Subscriber access provided by EDINBURGH UNIVERSITY LIBRARY | @ http://www.lib.ed.ac.uk
Review
Review on recent DNA-based methods for main food authentication topics Karola Böhme, Pilar Calo-Mata, Jorge Barros-Velázquez, and Ignacio Ortea J. Agric. Food Chem., Just Accepted Manuscript • DOI: 10.1021/acs.jafc.8b07016 • Publication Date (Web): 22 Mar 2019 Downloaded from http://pubs.acs.org on March 24, 2019
Just Accepted “Just Accepted” manuscripts have been peer-reviewed and accepted for publication. They are posted online prior to technical editing, formatting for publication and author proofing. The American Chemical Society provides “Just Accepted” as a service to the research community to expedite the dissemination of scientific material as soon as possible after acceptance. “Just Accepted” manuscripts appear in full in PDF format accompanied by an HTML abstract. “Just Accepted” manuscripts have been fully peer reviewed, but should not be considered the official version of record. They are citable by the Digital Object Identifier (DOI®). “Just Accepted” is an optional service offered to authors. Therefore, the “Just Accepted” Web site may not include all articles that will be published in the journal. After a manuscript is technically edited and formatted, it will be removed from the “Just Accepted” Web site and published as an ASAP article. Note that technical editing may introduce minor changes to the manuscript text and/or graphics which could affect content, and all legal disclaimers and ethical guidelines that apply to the journal pertain. ACS cannot be held responsible for errors or consequences arising from the use of information contained in these “Just Accepted” manuscripts.
is published by the American Chemical Society. 1155 Sixteenth Street N.W., Washington, DC 20036 Published by American Chemical Society. Copyright © American Chemical Society. However, no copyright claim is made to original U.S. Government works, or works produced by employees of any Commonwealth realm Crown government in the course of their duties.
Page 1 of 37
Journal of Agricultural and Food Chemistry
1
Review
on
recent
2
authentication topics
DNA-based
methods
for
main
food
3 4 5
Karola Böhmea, Pilar Calo-Mataa, Jorge Barros-Velázqueza, Ignacio Orteab*
6 7
aDepartment
8
Compostela, E-27002 Lugo, Spain.
9
bProteomics
10
of Analytical Chemistry, Nutrition and Food Science, University of Santiago de
Unit, Maimonides Institute for Biomedical Research (IMIBIC), E-14004
Córdoba, Spain.
11 12
* Corresponding author:
[email protected] 13 14 15 16 17 18 19 20 21 22 23 24
ACS Paragon Plus Environment
1
Journal of Agricultural and Food Chemistry
25
Page 2 of 37
ABSTRACT
26
Adulteration and mislabeling of food products, and the commercial fraud derived, either
27
intentionally or not, is a global source of economic fraud to consumers, but also for all
28
stakeholders involved in food production and distribution. Legislation has been enforced all
29
over the world aimed at guaranteeing the authenticity of the food products all along the
30
distribution chain, therefore avoiding food fraud and adulteration. Accordingly, there is a
31
growing need for new analytical methods able to verify that all the ingredients included in a
32
foodstuff match the qualities claimed by the manufacturer or distributor. In this sense, the
33
improved performance of most recent DNA-based tools in term of sensitivity, multiplexing
34
ability, high-throughput and relatively low cost, give them a game changer role in food
35
authenticity-related topics. Here, we provide a thorough and updated vision on the recently
36
reported approaches that are applying these DNA-based tools to assess the authenticity of
37
food components and products.
38 39
KEY WORDS
40
DNA; food authentication; food fraud; foodomics; next-generation sequencing; DNA
41
barcoding; PCR.
42 43 44 45 46 47 48 49
ACS Paragon Plus Environment
2
Page 3 of 37
50
Journal of Agricultural and Food Chemistry
INTRODUCTION
51
Food adulteration, either intentionally or not, is a global source of economic fraud to
52
consumers, but also for all stakeholders involved in food production and distribution. Since
53
most counterfeiting incidents do not cause a health harm, most of them keep undetected. It is
54
estimated that food fraud imply more than 40 billion dollars of yearly loss to the food
55
industry.1,2 Furthermore, the possible introduction of non-declared ingredients that might
56
cause allergic reactions in sensitized individuals have important safety implications.3
57
Legislation has been enforced all over the world aimed at guaranteeing the authenticity of the
58
food products all along the distribution chain, therefore avoiding mislabeling and food fraud
59
and adulteration.4,5 To comply with these regulations, there is an increasing need for analytical
60
methods that allow us to verify and assure that all the ingredients included in a foodstuff match
61
the qualities and features claimed by the manufacturer or distributor.
