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Turmeric (Curcuma longa) Root and Rhizome, and Root and Rhizome ExtractsBy Ezra Bejar, PhD*
American Botanical Council, PO Box
144345, Austin, TX 78714
*Corresponding
author: email
Keywords:
Curcuma
longa, turmeric, adulteration,
turmeric root, turmeric rhizome, turmeric powder, curry, turmeric oleoresin,
curcuminoids, curcumin
Goal: The goal of this bulletin is to
provide information on issues of adulteration of turmeric (Curcuma longa) root, turmeric extracts, and curcuminoids, in
particular with zedoary (Curcuma zedoaria, syn.
C. malabarica), yellow colorants,
and synthetic curcumin. Also
discussed is the mislabeling of previously extracted (spent) underground parts
of turmeric as genuine turmeric root and rhizome. The bulletin may serve as guidance
for quality control personnel, the international herbal products industry, and
extended natural products community in general. It is also intended to present a
summary of the scientific data and methods on the occurrence of species
substitution, adulteration, the market situation, and economic and safety consequences
for the consumer and the industry.
1 General Information
1.1
Common Names: Turmeric, common turmeric, Indian
saffron, yellow ginger1-3
1.2
Other Common Names:
Arabic: Kurkum4
Assamese: Lidar, halodhi1,4,5
Bengali: Halud1,4,5
Burmese: Tanum1
English: Curcuma2,6
Cambodian: Ro miet7
Chinese: Jiang huang (姜黄), [huang si] yu jin (郁金),2,8,9jianghuang,10 yu chin4
Danish: Gurkemeje10
Dutch: Geelwortel4
Filipino (Tagalog): dilau,luyang-dilau11
French: Curcuma, safran des Indes10
German: Kurkuma, Gelbwurzel10
Gujurati: Haldar (હળદર)1,4,5
Hindi: Haldi, haldee (हल्दी)12,13
Italian: Curcuma, zafferano delle Indie, turmerico4
Japanese: Ukon4
Kannada: Arishina, arisina1,4,5
Laotian: Khi min7 Malay: Kooneit, kunyit5 Malayalam: Manjal1,4,5 Marathi: Halad (हळद)1,4,5 Nepali: Besar(बेसार)1,4,5,14 Norwegian: Gurkemeie4 Oriya: Haladi1,4,5
Portuguese: Acafrao-da-India4
Russian: Yellow ginger - zheltyj imbir' (жёлтый имбирь), curcuma (куркума)4,14
Spanish: Curcuma4
Sanskrit: Gauti, varnavat, haridra, marmadri, nisha, shati4,10,13; haridra13
Swedish: Gurkmeja1,4,5
Tamil: Manjal1,4,5
Telugu: Pasupu, haridra4
Urdu: Haldi (ہلدی)1,5,12
Vietnamese: Nghệ, uất kim7,14
1.3
Accepted Latin binomial: Curcuma longa L.
1.4 Synonyms:
Curcuma domestica2,10,15,16
1.5
Botanical family: Zingiberaceae
1.6 Distribution: The plant is native to Southeast Asia,
especially India.1,11-13,17
It is available in
all states of India, but particularly in Tamil Nadu, West Bengal, and
Maharashtra.13 Turmeric is a tropical crop
cultivated at sea level to 1,200 meters above sea level. It grows in light
black clay loam soils and red soils under irrigated and rain-fed conditions.4 Turmeric is extensively cultivated in India, Pakistan, China, Haiti,
Jamaica, Peru, Taiwan, Nigeria, Bangladesh, and Thailand. Other important
producers include Japan, Indonesia, Sri Lanka, Burma (Myanmar), Cambodia,
Malaysia, and the Philippines.7,17-20 It has a wide distribution as a non-native species in
Madagascar, Oceania, and the Antilles.5,7
1.7
Plant part and form: Curcuma longa is an herbaceous perennial reaching 1.5
m (4.9 feet) in height. The part of the plant used is the rhizome, which is of stout,
short, cylindrical, or ellipsoidal structure, lateral-growing, branching, and
generally subterranean. It has a golden yellow color inside.4,7,13 The rhizome is used as a fresh root, powder,
herbal tea, or after extraction, as oleoresin, dry extract, or tincture with
70% ethanol.2,17 The deep orange-yellow powder known
as turmeric is prepared from peeled, boiled, and dried rhizomes of the plant.21
Depending
on its origin and the soil conditions where it is grown, turmeric rhizome naturally
contains between 2–9% curcuminoids.22
1.8
General uses: The
rhizome is used as a condiment, an ingredient in curry powder, and for coloring
food, cotton, silk, and wool.7,13 The powder is most widely used as a
spice to color and flavor food, such as curry powders, mustard, cheese, and
butter, and is consumed along with many foods.23 Turmeric spice is incorporated into
teas and is a base component in many culinary spice blends, specifically curry.
It is a component in ethnic dishes like kedgeree and piccalilli (England), sofrito (Africa), and la-kama (Morocco).17 Turmeric is extensively used in the
Indian systems of medicine (Ayurveda, Siddha, and Unani), as well as in Eastern
Asian systems (traditional Chinese medicine [TCM], Japanese Kampo, Korean, and
Malay medicine).17 Since the 1970s, Curcuma longa has been included in recognized pharmacopeial
monographs and compendial works, including the German Commission E, United States Pharmacopeia, British
Pharmacopoeia, European Pharmacopoeia, Mexican Herbal Pharmacopoeia, Japanese
Pharmacopoeia, Korean Herbal Pharmacopoeia, Pharmacopoeia of the People’s
Republic of China, Ayurvedic Pharmacopoeia of India, Unani Pharmacopoeia of
India, and many others.1,17,24,25 Turmeric uses include: in indigestion
(dyspepsia) treatment and joint pain alleviation, as an antioxidant, and as a
choleretic to increase bile excretion and stimulate gallbladder contraction
(cholagogue).26 Turmeric is also used topically in
the treatment of skin conditions and as an insect repellant.24,25,27 In Ayurvedic medicine,
turmeric is primarily used as a treatment
for inflammatory conditions25 and in TCM, it is used mainly as
stimulant, aspirant, carminative, cordial,
emmenagogue, astringent,
detergent, and diuretic.21,28,29 Additional indications
based on recent pharmacological studies include the prevention of
cardiovascular disease and cancer, improvement of liver function, metabolic
syndrome, topical treatment of skin diseases, and as adjuvant to conventional
cancer therapy.10,30,31
1.9 Nomenclature considerations: Turmeric is distinguished by the
presence of the orange pigment curcumin. Several other species of Curcuma, e.g., C. aromatica and C. zedoaria,
are also known to contain curcumin, which has caused some confusion in the
local vernacular names used in India.32
Today, C. domestica is considered a synonym of C. longa,2,10,15 but in older reference books the two were not
considered the same.33,34 Guenther, in Volume V of his The Essential Oils, p. 123, categorically
differentiated C. domestica as a distinct
species.32
Earlier references confused C. caesia and even C. zedoaria with C. longa.32 The Dictionary of the Economical Products of India suggested that the so-called
forms of C. longa were tubers of
different species. The Wealth of India,
published in 1950 by the Indian Council of Scientific and Industrial Research, mentioned
C. longa substitution with C. aromatica, as well as its close
resemblance to C. zedoaria.32 Both of these species, particularly
the latter (local name Kachura, Soti), are considered to be adulterants and have
been reportedly mixed with C. longa
in powdered form.32
2 Market
2.1. Importance in the trade: Turmeric-based dietary supplements (which also include standardized extracts with high concentrations of curcumin) have seen a steady increase in popularity in the United States and elsewhere (Tables 1 and 2). In the United States, the largest market for turmeric supplements, sales have almost tripled from 2013 to 2016, totaling over US $69 million (not including sales at stores like Walmart, Costco, and Whole Foods) in 2016 with ca. 70% being sold in the natural channel (Table 1).
