VIEW ARTICLE DOI: 10.1094/ASBCJ-54-0103
Preparation and Purification of Hop Acids and Their Derivatives. Patrick Lu-ping Ting and Henry Goldstein, Miller Brewing Company, 3939 West Highland Blvd., Milwaukee, WI 53208. J. Am. Soc. Brew. Chem. 54(2):103-109. Accepted September 28, 1995.
Pure individual
analogs and
stereoisomers
of the major
alpha-acids,
beta-acids,
cis and
trans-iso-alpha-acids,
cis and
trans-rho-iso-alpha-acids,
tetrahydrodesoxy-alpha-acids,
tetrahydro-alpha-acids,
and cis
and trans-tetrahydroiso-alpha-acids
have been prepared
and isolated
using fractional
recrystallization,
complexation,
pH partitioning,
and various
chromatographic
techniques (including
preparative
normal phase
and reverse
phase). Their
structures were
determined by
elemental analysis,
(^1)H and (^13)C
NMR, chirooptical
methods, gas
chromatography-mass
spectrometry
(MS), MS, UV,
and high-performance
liquid chromatography.
The configurations
of cis
and trans-iso-alpha-acids
were characterized
to help establish
the mechanism
for the formation
of rho-iso-alpha-acids.
The stereochemistry
of tetrahydroiso-alpha-acids,
prepared from
alpha-acids
and beta-acids,
has been clarified.
The availability
of these pure
standards simplifies
the analytical
procedures,
allowing the
brewer to take
full advantage
of the various
bittering agents.
Keywords: Bittering
compounds, Chiral
separation,
Hops, Hop acids,
Hop derivatives.
Los
análogos
individuales
puros y los
estereoisomeros
de los principales
alpha-ácidos,
beta-ácidos,
cis y
trans-iso-alpha-ácidos,
cis y
trans-rho-iso-alpha-ácidos,
tetrahidrodesoxi-alpha-ácidos,
tetrahidro-alpha-ácidos
y cis y
trans-tetrahidroiso-alpha-ácidos
fueron preparados
y aislados usando
recristalización
fraccionada,
formación
de complejos,
partición
por pH y varias
técnicas
cromatográficas
(incluyendo
preparative
en fase normal
y en fase invertida).
Sus estructuras
fueron determinadas
por análisis
elemental, espectros
de RMN de (^1)H
y (^13)C, métodos
quiroópticos,
GC-MS y MS,
UV y HPLC. Las
configuraciones
de los cis
y trans-iso-alpha-ácidos
fueron caracterizadas
para ayudar
a establecer
el mecanismo
de la formación
de los rho-iso-alpha-ácidos.
Las estereoquómicas
de los tetrahidroiso-alpha-ácidos
preparados a
partir de alpha-ácidos
y beta-ácidos
son diferentes.
La disponibilidad
de estos estándares
puros simplifica
los procedimientos
analíticos,
permitiendo
al cervecero
obtener la máxima
ventaja de estos
productos amargos.