Pungent principal of Alpinia galangal (L.) Swartz and its applications

Article abstract of DOI:10.1021/jf9808224

The pungent principal of galangal [Alpinia galangal (L.) Swartz] rhizomes was isolated and identified as 1'-acetoxychavicol acetate (galangal acetate). Galangal acetate exhibits a unique pungent sensation, which is less intense than that of capsaicin and without a lingering effect. Applications of galangal acetate were tested in beverages, sweet goods, dressings, and personal care products. In many applications, galangal acetate is preferred to other pungent ingredients. It can be used as an alcohol enhancer or an alcohol replacer in alcohol and alcohol-free beverages. Galangal acetate is not stable in aqueous solutions and undergoes hydrolysis/isomerization reactions. Therefore, galangal acetate was absent in galangal essential oil obtained by steam distillation. However, galangal acetate was found as one of the major volatile components of the galangal rhizomes by headspace GC analysis. The stability of galangal acetate was studied under various conditions.

Full text of DOI:10.1021/jf9808224

J. Agric. Food Chem. 1999, 47, 1657−1662
1657
P u n gen t P r in cip a l of Alpin ia ga la n ga l (L.) Sw a r tz a n d Its
Ap p lica tion s
Xiaogen Yang* and Robert G. Eilerman
Givaudan Roure Flavors Corporation, 1199 Edison Drive, Cincinnati, Ohio 45216
The pungent principal of galangal [Alpinia galangal (L.) Swartz] rhizomes was isolated and identified
as 1′-acetoxychavicol acetate (galangal acetate). Galangal acetate exhibits a unique pungent
sensation, which is less intense than that of capsaicin and without a lingering effect. Applications
of galangal acetate were tested in beverages, sweet goods, dressings, and personal care products.
In many applications, galangal acetate is preferred to other pungent ingredients. It can be used as
an alcohol enhancer or an alcohol replacer in alcohol and alcohol-free beverages. Galangal acetate
is not stable in aqueous solutions and undergoes hydrolysis/isomerization reactions. Therefore,
galangal acetate was absent in galangal essential oil obtained by steam distillation. However,
galangal acetate was found as one of the major volatile components of the galangal rhizomes by
headspace GC analysis. The stability of galangal acetate was studied under various conditions.
Keyw or d s: Alpinia galangal; spice; pungency; flavor; 1′-acetoxychavicol acetate; galangal acetate
INTRODUCTION
in galangal and to explore its potential for use in food,
beverage, and other related products.
Galangal, also called galanga, galingale, galangale,
and calangall, is a pungent aromatic rhizome produced
in eastern Asia. There are two different species of
galangal: one is the so-called lesser or smaller galangal
(Alpinia officinarum Hance Farw.), a perennial herb
native to China (Gao liang jiang), with pyramidal
racemes of rose-veined white flowers; the other is the
so-called greater galangal [Alpinia galanga (L.) Swartz.
or Languas galanga (L.) Stuntz], a stemless perennial
herb of southeastern Asia with fragrant short-lived,
largely white flowers. In this paper we deal with greater
galangal.
The rhizomes of galangal are widely used as spice or
ginger substitutes for flavoring foods (e.g., meat and
curries) throughout Asian countries. Galangal is also
used as a stomach ache medicine in China (Hong dou
kou) and in Thailand. The essential oil of galangal root
is also used in perfuming. The biological activities of
galangal have been intensively studied in recent years,
and it is reported as possessing antitumor, pungency,
antibacterial, antiulcer, antifungal, and insecticidal
properties (Itokawa et al., 1987; J anssen and Scheffer,
1985; Kondo et al., 1993). The essential oil composition
of galangal has been reported in several research
articles [e.g., Lawrence et al. (1969), Scheffer et al.
(1981), DePooter et al. (1985), and Charles et al. (1992)].
The antioxidant activities of galangal were also studied
(J itoe et al., 1992; Zheng et al., 1993).
MATERIALS AND METHODS
Ma ter ia ls. Dry galangal root was imported from Indonesia,
and frozen fresh galangal root was obtained in an oriental
grocery store in Clifton, NJ (imported from Thailand). Galan-
gal oleoresin was prepared by Soxhlet extraction of galangal
roots with ethanol, and then the solvent was removed.