Table 1: US Dollar sales data in the natural channel for turmeric dietary supplements from 2012–2016
2012
|
2013
|
2014
|
2015
|
2016
|
Rank
|
Sales
|
Rank
|
Sales
|
Rank
|
Sales
|
Rank
|
Sales
|
Rank
|
Sales
|
3
|
16,873,153
|
1
|
20,082,843
|
1
|
28,245,699
|
1
|
37,334,821
|
1
|
47,654,008
|
According
to SPINS (SPINS does not track Whole Foods Market
sales, which is a major natural products retailer in the US). Source:
Smith et al., 2017.35 Smith T (American Botanical
Council) email communications, September 2-3 2015; K. Kawa (SPINS) email
communication, July 11, 2016.
Table
2: US Dollar sales data in the mass market channel for turmeric dietary
supplements from 2012–2016
2012
|
2013
|
2014
|
2015
|
2016
|
Rank
|
Sales
|
Rank
|
Sales
|
Rank
|
Sales
|
Rank
|
Sales
|
Rank
|
Sales
|
22
|
9,752,445
|
30
|
4,428,543
|
29
|
7,227,447
|
17
|
15,735,163
|
10
|
22,057,946
|
According to SPINS/IRI (the Mainstream
Multi-outlet channel was formerly known as food, drug, and mass market channel [FDM], exclusive of
possible sales at Walmart from 2013-2015). Source: Smith et al.,
2017.35 Smith T (American Botanical Council) email
communications, September 2-3 2015; K. Kawa (SPINS) email communication, July
11, 2016.
2.2.
Supply sources: India
is by far the largest consumer, producer, and exporter of turmeric rhizome and
turmeric essential oil, turmeric oleoresin, and turmeric preparations. Other
important producers of turmeric are China and the countries of the West Indies.17
Turmeric
is grown all over India, but different sources contend as to which geographic
region is more widely cultivated and produced. The Annual Report of the Spices Board India, Ministry of Commerce &
Industry, Government of India, mentions 190,420 hectares of turmeric under
cultivation, resulting in a yearly production equivalent to 843,530 metric tons
in 2015-2016.4 This was an increase from the 178,470
hectares used for turmeric cultivation in 2014-2015. According to the Spices
Board of India, turmeric is extensively cultivated in the Northeastern States,
where agro-climatic conditions are more suitable for its cultivation.4 Yet, other sources indicate that
production of turmeric is greater in South and Central India, with Andhra
Pradesh state accounting for 60 % of total turmeric production, followed by
Tamil Nadu (13%), and Orissa (12%).18 In fact, the productivity of turmeric
in Andhra Pradesh state is estimated at a 5,404 kg/ha, which is 33% higher than
the national average (A. Benny [Arjuna Natural] email communication, May 5,
2017).
In terms of varieties, it
appears there are up to 30 different varieties growing in India, but only two
designations are commercially significant: Alleppey
and Madras turmeric, both named after
the places of cultivation.
The
Alleppey turmeric grows in the
Thodupuzha and Muvattupuzha regions of Kerala State, and this variety is predominantly
imported by the United States in unpolished form, where users prefer it as a
spice and a food colorant (A. Benny [Arjuna Natural] email communication, May
5, 2017). This turmeric contains about 3.5-5.5% volatile oil, and 4-7% curcumin.
In contrast, the Madras-type contains
only 2% of volatile oil and 2% of curcumin. Madras
turmeric is comprised of as many as nine cultivars, including Guntur, Salem, Rajamundry, Nizamabad, and Cuddappah. The British and Middle Eastern markets prefer the Madras
turmeric for its more intense, brighter, and lighter yellow color, and because
it is better suited for the mustard paste and curry powder or paste used in
oriental dishes (A. Benny [Arjuna Natural] email communication, May
5, 2017).
The
Lakadong/Megha variety of turmeric is
another variety considered by the Indian government as one particularly rich in
intrinsic qualities and very much preferred by exporters.4 The Lakadong turmeric has a high curcumin content (>8%). Non-availability
of quality planting materials is a major limiting factor in its production.
2.3 Raw material forms: Dried rhizome/root is sold in either whole
or powdered form. Turmeric rhizome in cylindrical or finger-like shape and in
tuberous-ovoid shape are sometimes distinguished as “Curcuma longa” and
“Curcuma rotunda,” respectively.31 Curcumin-rich extracts are obtained after
extraction with solvents like ethanol, methanol, or ethyl acetate and
subsequent spray drying or crystallization with ethanol or isopropanol.21 Commercial dietary supplement
extracts are often standardized to contain 95% curcuminoids. The extracts may
contain suitable added substances as carriers; some products contain piperine
or soy lecithin to increase curcuminoids’ bioavailability.
The word “curcuminoid” is used to describe a mixture of diarylheptanoids, mainly consisting of curcumin, demethoxycurcumin, and bisdemethoxycurcumin.22 Turmeric oleoresin, curcuma oil, or oil of turmeric is referred to as the organic extract of turmeric containing the volatile oil, but also resin waxes and other secondary metabolites, obtained by non-aqueous solvent extraction, with curcumin being the major component. Turmeric oleoresin may contain up to 55% curcumin.21 Curcumin is sometimes also referred to as a purified extract containing a mixture of the three major curcuminoids but most often describes a specific diarylheptanoid, also known as diferuloylmethane.21
2.4 Market dynamics: In the 2015-2016 period, a total
volume of 88,500 metric tons of turmeric was exported from India, versus 86,000
tons in the preceding period of 2014-2015.4
Besides
India, many other Asian, Latin American, and Caribbean countries have entered turmeric
production. Vietnam and Pakistan, as well as traditional-producing countries
like Peru, have also increased their production level.
Since
the late 1980s, the area, production, and productivity of turmeric have exhibited
an increasing trend. India is the most important exporter of turmeric, and the United
Arab Emirates are the major importer of turmeric from India, followed by the United
States, Japan, the United Kingdom, Iran, Singapore, Sri Lanka, and South
Africa. Turmeric export registered a growth rate of 7.56%, 17.19%, and 8.95% in
terms of quantity, value, and unit value, respectively, during the period
1981–1982 to 2000–2001. The International Trade Centre, Geneva, has estimated
an annual growth rate of 10% in the world demand for turmeric.36
3 Adulteration
3.1. Known adulterants: The fact that this spice is frequently
sold in powdered form (which renders identification to species by macroscopic visual
inspection impossible) makes it more susceptible to mixing with extraneous, lower-cost
botanical ingredients, starches, chalk powder, cassava, and synthetic dyes.32,37-40 A report has raised the issue regarding what appears to
be the trade of turmeric roots that were pre-extracted and mixed with
non-extracted roots. The spent roots were lighter, less dense, and of a red
color different from the roots that did not appear to be pre-extracted. (R.
