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Determination of Vitamin B2 Content in Black, Green, Sage, and Rosemary Tea Infusions by Capillary Electrophoresis with Laser-Induced Fluorescence Detection

Authors:

Abstract

Vitamin B2, also known as riboflavin (RF) is an essential micronutrient for human health and must be obtained from dietary sources. Plants biosynthesize riboflavin and are important dietary sources of vitamin B2 for humans. Our present study reports sensitive detection of vitamin B2 in widely consumed tea infusions, namely black, green, sage and rosemary tea infusions, by a capillary electrophoresis method combined with laser induced fluorescence detection. Moreover, the correlation between the vitamin B2 content of tea plants with their total phenolics (TPs) and antioxidant capacity are evaluated in this study. Whereas green teas have the highest TPs and antioxidant capacity, the highest RF content isin sage infusions. The RF content ranged between 0.34 and 10.36 µg/g for all tea samples studied. Comparing the RF content of tea samples found in this study to the RF content of known RF sources, tea infusions are proposed as important dietary sources of vitamin B2.
beverages
Article
Determination of Vitamin B2 Content in Black, Green,
Sage, and Rosemary Tea Infusions by Capillary
Electrophoresis with Laser-Induced
Fluorescence Detection
Filiz Tezcan * and F. Bedia Erim
Department of Chemistry, Istanbul Technical University, Maslak, Istanbul 34469, Turkey; erim@itu.edu.tr
*Correspondence: filiz.tezcan@acibadem.edu.tr; Tel.: +90-532-568-3669
Received: 18 October 2018; Accepted: 5 November 2018; Published: 10 November 2018


Abstract:
Vitamin B2, also known as riboflavin (RF) is an essential micronutrient for human health
and must be obtained from dietary sources. Plants biosynthesize riboflavin and are important
dietary sources of vitamin B2 for humans. Our present study reports sensitive detection of vitamin
B2 in widely consumed tea infusions, namely black, green, sage and rosemary tea infusions, by a
capillary electrophoresis method combined with laser induced fluorescence detection. Moreover,
the correlation between the vitamin B2 content of tea plants with their total phenolics (TPs) and
antioxidant capacity are evaluated in this study. Whereas green teas have the highest TPs and
antioxidant capacity, the highest RF content isin sage infusions. The RF content ranged between 0.34
and 10.36
µ
g/g for all tea samples studied. Comparing the RF content of tea samples found in this
study to the RF content of known RF sources, tea infusions are proposed as important dietary sources
of vitamin B2.
Keywords: tea; Salvia officinalis; Rosmarinus officinalis; total phenolic; antioxidant
1. Introduction
Tea from the leaves of the Camellia sinensis plant is the most widely consumed drink in the world,
after water. There are three kinds of tea products produced from the same plant: Black (fermented),
green (not fermented) and oolong (partially fermented) teas. The tea leaves are dried, crushed and left
for fermentation. Fermentation is a natural process and oxidation during fermentation is caused by a
natural enzyme in the tea leaves themselves. While green tea is not fermented, black tea is subjected
to full fermentation and the color of the tea leaves change to black. Tea is adietary source of many
bioactive compounds. Both black and green tea contain bioactive phenolic compounds mainly gallic,
trans-cinnamic, caffeic, ferulic, p-coumaric acids, catechin, epicatechin, quercetrin, and caffeine [
1
,
2
].
However their content differs with different processing levels of tea samples. Several chemo metric
studies have been developed for tea identification based on the bioactive ingredients and antioxidant
activities of tea samples [
1
,
2
]. The health benefit effects of tea on cancer and cardiovascular diseases,
to obesity and diabetes were extensively reviewed by Khan and Mukhtar [
3
]. Afzal et al. reviewed
the potential therapeutic role of epigallocatechin gallate, which is the main constituent of green
tea [
4
]. It was shown that this compound is associated with antitumor, anti-Alzheimer, and anti-aging
properties. Heber et al. reported that all three tea polyphenol extracts induced weight loss and had
anti-inflammatory and angiogenic effects [5].
In 2010, world tea production reached over 4.52 million tons [
6
]. Turkey is the fifth largest
producer of tea in the world after China, India, Kenya and Sri Lanka [
7
]. Furthermore, Turkey has one
of the highest per capita black tea consumption rates in the world. The attention given to green tea
Beverages 2018,4, 86; doi:10.3390/beverages4040086 www.mdpi.com/journal/beverages
Beverages 2018,4, 86 2 of 7
in Turkey has been increasing due to its effect against obesity. Sage (Salvia officials) tea is one of the
most popular herbal teas in Turkey. Like black and green teas, sage and rosemary contain many health
beneficial bioactive compounds [8,9].
Riboflavin (RF), or its commonly known name vitamin B2, is a water-soluble vitamin and essential
for human health. RF must be obtained from foods since it cannot be synthesized or stored in the
body. Vitamin B2 deficiency affects many organs and tissues [
10
]. Milk, dairy products, meat, fish,
dark-green vegetables, and some beverages like beer and wine are important sources of this vitamin.