62
A wide variety of analytical methodologies have been applied to food authentication
63
studies. Although pioneer techniques, such as liquid chromatography, electrophoretic
64
profiling, and sensory analysis are still commonly used, the addition of new DNA-related
65
techniques to the catalogue of available food assays, are surpassing limitations of those earlier
66
methodologies.6 Although enzyme-linked immunosorbent assay (ELISA) is still one of the
67
most frequently applied technique, the higher specificity, molecule stability and sensitivity
68
due to the amplification power of polymerase-chain reaction (PCR), makes DNA a perfect
69
target molecule for food authenticity purposes, allowing the detection of mislabelling and
70
food fraud even at trace levels and in processed foodstuffs.7
71
Current challenges associated with food authenticity were defined by Ortea et al.8 (Figure
72
1). The identification, detection and quantification of a certain species in a food product or
73
ingredient is the area of highest activity, but other food authentication topics such as variety
74
identification, production method, undeclared additions, component proportion and
ACS Paragon Plus Environment
3
Journal of Agricultural and Food Chemistry
Page 4 of 37
75
geographical origin have also great importance since they are a source for mislabeling and
76
commercial fraud.
77
The substitution of an animal or plant species of high commercial value by a
78
cheaper/lower-quality one is a common fraud in the food industry, including all branches from
79
meat, seafood, dairy products to food of plant origin, such as oil and juices. Accordingly,
80
elevated mislabeling levels have been continuously published: e.g. 57% in processed meat
81
products and 42.8% in fish fillets sold in Italy,9,10 up to 35% in meat products sold in US,11
82
24.4% in prawns and shrimps12 and up to 80% in dairy products.13 Meat is particularly
83
susceptible for fraudulent substitution by less valuable meat or meat coming from domestic
84
animals. In addition, the presence of rat, dog and cat meat in food products may represent
85
substantial threats to public health besides ethical reasons and has been objective of several
86
studies in the last years. Likewise, food products of plant origin, such as dietary supplements
87
and spices, are common products exposed to frauds, due to the substitution of the
88
corresponding plant species. In these cases, the mixed formulations in form of powder make
89
authentication especially challenging. Undeclared species substitution in food products might
90
also represent an important health threat to allergic consumers, related to the introduction of
91
food allergens, such as different kinds of nuts and molluscs.
92
Consequently, many of the studies published in the food authentication field are related to
93
species identification and discrimination. In this regards, developed DNA-based methods
94
have included DNA sequencing, restriction fragment length polymorphism (RFLP),
95
Randomly Amplified Polymorphic DNA (RAPD), multiplex-PCR, quantitative PCR (qPCR)
96
and Simple Sequence Repeats (SSR) or microsatellites.7,14 In the last years, new techniques
97
have started to be assessed for food authenticity purposes. New tools such as high resolution
98
melting (HRM) PCR, droplet digital PCR (ddPCR), isothermal amplification (e.g. loop-
99
mediated isothermal amplification (LAMP), recombinase polymerase amplification, strand
ACS Paragon Plus Environment
4
Page 5 of 37
Journal of Agricultural and Food Chemistry
100
displacement amplification, helicase-dependent amplification, rolling circle amplification)
101
and next-generation sequencing (NGS) are starting to show they are able to overcome the
102
performance of those prior methods in terms of specificity, sensitivity, speed and
103
multiplexing.
104
Besides species discrimination, food authenticity also requires the identification of a
105
certain animal breed or plant variety or cultivar, and the assessment of the origin of a food
106
component. Quality standards such as the Protected Designation of Origin (PDO) label
107
created by the EU, could greatly benefit from methodologies that can trace the food ingredient
108
or product to a specific geographical region. In this sense, DNA-based methods can only be
109
used when the geographic difference is related to genetic diversity, which must be studied at
110
the intra-species level, targeting many loci to achieve sufficient diversity and allowing
111
classification of the studied populations.
