Variations Amongst Beers and Lactic Acid Bacteria Relating to Beer Spoilage

Abstract

The ability of lactic acid bacteria to grow in beer has been studied using 31 beers, 13 strains of Lactobacillus and 3 strains of Pediococcus isolated from wort or beer. In 3 beers all the micro organisms were able to grow, in 5 beers none of them developed and diverse results were obtained with the remaining 23 beers. Resistance of the beers to spoilage was not correlated with values of pH, specific gravity, total or free amino nitrogen, individual or total fermentable sugars, colour or levels of sulphur dioxide. Resistant beers became sensitive after certain filtration treatments and after heating at 80°for 15 minutes, but not after treatment at 60°. Resistance to spoilage is tenta tively attributed to the presence of a yeast metabolite which is heat-labile. The lactic acid bacteria varied in their ability to grow in beer but those possessing a broad range of biochemical abilities had the greater propensity to cause spoilage.

Pathogens in Beer

“…According to the work of Fernandez and Simpson (1995) , levels of nitrogen (free amino and total soluble), amino acids, maltotriose, beer pH and color signifi cantly affected the resistance of beers to spoilage by lactic acid bacteria (non-pathogenic). Unlike the similar study by Dolezil and Kirsop (1980) , the cultures were adapted to grow in beer prior to inoculation, providing more reliable results. Table 39.4 summarizes the primary targets and mode of inhibition of many of the antipathogenic hurdles of beer, which are discussed in more detail below.…”

“…The majority of craft and microbreweries carbonate their products by bottle conditioning (secondary fermentation), and there is evidence that bottle conditioning reduces a beer ' s susceptibility to microbial attack, as the fermenting yeast reduces the O 2 content in the bottle headspace by approximately one-third ( Derdelinckx et al ., 1992 ). Dolezil and Kirsop (1980) reported that bottle conditioning appeared to be a factor in the production of resistant beer. Many breweries employ post-fermentation treatments such as fi ltration (physical exclusion), pasteurization (heat treatment), and cold storage to further protect the microbial stability of their beers.…”

The Genera of Lactic Acid Bacteria

“…They have included a French 'country beer' (Biere de garde) (Claussen, 1903), lager beer of the Pilsen type (Hansen, 1879;Back, 1978a) and stout (Andrews and Gilliland, 1952). Beers differ in their ability to support growth of pediococci (Dolezil and Kirsop, 1980). Fermentable carbohydrate, amino nitrogen (in the form of both amino acids and peptides), some vitamins, and minerals such as manganese, are limiting to growth (Uhl and Kiihbeck, 1969;Rainbow, 1981).…”

One Hundred Years of Yeast Research and Development in the Brewing Industry

“…Laboratory and pilot plant fermentations, as well as full scale trials in different breweries, have demonstrated the importance of the yeast strain [for a review see Engan]. 23 The formation of higher alcohols is also very dependent upon the fermentation temperature with an increase in temperature resulting in increased concentrations of higher alcohols in beer. It would appear that temperature changes have a more significant influence upon the formation of the aromatic alcohol 2-phcnylcthanol than on the aliphatic alcohols such as propanol, butanol and hexanol.…”