The analysis of RF in food samples is difficult because of the complex matrix of food and very low
content of RF in foodstuffs. Recently, capillary electrophoresis (CE) has receivedgreat attention in food
analysis due to its easy method, development availability, low sample consumption, fast analysis times,
and inexpensive separation columns [
11
]. Lately, a combination of laser induced fluorescence (LIF)
detectors with capillary electrophoresis has provided a remarkable improvement in detection limits.
Since RF has a native fluorescence, the RF content of various foods have been studied by capillary
electrophoretic methods using LIF detection [1217].
Although a significant number of studies have been reported on tea, sage, and rosemary phenolics,
almost no information exists concerning the vitamin content of these plants. Hu and coworkers
reportedvitamin B2 in two green tea samples [
14
]. To our knowledge, there is no study on the content
of vitamin B2 in sage and rosemary. The aim of this study is to contribute to the information on the
nutritional value of widely consumed tea infusions, by determining the vitamin B2 content of tea
plants using the CE-LIF method. Moreover, the correlation between the vitamin B2 content of tea
plants with their total phenolics and antioxidant capacity are evaluated in this study.
2. Materials and Methods
2.1. Materials
Riboflavin, Folin-iocalteu reagent, gallic acid, 2,4,6-tripyridyl-s-triazine and FeCl
3·
6H
2
O were
from Sigma Chemical Co. (Steinheim, Germany). Di-sodium hydrogen phosphate dehydrates,
sodium carbonate anhydrous, sodium acetate trihydrate, and FeSO
4·
7H
2
O were from Merck
(Darmstadt, Germany). All solutions were prepared with water purified by an ElgaPurelab Option-7–15
model system (Elga, UK).
Four Black (B1–B4) and two green (G1and G2) tea-bag samples were obtained from local markets
inIstanbul as known commercial brands. The B1 sample consisted of teas from the East Black Sea
region of Turkey. The others were tea blends. According to the labels, B2 was a blend of Kenyan and
Sri Lankan teas. B3 was a blend of Turkish, Kenyan, and Indonesian teas. B4 was a blend of Turkish,
Sri Lankan, Kenyan, and Indian teas. Sage and Rosemary samples were purchased from Istanbul
(S1, S2, R1 and R2) and Boston (S3, S4, R3 and R4) markets as known commercial brands.
2.2. Method
Separations were performed with an Agilent capillary electrophoresis system (Waldbronn,
Germany) equipped with a ZETALIF 2000 LIF detector (Picometrics, Montlaur, France). RF was
detected with an excitation of 488 nm and emission of 520 nm by an Ar-ion laser. The data processing
was carried out with the Agilent ChemStation software. The separation was performed at 25 kV.
The temperature was set at 25
C. Injections were made at 50 mbar for 6 s. The fused-silica capillary
used for separation experiments was 50
µ
m IDand was obtained from Polymicro Technologies (Phoenix,
AZ, USA). The total length of the capillary was 67 cm and the length to the detector was 50 cm. The new
fused-silica capillary was conditioned prior to use by rinsing with 1 M NaOH for 30 min and with
water for 10 min. The capillary was flushed successively by 0.1 M NaOH for 2 min, water for 2 min,
and buffer for 5 min, at the beginning of every working day and between runs.
Tea leaves were placed in a pot containing boiling water and the pot was incubated in a water bath
for 5 min. Incubation time was optimized by checking the degradation of riboflavin standard in hot
Beverages 2018,4, 86 3 of 7
water vs. time, as explained in Results. After filtration of tea leaves from the hot water, tea infusions
were directly injectedin to the capillary column.
2.3. Determination of Total Phenolics (TPs)
The total phenolics of each infusion were determined by using the Folin-Ciocalteu method [
18
].
For each type of infusion, 300
µ
L was mixed with 1.5 mL of Folin-Ciocalteu’s reagent (1:10 diluted
with water) and 1.2 mL of sodium carbonate solution (7.5% w/v).The mixture was allowed to stand
for 10 min at room temperature until a stable color was obtained. The absorbance of 1/10 fold
diluted samples weremeasured by a Shimadzu UV-1800 spectrophotometer (Shimadzu Scientific
Instruments, North America) at 760 nm. Results were expressed as gallic acid equivalents (GAE) in
mg/g. The calibration equation for gallic acid was y = 49.582x 0.0185 (R2 = 0.995).
2.4. FRAP Assay
The ferric-reducing antioxidant power (FRAP) of the infusions wasdetermined, following the
method of Benzie and Strain [
19
]. The FRAP reagent was prepared containing 1:1:10 ratio of 10 mM
2,4,6-tripyridyl-s-tri-azine (TPTZ) solution in 40 mM HCl, 20 mM FeCl
3
and 0.3 M acetate buffer at
pH 3.6, and warmed to 37
C for 10 min. prior to use. The mixture containing 100
µ
L sample, 100
µ
L
deionized water, and 1.8 mL FRAP reagent was incubated at 37
C for 10 min. The absorbance
of the 1/10 fold diluted mixture was measured by a Shimadzu UV-1800 spectrophotometer at
593 nm. Results were expressed as
µ
mol Fe+2/g. The calibration equation for FeSO
4·
7H
2
O was
y = 20.044x 0.0373 (R2 = 0.999).
2.5. Statistical Analysis
The statistical analysis was applied to the RF content, TPs, and FRAP values of tea samples.