Upton email communication to S. Gafner, April 16, 2018). Whole rhizomes of
turmeric have also been found to be adulterated with species from the same
genus containing curcumin, e.g., C.
zedoaria.27,32,38,40,41
The first
report of adulteration of C. longa with
C. zedoaria and C. aromatica was published in the 1970s.32
Curcuma zedoaria, a wild relative of turmeric, also sometimes known as
white turmeric, is a plant easy to mix with turmeric
powder due to its close resemblance and wide availability. The plant is
indigenous to Bangladesh, Sri Lanka, and India, and is also widely cultivated
in China, Japan, Brazil, Nepal, and Thailand.32,42 Adulteration has also been reported with C. zanthorrhiza.43
Due to the high demand in international
trade, turmeric powder has been subject to economically-driven adulteration
with potentially toxic chemical compounds. Metanil yellow (sodium 3-[4-anilinophenylazo] benzenesulfonate) is
a synthetic, non-permitted food color and additive, which has been used as a
turmeric adulterant, since it mimics the color appearance of curcumin.37,44 Other dyes which have been cited as adulterants in
turmeric are lead chromate,27,39,43 acid orange 7 (sodium 4-[(2E)-2-(2-oxonaphthalen-1-ylidene) hydrazinyl]benzenesulfonate),45 and Sudan Red G.46 Turmeric is also diluted with yellow
soapstone powder, a natural mineral.
Extracts
standardized to curcuminoids are among the fastest-growing herbal ingredients
presently in the United States (Tables 1 and 2). Prices for natural curcuminoids
from C. longa are above $150/kg, about
three times that of synthetic curcumin, which costs around $50/kg. This has
given rise to unethical suppliers spiking natural turmeric extracts with
synthetic curcumin (N. Kalyanam [Sabinsa] email communication, March 1, 2017).
3.2. Sources of information
supporting confirmation of adulteration: Scientific papers from the 1970s and 1980s describe
adulteration of turmeric with other Curcuma
species, starches, and dyes, and provide methodologies for their detection, but
no commercial samples were evaluated in these papers.32,46,47
In
2004, three market samples of turmeric powder brands in the Indian market were
analyzed based on genetic profiling (Random Amplified Polymorphic DNA [RAPD]
analysis) and compared to genuine powders of C. longa and C. zedoaria.
The analysis revealed the presence of more C.
zedoaria (wild species) powder than C.
longa (the common culinary turmeric) powder, even though the curcumin
levels of the samples met the quality standards.42
In 2011, six samples of
turmeric powder procured
from a local market at Calicut, Kerala, India were analyzed using two Sequence Characterized Amplified
Region (SCAR) markers, a method to determine the identity of turmeric based on
DNA markers. Both markers detected the presence of adulteration with C. zedoaria or C. malabarica in four market samples and in simulated mixtures,
i.e., samples of turmeric powder and the
adulterants made at different concentrations.48 In 2015, one out of 10 turmeric
samples analyzed by DNA using single nucleotide polymorphisms (SNPs) that
discriminate between C. longa and C. zedoaria was shown to be adulterated
with C. zeodaria.49
The Bureau of Indian
Standards suggests a minimum of 3% curcumin for powdered turmeric, whereas the
mandatory Prevention of Food Adulteration (PFA) Act of 1954 does not specify
any minimum curcumin limit.44 Despite the regulations in place in
India, the quality of turmeric products on the Indian market is highly variable.
In
2008, a report showed turmeric adulteration and detected the presence of organic
dyes, such as metanil yellow (1.5–4.6 mg/g), Sudan I (4.8–12.1 mg/g), and Sudan
IV (0.9–2 mg/g) in loose turmeric and chili samples from city markets across India.
The curcumin content in turmeric and mixed curry powder samples ranged from 6.5
to 36.4 mg/g and from 0.3 to 1.9 mg/g, respectively.37
In a 2013 report, four commercial
samples of whole dried rhizome turmeric were collected randomly from four
different areas of the spice market of Allahabad, India, and analyzed for
possible adulteration using laser-induced breakdown spectroscopy (LIBS), an
atomic absorption technique providing signatures of each element. The analysis
demonstrated that one of the four samples had spectral signatures corresponding
to lead (Pb) and chromium (Cr), suggesting they might contain lead chromate as
an adulterant providing color to make them more attractive to consumers.27
In
another study, food samples from the unorganized sector in West Bengal, India
were tested. The unorganized sector is comprised of private enterprises owned by individuals or households that produce or sell
goods and services, operate on a proprietary or partnership basis, and employ
less than ten workers. Fifty-eight samples of a total of 253 collected (20.94%)
contained metanil yellow, with 32.95% of the turmeric powder specimens and
31.32% of the laddoo (ball-shaped
traditional Indian dessert
made with flour, milk, sugar, and turmeric) samples containing metanil yellow. No
significant contamination of metanil yellow was found in besan (a flour made from a variety of ground chickpea) samples.50
A
recent review on ground turmeric as a source of lead exposure in the United
States was conducted by researchers at the Department of Environmental Health,
School of Public Health at Boston University. The review focused on the contamination
of turmeric with lead (with high lead levels likely coming from the addition of
lead chromate) in products imported from India and Bangladesh to the United
States. According to the authors, spices, food, and dietary supplements in the
United States may be extensively adulterated with lead to enhance its weight,
color, or both.39 In 2011 and 2012, the authors
purchased 32 samples of turmeric from mainstream grocery stores, specialty
stores, and ethnic markets throughout the greater Boston area and found
detectable levels of lead in all of the samples, with a median concentration of
0.11 μg/g (range: 0.03-99.50 μg/g), using inductively coupled plasma-mass
spectrometry. The authors cite several FDA enforcement reports from 2011 to
2014 showing 13 lead contaminated turmeric brands recalled (voluntarily) in
several US states. In 2016, seven brands of turmeric were recalled because of
elevated lead levels, as well as five brands of curry powder, amounting to
337,000 pounds.39
Most
recently, 38,000 pounds of turmeric that were distributed to Florida and New
York by Spices USA, Inc. were recalled because of elevated lead levels.51 The FDA issued an import alert of
lead poisoning on September 26, 2016, which allows ports to detain future
shipments from specific importers, targeting turmeric from Pran (Bangladesh),
Visakarega Trading (India), and Indo Vedic Nutrients (India).51
In
2014, Harvard University researchers reported lead concentrations of up to 483
μg/g in turmeric samples collected from 18 households in rural Bangladesh, a
country where the permissible level of lead in turmeric is 2.5 μg/g.39,52 A newspaper article (Times
of India, published May 10, 2010) reported a raid by the Indian Food and
Drug Authority in 2010, with inspectors discovering over 100 bags of raw turmeric
contaminated with lead chromate at a spice manufacturing plant.53
The
issue of adulteration of natural curcumin with synthetic curcumin was first
reported in 2011, when EuroPharma (Green Bay, WI), a US manufacturer of natural
turmeric extract supplements, considered the possibility of commercially
available curcumin supplements made with a lower-cost synthetic version and
began working with University of Georgia on tests using radiocarbon dating
techniques to analyze curcumin products on the market to determine the percentage
that contained synthetic versus natural curcumin, or a combination of both.23,54
After
the 2011 report by EuroPharma, other suppliers initiated strategies to identify
products adulterated with synthetic ingredients23,54,55 and, in some instances, apparently prompted industry members
to take legal action. On May 26, 2015, Sabinsa Corporation's parent company
Sami Labs Limited (Bangalore, India), filed a criminal complaint with the chief
magistrate, Bangalore and the Peenya police department, Bangalore, against
Bayir Extracts Private Limited, Bangalore, India for knowingly supplying
adulterated turmeric oleoresin with a forged Certificate of Analysis.56,57
The 14C
testing of five commercial samples of curcumin sold by Bayir for export to the
U.S. showed that four of the materials contained curcumin that was 32-45%
synthetic, while the fifth sample was 100% natural.57 Using the same testing approach,
materials from another supplier (Biotikon®, Gorxheimertal, Germany)
were also found to contain significant amounts of synthetic curcumin.58
3.3. Accidental or intentional adulteration: Turmeric is likely one of the spices most frequently
adulterated because of its widespread use and high cost. In some situations, the
use of C. zedoaria could be a case of mistaken identity and qualified to be an
accidental adulteration due to human error. But the uses of cassava, talc
powder, starches, yellow dyes, minerals and synthetic curcumin are clearly
intentional and constitute economically-motivated adulteration.