112
In a recent review, we compiled a broad but brief report of the proteomics, metabolomics
113
and genomics approaches used for food authentication purposes.15 Here, we offer a much
114
thorough vision focusing on the recently reported DNA-based approaches –the area of highest
115
scientific activity within the field of food authentication, including techniques recently
116
incorporated to the catalogue, but also those more classical techniques that are still used–
117
providing an updated and comprehensive overview of the recent (2014-2019) applications to
118
assess the authenticity of food components and products.
119 120
PCR AND qPCR
121
PCR has been proposed as a useful technique for the detection and identification of animal
122
and plant species in foods, because of the high sensitivity and specificity, in addition of being
123
relatively fast and not costly. Multiplexed PCR assays allow the simultaneous identification
124
of several species by using species-specific primers, and are being extensively applied to the
ACS Paragon Plus Environment
5
Journal of Agricultural and Food Chemistry
Page 6 of 37
125
detection and differentiation of the species present in food products. The exponentially
126
amplification of a target DNA molecule by use of a thermal cycler, generates up to millions
127
of copies and allows the detection of a target in a complex matrix at very low concentrations.16
128
Even though, the usefulness of the PCR assay depends to a great extent on the quality and
129
quantity of the targeted DNA. Mitochondrial DNA is often selected for sensitive qualitative
130
assays, due to its high cell copy number. In this sense, multiplex PCR assays, targeting
131
mitochondrial regions, have been developed to simultaneously detect different animal species
132
in meat, showing detection sensitivities down to 1pg DNA.17–20
133
Likewise, meat from dog, rat, rabbit and squirrel could be identified in meatballs down to
134
0,1% of adulteration.21,22 Nevertheless, since copy number per cell changes between species,
135
individuals and even tissues within the same individual, makes mitochondrial genes
136
unsuitable for quantification. Accordingly, in the cases where quantification is required to
137
assure food authenticity, nuclear genes are more appropriate.23
138
Quantitation of a certain species in a food product (e.g. animal species used in a meat
139
product) is a critical issue and common concern, since it is necessary to verify an intentional
140
or unintentional mixing, as the horse meat scandal proved.6 Accordingly, qPCR has turned
141
out to be especially convenient, being the method of choice for the quantitative assessment of
142
adulteration in mixed food products. In qPCR, nucleic acids are amplified, real-time
143
monitored and quantified by measuring the fluorescence coming from the release of a double-
144
strand DNA binding dye, measured in each PCR cycle.24 qPCR performance surpasses
145
traditional techniques in sensitivity, multiplexing, speed and cost. Since it is based on real-
146
time monitoring of the increasing number of target DNA molecules, the post-PCR processing
147
steps of conventional PCR are avoided.
148
Several works have been published, aimed at the development of qPCR assays for the
149
simultaneous detection of different animal species in game meat and the quantification of four
ACS Paragon Plus Environment
6
Page 7 of 37
Journal of Agricultural and Food Chemistry
150
deer species amount.25–28 Likewise, the presence of forbidden meat species (e.g. pork) in raw
151
and processed Halal products have been studied by qPCR.29,30 Regarding seafood, qPCR
152
systems have been recently applied to specifically detect fraud or mislabelling in tuna
153
products.31 Detection of fraud and mislabelling of dairy products has also been the aim of
154
developed multiplex qPCR assays.32–34
155
In this sense, it should be mentioned that qualitative detection of a certain species in a food
156
products can be carried out down to very low concentrations, because of the high specificity
157
of the targeted DNA regions. Nevertheless, absolute or relative quantification has some
158
limitations, mainly due to the effects of tissue composition or matrix components over the
159
PCR efficiency and precision.35
160
In some cases, qPCR assays allow estimation rather than an exact quantification of the
161
content and ratios of the different animal or plant species, as described for example in fruit
162
juices containing different ratios of mandarin and orange juice in the samples.36 Due to the
163
high sensitivity and specificity of qPCR-based approaches, their application to food
164
authenticity where traces have to be detected has been frequently described. Special efforts
165