F r a ction a tion for Scr een in g. Galangal oleoresin, dis-
solved in ethanol (95%), was fractionated by flash chromatog-
raphy (silica gel, 1 × 10 in., sample load ∼0.6 g of oleoresin).
The solvent systems were hexane/ethyl acetate (4:1), hexane/
ethyl acetate (1:1), ethyl acetate, ethyl acetate/ethanol (4:1),
ethyl acetate/ethanol (1:1), ethanol, and water. The eluate was
collected in 20-mL test tubes and recombined into fractions
according to the TLC results.
Extr a ction a n d F r a ction a tion of Ga la n ga l Oleor esin .
Galangal oleoresin was extracted with pentane. After the
solvent was removed, the pentane extract was fractionated by
flash chromatography (silica gel, 1 × 10 in.). A solvent system
composed of hexane and methyl tert-butyl ether (MTBE) was
used: hexane; hexane/MTBE (9:1); hexane/MTBE (4:1); hex-
ane/MTBE (1:1); and MTBE. The eluate was collected and
recombined into fractions. After the solvent was removed by
rotary evaporation and then by a nitrogen stream, a few
microliters of the concentrate were added to 0.5 mL of water
containing 10% ethanol for sensory screening.
Hyd r olysis of Ga la n ga l Aceta te. Hydrolysis reactions of
galangal acetate under various experimental conditions were
carried out in a 0.02 M KH2PO4 buffer solution, and the
concentration of galangal acetate was 100 ppm. The pH value
of the buffer was adjusted to a predetermined value using
diluted NaOH or HCl solution. After reaction, the mixture was
extracted by hexane/MTBE (1:1) and analyzed by GC/MS. The
specific experimental conditions are given in the corresponding
figures.
Deter m in a tion of Ga la n ga l Aceta te a n d Its Rea ction
P r od u cts. The concentration of galangal acetate in dry
galangal roots, frozen galangal roots, and galangal oleoresins
was determined by GC analysis with external calibration. The
relative concentrations of reaction products of galangal acetate
were calculated on the basis of GC peak areas relative to that
of galangal acetate.
Galangal has a unique flavor profile and is described
as having more woody, minty, and floral aromas than
ginger (Mori et al., 1995). The extract of galangal is used
for liquor flavoring. Most recently, galangal oleoresin
is also commercially available as a food spice. The
appearance and taste of the galangal root are very
similar to those of ginger. However, the chemical
composition of galangal oleoresin is very different from
that of ginger as indicated by a preliminary screening
using HPLC. It is of great importance for spice process-
ing and utilization to discover the pungent principles
10.1021/jf9808224 CCC: $18.00 © 1999 American Chemical Society
Published on Web 03/13/1999

1658 J. Agric. Food Chem., Vol. 47, No. 4, 1999
Yang and Eilerman
Ch a r t 1. Hyd r olysis of Ga la n ga l Aceta te
An a lytica l In str u m en ts. GC/MS analysis was carried out
on an HP 6890 gas chromatograph/HP 5972A quadrupole mass
spectrometer system. Separation was mostly performed using
a 30-m × 0.25-mm (i.d.) capillary column coated with a 1-mm
film of DB-1 stationary phase (J &W Scientific, Folsom, CA).
Helium was used as the carrier gas. The oven temperature
program used was from 80 to 270 °C at a rate of 4 °C/min.
The injector and transfer line temperatures were held at 250
°C. Injection was set as split with a ratio of 50:1. The mass
spectrometer was operated with an ionization voltage of 70
eV and was scanned from m/z 35 to 400 at ∼1 scan/s.
Purification of galangal acetate was performed on a Waters
HPLC system with a mobile phase of 75% methanol in water
(flow rate ) 4 mL/min). A 250-mm, 10-mm i.d. C18 column
was used. IR spectra were recorded using the Perkin-Elmer
system 2000 FTIR. A Varian Gemini 300 NMR (300 MHz) was
used for the NMR analysis.
Sen sor y Eva lu a tion of Ga la n ga l Aceta te. Informal
sensory screening was conducted during isolation and identi-
fication procedures. For evaluating the hotness of galangal
acetate, five panelists were recruited and trained with different
concentrations of capsaicin using a line scale. Synthesized
galangal acetate (racemate) was used for sensory evaluation.