3.4. Frequency of occurrence:
Adulteration of
turmeric powder commonly occurs with synthetic dyes, zedoary root, starch, and
cassava in food ingredients, and also with synthetic curcumin on turmeric
curcumin used as an ingredient in dietary supplements. The use of dyes in
unbranded turmeric powders sold in bulk is prevalent in different regions in
India. The frequency of adulteration of C.
longa with C. zedoaria is not
known. Morgan et al.59 suggest that adulteration with C. zedoaria is rare, but a large market
sample analysis has yet to be performed.
The
presence of C. zedoaria was detected
in all three samples of popular turmeric powder products tested.42 In another study, one out of 10 branded
samples from an Indian market showed the presence of zedoary and starches
although the label claimed nothing other than turmeric powder.49
Thin-layer
chromatography (TLC) analysis of market samples (of turmeric, chili, and curry purchased
in Lucknow, India) showed the presence of the food dyes metanil yellow (1.5–4.6
mg/g), Sudan I (4.8–12.1 mg/g), and Sudan IV (0.9–2.0 mg/g) in loose turmeric
and chili samples; the occurrence of the Sudan dyes was limited to the chili
samples.37
In a
more detailed study by the same group, 712 commercial samples in India were
tested using a two-dimensional high-performance thin-layer chromatography (HPTLC)
method. None of the branded samples (N =100) showed the presence of artificial
color, but 105 (17.2%) of the non-branded samples (N = 612) of turmeric powders
were dyed with metanil yellow.44
Four samples
of whole dried turmeric rhizome collected randomly from four different areas of
the spice market of Allahabad (India) were analyzed directly by the LIBS
technique for a complete profiling of elements present in the samples. Three samples
were found to be authentic, while one sample had a bright yellow color. This
latter sample was found to be adulterated with lead II chromate dye.27
Analysis of 253 food
samples, consisting of three different types of food items —turmeric powder,
laddoo, and besan — were tested for the presence of metanil yellow. Fifty-eight
out of the 253 samples collected, i.e., 20.9%,were found to contain metanil
yellow with 36.2% of the positive samples below the maximum permissible limit
and 63.8% above the maximum permissible limit of 100 mg/kg, as specified in the
Prevention of Food Adulteration Act of India.50,60 No metanil yellow was found in any
food samples prepared from the food items (turmeric powder, laddoo, and besan) produced
by the organized sector, i.e., those companies that are registered with the
Indian government and follow its rules and regulations.50
The practice
of adulteration with dyes in India is regional, and turmeric from poorer sectors
in the Indian state of West Bengal has been found to contain metanil yellow more
often than turmeric from the more affluent regions of the state.50
The occurrence
of adulteration of C. longa with
other Curcuma species as lower-cost substitutes
in the marketplace has been mentioned in many publications since the 1970s,32,38,49 but reports of the analysis of samples of branded commercial
turmeric products are limited. In one report, one of the 10 samples analyzed by
DNA barcoding showed the presence of C.
zedoaria DNA. The 10 samples were from popular brands of turmeric powder
procured locally from Kozhikode (Kerala state, India). Each of the 10 samples was
produced by a different company.49 Another report using RAPD
markers to distinguish among Curcuma
species found all three samples analyzed were adulterated with C. zedoaria.42 Finally, an investigation from 2014
into the quality of 39 commercial turmeric samples for food, dietary supplement
and cosmetic use sold in supermarkets and retail stores in the United Kingdom
(27), India (8), the Netherlands (2), Iceland (1), and Greenland (1) labeled to
contain C. longa (34), C. amada (1), C. aromatica (2), C. zanthorrhiza
(1), and C. kwangsiensis (1) by
HPTLC showed that three products did not contain any bands, one turmeric
product was adulterated with C. aromatica,
and one product from India contained merely curcumin, with little to no
demethoxy- and bisdemethoxycurcumin.41
As noted above, a more recent practice is the
use of synthetic curcumin to adulterate turmeric extracts claiming a specific curcuminoid
content. Since synthetic curcumin is of much lower cost, companies that produce
all-natural ingredients have reported that fraudulent suppliers of turmeric
extracts containing synthetic curcumin are able to offer materials at lower
prices (N. Kalyanam
[Sabinsa] email communication, April 2, 2017).
As stated in section 3.2
above, four out of five samples from one supplier were found to contain
synthetic curcumin.57 To date, no report with test results
of a larger set of commercial samples is available to confirm the frequency of
adulteration with synthetic curcumin, and its geographic distribution.