The significant differences between the mean values with p< 0.05 were evaluated by a one way
analysis (ANOVA) test and the Duncan’s new multiple range test using XLSTAT 2017 (Data Analysis
and Statistical Solution for Microsoft Excel. Addinsoft, Paris, France (2017)).
3. Results and Discussion
3.1. Optimization of Separation
Since the pKa value of RF is 9.69, the molecule gains a negative charge in basic solutions and
can migrate under an electrical field. Phosphate electrolyte was selected as the separation medium.
When the phosphate concentration was changed between 15 and 75 mM, no significant change
was observed in peak shapes. On the other hand, while the pH of separation electrolyte increased,
the RF peak separated from the electroosmotic peak (negative water peak) and was easily integrated.
The fluorescence intensity of RF was maximum at pH 9.9.Finally, 30 mM phosphate at pH 9.9 was
selected as the optimal medium for separation and detection.
3.2. Optimization of Extraction
RFis slightly soluble in water. One g dissolves in 3–15 L water, depending on the crystal structure
(Sigma-Aldrich, Steinheim, Germany). RFis heat stable but very sensitive to light [
20
]. Considering the
very small content of RF in food products, it can be expected that hot water will withdraw the RF in
tea leaves. In order to check the stability of RF in hot water vs. time, a RF standard was dissolved in
hot water (100
C). This solution was left in a water bath fordifferent times and riboflavin content of
these solutions was determined by the CE-LIF method. Figure 1shows the comparative results.
Beverages 2018,4, 86 4 of 7
Beverages 2018, 4, x 4 of 7
water bath for 5 min. In fact, this is the traditional tea brewing method in homes and coffee houses in
Turkey, and 5 min is the accepted time to obtain a good tea infusion.
Figure 1. Riboflavin amount in hot water vs. infusion time.
After filtration of tea leaves from hot water, tea infusions were directly injected in to the
capillary column. Figure 2 shows a representative electropherogram of one sage herbal tea infusion
(S3). As seen from the electropherogram, the RF peak came in less than 4 min. Since infusions were
directly injected without any purification or derivatization step, the analysis method of RF was very
short and simple.
2.5 3.0 3.5 4.0 4.5
1.2
1.4
1.6
1.8
2.5
RF
22.5 34
3.5
RFU
Time (minute)
Figure 2.Electropherogram of 1/2 diluted sage herbal tea (S3).Conditions; 50 µm × 50 cm capillary, 50
mbar 6s injection, 25 kV running voltage, 30 mM phosphate buffer at pH:9.9.
3.3. CE Method Validation
The calibration curve of RF was linear between 0.015 µM concentration ranges.The calibration
equation was calculated as y = 0.9544x 0.0375 (R2 = 0.999). The limit of dedection (LOD) value was
obtained from the software of the CE instrument. The calculation was based on the LOD
valuebeingthe concentration corresponding to the baseline average noise of electropherogram taken
from three different baseline areas. The LOD of the method for RFwas found as 1.08 ng/mL. The
limit of quantification (LOQ) was given as ten times the average noise as 3.58 ng/mL. For testing the
precision of the method, the RFstandard solution was injected 5 times in one day. For day-to-day
reproducibility, the same solution was injected five times in three different non-consecutive days. In
the same day, precision of the corrected peak areas (%RSD; relative standart deviation) was 2.48%.
Between days, the precision value was 4.58%.
The recovery experiments were done with one herbal tea sample. The infusion was spiked with
standard RF solution atthree different spike levels at the beginning of the extraction process.
Satisfactory recovery for RF was obtained as between 99.7 and 106%.
Figure 1. Riboflavin amount in hot water vs. infusion time.
As seen from Figure 1, at the end of the 5 min incubation time, we did not observe any decrease
in RF concentration in hot water. The decrease of RF content with time after 5 min is probably due to
light sensitivity of the molecule. Thereby, 5 min was applied as the optimal incubation time for all tea
infusions. 50 mL of boiling water was poured on 1 g of tea leaves and the pot was incubated in a water
bath for 5 min. In fact, this is the traditional tea brewing method in homes and coffee houses in Turkey,
and 5 min is the accepted time to obtain a good tea infusion.
After filtration of tea leaves from hot water, tea infusions were directly injected in to the capillary
column. Figure 2shows a representative electropherogram of one sage herbal tea infusion (S3). As seen
from the electropherogram, the RF peak came in less than 4 min. Since infusions were directly injected
without any purification or derivatization step, the analysis method of RF was very short and simple.
Beverages 2018, 4, x 4 of 7
water bath for 5 min. In fact, this is the traditional tea brewing method in homes and coffee houses in
Turkey, and 5 min is the accepted time to obtain a good tea infusion.
Figure 1. Riboflavin amount in hot water vs. infusion time.
After filtration of tea leaves from hot water, tea infusions were directly injected in to the
capillary column. Figure 2 shows a representative electropherogram of one sage herbal tea infusion
(S3). As seen from the electropherogram, the RF peak came in less than 4 min. Since infusions were
directly injected without any purification or derivatization step, the analysis method of RF was very
short and simple.
2.5 3.0 3.5 4.0 4.5
1.2
1.4
1.6
1.8
2.5
RF
22.5 34
3.5
RFU
Time (minute)
Figure 2.Electropherogram of 1/2 diluted sage herbal tea (S3).Conditions; 50 µm × 50 cm capillary, 50
mbar 6s injection, 25 kV running voltage, 30 mM phosphate buffer at pH:9.9.
