COMPOSITION FOR INHIBITING LACTIC ACID BACTERIA CONTAMINATING PROCESS MEDIUM DURING PRODUCTION OF ETHANOL FUEL (VERSIONS), METHOD OF MONITORING LACTIC ACID BACTERIA CONTAMINATION OF SAID MEDIUM AND METHOD OF MONITORING GROWTH OF LACTIC ACID BACTERIA IN FERMENTATION PROCESS

摘要

FIELD: chemistry.;SUBSTANCE: invention relates to production of ethanol fuel using hop acids. Six hop acids - alpha acid, beta acid, iso-alpha acid, rho-iso-alpha acid, tetrahydroiso-alpha acid and hexahydroiso-alpha acid were tested so as to determine which among them is the most effective in inhibiting growth of bacteria, usually during production of ethanol fuel. Bacteria used in these tests were Lactobacillus brevis and Lactobacillus fermentum. Minimum inhibitory concentration (MIC) of the hop acids were determined using MRS broth, as well as a medium of molasses wort and wheat mash during their fermentation. In all cases the hop acids controlled growth of these two Lactobacillus bacteria, while the tetrahydroiso-alpha acid, hexahydroiso-alpha and iso-alpha acid killed the most bacteria at the lowest MIC.;EFFECT: treatment of yeast propagation agents, steep tanks and enzymes using hop acids with minimum inhibitory concentration will stop growth of bacteria, increase ethanol output and avoid the need for antibiotics.;59 cl, 49 dwg, 2 tbl, 7 ex