Investigating the effect of processing conditions on the content of glycyrrhizic acid in licorice (Radix et Rhizoma Glycyrrhizae)

Abstract

Introduction: Licorice is the root of Glycyrrhiza uralensis Fisch or Glycyrrhizae inflata L. or Glycyrrhiziae glabra L. It was a familiar medicinal herb in traditional medicine, which was commonly used in two different forms raw licorice (Sinh Cam thao) and honey-fried licorice (Chich Cam thao), with completely different effects. The processing enhanced the impact on the Spleen and Stomach organs and tonified Qi but reduced the bioactivities of clearing heat, antitussive, and detoxifying. The purpose of this study was to propose a processing method that minimizes the degradation of the main bioactive compound, glycyrrhizic acid in licorice. Methods: Honey-fired licorice was processed according to the guidance of Circular 30/2017/TT-BYT of the Vietnamese Ministry of Health. The frying conditions such as frying temperature, honey soaking time, the ratio of honey to licorice, and the ratio of water to honey were investigated in order. The content of glycyrrhizic acid was determined according to the process of Vietnamese Pharmacopoeia V. Results: Glycyrrhizic acid was least decomposed when processing honey-fired licorice under the following conditions: the frying temperature of 260℃, the honey soaking time of 1 hour, the ratio of honey to licorice was 1:10, and the ratio of water to honey was 1:1. Conclusions: The content of glycyrrhizic acid in licorice was influenced by the frying process, in which temperature was the most significant factor. Honey was an ingredient that altered the effects of licorice in traditional medicine, however, the presence of honey also contributed to the degradation of glycyrrhizic acid in this medicinal herb.

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Original Article
MedPharmRes 2024;8(1):52-63
https://doi.org/10.32895/UMP.MPR.8.1.6
eISSN 2615-9137
Investigating the e󰀨ect of processing conditions on the content
of glycyrrhizic acid in licorice (Radix et Rhizoma Glycyrrhizae)
Minh-Nhut Truong, Quang-Tu Tran, Le Thi Qua, and Lan-Phuong Thi Le*
Faculty of Traditional Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam
Abstract
Introduction: Licorice is the root of Glycyrrhiza uralensis Fisch or Glycyrrhizae inata L. or Glycyrrhiziae glabra L. It
was a familiar medicinal herb in traditional medicine, which was commonly used in two di󰀨erent forms raw licorice (Sinh
Cam thao) and honey-fried licorice (Chich Cam thao), with completely di󰀨erent e󰀨ects. The processing enhanced the
impact on the Spleen and Stomach organs and tonied Qi but reduced the bioactivities of clearing heat, antitussive, and
detoxifying. The purpose of this study was to propose a processing method that minimizes the degradation of the main
bioactive compound, glycyrrhizic acid in licorice.
Methods: Honey-red licorice was processed according to the guidance of Circular 30/2017/TT-BYT of the Vietnamese
Ministry of Health. The frying conditions such as frying temperature, honey soaking time, the ratio of honey to licorice,
and the ratio of water to honey were investigated in order. The content of glycyrrhizic acid was determined according to
the process of Vietnamese Pharmacopoeia V.
Results: Glycyrrhizic acid was least decomposed when processing honey-red licorice under the following conditions:
the frying temperature of 260℃, the honey soaking time of 1 hour, the ratio of honey to licorice was 1:10, and the ratio of
water to honey was 1:1.
Conclusions: The content of glycyrrhizic acid in licorice was inuenced by the frying process, in which temperature was
the most signicant factor. Honey was an ingredient that altered the e󰀨ects of licorice in traditional medicine, however,
the presence of honey also contributed to the degradation of glycyrrhizic acid in this medicinal herb.
Keywords: glycyrrhiza; honey; glycyrrhizic acid; temperature
Received: Jun 22, 2023 / Revised: Aug 29, 2023 / Accepted: Sep 16, 2023
*Corresponding author: Lan-Phuong Thi Le. Faculty of Traditional Medicine, University of Medicine and Pharmacy at Ho Chi Minh City, Ho Chi Minh City, Vietnam.
