A feed composition comprising hexahydro--acid component compounds shown in formula I, i.e. hexahydrocolupulone and/or hexahydroadlupulone, applications of the feed composition and the hexahydro--acid component compounds, and a method for using the feed composition to improve animal production performance. ##STR00001##

Disclosed are monoesters, inner complex salts or monoester salts of hexahydro--acid, and application thereof as animal feed additives. The compounds as shown in formula (I), (II) and (III) show low toxicity or non-toxicity to animals, and have higher stability and better growth promotion effects than those disclosed in other patents, which make them more suitable to be applied as growth promoters used in feed and have a very good application prospect in cultivation industry.

Disclosed are monoesters, inner complex salts or monoester salts of hexahydro--acid, and application thereof as animal feed additives. The compounds as shown in formula (I), (II) and (III) show low toxicity or non-toxicity to animals, and have higher stability and better growth promotion effects than those disclosed in other patents, which make them more suitable to be applied as growth promoters used in feed and have a very good application prospect in cultivation industry.

A method for preparing a hop acid mixture having an enantiomeric excess of a (+)-tetrahydro--acid is disclosed. In the method, a racemate of a tetrahydro--acid is contacted with an amine to form a precipitate having an enantiomeric excess of the (+)-tetrahydro--acid. A method for preparing a hop acid is also disclosed. In the method, a racemate of a tetrahydro--acid is contacted with an amine to form a precipitate comprising a (+)-tetrahydro--acid, and the (+)-tetrahydro--acid is isomerized to a hop acid selected from the group consisting of (+)-trans-tetrahydro-iso--acids, ()-cis-tetrahydro-iso--acids, and mixtures thereof, and reduced to (+)-trans-hexahydroiso--acids and ()-cis-hexahydroiso--acids. An additive for flavoring a malt beverage is also disclosed. The additive includes a bittering agent selected from the group consisting of (+)-trans-tetrahydro-iso--acids, ()-cis-tetrahydro-iso--acids, (+)-trans-hexahydroiso--acids, ()-cis-hexahydroiso--acids, and mixtures thereof.

A method for preparing a hop acid mixture having an enantiomeric excess of a (+)-tetrahydro--acid is disclosed. In the method, a racemate of a tetrahydro--acid is contacted with an amine to form a precipitate having an enantiomeric excess of the (+)-tetrahydro--acid. A method for preparing a hop acid is also disclosed. In the method, a racemate of a tetrahydro--acid is contacted with an amine to form a precipitate comprising a (+)-tetrahydro--acid, and the (+)-tetrahydro--acid is isomerized to a hop acid selected from the group consisting of (+)-trans-tetrahydro-iso--acids, ()-cis-tetrahydro-iso--acids, and mixtures thereof, and reduced to (+)-trans-hexahydroiso--acids and ()-cis-hexahydroiso--acids. An additive for flavoring a malt beverage is also disclosed. The additive includes a bittering agent selected from the group consisting of (+)-trans-tetrahydro-iso--acids, ()-cis-tetrahydro-iso--acids, (+)-trans-hexahydroiso--acids, ()-cis-hexahydroiso--acids, and mixtures thereof.