have been made in the detection and quantification of low levels of allergens, such as
166
hazelnut.37
167
Recently, a new performance of PCR has been developed, named digital droplet PCR
168
(ddPCR). ddPCR consists on the massive partitioning of the amplification reaction into
169
nanoliter size samples which are encapsulated into oil droplets, in order to carry out one PCR
170
on each individual droplet.38 ddPCR outperforms qPCR in sensitivity and precision,
171
measuring the targeted DNA content with no need for standard curves. This technique has
172
been successfully applied to the authentication and quantitation of meat species.39
173
A main objective of research in the field of food control and authenticity is to dispose of a
174
technology that allows point-of-care food analysis. In this sense, the combination of PCR-
ACS Paragon Plus Environment
7
Journal of Agricultural and Food Chemistry
Page 8 of 37
175
based approaches with other technologies, such as microfluidics, biosensors or
176
nanotechnology gained special interest for on-site applications. Furutani et al.40 used a
177
portable qPCR system to detect beef, pork, chicken, rabbit, horse and mutton in processed
178
foods, achieving correct species identification in 20 min. Lin et al.41 reported an approach,
179
based on species-specific probes targeting the cytochrome c oxidase subunit 1 (COI) gene
180
combined with flow-through hybridisation detection, for the multiplexed identification of
181
multiple meat species. Since this assay is fast and relatively cheap, it could be suitable as a
182
routine test. Wang et al.42 described an optical thin-film biosensor test that can monitor and
183
distinguish up to eight meat species down to 0.001% by a colour change that is perceivable
184
by naked eye. An interesting methodology described by Kitpipit et al.43 allowed the detection
185
of six common meat species by PCR amplification directly on the sample, avoiding the
186
previous step of DNA extraction. In another study, an ultra-fast method based on convection
187
Palm PCR of the cyt b gene was used for meat identification, with high potential for on-site
188
applications.44 Detection of the targeted species could be carried out using either singleplex
189
or multiplex procedures in 24 minutes, since this approach avoids the need for ramping
190
between temperatures as for standard PCR, and limits down to 1% of meat adulteration and 1
191
pg DNA were achieved.
192
Taboada et al.45 developed a species-specific 4-plex PCR system coupled with detection
193
by a lateral flow dipstick (LFD) assay for the in-situ screening of two cod species, pollock
194
and ling, in seafood products. LFD proved to be particularly useful because its portability and
195
simplicity, allowing a naked-eye monitoring of the results. A similar detection multiplex PCR
196
method, in this case using gel-based detection of the amplification products, was reported to
197
differentiate between five edibe or potentially edible jellyfish species.46
198 199
Recent representative studies applying standard PCR and qPCR to food authentication are shown in Table 1.
ACS Paragon Plus Environment
8
Page 9 of 37
Journal of Agricultural and Food Chemistry
200 201
DNA BARCODING AND NEXT-GENERATION SEQUENCING
202
DNA barcoding, consisting on sequencing and comparing orthologous DNA regions for
203
taxonomic identification, has been proposed as a standardized method for species (and other
204
taxa) authentication.47 DNA barcoding, either by using conventional Sanger DNA sequencers
205
or NGS technologies, represents an important progress in food species identification and
206
traceability.48 A challenge of DNA-barcoding is the search for the “perfect” gene that presents
207
low variability within a certain taxa but also a high level of inter-species variability. Therefore,
208
the detection of a region conserved in several species can allow their identification. The most
209
targeted genes for species discrimination are COI and cytochrome b (cytb) for animal species
210
and the maturase K (matK) and carboxylase gene (rbcL) for plant species. The advantage of
211
these genes of mitochondrial and plastid DNA is the higher number of copies present in the
212
cells, making them the selected genes in most qualitative approaches, such as DNA barcoding,
213
where a high sensitivity is required to detect the corresponding species at low
214
concentrations.23
215
PCR amplification of standard-length (around 650 bp) barcodes in moderate/highly
216
processed and preserved products is challenging, due to DNA degradation. In this sense, mini-
217
barcoding approaches, focusing on shorter DNA fragments (100-200 bp), have been
218
successfully tested for the authentication of fish products achieving a 93% success rate (vs.