E-mail: ltlphuong@ump.edu.vn
Copyright © 2024 MedPharmRes. This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://
creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
1. INTRODUCTION
Licorice is the root of Glycyrrhiza uralensis Fisch or Gly-
cyrrhizae inata L. or Glycyrrhiziae glabra L. It is a familiar
medicinal herb in traditional medicine widely used today for
its numerous benecial eects on blood circulation, detox-
ification, phlegm relief, digestion, and harmonizing the ef-
fects of other medicines [1]. In addition, this medicinal herb
has been proven to have some valuable biological activities
such as antioxidant, anti-inammatory, antifungal, antiviral,
and so on [2]. Moreover, several phytochemical studies were
conducted leading to the isolation and identication of more
and more chemical compounds such as saponins (glycyrrhizic
acid, 18β-glycyrrhetinic acid), and flavonoids (liquiritin,

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Truong et al.
isoliquiritin, liquiritigenin, isoliquiritigenin) [3].
There were 2 dierent forms of licorice used in Vietnam-
ese traditional medicine which were Sinh Cam thao (raw lic-
orice, RL) and Chich Cam thao (honey-fried licorice, HFL).
In traditional medicine, material processing was vital to
create new and enhanced therapeutic eects, change herbal
medicine’s taste, and reduce or eliminate the drug’s adverse
reactions. HFL, which was prepared according to the Yin-
Yang Theory and Five Elements Theory, had the potential to
enhance the eects on the Spleen and Stomach organs, toni-
fy Qi, and improve blood circulation [4].
HFL was processed by re technique that used heat with
excipient honeyaccording to the guidance of Circular No
30/2017/TT-BYT of the Vietnamese Ministry of Health on
“Directions guide to processing methods of traditional in-
gredients” [5]. Exposure to heat during frying was one of
the reasons that can aect the marker compounds in licorice,
especially glycyrrhizic acid, thus reducing the therapeutic
effects of this herbal drug. Therefore, our study aims to
investigate the process conditions to the content of glycyr-
rhizic acid in licorice, and then propose the optimal roasting
process for Chich Cam thao.
2. MATERIALS AND METHODS
2.1. Materials
Medicinal materials: Raw licorice (Radix et Rhizoma
Glycyrrhizae) was provided by Khai Ha Pharmaceutical and
Medical Supplies Trading Joint Stock Company and met the
quality standards of Vietnamese Pharmacopoeia V. A portion
of the slice medicinal herb was ground and sieved through a
355-micrometer sieve to obtain ne powder for the quantita-
tion process.
Excipient: honey (whose moisture content was 5.5%, me-
dicinal use).
Chemical materials: Ethanol, acetonitrile, phosphoric acid
(HPLC-grade, Merck, Darmstadt, Germany), and ammonium
glycyrrhizate reference standard (75.2%, Code G0460000,
EP).
Equipment: High-performance liquid chromatography
system C18 column (Agilent – 1220, Agilent Technologies,
Santa Clara, CA, USA).
2.2. HFL preparation according to the circular 30/2017/
TT-BYT
200 g of honey was dissolved with the equivalent weight
of boiling water. The solution was then mixed well with 1 kg
licorice and soaked for 1–2 hours. Finally, the mixture was
fried with a small fire and stirred until the medicinal herb
turned dark yellow at the surface, brown at the edge, and did
not stick to the hand when touched [5].
2.3. Investigating the frying processing conditions
The frying processing conditions were investigated by
selecting the factors and studying them independently. When
one factor was being investigated, the remaining were xed
at a level according to Circular 30/2017/TT-BYT. The sam-
ple size for each experiment was 100 g of licorice.
The investigated factors in the frying processing method
for HFL included: the frying temperature, honey soaking
time, ratio of honey to licorice, and ratio of water tohoney.
These experiments were conducted according to Table 1.