3.5. Possible safety/therapeutic issues:
Metanil yellow, a
common adulterant of turmeric and curry powders, is not approved as a food
colorant by the UN FAO/WHO Codex Alimentarius or the US FDA.50,61 Studies on rats show that long-term
consumption of metanil yellow causes neurotoxicity, hepatocellular carcinoma, tumor
development, deleterious effect on gastric mucin, and lymphocytic leukemia.45,61 This dye is potentially dangerous to
human health and has been toxicologically classified under the category CII, a
category of food colorants for which the available safety data are inadequate,
by the joint FAO/WHO Expert Committee on Food Additives in 1965.62 When evaluating the risk of
carcinogenicity, the International Agency for Research on Cancer (IARC)
classified lead chromate, and Sudan dyes in group 3, which means that the
available studies do not permit conclusions regarding the causality between
exposure and cancer occurrence.63
Some cases of lead
poisoning may be attributed to the consumption of turmeric. In 2010, a report
detailed the case of a 12-month-old baby with a blood level of 28 mg/dL,3
which exceeded the Centers for Disease Control and Prevention’s reference level
of 5 mg/dL.4 After conducting a detailed investigation of the
child’s home, the Massachusetts Department of Public Health determined that
daily consumption of several lead contaminated spices, including turmeric, was
the primary pathway of exposure.39
Safety
of Curcuma zedoaria
Despite
several reports about the potential toxicity of C. zeodaria rhizome, information from authoritative sources suggest
no risks for consumption at the low amounts used in cooking and as a stomachic;
therefore, it should not be generally considered a health concern in
adulterated turmeric powder.24,38,49,64-66 A pharmacological and chemical toxicity study of zedoary
rhizome extracts on mice showed the botanical ingredient to be relatively non-toxic
at low doses. However, high doses of the rhizome extracts caused CNS depression
and elevation of liver enzymes.65 Some reports cite a paper by Lakshmi
et al. as conclusive evidence of the possible toxicity of zedoary.49 An additional report on
potential adverse effects using zedoary comes from a published review of the
chemistry, pharmacology, and ethnomedicinal value by Lobo et al. in 2009. Since
this publication provided data on rats and chickens fed between 100 and 400 g/kg
body weight of a turmeric flour preparation, it is not representative of the
turmeric materials or dosages used in food or medicine.64 Despite the fact that the high doses used
in these studies will not be ingested when consuming adulterated turmeric in
food and or a turmeric supplement, the reports have raised some cautions about
the safety of turmeric adulterated with zedoary. The second edition of the
American Herbal Products Association’s Botanical
Safety Handbook lists zedoary as contraindicated during pregnancy but otherwise
it is considered safe under normal conditions of use.
A
new potential safety concern has risen with turmeric or curcumin ingredients
partially adulterated or completely substituted with synthetic curcumin. This
less expensive synthetic curcumin has not been studied to assess its safety.
In
2006, the Canadian safety assessment and regulatory affairs consulting company
Cantox submitted a New Dietary Ingredient (NDI) Notification to the US FDA on
behalf of Yung Zip Chemical's Elite (synthetic) Curcumin.67 The safety data provided for
synthetic curcumin came exclusively from animal toxicity studies using the natural
diarylheptanoid extracted from turmeric. The argument by Cantox was that
although Yung Zip's Elite curcumin was synthetically prepared, it was
chemically identical to the compound obtained through solvent extraction from a
natural source. The FDA rejected the filing, stating that it was unable to
determine the identity of the NDI and therefore could not assess that the NDI
does not present a significant or unreasonable risk of illness or injury.68
3.6. Analytical methods to detect
adulteration: Details on the microscopic features of turmeric root and other Curcuma species such as C. aromatica, C. longa, C. zanthorrhiza, and
C. zeodaria have been published by several authors.69-74 Based on the published
data, it is not clear if the microscopic features are distinct enough to
determine the identity to the species level.
A number of simple
physical and colorimetric tests using reagents have been used to test for the
presence of chalk, yellow soapstone, starch, and dyes.75,76 These physical and colorimetric methods are suitable as screening
tests to allow for a quick determination of adulteration with the
above-mentioned coloring materials.
A rapid TLC technique
was developed to identify C. longa
and distinguish it from other Curcuma
species. The method involves a three-step color sequence for the detection of
camphor and camphene, chemicals found in these adulterants, which are absent in
turmeric.32,77 More recently, the HPTLC Association
published a method to distinguish C.
longa and C. zanthorrhiza.78 The same method allowed detection of
adulteration with C. aromatica.41
A two-dimensional
HPTLC was used to detect adulteration of turmeric by dyes and identify them. The
method offers resolution of the three curcuminoids and the synthetic dye
metanil yellow by the initial development. Resolution of Sudan I and Sudan IV
was achieved by developing the plate in the second direction.37
Since many
commercial turmeric dietary supplements contain essential oil in addition to
the curcuminoids, distinction among Curcuma
species can also be achieved by analyzing the essential oil fraction using gas
chromatography. There are substantial differences in the composition of the
sesquiterpene fraction and lower amounts or absence of turmerones in some of
the adulterating species.77,79
A number of HPLC methods have
been used for the detection and estimation of curcuminoids as a tool for the
evaluation of the quality of commercial ingredients and products. The methods
include a variety of detection systems (UV, diode array, mass spectrometric,
and fluorescence) and chromatographic techniques (HPLC, GC, CE).80-86
For turmeric extracts, HPLC
chromatograms showing a characteristic fingerprint of the three curcuminoids in
a consistent ratio (∼77%
curcumin, ~17% demethoxycurcumin and ~3% bisdemethoxycurcumin) has been, for many years, the approach
to determine the product identity and quality.21,83-86 Bisdemethoxycurcumin is reportedly absent in C. aromatica and C. zanthorrhiza, allowing for a distinction from C. longa based on this compound.41,78 Curcuma zedoaria
has demethoxycurcumin as the main curcuminoid, contrary to C. longa where curcumin is the most abundant.87,88 However, identification of the correct Curcuma species solely based on the
curcuminoid analysis may not be appropriate due to the presence of cultivars
and hybrids that may represent variations from the curcuminoid ratio mentioned
above.21 In 2010, the NIH ODS Dietary
Supplements Presidential Task Force identified turmeric as a high–priority
supplement requiring a validated method for the determination of curcuminoids
in raw materials and finished products. Turmeric methods were evaluated by an
AOAC committee, and the selected HPLC method was subjected to a
single-laboratory validation, according to the AOAC International guidelines using
12 raw materials and finished products containing turmeric roots.81
Recently, laser-induced
breakdown spectroscopy has been used to detect the presence of dyes in
turmeric. The elements of the samples, carbon, sodium, potassium, magnesium,
calcium, iron, and molecular bands of cyanide, are identified as well as the spectral
signatures of the toxic elements like lead and chromium, which were found in
one of the four commercial samples analyzed, demonstrating adulteration.27
The
presence of metanil yellow is easily detected by simple acid-base tests and can
also be done by Fourier Transform-Raman (FT-Raman) and Fourier Transform-infrared
(FT-IR) spectroscopy.89 (N. Kalyanam [Sabinsa] email communication, April 2,
2017) FT-IR can detect metanil yellow in concentrations of 5% and higher, while
the FT-Raman method is more sensitive, detecting as little as 1% of metanil
yellow in the sample.89 The use of HPLC-MS provides even lower sensitivity with
a limit of detection of as little as 100 pg/mL.90
1H NMR spectroscopy-metabolomics has been used to identify Curcuma species and authenticate
turmeric samples. 1H NMR spectra of turmeric samples were examined
visually for appropriate reference peaks for the identification of
curcuminoids. Using this method it was possible to differentiate C. longa from C. aromatica and C.
zanthorrhiza based on principal component analysis (PCA). A contribution plot also allowed
determination of the main metabolite differences among the Curcuma species (the absence of bisdemethoxycurcumin in C. aromatica and C. zanthorrhiza being one of the main distinguishing factors) and
among C. longa extracts made with
different solvents.41
Genetic
methods have been used to detect adulteration with fresh or dried, whole or
powdered material from other botanicals. Sasikumar et al. reported a genetic
method to detect adulteration of turmeric with white turmeric in market samples.