3.3. CE Method Validation
The calibration curve of RF was linear between 0.015 µM concentration ranges.The calibration
equation was calculated as y = 0.9544x 0.0375 (R2 = 0.999). The limit of dedection (LOD) value was
obtained from the software of the CE instrument. The calculation was based on the LOD
valuebeingthe concentration corresponding to the baseline average noise of electropherogram taken
from three different baseline areas. The LOD of the method for RFwas found as 1.08 ng/mL. The
limit of quantification (LOQ) was given as ten times the average noise as 3.58 ng/mL. For testing the
precision of the method, the RFstandard solution was injected 5 times in one day. For day-to-day
reproducibility, the same solution was injected five times in three different non-consecutive days. In
the same day, precision of the corrected peak areas (%RSD; relative standart deviation) was 2.48%.
Between days, the precision value was 4.58%.
The recovery experiments were done with one herbal tea sample. The infusion was spiked with
standard RF solution atthree different spike levels at the beginning of the extraction process.
Satisfactory recovery for RF was obtained as between 99.7 and 106%.
Figure 2.
Electropherogram of 1/2 diluted sage herbal tea (S3).Conditions; 50
µ
m
×
50 cm capillary,
50 mbar 6s injection, 25 kV running voltage, 30 mM phosphate buffer at pH: 9.9.
3.3. CE Method Validation
The calibration curve of RF was linear between 0.01–5 µM concentration ranges. The calibration
equation was calculated as y = 0.9544x
0.0375 (R
2
= 0.999). The limit of dedection (LOD) value was
obtained from the software of the CE instrument. The calculation was based on the LOD valuebeingthe
concentration corresponding to the baseline average noise of electropherogram taken from three
different baseline areas. The LOD of the method for RFwas found as 1.08 ng/mL. The limit of
quantification (LOQ) was given as ten times the average noise as 3.58 ng/mL. For testing the precision
of the method, the RFstandard solution was injected 5 times in one day. For day-to-day reproducibility,
the same solution was injected five times in three different non-consecutive days. In the same day,
precision of the corrected peak areas (%RSD; relative standart deviation) was 2.48%. Between days,
the precision value was 4.58%.
The recovery experiments were done with one herbal tea sample. The infusion was spiked
with standard RF solution atthree different spike levels at the beginning of the extraction process.
Satisfactory recovery for RF was obtained as between 99.7 and 106%.
Beverages 2018,4, 86 5 of 7
3.4. Riboflavin Content of Tea Samples
The RF content of tea infusions are given as the averages of three infusions with their standard
deviations in Table 1.
Table 1. RF content of tea infusions (B: Black, G: Green, S: Sage, R: Rosemary).
RF
(µg/g ±SD) *
RF
(µg/g ±SD) *
B1 3.34 ±0.19 dS1 5.36 ±0.72 e
B2 0.58 ±0.16 abc S2 5.22 ±0.29 e
B3 1.57 ±0.06 bc S3 6.18 ±0.31 e
B4 1.07 ±0.05 abc S4 10.36 ±0.79 f
G1 3.26 ±0.46 dR1 2.87 ±0.06 d
G2 2.80 ±0.10 dR2 0.42 ±0.08 ab
R3 1.72 ±0.35 c
R4 0.34 ±0.01 a
* Means
±
standard deviations. Different letters in the same lines are significantly different at the 5% level (p< 0.05).
As seen from Table 1, the RF content changes between 0.34 and 10.36
µ
g/g for all tea samples.
Amongst the tested black tea samples, the B1 sample which contains tea leaves fromthe East Black
Sea region of Turkey was found to have the richest RF content. The RF content of the blends tested
are smaller than in this tea. The RF content of two green tea samples were higher compared to the RF
content of black teas. The RF content of rosemary samples were rather similar to the RF content of
black tea blends. However, the RF content of all sage teas were substantially higher than those of black
and green teas, and rosemary infusions. S4 especially contained significantly higher RF.
3.5. Total Phenolics (TPs) and Antioxidant Capacities
The TPs and FRAP values of tea infusions are given in Table 2. TPs ranged from 4.91 to 114 mg
GAE/g dry tea leaves for all tea types tested. Green tea samples hadthe highest TPs compared to both
black tea and herbal tea samples.
Table 2. The TPs and FRAP values of tea infusions. (B: Black, G: Green, S: Sage, R: Rosemary).
TPs (mg GAE/g ±SD) * FRAP (µmol Fe+2/g ±SD) *
B1 73.55 ±2.33 c462.3 ±0.6 b
B2 94.21 ±1.59 e491.8 ±4.2 b
B3 67.71 ±1.68 d449.2 ±3.7 b
B4 91.39 ±1.99 e479.4 ±10.2 b
G1 113.6 ±1.9 f601.4 ±56.1 d
G2 112.8 ±1.8 f551.5 ±17.5 c
S1 16.86 ±0.15 b64.64±8.65 a
S2 17.14 ±0.10 b65.08 ±2.00 a
S3 17.27 ±0.13 b78.44 ±2.22 a
S4 17.97 ±0.2 b81.86 ±0.32 a
R1 17.16 ±0.62 b81.34 ±3.81 a
R2 4.91 ±0.06 a63.84 ±0.84 a
R3 17.14 ±0.23 b76.62 ±1.37 a
R4 5.19 ±0.02 a65.89 ±0.84 a
* Means
±
standard deviations. Different letters in the same lines are significantly different at the 5% level (p< 0.05).
