growth of Pof + wild yeast contaminants. Typically, colonies of Saccharomyces cerevisiae var. diastaticus (Pof+) mixed with brewing yeast (S. cerevisiae NCYC 240) were visible after 5d incubation at 25°C. The incubation time required to detect a selection of brewery wild yeast isolates was found to vary from 3-12 d.

Characterization of the volatile profiles of beer using headspace solid‐phase microextraction and gas chromatography–mass spectrometry

“…Linalool, which comes from the essential oils of hops, gives a fruity aroma to the beer . Styrene derives from the decarboxylation of cinnamic acid present in the raw materials, especially barley malt . The decarboxylation can proceed either as an enzymatic or as a thermal decarboxylation .…”

“…14 Styrene derives from the decarboxylation of cinnamic acid present in the raw materials, especially barley malt. 32 The decarboxylation can proceed either as an enzymatic 33 or as a thermal decarboxylation. 34 The enzymatic decomposition of cinnamic acid to styrene is encoded by the same phenyl acrylic acid decarboxylase (PAD1) and ferulic acid decarboxylase (FDC1) genes as the decomposition of phenol carboxylic acids to the corresponding phenols.…”

Brewing microbiology - wild yeasts and methods of their detection.

“…Kvasinky POF + rostou na půdě s kyselinou skořicovou, zatímco růst kontrolního svrchního kmene S. cerevisiae je inhibován. Nevýhodou této půdy je dlouhá inkubační doba potřebná pro detekci divokých kvasinek, která se pohybuje v rozmezí 3-12 dnů (Hope, 1987). Svrchní pivovarské kvasinky vyžadují pro svůj růst pantotenát -kultivační médium bez pantotenátu bylo použito pro detekci divokých kvasinek Saccharomyces i non-Saccharomyces a spodních pivovarských kvasinek jako kontaminant pivovaru s produkcí svrchně kvašených piv (Röcken, 1983).…”

“…The spectrum of different media used for detection of wild yeasts includes some media that have been published but are for some reason less widely known or rarely used routinely, such as, e.g., the medium with cinnamic acid according to Hope (1987). POF + yeast can grow on media containing cinnamic acid while the growth of ale yeast S. cerevisiae is inhibited.…”

“…POF + yeast can grow on media containing cinnamic acid while the growth of ale yeast S. cerevisiae is inhibited. The disadvantage of this medium is the long cultivation period (3 -12 days) necessary for detection of wild yeasts (Hope, 1987). Since top brewer's yeast requires for growth pantothenate, a cultivation medium without pantothenate was used for detection of both Saccharomyces and non-Saccharomyces wild yeast and bottom brewer's yeast as contaminants in a brewery producing top-fermented beers (Röcken, 1983).…”