Identification of spoilage microflora in draught beer using culture-dependent methods.

Aims: To determine whether the culture-dependent spoilage microflora found in draught beer are influenced by beer style.

Methods And Results: Four beer styles-lager, ale, stout and cask ale - were sampled twice from five different public houses (accounts) in four different locations. The microbiological quality of the dispensed beers was determined by a culture-dependent method ('forcing'), measuring the increase in turbidity after incubation at 30°C.

Chitin scar breaks in aged Saccharomyces cerevisiae.

Ageing in budding yeast is not determined by chronological lifespan, but by the number of times an individual cell is capable of dividing, termed its replicative capacity. As cells age they are subject to characteristic cell surface changes. Saccharomyces cerevisiae reproduces asexually by budding and as a consequence of this process both mother and daughter cell retain chitinous scar tissue at the point of cytokinesis.

The impact of brewing yeast cell age on fermentation performance, attenuation and flocculation.

Individual cells of the yeast Saccharomyces cerevisiae exhibit a finite replicative lifespan, which is widely believed to be a function of the number of divisions undertaken. As a consequence of ageing, yeast cells undergo constant modifications in terms of physiology, morphology and gene expression. Such characteristics play an important role in the performance of yeast during alcoholic beverage production, influencing sugar uptake, alcohol and flavour production and also the flocculation properties of the yeast strain.