The FRAP values of the tested teas ranged between 449–492
µ
mol/g for black tea samples and
552–601
µ
mol/g for green tea samples. Benzie and Szeto reported FRAP values for 25 types of teas,
ranging between 132–654
µ
mol/g for black teas and 272–1144
µ
mol/g for green teas [
21
]. The FRAP
values for black and green tea infusions found in this study are in agreement with these reported FRAP
Beverages 2018,4, 86 6 of 7
values. The antioxidant capacities of sage and rosemary teas ranged between 63.8–81.9
µ
mol/g for
8 herbal tea infusions.
TPs and the antioxidant capacities of black and green tea infusions are obviously higher than
those of herbal tea infusions. As expected, there is a strong correlation (0.985) between TPs and the
antioxidant capacities of all tea infusions tested in this study. However, there is no correlation between
TPs or antioxidant capacity and RF content of teas. Whereas green teas have the highest TPs and
antioxidant capacity, the highest RF content was determined to be in sage infusions.
Hu and coworkers reported 2.8 and 5.4
µ
g/g RF for two green tea samples, which is in agreement
with our reported values [
14
]. RF content of several foods have been reported in the literature.
Cataldi et al. have reported the RF content of 8 vegetables ranging between 0.34–1.67
µ
g/g [
12
].
The RF content in five milk samples having different animal origins were reported to be between
101 and 175
µ
g/100 mL, in 2 white wine samples as 12 and 13
µ
g/100 mL, in raw egg white as
3.8
µ
g/g, and in raw egg yolk as 3.2
µ
g/g [
13
]. The RF in 12 commercial beers was reported as
13–28
µ
g/100 mL [
15
]. The RF content of honeys was reported to change in a wide range as from
non-detectable to 18.04
µ
g/g [
16
]. RFcontent of five saffron samples from two of the biggest producers
in the global market (Iran and Spain) were reported in the range of 5.02–13.86 µg/g [17].
Assuming a tea brew obtained from 2 g of dry tea (around the mass of dry tea in one tea bag)
and 200 mL of hot water (the volume of a tea mug), our reported RF values for dry tea samples
of0.34–10.36
µ
g/g correspond to 0.34–10.36
µ
g RF/100 mL infusion. When the RF content of tea
samples found in this study are compared to the RF content of green vegetables, milk, egg, wine, beer,
honey, and saffron samples, known as important RF sources, it can be seen that tea infusions are also
important dietary sources of vitamin B2.
4. Conclusions
A fast, simple, and sensitive CE-LIF system was used to determine the riboflavin (vitamin B2)
content of 14 tea infusions including black, green, sage, and rosemary teas. The RF content of all tea
samples suggests that tea infusions are amongst important dietary sources of RF for prevention of
diseases caused by vitamin B2 deficiency.
Author Contributions:
Both of theauthors designed the experiments; F.T. has done experiments and also
calculated-analyzed the data; F.T. wrote the manuscript; F.B.E. supervised the research and wrote and edited
the manuscript.
Funding: This research received funding from the Research Foundation of Istanbul Technical University.
Conflicts of Interest: The authors declare no conflict of interest.
References
1.
Azevedo, R.S.A.; Teixeira, B.S.; Sauthier, M.C.D.; Santana, M.V.A.; Dossantos, W.N.L.; Santana, D.D.
Multivariate eanalysis of the composition of bioactive in tea the species Camellia sinensis.Food Chem.
2019,273, 39–44. [CrossRef] [PubMed]
2.
Zielinski, A.A.F.; Haminniuk, C.W.I.; Alberti, A.; Nogueira, A.; Demiate, I.M.; Granato, D. A comparative
srudy of the phenolic compounds and the
in vitro
antioxidant activity of different Brazilian teas using
multivariate statistical techniques. Food Res. Int. 2014,60, 246–254. [CrossRef]
3.
Khan, N.; Mukhtar, H. Tea polyphenols for health promotion. LifeSci.
2007
,81, 519–533. [CrossRef] [PubMed]
4.
Afzal, M.; Safer, A.M.; Menon, M. Green tea poly phenols and their potential role in health and disease.
Inflammopharmacology 2015,23, 151–161. [CrossRef] [PubMed]
5.
Heber, D.; Zhang, Y.J.; Yang, J.P.; Ma, J.E.; Henning, S.M.; Li, Z.P. Green tea, black tea, and oolong tea
polyphenols reduce visceral fat and inflammation in mice fed high-fat, high-sucrose obesogenic diets. J. Nutr.
2014,144, 1385–1393. [CrossRef] [PubMed]
6. FAOSTAT. 2010. Available online: http://faostat.fao.org (accessed on 8 September 2018).
7.
WORLDATLAS. Available online: https://www.worldatlas.com/articles/the-worlds-top-10-tea-producing-
nations.html (accessed on 22 September 2018).
Beverages 2018,4, 86 7 of 7
8.