The authors used eight selected random decamer primers as molecular markers to
be analyzed by the RAPD technique.42 DNA barcoding was used to detect
plant-based adulterants in turmeric powder using a library of authentic
rhizomes from C. longa and C. zedoaria. The
genetic ITS region contained single nucleotide polymorphisms (SNPs) specific to
C. zedoaria DNA. These SNPs proved
useful in detecting adulteration.49
The method of choice to determine whether a chemical
compound is plant-derived or of synthetic origin is via 14C
measurement. There is a steady-state between incorporation of 14C
(via photosynthesis using CO2) into plant material and its decay
(half-life of 5730 years). After a plant dies, there is no further
incorporation of 14C; therefore, the concentration of 14C
is highest in living plants, while fossil fuel-derived products have little or
no 14C. The concentration of 14C can be measured using
specific mass spectrometers. In case of the presence of synthetic curcumin, the
14C concentration will be very low or 14C will be absent
altogether. Alternatively, in the manufacturing of synthetic curcumin, vanillin
is used as the starting material,67
and traces of vanillin may be detected by HPLC-MS and
thus determine the presence of synthetic curcumin in the sample.22
4
Conclusions
Powdered
turmeric root and rhizome and turmeric extracts are valued both for their medicinal
properties and for their popular culinary use, such as being a component in
curry powder. Due to turmeric’s high demand in international trade, turmeric
powder and extracts have been subject to deliberate, economically-motivated adulteration.
The adulteration of this plant species is an extensive, complex, and
multifactorial enterprise driven by economic incentive within the food ingredient
category. The curcuminoids, which are some of the principal compounds of
turmeric, are responsible for its yellow color; thus, color was a good
indicator as a measure of turmeric quality in antiquity. However, many bright
yellow turmeric powders may currently be adulterated with synthetic dyes, such
as metanil yellow, or lead chromate, decreasing the usefulness of color as a
measure of quality. Addition of these colorants may pose a safety risk, and
these ingredients are not accepted food-coloring agents according to
international regulatory authorities. Turmeric can also be adulterated with other Curcuma species, such as zedoary, containing
curcumin or their curcumin/volatile oil-extracted matrices; foreign starches (cassava), talc, and, more
recently, synthetic curcumin, which is intended to serve as a lower-cost substitute. These latter adulterants dilute curcumin and turmeric quality and efficacy, but do not
impact its safety. The replacement of natural curcumin with synthetic
curcumin is a deliberate practice that eludes most spectroscopic and analytical
tests. Carbon isotope measurement, requiring a sophisticated accelerator mass
spectrometer to measure 14C in the sample, is the most effective method to determine if a curcumin
material is plant-derived or of synthetic origin. With help of this analytical technology,
industry laboratories can detect samples containing synthetic curcumin in the
marketplace, a practice which is leading to legal battles and a re-definition
of turmeric adulteration practices.
Curcumin in
this document is defined as the chemical compound diferuloylmethane, or(1E,6E)-1,7-bis(4-hydroxy-3-methoxyphenyl)hepta-1,6-diene-3,5-dione.
The term curcumin is also used by members of the dietary supplement industry to
describe a turmeric extract enriched in curcuminoids at a ratio of
curcumin:demethoxycurmin:bisdemethoxycurcumin of approximately 77:17:3. To
avoid confusion, extracts enriched in curcuminoids will be indicated as
turmeric extracts.
The term
“Indian saffron” is also used for saffron (Crocus
sativus, Iridaceae) cultivated in India; the two materials should not be
confused.
The term “Curcuma rotunda” should not be confused with the scientific nameCurcuma rotundaL., which is a synonym ofBoesenbergia rotunda(L.) Mansf. (Zingiberaceae).5 References
- Nadkarni
KM, Nadkarni AK. Dr. K. M. Nadkarni's
Indian Materia Medica: with Ayurvedic, Unani-Tibbi, Siddha, Allopathic, Homeopathic,
Naturopathic & Home Remedies, app. & indexes. 3rd ed. Bombay,
India: Popular Book Depot; Popular Prakashan; 1982.
- McGuffin M, Kartesz JT, Leung AY, Tucker AO. American Herbal Products Association's Herbs
of Commerce. 2nd ed. Silver Spring, MD: American Herbal Products
Association; 2000.
- Biodiversity of India: a Wiki resource for
Indian biodiversity. 2010. Available at: http://www.biodiversityofindia.org/index.php?title=Curcuma_longa.
Accessed May 25, 2017.
- Turmeric. Spices Board of India website. 2017.
Available at: http://www.indianspices.com/spice-catalog/turmeric-1.
Accessed May 25, 2017.
- Tropicos.org. Missouri Botanical Garden
website. Available at: http://www.tropicos.org.
Accessed January 9, 2018.
- Moley T, Foster S, Awang D, Hu SY, Kartesz
JT, Tucker AO. Herbs of Commerce. 1st
ed. Austin, TX: American Herbal Products Association; 1992.
- Nguyen VD. Medicinal Plants of Vietnam, Cambodia and Laos. Santa Ana, CA:
Mekong Printing; 1993.
- Turmeric. Flora of China. Missouri Botanical
Garden & Harvard University Herbaria. Available at: http://www.efloras.org/florataxon.aspx?flora_id=2&taxon_id=200028370.
Accessed May 25, 2017.
- Zhao Z, Chen H. Yu jin. Chinese Medicinal Identification. An Illustrated Approach. Taos,
NM: Paradigm Publications; 2014.
- Mills S, Bone K. Turmeric. Principles and Practice of Phytotherapy: Modern Herbal Medicine.
Edinburgh, Scotland: Churchill Livingstone Elsevier; 2013: 900-922.
- Quisumbing EA. Medicinal Plants of the Philippines. Quezon City, Philippines:
Katha Publishing Co; 1978.
- Turmeric Flowers of India website. Available
at: http://www.flowersofindia.net/catalog/slides/Turmeric.html.
Accessed May 25, 2017.
- Williamson E. Major Herbs of Ayurveda. Churchill Livingstone; 2002.
- Lim TK. Curcuma longa. Edible Medicinal and Non-Medicinal Plants, Vol. 12. Modified Stems,
Roots, Bulbs. Cham, Switzerland. 2016: 241-362.
- Asolkar LV, Kakkar KK, Chakre OJ. Second Supplement to Glossary of Indian
Medicinal Plants with Active Principles, Part-I (A-K) (1965-1981), Dr. K.S.
Krishnan Marg, New Delhi, Pp 246-248. New Delhi, India: Publications &
Information Directorate, CSIR; 1992.
- Curcuma. The Plant List website. Available at: http://www.theplantlist.org/tpl1.1/search?q=Curcuma.
Accessed May 19, 2017.
- Engels G. Turmeric. HerbalGram. 2009;84:1-3.
- Production. Aaditya Turmeric World website. 2009;
Available at: http://turmericworld.com/production.php.
Accessed June 16, 2017.
- Plotto A. Turmeric:
Post-Production Management. Rome, Italy: Food and Agriculture Organization
of the United Nations (FAO); 2004.
- Turmeric. TNAU Agritech Portal website.
Available at: http://agritech.tnau.ac.in/banking/PDF/Tumeric.pdf.
Accessed June 16, 2017.