All samples were served at room temperature in 1-oz souffle´
cups. Unsalted crackers were provided, as well as water for
rinsing, between tastings. Specific rinsing procedures were
followed according to the ASTM method to reduce effects of
desensitization and excitation (Annual Book of ASTM Stan-
dards, 1995). Synthetic 1′-acetoxychavicol acetate (99%) was
used for the testing, and pelargonic acid vanillylamide (syn-
thetic capsaicin, Fluka) was used as the reference.
IR and MS. However, it is unknown in our mass spectra
and IR spectra libraries and was subjected to further
structural analysis.
Id en tifica tion . The compound isolated from fraction
D was found to be a colorless oily liquid, although it
can be crystallized by seeding its solution. The structure
elucidation was based on IR, MS, and NMR spectra.
The IR spectrum showed strong absorptions at 1742
and 1204 cm-1, which indicated the presence of a
carbonyl CdO group and a single C-O bond. C-H
valence stretching around 3000 cm-1 indicated C-H
bonds both on unsaturated (>3000 cm-1) and on ali-
phatic (2919, 2851 cm-1) C-bonds. The aromatic CdC
valence vibration also clearly showed up at 1608 and
1508 cm-1. The IR spectrum suggested an aromatic
ester.
RESULTS AND DISCUSSION
In the mass spectrum of the pungent compound, the
most abundant mass peaks were 192, 150, 132, and 43.
The molecular weight of this compound was estimated
as 234. Characteristic fragments included CH3-CtO+
P r elim in a r y Scr een in g. Galangal oleoresin was
fractionated by flash chromatography. Sensory testing
(taste) was carried out by four panelists. Two fractions
were found to be “hot”. There were, however, two
different hot sensations: One fraction had a “bite” effect
and was described as heat similar to that of capsaicin;
the other fraction had no “bite” effect and was described
as astringent. The fraction described as a “bite” sensa-
tion was chosen as the analytical target, which is a
relatively nonpolar fraction and also contains essential
oil components. The other fraction is a relatively polar
fraction.
F r a ct ion a t ion a n d Isola t ion . Because the hot
principal component was found in a relatively nonpolar
fraction in the preliminary experiments, further extrac-
tion on a larger scale was carried out using a nonpolar
solvent. The galangal oleoresin was dissolved in 95%
ethanol and then diluted with water. After extraction
with hexane, the organic phase was dried and the
solvent removed. For tasting, a small amount of the
extract was dissolved in 10% ethanol. The extract was
much hotter than the oleoresin. This clearly confirmed
that the hot component(s) was (were) indeed in the
hexane extract.
The extract was then fractionated into seven fractions
(fractions A-G) by flash chromatography. The aqueous
solution was tasted by four panelists. Fraction D was
clearly identified as the major hot fraction. GC analysis
revealed that fraction D contained a major component
of 92%.
The major component in fraction D was purified
further by semipreparative HPLC (C-18, 10 × 250 mm)
with a mobile phase of 75% methanol in water (4 mL/
min). The purity of this compound was >99% by GC/
FID. The hot taste of this compound did not change after
the purification. It is concluded that it is indeed the hot
principal of galangal. This compound was analyzed by
+
at m/z 43 from methyl ketones, C6H5 at m/z 77 from
phenyl derivatives, and loss mass 42 (234 - 192, 192 -
150) due to formation of CH2dCdO by a McLafferty
rearrangement.
The proton NMR spectrum showed 14 protons in the
molecule. Two symmetrical doublets at 7.3 and 7.6 ppm
indicated four protons on a para-substituted benzene
ring. Proton resonances at 5.54 (2H, dd), 6.25 (1H, ddd),
and 6.52 (1H, d) probably correspond to protons on an
allyl group. Two methyl groups at 2.35 and 2.55 ppm
suggested two acetyl groups. Carbon-13 APT and DEPT
indicated 13 carbons: 2 CH3, 1 CH2, 6 CH, and 4
quaternary carbons. Two carbon signals at 169.8 and
169.9 ppm are typically from carboxyl groups. Two pairs
of carbon atoms have identical chemical shifts at 121.6
and 128.4 ppm, confirming a para-substituted benzene
1
ring. 1H-1H and H-13C correlation NMR experiments
showed cross-peaks in COSY, HETCOR, and long-range
HETCOR, clearly suggesting an allyl group and two
acetyl groups. The chemical structure of the molecule
isolated from fraction D is proposed as 1′-acetoxychavi-
col acetate (galangal acetate) (Chart 1).
