Application for hop acids as anti-microbial agents
The alkali metal salts form of β-acids dissolved in propylene glycol is used to control microbial growth in food products, process streams and other applications, including in cosmetic formulations.
1. A process for the preparation of a solution of hop-derived β-acids suitable for use in the inhibition of bacterial growth and comprising the steps of:
(a) heating a mixture of β-acids and propylene glycol;
(b) simultaneously or sequentially adding a concentrated, aqueous solution of an alkali metal hydroxide to the heated mixture sufficient to obtain a homogeneous solution having a pH of at least about 9.0 (as measured after 3x dilution into water), and
(c) cooling said homogeneous solution.
2. The process of claim 1 , wherein the alkali metal is potassium or sodium.
3. The process of claim 1 , wherein the β-acids solution contains from about 1 to 30 weight percent of β-acids.
4. The process of claim 1 , wherein the β-acids solution contains from about 5 to 25 weight percent of β-acids.
5. The process of claim 1 , wherein the β-acids solution contains about 20 weight percent of β-acids.
6. A preparation of the alkali metal salts of hop-derived β-acids in an aqueous solution of propylene glycol prepared according to the process as claimed in claim 1 and in which the concentration of the β-acids exceeds 10 weight percent.
7. A preparation of the alkali metal salts of hop-derived β-acids in an aqueous solution of propylene glycol as claimed in claim 6 , having a water content below about 7%.