- Li S, Yuan W, Deng G, Wang P, Yang P, Aggarwal
B. Chemical composition and product quality control of turmeric. Pharm Crops 2011;2:28-54.
- Priyadarsini KI. The chemistry of curcumin:
from extraction to therapeutic agent. Molecules.
2014;19(12):20091-20112.
- Rafi MM. Natural curcumin of turmeric origin -
the untold story. Natural Products
Insider [White Paper]: Informa Exhibitions, LLC; 2016:1-11.
- Blumenthal M, Goldberg A, Brinckmann J, eds. Herbal Medicine: Expanded Commission E
Monographs. Austin, TX: American Botanical Council; Newton, MA: Integrative
Medicine Communications; 2000.
- Turmeric. Ottawa, ON, Canada: Natural Health
Products Directorate, Health Canada; 2010.
- Community herbal monohraph on Curcuma longa L., rhizoma. London,
United Kingdom: European Medicines Agency Committee on Herbal Medicinal
Products (HMPC); 2009:1-5.
- Tiwari M, Agrawal R, Pathak AK, Rai AK, Rai GK.
Laser-Induced breakdown spectroscopy: an approach to detect adulteration in
turmeric. Spectroscopy Lett. 2013;46(3):155-159.
- Pole S. Turmeric. Ayurvedic Medicine. The Principles of Traditional Practice. London,
United Kingdom, and Philadelphia, PA: Singing Dragon; 2013: 282-283.
- Remadevi R, Surendran E, Kimura T. Turmeric in
traditional medicine. In: Ravindran PV, Nirmal Babu K, Sivaraman K, eds. Turmeric: The Genus Curcuma. Vol 45. Boca Raton, FL: CRC Press;
2007:409-436.
- Mirzaei H, Shakeri A, Rashidi B, Jalili A,
Banikazemi Z, Sahebkar A. Phytosomal curcumin: A review of pharmacokinetic,
experimental and clinical studies. Biomed
Pharmacother. 2017;85:102-112.
- Blaschek W, Frohne D, Loew D. Curcumae longae
rhizoma. In: Blaschek W, ed. Wichtl -
Teedrogen und Phytopharmaka. Stuttgart, Germany: Wissenschaftliche
Verlagsgesellschaft mbH; 2016:210-212.
- Sen AR, Gupta PS, Dastidar NG. Detection of Curcuma zedoaria and Curcuma aromatica in Curcuma longa (turmeric) by thin-layer
chromatography. Analyst. 1974;99:153-155.
- Bailey LH. Manual
of Cultivated Plants. New York, NY: The Macmillan Company; 1949.
- Watt G. A
Dictionary of the Economical Products of India. Calcutta, India: Government
of India, Department of Revenue and Agriculture. 1889.
- Smith T, Kawa K, Eckl V. Herbal supplement
sales in US increase 7.7% in 2016. HerbalGram.
2017;115:56-65.
- Turmeric:
The Genus Curcuma. Vol. 45. Boca
Raton, FL: CRC Press; 2007.
- Dixit S, Khanna SK, Das M. A simple 2-directional
high-performance thin-layer chromatographic method for the simultaneous
determination of curcumin, metanil yellow, and Sudan dyes in turmeric, chili,
and curry powders. J AOAC Int. 2008;91(6):1387-1396.
- Mezzasalma V, Ganopoulos I, Galimberti A,
Cornara L, Ferri E, Labra M. Poisonous or non-poisonous plants? DNA-based tools
and applications for accurate identification. Int J Leg Med. 2017;131(1):1-19.
- Cowell W, Ireland T, Vorhees D, Heiger-Bernays
W. Ground turmeric as a source of lead exposure in the United States. Public Health Reports. 2017;132(3):289-293.
- Balakrishnan KV. Postharvest technology and
processing of turmeric. In: Ravindran PV, Nirmal Babu K, Sivaraman K, eds. Turmeric: The Genus Curcuma. Vol 45. Boca Raton, FL: CRC Press;
2007:193-256.
- Booker A, Frommenwiler D, Johnston D,
Umealajekwu C, Reich E, Heinrich M. Chemical variability along the value chains
of turmeric (Curcuma longa): A
comparison of nuclear magnetic resonance spectroscopy and high performance thin
layer chromatography. J Ethnopharmacol. 2014;152(2):292-301.
- Sasikumar B, Syamkumar S, Remya R, Zachariah
TJ. PCR based detection of adulteration in the market samples of turmeric
powder. Food Biotechnol. 2004;18(3):299-306.
- Dhanya K, Sasikumar B. Molecular marker based
adulteration detection in traded food and agricultural commodities of plant
origin with special reference to spices. Curr
Trends Biotechnol Pharm. 2010;4(1):454-489.
- Dixit S, Purshottam SK, Khanna SK, Das M.
Surveillance of the quality of turmeric powders from city markets of India on
the basis of curcumin content and the presence of extraneous colours. Food Addit Contam Part A. 2009;26(9):1227-1231.
- Sarkar R, Ghosh AR. Metanil yellow – an azo dye
induced histopathological and ultrastructural changes in albino rat (Rattus norvegicus). Bioscan. 2012;7(1):427-432.
- Salmén R, Fjærtoft Pedersen B, Malterud KE.
Sudanrot G als Zusatz in Gelbwurzel (Curcuma
longa L.). Z Lebensm Unters Forsch. 1987;184(1):33-34.
- Nethsingha C, Paskaranathan U. Turmeric – a literature survey. Colombo,
Sri Lanka: Ceylon Institute for Scientific and Industrial Research &
National Science Council of Sri Lanka; 1976.
- Dhanya K, Syamkumar S, Siju S, Sasikumar B.
Sequence characterized amplified region markers: A reliable tool for adulterant
detection in turmeric powder. Food Res
Int. 2011;44(9):2889-2895.
- Parvathy VA, Swetha VP, Sheeja TE, Sasikumar B.
Detection of plant-based adulterants in turmeric powder using DNA barcoding. Pharm Biol. 2015;53(12):1774-1779.
- Nath P, Sarkar K, Tarafder P, Mondal M, Das M,
Paul G. Practice of using metanil yellow as food colour to process food in
unorganized sector of West Bengal – A case study. Int Food Res J. 2015;22(4):1424-1428.
- Spices USA Inc. Issues Alert on Elevated Levels
of Lead in Ground Turmeric. U.S. Food and Drug Administration; 2016. https://www.fda.gov/Safety/Recalls/ucm523561.htm.
Accessed April 16, 2018.
- Gleason K, Shine JP, Shobnam N, et al.
Contaminated turmeric Is a potential source of lead exposure for children in
rural Bangladesh. J Environ Public
Health. 2014;2014:5.
- Mishral A. This food could be injurious to
health. Times of India. Kanpur City,
India: Bennett, Coleman & Co., Ltd.; 2010.
- Watson E. Europharma to launch probe into
synthetic vs. natural curcumin. NutraIngredients-USA
[online]: William Reed Business Media Ltd; 2011.
- Krishnakumar PK, Sanandakumar S. User
industries trade in synthetic substitutes for costly commodities. The Economic Times. February 24, 2011,
2011.
