Nylon Oxygen Barrier Tubing Reduces Biofouling in Beer Draught Lines

Abstract

Beer draught lines are frequently contaminated with biofilm-forming microorganisms, which forces retailers to spend considerable time and money cleaning and replacing lines. In light of this financial burden, draught tubing composition was examined for its role in the prevention of biofouling in beer lines. Three types of draught tubing - vinyl, polyethylene, and nylon barrier - were inoculated with a combination of biofilm-forming microorganisms (Hafnia paralvei, Raoultella planticola, Pediococcus damnosus and Saccharomyces cerevisiae) and used to simulate a bar environment for sixteen weeks. Following simulation, the degree of biofouling in each draught line was determined by spectrophotometry and microscopy. Absorption values and fluorescence images showed that nylon barrier tubing was superior to the other lines at resisting biofilm maturation.These results suggest that tubing composition plays a significant role in the prevention of biofilm formation in beer draught lines and supports the adoption of nylon barrier tubing as an effective strategy against biofouling in a variety of applications.

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

“…Ingress of oxygen inevitably occurs during the dispense of cask beer and 46% of the microflora identified in cask ale samples were acetic acid bacteria. At packaging, the specification for oxygen in keg beers is <100 μg/L (Rod White, personal communication), with any additional oxygen pick‐up during dispense restricted to gas permeation through beer dispense tubing (Heger & Russell, 2021) and the beer/air interface at the keg connector and tap nozzle. Given this, as noted by Harper et al (1980), ‘the prevalence of acetic acid in (keg) beer is surprising’ reflecting the ‘microaerophilic conditions in the pipes’.…”

“…Whilst presumably planktonic, micro‐organisms in dispensed keg lager, ale, stout and cask ale can form biofilms when incubated in microplates (Jevons & Quain, 2021). Indeed, many of the micro‐organisms in Table 2 have been identified in dispense biofilms including acetic acid bacteria (Kubizniaková et al, 2021; Thomas & Whitham, 1996), Lactobacillus species (Walker et al, 2007), Pediococcus (Heger & Russell, 2021; Thomas & Whitham, 1996) and Saccharomyces species (including S. diastaticus ) (Riedl, Fütterer, et al, 2019; Walker et al, 2007). Elsewhere biofilm formation has been reported for B. bruxellensis from beer in wine (Dimopoulou et al, 2019), R. mucilaginosa (Riedl, Fütterer, et al, 2019) in beer, some (but not all) 20 brewery isolates of L. brevis in beer (Riedl, Dünzer, et al, 2019) and five species of Lactobacillus in beer (Wang et al, 2020).…”

“…The composition and incorporation of barrier layers in dispense lines can reduce the ingress of oxygen by 20-80 fold (https://www.micro matic.com/5-16-inch-id-barri ermas ter-flavo urloc k-tubin g-549BF). Reduced access to oxygen, together with smoother internal surfaces, reduces biofilm formation in draught beer lines (Heger & Russell, 2021;Thomas & Whitham, 1996).…”

Transition metals in brewing and their role in wort and beer oxidative stability: a review

“…With keg beer, gases can permeate through some grades of dispense tubing with CO 2 leaving and air entering the system ( 143 ) . This is of greater concern with keg beers that are ‘slow moving‘.…”