Fraction E, one of the major components in the
galangal extract, is a tasteless solid. It has IR, MS, and
NMR spectra very similar to those of the hot component
1′-acetoxychavicol acetate. It is also unknown in our
mass spectra and IR libraries. Structure elucidation
concluded that it has the structure of p-coumaryl
diacetate (Chart 1).
1′-Acetoxyeugenol acetate (Chart 2) was also found
in galangal root and described as pungent. However, its
concentration is much lower (2% of galangal acetate)
in galangal roots. Therefore, the major contributor to
galangal pungency is believed to be galangal acetate.

Pungent Principal of Galangal
J. Agric. Food Chem., Vol. 47, No. 4, 1999 1659
Ta ble 3. Com p a r ison of Hotn ess of Ga la n ga l Aceta te a n d
Ca p sa icin
Ch a r t 2. 1′-Acetoxyeu gen ol Aceta te
concn of galangal
acetate (ppm)
av Scoville
heat units (N ) 5)
calcd concn of
capsaicin (ppm)
5
10
15
20
45543
55593
60317
67854
0.69
0.85
0.92
1.03
Ta ble 1. Con ten ts of 1′-Acetoxych a vicol Aceta te in
Ga la n ga l
Ch a r t 3. P r op osed Rea ction In ter m ed ia te
sample
% (w/w)
sample
% (w/w)
dry galangal
frozen fresh galangal
2.4
0.6
oleoresin (lot 1)
oleoresin (lot 2)
3.7
4.7
Ta ble 2. Com p osition of Sta r tin g Ma ter ia l a n d Its
Rea ction Mixtu r e (P er cen t)
Ch a r t 4. P r op osed Sigm a tr op ic Rea r r a n gem en t of
Ga la n ga l Aceta te
starting
material
2 h of
reflux
24 h of
storage
component
1′-hydroxychavicol acetate
1′-acetoxychavicol acetate
p-acetoxycinnamic alcohol
p-coumaryl diacetate
nda
97.4
nd
37.6
nd
53.9
5.9
22.6
62.0
11.3
3.1
0.2
a
nd, not detected.
aqueous solution (10% ethanol) of galangal acetate
disappeared. Because the stability of galangal acetate
is one of the determining factors for its applicability in
food systems, it is of great interest to study the reaction
products and reaction mechanism.
A literature search revealed that galangal acetate is
known as a component in galangal and was described
as an antiulcer, antifungal, and antitumor substance,
a xanthine oxidase inhibitor, and an inhibitor of Ep-
stein-Barr virus activation and phagocytosis (Wa-
tanabe et al., 1995). The synthesis method is also
described (Mitsui et al., 1976). p-Coumaryl diacetate is
also known as an inhibitor of xanthine oxidase (Noro
et al., 1988). Synthesis of galangal acetate verified the
chemical structure (Bachmann et al., 1997).
Con cen tr a tion of Ga la n ga l Aceta te in Ga la n ga l.
The concentration of galangal acetate was determined
in dried galangal roots, frozen fresh galangal roots, and
galangal oleoresin (Table 1). The samples were extracted
by hexane and analyzed by GC. Although galangal has
a high concentration of galangal acetate, it was not
reported as a component in galangal essential oils
(Lawrence et al., 1969; Scheffer et al., 1981; DePooter
et al., 1985; Charles et al., 1992; Rui et al., 1982; Xue
et al., 1987). Galangal acetate was found in trace
amounts in an extract by simultaneous distillation
extraction but was one of the major GC peaks by
headspace analysis of galangal roots in our laboratory.
Hotn ess of Ga la n ga l Aceta te. Synthetic galangal
acetate (racemic) was used for the sensory evaluation.
From an informal evaluation of galangal acetate solu-
tion, it was described as spicy with a quicker onset of
heat sensation as compared to capsaicin. The heat
sensation was perceived initially at the tip of tongue,
which then spread to the rest of the oral cavity and
throat. Compared to the pungent type of heat sensation
from capsaicin, galangal acetate was described as being
less pungent and less warming. Scoville heat units for
four concentrations of galangal acetate were obtained
using the ASTM standard method of evaluating red
pepper heat (Annual Book of ASTM Standards, 1995).