Ba¸skan, S.; Öztekin, N.; Erim, F.B. Determination of carnosic acid and rosmarinic acid in sage by capillary
electrophoresis. Food Chem. 2007,101, 1748–1752. [CrossRef]
9. Topcu, G. Bioactive triterpenoids from Salvia species. J. Nat. Pro. 2006,69, 482–487. [CrossRef] [PubMed]
10.
Powers, H.J. Riboflavin (vitamin B-2) and health. Am. J. Clin. Nutr.
2003
,77, 1352–1360. [CrossRef] [PubMed]
11.
Castro-Puyana, M.; Garcia-Canas, V.; Carolina, S.; Cifuentes, A. Recent advances in the application of
capillary electromigration methods for food analysis and Foodomics. Electrophoresis
2012
,33, 147–167.
[CrossRef] [PubMed]
12.
Cataldi, T.R.I.; Nardiello, D.; Carrara, V.; Ciriello, R.; De Benedetto, G.E. Assessment of riboflavin and flavin
content in common food samples by capillary electrophoresis with laser-induced fluorescence detection.
Food Chem. 2003,82, 309–314. [CrossRef]
13.
Cataldi, T.R.I.; Nardiello, D.; De Benedetto, G.E.; Bufo, S.A. Optimizing separation conditions for riboflavin,
flavin mononucleotide and flavin adenine dinucleotide in capillary zone electrophoresis with laser-induced
fluorescence detection. J. Chromatogr. A 2002,968, 229–239. [CrossRef]
14.
Hu, L.; Yang, X.; Wang, C.; Yuan, H.; Xiao, D. Determination of riboflavin in urine and beverages by capillary
electrophoresis with in-column optical fiber laser-induced fluorescence detection. J. Chromatogr. B
2007
,856,
245–251. [CrossRef] [PubMed]
15.
Su, A.K.; Chang, Y.S.; Lin, C.H. Analysis of riboflavin in beer by capillary electrophoresis/blue light emitting
diode (LED)-induced fluorescence detection combined with a dynamic pH junction technique. Talanta
2004
,
64, 970–974. [CrossRef] [PubMed]
16.
Kaygusuz, H.; Tezcan, F.; Erim, F.B.; Yıldız, O.; ¸Sahin, H.; Can, Z.; Kolaylı, S. Characterization of Anatolian
honeys based on minerals, bioactive components and principal component analysis. LWT-Food Sci. Technol.
2016,68, 273–279. [CrossRef]
17.
Hashemi, P.; Erim, F.B. Analysis of vitamin B2 in saffron stigmas (Crocus sativus L.) by capillary electrophoresis
coupled with laser-induced fluorescence detector. Food Anal. Methods 2016,9, 2395–2399. [CrossRef]
18.
Singleton, V.L.; Rossi, J.L. Colorimetry of total phenolics with phosphomolybdic-phosphotungstic acid
reagents. Am. J. Enol. Vitic. 1965,16, 144–158.
19.
Benzie, I.F.F.; Strain, J.J. The ferric reducing ability of plasma (FRAP) as a measure of “antioxidant power”:
The FRAP assay. Anal. Biochem. 1996,239, 70–76. [CrossRef] [PubMed]
20.
Choe, E.; Huang, R.; Min, D.B. Chemical reactions and stability of riboflavin in foods. J. Food Sci.
2005
,70,
R28–R36. [CrossRef]
21.
Benzie, I.F.F.; Szeto, Y.T. Total antioxidant capacity of teas by the ferric reducing/antioxidant power assay.
J. Agric. Food Chem. 1999,47, 633–636. [CrossRef]
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(CC BY) license (http://creativecommons.org/licenses/by/4.0/).
... The literature review shows that in CE-UV detection is also replaced by fluorescence detection ( Table 4). Combination of CE with laser induced fluorescence (LIF) has provided improvement in detection limit, compared with UV detector [71]. This type of detection was used to determine the amino acids in tea infusions, oolong tea and jasmine tea [72][73][74] and riboflavin in Camelia sinensis [71] and green tea name Zhuyeqing [75]. ...
... Combination of CE with laser induced fluorescence (LIF) has provided improvement in detection limit, compared with UV detector [71]. This type of detection was used to determine the amino acids in tea infusions, oolong tea and jasmine tea [72][73][74] and riboflavin in Camelia sinensis [71] and green tea name Zhuyeqing [75]. CE derivatization methods were used to determine γ-aminobutyric acid (GABA) and alanine in aqueous extract of Chinese tea after derivatization with o-phtaldialdehyde/2-mercaptoethanol (OPA/2-ME) to produce fluorescently labeled analytes [72]. ...
... Authors claimed that by using 0.5% PEO solution (prepared in 10 mM L −1 Na 2 B 4 O 7 at 9.3 pH) and 60 cm capillary length, GABA, GL, and aspartic acid (ASP) were marketed within 16 min. Moreover, fluorescence detector was used in the analysis of riboflavin (RF) concentration in Camelia sinensis [71,75]. RF was determined in green tea by CE with in-column optical fiber laser-induced fluorescence detection (CE-LIF). ...