During the frying process, the temperature was maintained
by controlling the temperature of the electric stove and mea-
sured using a specialized thermometer.
All samples were evaluated the sensory, the processing ef-
ciency, the processing time, and the content of glycyrrhizic
acid. The processing eciency of HFL was calculated by the
following formula:
( )
( ) ( )
11
0022
1
(%)
11
mh
H
mhmh
×−
=×− + ×−
when:
m1: Mass of HFL (g) h1: Moisture content of HFL (%)
m0: Mass of RL (g) h0: Moisture content of RL (%)
m2: Mass of honey (g) h2: Moisture content of honey (%)
2.4. Determination of the content of glycyrrhizic acid
The content of glycyrrhizic acid in RL and HFL samples
were determined according to the guidance of Vietnamese
Pharmacopoeia V with small modication [6].

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Sample solution: Accurately weight about 0.2 g of the
ne powder of licorice/HFL to a 250-mL Erlenmeyer ask,
add precisely 100 mL of ethanol 70% (v/v), seal tightly, and
weight. Sonicate for 30 minutes, let cool, weight again, make
up the lost weight with ethanol 70%, shake well, lter, and
take the subsequent ltrate to obtain the sample solution.
Standard solution: 0.2 mg/mL of ammonium glycyrrhizate
solution in ethanol 70%.
Chromatographic conditions:
Column: C18 column (150×4.6 mm; 5.0 μm)
Mobile phase: Acetonitrile – Phosphoric acid 0.05% (38:62)
Injection volume: 10 μL
Flow rate: 0.9 mL/min
Detector: 254 nm
The sample and standard solutions were analyzed. The
content of glycyrrhizic acid in licorice/HFL was calculated
by the following formula:
10
(%) (1 ) 1.0207
T
C
C
S
XC
S mH
α
= × ×× ×− ×
where:
ST: Peak area of sample solution
SC: Peak area of standard solution
CC: Concentration of standard solution (mg/mL)
α: Purity of reference standard (%)
m: Mass of the sample (g)
H: Humidity of sample (%)
2.5. Statistical analysis
Each sample was determined the content of glycyrrhizic
acid six (6) times. The content of glycyrrhizic acid between
RL and each of the HFL sample were presented as Mean±SD
and statistically compared by t-tests in Excel 2016. The dif-
ference between groups was considered statistically signi-
cant at a p-value < 0.05.
3. RESULTS
3.1. The e󰀨ect of frying temperature
After processing, all 5 samples of HFL (after soaking 1
hour) under the dierent frying temperature conditions had a
darker yellow color compared to licorice. In addition, they had
a brown outer edge and a characteristic sweet taste (Fig. 1).
The processing time varied inversely with the frying tem-
perature. As the frying temperature increased, the processing
time was shorter and stabilized at temperatures above 230℃.
The processing of HFL was more than 85% and was less af-
fected by the frying temperature.
The content of glycyrrhizic acid in RL and HFL samples
was shown in Table 2 and Fig. 2.
The frying temperature affected strongly the content of
glycyrrhizic acid in HFL. The sample fried at 100℃ had the
Table 1. Experimental design
FT ST H-L H-W FT ST H-L H-W
1100℃
1 h 1:5 1:1
11
OT OST
0%
1:1
2200℃12 10%
3230℃13 20%
4260℃14 30%
5350℃15 50%
6
OT
0 h
1:5 1:1
16
OT OST OR of H-L
10%
71 h 17 20%
82 h 18 30%
94 h 19 50%
10 24 h 20 70%
FT, frying temperature; ST, soaking time; H-L, ratio of honey-Licorice; H-W, ratio of honey-water; OT, optimal temperature; OST, optimal soaking time; OR of H-L, optimal
ratio of honey-Licorice.