- Vijay N. Karnataka DC to examine issue of
adulterated curcumin sale by Bayir as Sami Labs takes legal action Ingredients South Asia [online].
Bengaluru, India: Saffron Media Pvt Ltd. ; 2015.
- Sabinsa takes action against synthetic curcumin
[press release]. Bangalore, India: Sabinsa Corporation2015.
- Anonymous. Sabinsa takes action against
Biotikon for synthetic curcumin adulteration. Nutraceutical Business Review [online]: HPCi Media Ltd; 2017.
- Morgan M, Mills S, Bone KM, McMillan J.
Turmeric. In: Mills S, Bone K, eds. The
Essential Guide to Herbal Safety. St. Louis, MO: Elsevier, Inc.; 2005: 609-613.
- Prevention
of Food Adulteration Act, 1954. 28 ed. Lucknow, India: Eastern Book Co;
2008.
- Khanna SK, Srivastava LP, Singh GB. Toxicity
studies on metanil yellow in rats. Environ
Res. 1978;15(2):227-231.
- Specifications for the identity and purity of
food additives and their toxicological evaluation: food colours and some antimicrobials
and antioxidants Geneva, Switzerland: Joint FAO/WHO Expert Committee on Food
Additives; 1965.
- IARC monographs on the evaluation of
carcinogenic risks to humans - overaIl evaluations of carcinogenicity: an
updating of IARC monographs volumes 1 to 42. Vol Supplement 7. Lyon, France:
International Agency for Research on Cancer (IARC); 1987.
- Lobo R, Prabhu KS, Shirwaikar A, Shirwaikar A. Curcuma zedoaria Rosc. (white turmeric):
a review of its chemical, pharmacological and ethnomedicinal properties. J Pharm Pharmacol. 2009;61(1):13-21.
- Lakshmi S, Padmaja G, Remani P. Antitumour
effects of isocurcumenol isolated from Curcuma
zedoaria rhizomes on human and murine cancer cells. Int J Med Chem. 2011;2011(253962):1-11.
- Gardner Z, McGuffin M. American Herbal Products Association’s Botanical Safety Handbook.
2nd ed. Boca Raton, FL: CRC Press; 2013.
- Cantox Health Sciences International. New Dietary Ingredient Notification for Yung
Zip Chemical's Elite Curcumin. March
2, 2006.
- Walker S. Letter from CFSAN to Cantox U.S. Inc.
College Park, MD: Center for Food Safety and Applied Nutrition; 2006:1-3.
- Eschrich W. Pulver-Atlas
der Drogen. 7th ed. Stuttgart, Germany: Deutscher Apotheker Verlag; 1999.
- Upton R, Graff A, Jolliffe G, Länger R,
Williamson E. American Herbal
Pharmacopoeia: Botanical Pharmacognosy—Microscopic Characterization of
Botanical Medicines. Boca Raton, FL: CRC Press; 2011.
- Amel B. Microscopic analysis of Curcuma longa L. using multivariate
test. Int J Pharmacognosy. 2015;2(4):173-177.
- Curcuma
longa Linn. In: Tandon N, Sharma P, Gupta AK, eds. Quality Standards of Indian Medicinal Plants. Vol 8. New Delhi,
India: Indian Council of Medical Research; 2010:138-148.
- Curcuma
aromatica Salisb. In: Tandon N, Sharma P, Gupta AK, eds. Quality Standards of Indian Medicinal
Plants. Vol 6. New Delhi, India: Indian Council of Medical Research;
2008:101-109.
- Curcuma
zedoaria (Christm.) Rose. In: Tandon N, Sharma P, Gupta AK, eds. Quality Standards of Indian Medicinal
Plants. Vol 7. New Delhi, India: Indian Council of Medical Research;
2008:67-77.
- How to test turmeric powder for quality and
avoid adulterated products? 2016; Available at: https://www.turmericforhealth.com/general-info/how-to-test-turmeric-powder-for-quality-and-avoid-adulterated-products.
Accessed May 30, 2017.
- Quick test for some adulterants in food. New
Delhi, India: Food Safety and Standards Authority of India (FSSAI); 2012:1-29.
- Raghuveer KG, Govindarajan VS. Detection of
admixtures of turmeric, Curcuma longa,
Linn., with Curcuma aromatica Salisb.
by thin layer and gas-liquid chromatography [Adulteration]. J AOAC Int. 1979;62:1333-1337.
- Turmeric rhizome (Curcuma longa). HPTLC Association. Available at: http://www.hptlc-association.org/methods.cfm.
Accessed May 30, 2017.
- Sasikumar B. Genetic resources of Curcuma: diversity, characterization and
utilization. Plant Genet Resour. 2007;3(02):230-251.
- Sólyom AM. A single laboratory validation study
for the determination of curcuminoids in dietary supplements and foods by rapid
resolution HPLC using PDA detection. Presented at: 123rd AOAC International
Annual Meeting and Exposition; 2009; Philadelphia, PA.
- Mudge E, Chan M, Venkataraman S, Brown PN. Curcuminoids
in turmeric roots and supplements: method optimization and validation. Food Anal Methods. 2016;9(5):1428-1435.
- Hong E, Lee SY, Jeong JY, et al. Modern
analytical methods for the detection of food fraud and adulteration by food
category. J Sci Food Agric. 2017;97(12):3877-3896.
- Rohman A. Analysis of curcuminoids in food and
pharmaceutical products. Int Food Res J. 2012;19(1):19-27.
- Lee JH, Choung M-G. Determination of
curcuminoid colouring principles in commercial foods by HPLC. Food Chem. 2011;124(3):1217-1222.
- Wichitnithad W, Jongaroonngamsang N, Pummangura
S, Rojsitthisak P. A simple isocratic HPLC method for the simultaneous
determination of curcuminoids in commercial turmeric extracts. Phytochem Anal. 2009;20(4):314-319.
- Jayaprakasha GK, Jagan Mohan Rao L, Sakariah
KK. Improved HPLC method for the determination of curcumin, demethoxycurcumin,
and bisdemethoxycurcumin. J Agric Food
Chem. 2002;50(13):3668-3672.
- Paramapojn S, Gritsanapan W. Free radical
scavenging activity determination and quantitative analysis of curcuminoids in Curcuma zedoaria rhizome extracts by
HPLC method Curr Sci. 2009;97(7):1069-1073.
- Avula B, Wang YH, Khan IA. Quantitative
determination of curcuminoids from the roots of Curcuma longa, Curcuma species
and dietary supplements using an UPLC-UV-MS method. J Chromatogr Sep Tech. 2012;3:120.
- Dhakal S, Chao K, Schmidt W, Qin J, Kim M, Chan
D. Evaluation of turmeric powder adulterated with metanil yellow using FT-Raman
and FT-IR spectroscopy. Foods. 2016;5(2).
- Feng F, Zhao Y, Yong W, Sun L, Jiang G, Chu X.
Highly sensitive and accurate screening of 40 dyes in soft drinks by liquid
chromatography–electrospray tandem mass spectrometry. J Chromatogr B. 2011;879(20):1813-1818.
REVISION SUMMARY
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Version 2, E. Bejar |
8/23/2019 by S. Gafner |
1.2 |
Corrected spelling errors of languages and common names |
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