TY - JOUR
T1 - Importance of tetrahydroiso α-acids to the microbiological stability of beer
AU - Caballero, Isabel
AU - Agut, Montserrat
AU - Armentia, Alicia
AU - Blanco, Carlos A.
PY - 2009
Y1 - 2009
N2 - While beer provides a very stable microbiological environment, a few niche microorganisms are capable of growth in malt, wort, and beer. The production of off-flavors and development of turbidity in the packaged product are due to the growth and metabolic activity of wild yeast, certain lactic acid bacteria (LAB) and anaerobic Gram-negative bacteria. Beer also contains bitter hop compounds, which are toxic to Gram-positive and Gram-negative bacteria, and contribute to preventing the spoilage of this beverage. In the boiling process, the hop α-acids (humulones) are isomerized into iso α-acids. These products are responsible for the bitter taste of beer, but they also play an essential role in enhancing foam stability. Antibacterial activity of iso a-acids and their hydrogenated derivates (rhoiso α-acids and tetrahydroiso α-acids) in MRS broth and beer have been evaluated against different LAB (Lactobacillus and Pediococcus) for the determination of their beer-stabilizing capabilities. Besides this, we have determined the minimum inhibitory concentration and the bacteriostatic effect of each compound against Pediococcus. We found that tetrahydroiso α-acids (added directly to beer during production processes) are the compounds that present the greatest antibacterial activity against the main agents implicated in beer spoilage.
AB - While beer provides a very stable microbiological environment, a few niche microorganisms are capable of growth in malt, wort, and beer. The production of off-flavors and development of turbidity in the packaged product are due to the growth and metabolic activity of wild yeast, certain lactic acid bacteria (LAB) and anaerobic Gram-negative bacteria. Beer also contains bitter hop compounds, which are toxic to Gram-positive and Gram-negative bacteria, and contribute to preventing the spoilage of this beverage. In the boiling process, the hop α-acids (humulones) are isomerized into iso α-acids. These products are responsible for the bitter taste of beer, but they also play an essential role in enhancing foam stability. Antibacterial activity of iso a-acids and their hydrogenated derivates (rhoiso α-acids and tetrahydroiso α-acids) in MRS broth and beer have been evaluated against different LAB (Lactobacillus and Pediococcus) for the determination of their beer-stabilizing capabilities. Besides this, we have determined the minimum inhibitory concentration and the bacteriostatic effect of each compound against Pediococcus. We found that tetrahydroiso α-acids (added directly to beer during production processes) are the compounds that present the greatest antibacterial activity against the main agents implicated in beer spoilage.
UR - http://www.scopus.com/inward/record.url?scp=70349314521&partnerID=8YFLogxK
U2 - 10.1093/jaoac/92.4.1160
DO - 10.1093/jaoac/92.4.1160
M3 - Article
C2 - 19714985
AN - SCOPUS:70349314521
SN - 1060-3271
VL - 92
SP - 1160
EP - 1164
JO - Journal of AOAC International
JF - Journal of AOAC International
IS - 4
ER -