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Table 2. The content of glycyrrhizic acid in RL and HFL samples under di󰀨erent frying temperatures
Content of glycyrrhizic acid (%)
RL 100℃200℃230℃260℃350℃
14.64 3.32 3.15 2.96 3.09 2.75
24.74 3.27 3.22 2.93 3.14 2.72
34.66 3.25 3.19 2.94 3.10 2.69
44.58 3.23 3.12 2.90 3.15 2.70
54.70 3.34 3.15 2.91 3.09 2.72
64.54 3.21 3.13 2.91 3.09 2.73
Average 4.64 3.27 3.16 2.93 3.11 2.72
SD 0.08 0.05 0.04 0.02 0.03 0.02
RL, raw licorice; HFL, honey-fried licorice.
Fig. 1. HFL with di󰀨erent frying temperature conditions (A) and a line chart illustrating the processing time and e󰀩ciency of 5 HFL under
di󰀨erent roasting temperatures (B). HFL, honey-fried licorice.
Fig. 2. The content of glycyrrhizic acid of RL and HFL samples under frying temperature conditions. RL, raw licorice; HFL, honey-fried licorice.

Material processing a󰀨ect the content of glycyrrhizic acid in licorice
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least degradation of glycyrrhizic acid (3.27±0.05%; reduced
29% compared to RL), while this marker compound was
strongly decomposed when frying at 350℃ (2.72±0.02%; a
41% reduction compared to RL). Statistical evaluation using
a t-test for the results of the content of glycyrrhizic acid of
HFL samples were different significantly compared to raw
licorice and dierent from each other (p<0.05) (Table 3).
The marker compound in licorice, glycyrrhizic acid, was
less degraded when processed with honey at 100℃ and
200℃ (reduced by 29% and 32% compared to RL, respec-
tively). However, this processing method took longer time
(processing time >60 minutes). In contrast, HFL which was
roasted at 350℃ had a shorter processing time (22 minutes)
but higher degradation of active ingredient (reduced 41%
compared to RL). At a frying temperature of 260℃, glycyr-
rhizic acid in HFL was less degraded (a 33% reduction), and
the processing time was relatively fast (32 minutes). There-
fore, a frying temperature of 260℃ was selected.
3.2. The e󰀨ect of honey soaking time
All of the HFL samples (fried at 260℃ with different
soaking times) met the sensory requirements according to
Circular 30/2017/TT-BYT. The honey soaking time had little
effect on the processing time and efficiency of HFL. The
roasting process was fast (processing time<60 minutes) and
the eciency was more than 85% (Fig. 3).
The content of glycyrrhizic acid in RL and HFL samples
were performed in Table 4 and Fig. 4.
There was little difference in the degradation of glycyr-
rhizic acid among HFL samples processed with different
honey soaking times. The sample without soaking had the
lowest content of glycyrrhizic acid (2.97±0.06%; reduced
36% compared to RL), while the sample processed after 2
hours of soaking had the least degradation of active ingredi-
ent (3.13±0.03%; reduced 33%). Statistical analysis using a
t-test showed that the content of glycyrrhizic acid in dier-
ent HFL samples was significant compared to raw licorice
Table 3. The p-value of the content of glycyrrhizic acid in RL and HFL samples under di󰀨erent frying temperatures
RL
5.29E-12 100
℃
1.18E-12 1.58E-03 200
℃
1.44E-13 3.18E-08 1.46E-07 230
℃
5.51E-13 5.16E-05 0.03 2.27E-07 260
℃
4.37E-14 2.82E-10 2.53E-10 1.82E-08 1.17E-10 350
℃
RL, raw licorice; HFL, honey-fried licorice.
Fig. 3. HFL with different honey soaking time conditions (A) and a line chart illustrating the processing time and efficiency of 5 HFL
samples under di󰀨erent honey soaking times (B). HFL, honey-fried licorice.

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(p<0.05). The content of glycyrrhizic acid in processed Lic-
orice samples processed after 1, 2, and 24 hours of soaking
was not significantly different (p>0.05). Additionally, the
content of glycyrrhizic acid in the sample processed without
soaking was similar to that of the sample processed after 4
hours of soaking (p=0.16) (Table 5).