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The article is a summary of scientific reports from the last 16 years (2005–2021) on the use of capillary electrophoresis to analyze polyphenolic compounds, coumarins, amino acids, and alkaloids in teas or different parts of plants used to prepare aqueous infusions, commonly known as “tea” or decoctions. This literature review is based on PRISMA guidelines and articles selected in base of criteria carried out using PICOS (Population, Intervention, Comparison, Outcome, Study type). The analysis showed that over 60% of articles included in this manuscript comes from China. The literature review shows that for the selective electrophoretic separation of polyphenolic and flavonoid compounds, the most frequently used capillary electromigration technique is capillary electrophoresis with ultraviolet detection. Nevertheless, the use of capillary electrophoresis-mass spectrometry allows for the sensitive determination of analytes with a lower limit of detection and gives hope for routine use in the analysis of functional foods. Moreover, using the modifications in electrochemical techniques allows methods sensitivity reduction along with the reduction of analysis time.
... Due to the extremely low concentration of the vitamin in many samples, detection methods with high sensitivity are required. Various methods have been adopted for vitamin detection, including fluorescence [2], surface-enhanced Raman spectroscopy (SERS) [3], ultra-performance liquid chromatography-electrospray ionization multiple reaction monitoring/mass spectrometry (UPLC-ESIMRM/MS) [4], surface plasmon resonance [5], ultraviolet-visible spectroscopy [6], and capillary electrophoresis [7]. Although these methods have high selectivity and resolution, they have some limitations in sample consumption, analysis time, detection cost, and operational complexity. ...
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Vitamins are essential and necessary nutrients for the human body. Rapid and accurate quantification of their levels in various samples has attracted much attention. Compared with traditional analytical methods, electrochemical techniques, with the advantages of low cost, high sensitivity, flexible detection strategies, easy integration, and miniaturization, have gradually become the main tools in vitamin detection. In this paper, the advance of electrochemical sensing of vitamins in recent years is reviewed. Firstly, the basics of different vitamins are briefly introduced. Then, the commonly-used electrodes and electrochemical methods for vitamin electrochemical detection, as well as the specific implementation strategy and performance, are described in detail. The development of miniaturization devices, especially microfluidic and microsensor devices, is also presented. Finally, the challenges faced by the electrochemical detection of vitamins are discussed, and future development is prospected.
... Ultra-performance liquid chromatography (UPLC) with DAD (Xie et al.), MS (Manful et al., 2019), and FLD detection (Ritota & Manzi, 2020). Capillary electrophoresis (CE) with DAD (Alshana et al., 2015), amperometric (AD) (Sun et al., 2002), MS (Daniel et al., 2018), conductivity (CD) (Klampfl & Katzmayr, 1998) and FLD detection (Tezcan & Erim, 2018). Flame-atomic absorption spectrometry (FAAS) , electrothermal-atomic absorption spectrometry (ETAAS) (Xing et al., 2021), inductively coupled plasma-optical emission spectrometry (ICP-OES) (Bozorgzadeh et al., 2021), and ICP-MS (Liu et al., 2021). ...
Thesis
In this study, microextraction techniques including two liquid–liquid microextraction (LLME) techniques and dispersive solid-phase microextraction (DSPME) were combined with smartphone digital image colorimetry (SDIC) for the determination of ionic, molecular, and elemental analytes in food samples. In the first study, solidification of floating organic drop-dispersive liquid–liquid microextraction (SFOD-DLLME) was combined with SDIC for the determination of iodate in table salt. A colorimetric box was constructed to capture reproducible images of the colored samples. Factors affecting the performance of both SFOD-DLLME and SDIC were optimized. The optimum conditions for SFOD-DLLME include the type and volume of the extraction solvent (1-undecanol, 500 µL), the disperser solvent (ethanol, 1.5 mL), and the extraction time (20 s). The limit of detection (LOD) obtained was found as 0.10 µmol L-1 (0.2 µg g-1) and enrichment factors ranged between 17.4 and 25.0. A good linearity, with coefficients of determination (R2) above 0.9954 was obtained. The method was applied for the quantitation of iodate in table salt with percentage relative recovery (%RR) between 89.3 to 109.3% and percentage relative standard deviation (%RSD) below 5.6%. In the second study, supramolecular solvent liquid–liquid microextraction (SMS-LLME) was combined with SDIC for the determination of curcumin in tea and spices using a modified version of the colorimetric box used in the previous study by replacing the continuum light source with a monochromatic source. The optimum conditions for SMS-LLME were achieved using 1000 µL of tetrahydrofuran/1-undecanol (4:1, v/v) as the extraction solvent, 2.0% (w/v) of sodium chloride for adjusting the ionic strength, an extraction time of 60 min and pH of the sample solution at 7.0. LOD was found to range between 0.2 to 0.9 µg mL^(-1) (0.04 to 0.18% w/w). Linear calibration graphs were obtained with R^2 values above 0.9965. The method was applied for the quantitation of curcumin in tea and spices with %RSD below 8.5% and %RR between 94.0 to 104.0%. In the third study, DSPME was combined with SDIC for the determination of boron in nuts using a monochromatic light source similar to the second study. Optimum DSPME conditions were obtained with zirconium nanoparticles (30 mg) as the adsorbent, acetone (100 µL) as the eluent, pH of the sample solution adjusted to 2.5 with phosphate buffer (25.0 mmol L-1), at adsorption and desorption times of 2.0 and 1.0 min, respectively. Under optimum conditions, LOD values ranged between 0.05 and 0.11 µg mL-1 (1.27 to 2.83 µg g-1) and calibration graphs showed a good linearity with R^2 above 0.9954. The method was applied for the quantitation of boron in nuts with %RR between 91.0 and 105.6% and %RSD below 6.77%. The three studies demonstrated the potential of SDIC, when combined with a suitable microextraction technique, to replace more sophisticated analytical techniques for the determination of ionic, molecular, and elemental analytes in complicated food matrices.
