The Occurrence of Beer Spoilage Lactic Acid Bacteria in Craft Beer Production.
Beer is one of the world's most ancient and widely consumed fermented alcoholic beverages produced with water, malted cereal grains (generally barley and wheat), hops, and yeast. Beer is considered an unfavorable substrate of growth for many microorganisms, however, there are a limited number of bacteria and yeasts, which are capable of growth and may spoil beer especially if it is not pasteurized or sterile-filtered as craft beer. The aim of this research study was to track beer spoilage lactic acid bacteria (LAB) inside a brewery and during the craft beer production process. To that end, indoor air and work surface samples, collected in the brewery under study, together with commercial active dry yeasts, exhausted yeasts, yeast pellet (obtained after mature beer centrifugation), and spoiled beers were analyzed through culture-dependent methods and PCR-DGGE in order to identify the contaminant LAB species and the source of contamination. Lactobacillus brevis was detected in a spoiled beer and in a commercial active dry yeast. Other LAB species and bacteria ascribed to Staphylococcus sp., Enterobaceriaceae, and Acetobacter sp. were found in the brewery. In conclusion, the PCR-DGGE technique coupled with the culture-dependent method was found to be a useful tool for identifying the beer spoilage bacteria and the source of contamination. The analyses carried out on raw materials, by-products, final products, and the brewery were useful for implementing a sanitization plan to be adopted in the production plant.
Dipart. di Scienze Agrarie, Alimentari ed Ambientali, Univ. Politecnica delle Marche, via Brecce Bianche, 60131, Ancona, Italy.
Cristiana
C
Garofalo
Dipart. di Scienze Agrarie, Alimentari ed Ambientali, Univ. Politecnica delle Marche, via Brecce Bianche, 60131, Ancona, Italy.
Andrea
A
Osimani
Dipart. di Scienze Agrarie, Alimentari ed Ambientali, Univ. Politecnica delle Marche, via Brecce Bianche, 60131, Ancona, Italy.
Vesna
V
Milanović
Dipart. di Scienze Agrarie, Alimentari ed Ambientali, Univ. Politecnica delle Marche, via Brecce Bianche, 60131, Ancona, Italy.
Manuela
M
Taccari
Dipart. di Scienze Agrarie, Alimentari ed Ambientali, Univ. Politecnica delle Marche, via Brecce Bianche, 60131, Ancona, Italy.
Lucia
L
Aquilanti
Dipart. di Scienze Agrarie, Alimentari ed Ambientali, Univ. Politecnica delle Marche, via Brecce Bianche, 60131, Ancona, Italy.
Francesca
F
Clementi
D001419:Bacteria / Q000235:genetics / Q000254:growth & development*; D001515:Beer / Q000382:microbiology*; D005285:Fermentation; D005511:Food Handling; D005516:Food Microbiology; D006801:Humans; D019344:Lactic Acid; D007778:Lactobacillus / Q000254:growth & development*; D016133:Polymerase Chain Reaction / Q000379:methods; D015003:Yeasts
D019344:Lactic Acid
Lactobacillus brevis; PCR-DGGE; air sampling; brewery hygiene; craft beer