HFL without soaking saved time in the processing of me-
dicinal herbs. However, the content of glycyrrhizic acid in
the herbal medicine was signicantly reduced (reduced 36%
compared to RL). The licorice root extract processed after 2
hours of soaking had the highest content of glycyrrhizic acid,
but there was no signicant dierence between the sample
processed after soaking for 1 hour. Therefore, the honey
soaking time of 1 hour was selected.
3.3. The e󰀨ect of the ratio of honey-licorice
Similarly, all 5 samples of HFL under the dierent ratios
of honey to licorice conditions (fried at 260℃ after soaking
for 1 hour) had a darker yellow color, a brown outer edge,
and a characteristic sweet taste compared to RL. Overall, the
processing of HFL with dierent ratios of honey was fast (<60
minutes) and the efficiency was more than 85%. The pro-
cessing eciency of the HFL sample with a ratio of honey to
licorice of 1:2 was the lowest (86.56%) while requiring the
longest processing time (58 minutes) (Fig. 5).
The amount of honey has a signicant impact on the deg-
radation of glycyrrhizic acid in HFL (Fig. 6). Statistical anal-
ysis using a t-test shows that the content of glycyrrhizic acid
in different HFL samples was significant compared to RL
Table 4. The content of glycyrrhizic acid in RL and HFL samples under di󰀨erent honey soaking time conditions
Content of glycyrrhizic acid (%)
RL 0 h 1 h 2 h 4 h 24 h
14.64 3.07 3.09 3.11 3.12 3.13
24.74 2.98 3.14 3.11 3.03 3.08
34.66 2.98 3.10 3.16 3.08 3.16
44.58 2.98 3.15 3.16 3.11 3.03
54.70 2.91 3.09 3.10 3.09 3.06
64.54 2.91 3.09 3.13 3.07 3.10
Average 4.64 2.97 3.11 3.13 3.08 3.09
SD 0.08 0.06 0.03 0.03 0.03 0.05
RL, raw licorice; HFL, honey-fried licorice.
Fig. 4. The content of glycyrrhizic acid of RL and HFL samples under honey soaking time conditions. RL, raw licorice; HFL, honey-fried licorice.

Material processing a󰀨ect the content of glycyrrhizic acid in licorice
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(p<0.05) (Table 6). The content of glycyrrhizic acid in pro-
cessed samples without honey decreased by 25% compared
to RL. When honey was present, this marker component
was less signicantly degraded (3.90±0.04%; reduced 16%).
However, as the honey ratio increased in the processing, gly-
cyrrhizic acid was more decomposed, with the lowest con-
Table 5. The p-value of the content of glycyrrhizic acid in RL and HFL samples under di󰀨erent honey soaking time conditions
RL
1.33E-12 0 h
5.51E-13 3.39E-04 1 h
5.68E-13 1.13E-04 0.27 2 h
5.28E-13 1.78E-03 0.16 0.02 4 h
1.43E-12 2.76E-03 0.46 0.14 0.72 24 h
RL, raw licorice; HFL, honey-fried licorice.
Fig. 5. HFL with di󰀨erent ratio of honey-Licorice conditions (A) and a line chart illustrating the processing time and e󰀩ciency of 5 HFL
under di󰀨erent ratios of honey-Licorice (B). HFL, honey-fried licorice.
Fig. 6. The content of glycyrrhizic acid of RL and HFL samples HFL under di󰀨erent ratios of honey-Licorice. RL, raw licorice; HFL, honey-fried
licorice.

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tent in the sample processed with a ratio of honey to licorice
of 1:2 (2.54±0.02%; reduced 45% compared to RL). The
HFL sample processed with a ratio of honey to licorice of
1:10 had a short processing time, high processing eciency,
and the least degradation of glycyrrhizic acid. Therefore, a
ratio of honey to licorice of 1:10 was chosen (Table 7).