219
20.5% when a standard-length barcode was used).49
220
In the last years, the global project Barcode of Life Data System (BOLD) put much effort
221
to create public databases of barcodes for all species of life. Special attention is given to plant
222
species and fish and seafood, due to the high similarity in DNA sequences of closely related
223
species. In comparison to meat, diversity of edible seafood and plant species is very high and
224
discrimination between similar individuals results challenging, especially in processed food
ACS Paragon Plus Environment
9
Journal of Agricultural and Food Chemistry
Page 10 of 37
225
products. In many cases, a high percentage of mislabelling could be detected by barcode
226
analysis, being unclear if the fraud has been either intentionally or accidently, due to the high
227
similarity of the species. The Fish Barcode of Life Initiative (FISH-BOL), is a public library
228
of standardised reference sequences for all fish species, aimed at the unequivocal
229
discrimination and identification. In this sense, DNA barcoding has been successfully applied
230
to detect frauds and mislabelling in the seafood sector, including fresh, frozen and processed
231
products.50–56
232
The authenticity of food additives and supplements of plant origin is another field of raising
233
concern for consumers, highlighting the need for accurate methods to assure the quality.
234
Nevertheless, the efforts to create reference sequence libraries for plant species discrimination
235
result more challenging due to the absence of a unique barcode candidate. Recently, a number
236
of different genes have been studied as possible markers for the discrimination of plant species
237
by barcoding.57,5858 DNA barcoding has been applied to authenticity purposes in plant-related
238
food additives,59 poisonous plants,60 herbal infusions61 and spices such as tumeric.62 In a
239
similar study, small quantities of up to ten different plant oils could be detected in olive oil by
240
a DNA barcode assay together with PCR-capillary electrophoresis.63 In another study, DNA
241
barcoding succeed in detecting as low as 1% of berry fruits added to fruit juices.64
242
Plant and entomological origin of honey greatly affects its properties and quality. DNA
243
barcoding showed to be able to identify the plant origin in honey by targeting different plastid
244
regions. Up to 39 different plant species could be identified in honey samples.65 In a similar
245
study, DNA barcoding, using three different genes, provided information not only on the
246
botanical origin of honey, but also on the honeybee species producing a specific honey
247
(entomological origin).66 The authors also discussed the difficulties found when analysing
248
honeys with high content of polyphenolic compounds or subjected to crystallization.
ACS Paragon Plus Environment
10
Page 11 of 37
Journal of Agricultural and Food Chemistry
249
Recently, DNA barcoding approaches have been integrated into high-throughput
250
sequencing formats (formerly next-generation sequencing, NGS), demonstrating high
251
potential for the simultaneous identification of species of animal and plant origin in food
252
products. NGS, which has revolutionised genomic research, is able to sequence millions of
253
small DNA fragments in parallel.67 In this sense, NGS is much faster and higher throughput
254
than Sanger sequencing, since it does not require post-reaction steps and the detection is real-
255
time. The combination of DNA barcoding and pyrosequencing technologies have been
256
successfully used for the authentication of fish and seafood species68–70 and meat species71 in
257
processed food products. Likewise, the animal species of milk origin could be detected in
258
dairy products, including the detection of undeclared species and human DNA, being the latter
259
one an indicator for the hygienic level of the food products.72 Qualitative detection of the milk
260
producing species could be carried out down to very low concentrations.