... Identification is based on specific optical rotation, thin-layer chromatography and ultraviolet/visible spectrophotometry, while quantification is based on spectrophotometry at λ = 444 nm. In addition, various analytical methods have been used in the literature to determine RF, which typically involved the conversion of FMN and FAD to RF, such as high-performance liquid chromatography [25], chemiluminescence [26], fluorescence [27], capillary electrophoresis [28], and UVvis [29]. However, these detection pathways are relatively time-consuming, expensive, lack sensitivity and selectivity, and require a highly skilled technicians and tedious instrumentation. ...
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Nickel acetate tetrahydrate (NAT) sample series were used to modify screen-printed carbon electrodes (SPCE). The samples were hybrid Ni/NiO nanocomposites, where the NiO phase increased with an applied treatment temperature. Results of electrochemical measurements pointed that the Ni/NiO550/SPCE-modified electrode had the best analytical performance toward the detection of riboflavin (RF). The Ni/NiO550/SPCE-based sensor showed linear response with RF in the concentration range of 0.5-75 μM and 0.15 μM LOD in BRBS. Sensor offered fast response time, good repeatability, and selectivity with an RSD of 1.4%. Our results show that the Ni:NiO nanocomposite ratio strongly influenced the electroanalytical performance of SPCE.
... In 1985, Zare et al. first used LIF into CE detection for separation and determination of dansyl chloride-amino acid derivatives [27]. Recently, CE-ILIFD has been extensively used in detection of drugs [28,29], biology [30][31][32][33][34], and food [35]. When analyte molecules do not have any fluorescent group or even have no ultraviolet absorption, ILIFD is a universally applicable mode. ...
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A capillary electrophoresis-indirect laser-induced fluorescence detection method was established for neomycin detection in fish. With rhodamine 6G as the background fluorescent substance, neomycin with weak ultraviolet absorption can be detected effectively. The types and concentrations of background buffer, pH, and separation voltage which affected the separation and analysis were all studied. With the optimal conditions, the limit of detection of neomycin was 5.0 ng/g, the recovery of fish samples is between 95.2 and 99.7%, and the relative standard deviation is between 2.7 and 3.6%.
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Innate immunity impairment led to disruption in cascade of signaling pathways upregulating pro-inflammatory cytokines, diminish interferons, depleted natural killer cells and activate reactive oxygen species production. These conditions severely affected body’s ability to fight against infectious diseases and also plays a pivotal role in disease progression. Here, in emphasis is on nutritional immunity for regulating effective innate immune response for combating against infectious diseases like novel coronavirus disease (COVID 19). Drawing from discoveries on in-vitro experiments, animal models and human trials, tea polyphenols, micronutrients, and vitamins has the potential to modulate and enhance innate immune response. This article provides a comprehensive review on tea (Camellia sinensis L) infusion (a hot water extract of dried processed tea leaves prepared from young shoots of tea plant) as an innate immunity modulator. Tea infusion is rich in polyphenols; epigallocatechin gallate (EGCG) and theaflavin (TF), major green and black tea polyphenols, respectively. Studies showed their immunomodulatory competence. Tea infusions are also rich in alkaloids; caffeine and its intermediates, theophylline and theobromine, which have anti-inflammatory properties. Tea plant being an acidophilic perennial crop can accumulate different micronutrients, viz., copper (Cu), iron (Fe), manganese (Mn), selenium (Se), and zinc (Zn) from growing medium, i.e., from soil, which led to their considerable presence in tea infusion. Micronutrients are integral part of innate immune response. Overall, this review presents tea infusion as an important source of nutritional immunity which can enhance innate immune response in order to mitigate the unprecedented COVID-19 pandemic.
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Saffron is the most expensive spice derived from the flower of Crocus sativus. The purpose of this study is to determine the vitamin B2 level in saffron using a trustable, easy, and sensitive analytical method and therefore to provide the missing information on the nutritional value of this spice. In our current study, by separating with the fast separation technique capillary electrophoresis (CE) and using a laser-induced fluorescence (LIF) detector which is both sensitive and discriminating from other UV active ingredients, the precise determination of vitamin B2 in saffron was achieved. Saffron samples were extracted by boiling water and directly injected to the separation buffer, borate at pH 9.5. The repeatability of the peak areas (%RSD) of riboflavin for intraday and interday was in the satisfactory range of equal to or less than 2.32 and 4.70 %, respectively. The limit of detection (LOD) and limit of quantification (LOQ) values for the method were 4.15 and 13 nM, respectively. Determination of riboflavin was performed by the standard addition method. Riboflavin contents of five saffron samples from two of the biggest producers in the global market (Iran and Spain) were in the range of 5.02–13.86 μg/g.
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