3.4. The e󰀨ect of the ratio of water-honey
All of the HFL samples (fried at 260℃ after soaking for 1
hour with honey (ratio of 1:10) met the sensory requirements
according to Circular 30/2017/TT-BYT. Overall, the process-
ing of HFL with different ratios of water tohoney was fast
(<60 minutes) and the efficiency was more than 95%. The
processing eciency of the HFL sample tended to increase as
the ratio of diluted distilled water to honey increased (Fig. 7).
The ratio of water in the processing had an impact on the
degradation of glycyrrhizic acid in HFL. Statistical analysis
using a t-test shows that the content of glycyrrhizic acid in
dierent HFL samples is signicant compared to raw licorice
(p<0.05) (Table 8). The content of glycyrrhizic acid in the
fried sample processed with a distilled water to honey ratio
of 1.5:1 was the lowest, with a reduction of 29% compared
to RL. Meanwhile, the HFL processed with a distilled water
to honey ratio of 1:1 had the highest content of glycyrrhizic
acid (3.90±0.04%; reduced 16%) (Table 9). Therefore, the
ratio of water to honey of 1:1 was selected (Fig. 8).
4. DISCUSSION
Frying temperature is one of the factors that directly aect
the changes in the composition and quantity of active plant
compounds in medicinal herbs during processing. Under the
influence of temperature, many chemical compounds un-
dergo structural changes or are degraded to other products.
Glycyrrhizic acid was a chemical compound in icorice with
many biological eects, such as antibacterial, anti-inamma-
tory, antiviral, antioxidant, anti-cough, expectorant, detoxi-
fying, etc. [7]–[9]. Raw licorice has a high content of glycyr-
rhizic acid; therefore, it possesses the function of tonifying
the Spleen organ, regulating Qi, moistening Lung, relieving
toxicity, promoting digestion, clearing heat, and detoxifying.
The processing of HFL signicantly reduced the content
of glycyrrhizic acid. A study by Ota et al. in 2018 showed
that glycyrrhizic acid was degraded into glycyrrhetinic
3-O-glucuronide and glycyrrhetic acid during the processing
of HFL. When increasing the temperature and duration of
the processing, glycyrrhizic acid was completely degraded,
and glycyrrhetic acid 3-O-glucuronide went on decomposing
into 18β-glycyrrhetinic acid, thereby reducing the function
of promoting digestion and detoxication of RL [10].
The HFL sample processed at 100℃ had the highest con-
tent of glycyrrhizic acid, but the processing time was too
long (300 minutes), which was not suitable for industrial
scale-up. On the other hand, the HFL roasted with honey at
350℃ was the fastest (22 minutes), but the content of gly-
cyrrhizic acid in the final product was the lowest (2.72%).
Table 6. The content of glycyrrhizic acid in RL and HFL samples under di󰀨erent ratios of honey-Licorice
Content of glycyrrhizic acid (%)
RL 0:1 1:10 1:5 1:4 1:2
14.64 3.48 3.96 3.09 2.97 2.56
24.74 3.54 3.90 3.14 2.93 2.51
34.66 3.49 3.94 3.10 2.98 2.55
44.58 3.44 3.85 3.15 2.93 2.54
54.70 3.47 3.89 3.09 2.95 2.54
64.54 3.46 3.86 3.09 2.98 2.56
Average 4.64 3.48 3.90 3.11 2.95 2.54
SD 0.08 0.03 0.04 0.03 0.02 0.02
RL, raw licorice; HFL, honey-fried licorice.

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The processing of HFL at 260℃ for 32 minutes was suitable,
and the content of active compounds in the nal product was
not signicantly degraded (67% compared to the content of
glycyrrhizic acid in RL).
The stage of soaking RL in honey before processing helps
the herbal medicine to absorb honey evenly, increasing the
tonifying function of the Spleen according to traditional
medicine. The quantification of glycyrrhizic acid content
in the processed HFL samples at different soaking times
showed no significant changes in this marker compound.
The HFL samples processed after soaking in honey for 1
and 2 hours had the highest content of glycyrrhizic acid, and
Fig. 7. HFL with di󰀨erent ratio of water-honey conditions (A) and a line chart illustrating the processing time and e󰀩ciency of 5 HFL under
di󰀨erent ratios of water-honey (B). HFL, honey-fried licorice.