A linear correlation was obtained between the strength
of heat and the concentration of galangal acetate within
the tested range (Table 3).
We refluxed a 100 ppm aqueous solution of galangal
acetate for 2 h. The aqueous solution was no longer
pungent after reflux. The reaction products were ex-
tracted with methylene chloride and analyzed by GC/
MS. The starting material was not detectable in the
reaction mixture. Three major products were identified
as 1′-hydroxychavicol acetate, p-acetoxycinnamic alco-
hol, and p-coumaryl diacetate (Chart 1) by comparison
of their mass spectra with reference mass spectra.
It was reported that 1′-acetoxychavicol acetate un-
dergoes hydrolysis reactions when refluxed with water,
and p-acetoxy-trans-cinnamic alcohol and 1′-hydroxy-
chavicol acetate were the hydrolysis products (Xue et
al., 1987). p-Coumaryl diacetate was not reported as a
reaction product of galangal acetate under hydrolysis
conditions in the literature. Mori and co-workers also
observed the instability of galangal acetate during
steam distillation (Mori et al., 1995).
An aqueous solution of galangal acetate (100 ppm, 1%
ethanol) was stored at ambient temperature. The pun-
gency of the solution was reduced after overnight
storage. Analysis of the stored solution also found the
three hydrolysis products mentioned above. The relative
concentrations of the hydrolysis products are shown in
Table 2.
The formation of galangal acetate and p-acetoxycin-
namic alcohol is probably through an acid-catalyzed SN1
reaction mechanism, and the carbocation shown in
Chart 3 is probably involved as the intermiediate.
The isomerization of galangal acetate to p-coumaryl
diacetate looks like a [3,3] sigmatropic rearrangement,
which occurs when 1,5-dienes are heated (Chart 4).
p-Coumaryl diacetate can also be derived from the
intermediate as shown in Chart 3.
Temperature certainly plays an important role in the
hydrolysis reactions. If the aqueous solution of 100 ppm
galangal acetate is stored in the refrigerator, it remains
“hot” for at least several days. All hydrolysis products
mentioned above are not pungent or much less pungent
than galangal acetate. Therefore, the hydrolysis reac-
tions lead to instability of the pungency of this com-
Sta bility of Ga la n ga l Aceta te. During the isolation
experiments and sensory evaluation, it was found that
1′-acetoxychavicol acetate was not stable in aqueous
solution. After an aqueous solution had stood for a few
hours at room temperature, the pungent taste of the

1660 J. Agric. Food Chem., Vol. 47, No. 4, 1999
Yang and Eilerman
F igu r e 1. Temperature effect on reactions of galangal acetate
in 5% ethanol for 1 h: (O) 1′-hydroxychavicol acetate; (9)
galangal acetate; (4) p-acetoxycinnamic alcohol; (×) p-cou-
maryl diacetate.
F igu r e 3. pH effect on reactions of galangal acetate in 5%
ethanol at 60 °C for 1 h: (O) 1′-hydroxychavicol acetate; (9)
galangal acetate; (4) p-acetoxycinnamic alcohol; (×) p-cou-
maryl diacetate.
p-acetoxycinnamic alcohol decreases with increasing pH
value, while the concentration of p-coumaryl diacetate
remains practically constant.
In vegetable oil 1400, galangal acetate was heated at
80 and 120 °C for 1 h. HPLC analysis indicated that
galangal acetate remained practically unchanged after
heating.
Solutions to the Instability of Galangal Acetate. Ga-
langal acetate is stable in lower temperature, higher
alcohol content and in neutral solutions. As estimated,
galangal acetate is stable in 30-40% ethanol, pH 6-7,
and at room temperature for several months. The
instability of galangal acetate limited its applications.
Therefore, we tried to find more stable analogues of
galangal acetate. The allylic acetate structure plays a
very important role in the hydrolysis/isomerization
reactions. Modification of this part of the chemical
structure could improve the stability. On the other hand,
any changes of the chemical structure could affect the
pungency of the derived compounds. A series of ana-
logues of galangal acetate has been synthesized, and the
relationship among pungency, stability, and chemical
structure has been further studied (Bachmann et al.,
1997).