261 262
HRM
263
HRM is a rapid high-throughput technique that allows genotyping and sequence matching
264
(and therefore differentiation of taxa) according to the Tm of specific DNA amplicons which
265
reflects genetic variations.73 This post-PCR method uses a fluorescence intercalating DNA
266
dye that allows monitoring dsDNA denaturing as temperature increases. Resolving power of
267
HRM relies on sequence divergence, and therefore, even a few base-pair differences alter the
268
melting curve, discrimination of species is challenging when the analysed DNA sequences
269
are very similar. HRM has succeed in the simultaneous detection of up to eight different
270
animal species in meat with 0.1 ng DNA detection limit.74 In a similar study, this time related
271
to entomological authentication of honey, honeybee species were identified by analysing
272
honey samples.75
ACS Paragon Plus Environment
11
Journal of Agricultural and Food Chemistry
Page 12 of 37
273
Another recently developed methodology is the combination of HRM with DNA
274
barcoding, termed Bar-HRM, which has proved a great potential when used for species and
275
subspecies differentiation.76 The method consists on designing HRM specific primers based
276
on the sequences derived for the barcoding markers. Bar-HRM has the advantage over DNA
277
barcoding that it allows quantitative measurements and at the same time it surpass the
278
resolving power of conventional melting curve analysis.77 Bar-HRM was reported to
279
differentiate the five most commercially-relevant shrimp species, achieving an identification
280
accuracy above 99%.78 The same methodology was applied for discriminatiing five hake
281
species, a group of highly appreciated fish which are prone to be adulterated.79 Two out of 45
282
commercial products analyzed with the developed method showed mislabeling or species
283
substitution. Adulteration of Chinese commercial sea buckthorn products, an ancient crop,
284
has also been studied by Bar-HRM.80 Five out of ten commercial products tested showed
285
either adulteration or contamination with species different from those specified in the
286
labelling. A similar mislabelling rate (e.g. 48.5%) was found when analysing commercial
287
curry powders with a Bar-HRM developed for identifying seven Zingiberaceae curry
288
species.81 The combination of HRM and DNA barcoding has also been applied to the
289
authentication of wines.82 In this study, 13 grapevine varieties could be differentiated in musts
290
and wines. This method, apart from identifying the fruit variety used, could be useful also for
291
protecting PDO wines.
292 293
LAMP
294
Recently, a nucleic acid amplification technique named LAMP, has started to be used with
295
food authentication purposes. As PCR and qPCR, LAMP detects specific DNA sequences,
296
but it can target up to eight different sequences. The LAMP method uses self-recurring strand-
ACS Paragon Plus Environment
12
Page 13 of 37
Journal of Agricultural and Food Chemistry
297
displacement DNA synthesis, replicating a target DNA at constant temperature and avoiding
298
the lengthy steps of PCR amplification.83
299
Regarding the introduction of food allergens in foodstuffs, it has been applied to the
300
quantification of peanut.84 A LAMP assay has also been used in a method for detecting the
301
addition of five vegetables not allowed in Chinese vegetarian diets (e.g. leek, several onion
302
varieties and garlic) to other plant ingredients.85 LAMP has some advantages over previous
303
techniques, such as the naked-eye result observation, although the use of intercalating
304
fluorescence dyes allows real-time tracking. Additionally, there is no need for a thermal
305
cycler, since the reaction is performed at isothermal conditions, and therefore it facilitates on-
306
site detection. The sensitivity of LAMP has been found to be higher than PCR in some
307
cases.84,85 However, real-time LAMP (qLAMP) has showed lower sensitivity than qPCR
308
when used for monitoring and quantifying gluten in wheat and corn samples (limits of
309
detection 0.0015 ng/L and 0.15 ng/L for qPCR and qLAMP, respectively).86 Regarding milk
310
adulteration, as low as 5 % addition of cow milk could be detected in buffalo milk using
311
LAMP.87
312
Regarding the assessment of halal claims, qLAMP and the combination of LAMP and
313
electrochemiluminescence (ECL) sensors, targeting pork specific DNA, have achieved
314
detection limits as low as 0.01 % of pork in beef meat and 0.1 pg/µL pork DNA content,
315
respectively.88,89 The LAMP-ECL sensor, apart from showing a high sensitivity, could be
316
incorporated into a compact, simple and rapid (around 5 min for detection) biosensor useful
317
for on-site food authentication assessment. The simultaneous detection of eight different meat
318
species has also been described by a LAMP assay.90 Regarding the development of on-site
319
applications, a specific LAMP reaction was combined with a LFD to develop a rapid testing
320
biosensor able of detecting down to 10 pg of mammalian species DNA.91
321
ACS Paragon Plus Environment
13
Journal of Agricultural and Food Chemistry
322
Page 14 of 37
CLASSICAL DNA MARKERS
323
Classical DNA markers widely used in population genetics studies, such as microsatellites,
324
RAPD, amplified fragment length polymorphism (AFLP), RFLP, sequence-characterized
325
amplified regions, and more recently, single-nucleotide polymorphisms (SNPs),
326
demonstrated to be very useful also for the authentication of food products, and several
327
reviews have appeared in the past focusing on their application to food authenticity
328
assessment.3,7,92,93 Actually, RFLP, combined to PCR, is one of the molecular-based methods
329
that are commonly available at analytical facilities for species identification in foodstuffs.