Table 8. The content of glycyrrhizic acid in RL and HFL samples under di󰀨erent ratios of water-honey
Content of glycyrrhizic acid (%)
RL 0:1 0.5:1 1:1 1.5:1 2:1
14.64 3.68 3.34 3.96 3.27 3.40
24.74 3.73 3.38 3.90 3.29 3.50
34.66 3.82 3.37 3.94 3.27 3.43
44.58 3.76 3.34 3.85 3.29 3.45
54.70 3.73 3.33 3.89 3.26 3.37
64.54 3.75 3.43 3.86 3.37 3.42
Average 4.64 3.75 3.36 3.90 3.29 3.43
SD 0.08 0.05 0.04 0.04 0.04 0.05
RL, raw licorice; HFL, honey-fried licorice.
Table 7. The p-value of the content of glycyrrhizic acid in RL and HFL samples under di󰀨erent ratios of honey-Licorice
RL
1.15E-11 0:1
1.53E-09 5.00E-09 1:10
5.51E-13 2.03E-09 4.98E-12 1:5
1.63E-13 2.68E-11 4.43E-13 8.89E-07 1:4
1.76E-14 7.10E-14 1.06E-14 2.51E-12 1.40E-11 1:2
RL, raw licorice; HFL, honey-fried licorice.

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Truong et al.
the dierence between them was not statistically signicant
(p=0.27). This result was consistent with the guidelines of
Circular 30/2017/TT-BYT regarding the soaking time of lic-
orice root in honey for around 1–2 hours.
Honey is one of the common adjuvants used in the pro-
cessing of medicinal herbs. The chemical composition of
honey includes water, sugar, amino acids, vitamins, en-
zymes, and other components that contribute to its nutrition-
al value. Additionally, honey contains a signicant number
of polyphenolic compounds, phenolic acids, and avonoids,
which exhibit biological effects such as anti-inflammatory,
antioxidant, and immune-enhancing properties [11].
The process of roasting licorice with honey follows the
theoretical principles of Yin-Yang and Five Elements. Ac-
cording to traditional medicine, honey has a sweet taste
and affects the Heart, Lungs, Spleen, Stomach, and Large
Intestine meridians, and has the function of tonifying, regu-
lating the intestines, moisturizing the lungs, detoxifying, and
promoting digestion. The honey-fried processing helps to en-
hance the sweetness and yellowish color of the herbal med-
icine, thereby increasing its Yang properties and directing it
to the Spleen meridian, which helps to tonify Qi, moisturize
the lungs, and delay the release of herbs [4],[12].
However, honey also affected the chemical composition
of licorice root extract, especially the marker compound gly-
cyrrhizic acid. In 2004, Sung et al. studied the degradation
of glycyrrhizic acid under the inuence of temperature and
honey. The results showed that the presence of honey stim-
ulated the degradation process, and glycyrrhizic acid was
deglycosylase into 18β-glycyrrhetinic acid [13].
In addition to glycyrrhizic acid and saponins, flavonoid
compounds in licorice root are also aected by the process-
ing factors of temperature and honey. The study by Ota et al.
in 2018 showed that under the inuence of honey, liquiritin
Table 9. The p-value of the content of glycyrrhizic acid in RL and HFL samples under di󰀨erent ratios of water-honey
RL
2.87E-10 0:1
4.90E-12 2.28E-08
0
.5:1
1.53E-09 1.56E-04 5.55E-10 1:1
3.22E-12 5.41E-09 7.80E-03 2.10E-10 1.5:1
1.28E-11 3.04E-07 0.02 4.88E-09 2.19E-04 2:1
RL, raw licorice; HFL, honey-fried licorice.
Fig. 8. The content of glycyrrhizic acid of RL and HFL samples HFL under di󰀨erent ratios of water-honey. RL, raw licorice; HFL, honey-fried
licorice.