F igu r e 2. Ethanol concentration effect on reactions of galan-
gal acetate at 60 °C for 5 h: (O) 1′-hydroxychavicol acetate;
(9) galangal acetate; (4) p-acetoxycinnamic alcohol; (×) p-
coumaryl diacetate.
pound. The stability of galangal acetate was further
studied under various experimental conditions.
Temperature. Under hydrolytic conditions, the reac-
tion rate of galangal acetate increases with increasing
temperature. In 5% ethanol solution, the starting mate-
rial is almost completely converted after 1 h of reflux.
At room temperature, the reaction is slow. At higher
temperature, the isomerization rate is higher than the
hydrolysis reaction rate. Under refrigerated conditions,
galangal acetate is stable for several days, even in 1%
ethanol solution (Figure 1).
Ap p lica tion s. Although galangal acetate was found
as one of the major volatile components of galangal roots
by headspace GC, the pure compound has a very weak
odor. The flavor value of galangal acetate is mainly due
to its trigeminal impact.
Pungency is a very important flavor-related sensation
for many types of food, beverages, and personal care
products. Pungency includes various sensory effects
which can be described as biting, stinging, hot, sharp,
burning, and warm. Most well-known pungent stimuli
originate from spices and vegetables, such as capsaici-
noids (chili pepper), piperines (black pepper), gingerols
(ginger), and isothiocyanates (mustard, horseradish).
These spices and vegetables, which are widely used in
savory products, enhance and provide product-specific
flavor characters. For beverages, the most common
pungent stimuli are carbon dioxide and ethanol. The
consumption of alcoholic beverages is an important part
of diverse cultures. The excess consumption of alcohol,
however, can cause social and health-related problems.
Therefore, demands for alcohol-free beverages with the
alcohol sensations are increasing on the beverage
market. It is a challenging task for the beverage and
flavor industry to develop products mimicking the
alcohol sensations. So far, an effective alcohol enhancer
Ethanol Concentration. The reaction rate of both
hydrolysis and isomerization of 1′-acetoxychavicol ac-
etate is affected by ethanol concentration. The overall
reaction rate of 1′-acetoxychavicol acetate decreases
with increasing ethanol concentration. The formation
of p-coumaryl diacetate is inhibited in higher ethanol
concentration, whereas the formation rate of 1′-hy-
droxychavicol acetate and p-acetoxycinnamic alcohol
increases with increasing ethanol concentration when
c(EtOH) < 10% and then decreases when c(EtOH) >
10% (Figure 2).
pH Effect. Hydrolysis of galangal acetate can be
catalyzed by hydrogen ions. Therefore, the pH value of
the reaction system affects the stability of this com-
pound. As shown in Figure 3, galangal acetate is more
stable in neutral solutions. Its reaction rate increases
with decreasing pH value. The influence of solution
acidity on the formation of the different reaction prod-
ucts varies. The concentration of galangal acetate and

Pungent Principal of Galangal
J. Agric. Food Chem., Vol. 47, No. 4, 1999 1661
or replacement without undesirable aroma/taste and
without a lingering effect has not been found. As
discovered by sensory evaluation, galangal acetate
exhibits a “clean” pungent sensationsit is tasteless and
odorless at concentrations in the parts per million range,
and the duration of pungency is much shorter than that
of capsaicinoids. Therefore, galangal acetate is ideal for
applications not only for savory products and sweet
goods but also for beverages and personal care products.
The applications of galangal acetate were examined.
Beverages. Galangal acetate enhances the alcohol
taste (giving the alcohol more “burning” or “warming”
effects). It can be used as a partial replacement of
alcohol in beverages. For example, the taste of a 40-
proof alcoholic beverage base with 50 ppm of galangal
acetate was described as excellent, having a good
balance of initial burn and aftertaste burn, and the
effects on taste from the 40-proof beverage were judged
to be greater than those of a 60-proof beverage. Galangal
acetate was applied to an alcohol-free base (160 ppm)
and resulted in a taste like an alcoholic beverage.
Corresponding alcoholic beverages were used as refer-
ences. Informal sensory evaluation was conducted in the
beverage application group.
Sweet Goods. Galangal acetate was applied to hard
candy and chewing gum and imparted a peppery
pungent taste without an undesired lingering effect.