Material processing a󰀨ect the content of glycyrrhizic acid in licorice
62 | https://www.medpharmres.com
https://doi.org/10.32895/UMP.MPR.8.1.6
was degraded into isoliquiritigenin, while isoliquiritin was
degraded into liquiritigenin, and these two flavonoid agly-
cones can be converted reversibly [10].
The proportion of honey in the processing did not sig-
nificantly affect the frying time and process efficiency of
the herbal medicine. However, when roasting with a high
proportion of honey (1:2), the processing time may need
to be extended to achieve the criterion of non-stickiness.
Moreover, a high proportion of honey may cause the herbal
medicine to burn, aecting the quality and therapeutic eect
of the HFL.
The changing of glycyrrhizic acid content in the processed
samples showed that a certain proportion of honey could
reduce the degradation of this marker compound in herbal
medicine. Specically, HFL processed with the ratio of honey
to licorice of 1:10 had the least degradation of glycyrrhizic
acid (84% compared to RL). However, as the proportion of
honey in the processing increased, the content of glycyrrhizic
acid went down, with the lowest in the sample processed with
a ratio of 1:2 (45% reduction compared to RL).
Raw honey can be dense, and viscous, and have a rela-
tively low moisture content (5.5%), which can make it di-
cult to mix evenly during the soaking and roasting process.
Therefore, a certain amount of distilled water is needed to
dilute the honey before processing with licorice root.
The proportion of water in the processing also affected
the degradation of glycyrrhizic acid in HFL. Specifically,
the processing of HFL with a water to honey ratio of 1.5:1
had the highest degradation of glycyrrhizic acid, while with
a ratio of 1:1, this saponin component was less degraded
(3.90±0.04%). This result was consistent with the guidance
of Circular 30/2017/TT-BYT on using an equal amount of
boiling water to dilute honey. The obtained results in the
present study suggest that the ratio of water to honey of 1:1
is suitable for the processing.
For the limitations of the present paper, there was no study
on the other chemical compounds of licorice and HFL such
as avonoids, and phenolic compounds besides the glycyr-
rhizic acid content. Moreover, the study has not evaluated
the stability of the processing yet by replicating 3 times. For
future research, it is necessary to study the change of other
chemical compositions of licorice before and after process-
ing and upgrade the batch size of the HFL processing.
5. CONCLUSION
The present paper was conducted to optimize the process-
ing condition for licorice to conserve the content of glycyr-
rhizic acid. Honey was an ingredient that altered the eects
of licorice in Traditional Medicine;however, the presence
of honey also contributed to the degradation of glycyrrhizic
acid in this medicinal herb. Conversely, the honey soaking
time and the ratio of distilled water contributed to a favorable
processing method and had little impact on the alteration of
this marker’s content.
Acknowledgements
Not applicable.
Funding sources
The authors received nancial support from the University
of Medicine and Pharmacy at Ho Chi Minh City for the re-
search, authorship, and/or publication of this article.
Conict of interest
No potential conict of interest relevant to this article was
reported.
ORCID
Minh-Nhut Truong
https://orcid.org/0009-0003-6483-4362
Quang-Tu Tran
https://orcid.org/0000-0001-8049-2444
Le Thi Qua
https://orcid.org/0009-0007-7608-6882
Lan-Phuong Thi Le
https://orcid.org/0009-0008-3761-140X
Authors' contributions
Conceptualization: MN Truong, LPT Le.
Data curation: MN Truong.
Investigation: MN Truong, QT Tran, LT Qua.

https://doi.org/10.32895/UMP.MPR.8.1.6
https://www.medpharmres.com | 63
Truong et al.
Writing - original draft: MN Truong.
Writing - review & editing: MN Truong, QT Tran, LT Qua,
LPT Le.
Availability of data and material
Upon reasonable request, the datasets of this study can be
available from the corresponding author.
Ethics Approval
This research was conducted without experimenting on ani-
mals or human, and therefore didn’t violate the ethical stan-
dards in biomedical research.
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