Dressings (Savory). Without a lingering effect, galan-
gal acetate contributed spicy and pungent characters
to mayonnaise, sour cream, and ketchup at a usage level
of 500-1000 ppm.
Personal Care Products. By the addition of galangal
acetate at a level of 100 ppm, toothpaste or mouthwash
bases imparted a warm/hot sensation.
147 (24), 151 (14), 162 (85), 163 (17), 179 (14), 180 (93),
181 (11), 222 (46), 264 (7).
1′-Hydroxychavicol acetate: MS (EI), m/z 39 (16), 43
(56), 51 (10), 55 (35), 65 (16), 77.1 (32), 94 (37), 95 (43),
107 (40), 121 (47), 123 (37), 131 (12), 133 (21), 149 (59),
150 (100), 192 (11).
1′-Acetoxycinnamic alcohol: MS (EI), m/z 39 (10), 43
(35), 55 (11), 65 (11), 77 (20), 91 (14), 94 (53), 107 (100),
108 (12), 131 (10), 150 (70), 192 (16).
Su m m a r y. Galangal acetate was identified as the
pungent principal of galangal rhizomes. In comparison
with other known pungent components, it imparts a
delayed spicy and pungent sensation and a clean taste
without a lingering effect. It can be used as an alcohol
enhancer or replacement in beverages. Application of
galangal acetate in sweet goods, dressings, and personal
care products produces a desirable pungent taste.
However, galangal acetate easily undergoes hydrolysis/
isomerization reactions under typical hydrolytic condi-
tions in water or aqueous ethanol. The reaction can be
slowed at a lower temperature, in higher alcohol con-
centration, and in a medium with a higher pH value.
The reaction products are not pungent at all or are much
less pungent than the starting material. The hydrolytic
instability of galangal acetate limits the applications.
Because the allylic acetate structure facilitates the
hydrolytic reactions, modification of the chemical struc-
ture could improve the stability. Pungent and stable
analogues of galangal acetate, which broaden the po-
tential applicability of this class of compounds in
beverage, food, and personal care products, are under
investigation.
ACKNOWLEDGMENT
This project was carried out in cooperation with the
groups of Flavor Science and Technology (Ms. J . Sciple,
Ms. C. Goodwin, and Dr. J . LaMarta) and Sensory
Science (Ms. D. Hong) of the Department of Science and
Technology and Beverage Application Laboratory (Mr.
J . Dono and Mr. D. Healy) of Givaudan Roure Flavors
Corp., Clifton, NJ . The synthesis of galangal acetate and
its analogues was conducted in Corporate Research,
Du¨bendorf, Switzerland (Dr. B. Hostettler, Dr. M.
Gautschi, and Mr. J .-P. Bachmann). We thank Dr. T.
Peppard and Dr. P. Christenson for valuable discus-
sions. Finally, we acknowledge the officers of Givaudan
Roure Flavors Corp. for permission to publish this
paper.
For a more detailed description of the use of galangal
acetate in food and beverage applications, the reader is
referred to the patent (Bachmann et al., 1997).
1
Sp ectr oscop ic Da ta . The H and 13C NMR and MS
data are summarized below for 1′-acetoxychavicol ac-
etate, as are the MS data for 1′-acetoxyeugenol acetate
and the hydrolysis reaction products p-coumaryl diac-
etate, 1′-hydroxychavicol acetate, and 1′-acetoxycin-
namic alcohol.
The NMR spectra were recorded using a Varian
Gemini 300; CDCl3 was used as solvent. The chemical
shifts (ppm) are reported relative to TMS.
1′-Acetoxychavicol acetate (galangal acetate): 1H NMR
(300 MHz, CDCl3) δ 2.35 (3H, s), 2.55 (3H, s), 5.54 (2H,
dd), 6.25 (1H, ddd), 6.52 (1H, d, J ) 5.3 Hz), 7.33 (2H,
d, J ) 7.0 Hz), 7.63 (2H, d, J ) 7.0 Hz); 13C NMR δ
21.09 (CH3), 21.19 (CH3), 75.47 (CH), 117.04 (CH2),
121.63 (CH), 128.38 (2CH), 135.98 (2CH), 136.40 (C),
150.40 (C), 169.33 (C), 169.86 (C); IR (neat) 2919 m,
2851 m, 1764 s, 1742 s, 1608 w, 1508 m, 1371 m, 1234
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J F9808224