330
Nevertheless, since these techniques are generally less sensitive and selective and more
331
laborious, they became less interesting when DNA-barcoding arose. However, PCR-RFLP
332
has been widely used for the identification of the species present in seafood products, and this
333
technique is still applied. In RFLP, target DNA, after PCR amplification, is digested using
334
enzymes and the resulting restriction profiles are monitored by gel electrophoresis, so the
335
profiles of different samples can be compared.94 Five tuna species, nine different snapper
336
species and 16 commercial sea cucumber species have been recently discriminated by PCR-
337
RFLP, targeting mitochondrial regions.95–97 An RFLP approach was also used for detecting
338
as low as 0.01% cat meat content in mixtures and meatballs.98 In spite of being one of the
339
techniques most frequently used, RFLP analyses, and the other classical DNA markers, suffer
340
from an unsuitability for obtaining reliable quantitative information. Moreover, since the
341
analysis is based on fingerprint-like amplification patterns that may be compared to reference
342
samples, they are difficult to standardize.
have
343
Besides species identification, discrimination between different cultivars and varieties is
344
important in some foods of plant origin. In that sense, different cocoa and sugarcane cultivars
345
have been assessed through microsatellite markers, with the aim to differentiate varieties or
346
cultivars.99,100 Microsatellites or SSR consist on simple repeat sequences along the genome,
ACS Paragon Plus Environment
14
Page 15 of 37
Journal of Agricultural and Food Chemistry
347
characterized by a short (2-8 basepairs) DNA sequence that is repeated up to 100 times.101
348
Microsatellite markers have been used to identify local varieties of barley orzo Agordino.102
349
Microsatellites are highly polymorphic markers that have revealed useful for detecting intra-
350
population difference, such as the one produced by geographical divergence. In this regard,
351
different geographical origins of sesame seeds and oil could be discriminated using DNA
352
microsatellite markers.103
353
A SNP is a DNA sequence variation at a single position, and therefore SNP analysis allows
354
the differentiation of phylogenetically closely related specimens, having proved very useful
355
for diagnosis of human diseases.104 Since the analysis focuses on single nucleotide changes
356
instead of the whole sequences, this methodology is especially indicated for the identification
357
of very similar cultivars or breeds. In this regard, SNP genotyping on a suspension of
358
fluorescence-encoded microspheres has been used for the identification of five Greek olive
359
oil cultivars.105 Table 2 compiles recent studies that have used these classical DNA markers
360
for food authentication.
361 362
CONCLUDING REMARKS AND FUTURE TRENDS
363
Consumers, governments and the food industry demand a strict control and monitoring of
364
food labeling and authenticity, assuring food quality and safety. The analytical methods used
365
for assessing food authenticity may fulfill several requirements, apart from being accurate and
366
reliable: sensitive, due to the often low amount of target DNA, which is frequently highly
367
fragmented; highly specific, able to differentiate between DNA molecules presenting
368
minimum differences; multiplexing capability, in order to perform the identification of several
369
features in parallel in the same analysis; high-throughput and low analysis time, so many
370
samples can be analyzed in less time. In this sense, recently-developed technologies such as
371
NGS, DNA-metabarcoding, Bar-HRM, LAMP and ddPCR are surpassing classical methods.
ACS Paragon Plus Environment
15
Journal of Agricultural and Food Chemistry
Page 16 of 37
372
We anticipate that the combination of techniques such as digital PCR and LAMP with micro-
373
and nano-fluidic systems and novel nanobiosensor systems will significantly improve the
374
performance of DNA-based methodologies.106–108 Biosensors based on nanoparticles are
375
attracting great interest in the last years. Since they allow analytical platforms massively
376
parallel, portable and avoiding sample preparation (or highly reducing it), nanoparticles are
377
already being incorporated to food applications, such as the detection of allergenic and
378
toxicant compounds,109,110 and even food authentication.111 Since food samples frequently
379
contain fragmented DNA and minute concentrations, new sample preparation protocols, able
380
to deal with these trace-level DNA amount, will also be needed. In this sense, the use of
381
microfluidic devices and nanoparticles is already improving DNA recovery and extraction
382
process from complex food matrices.112,113
383
Besides advances in technologies and instrumentation, method development, validation
384
and harmonization issues have to be addressed in terms of assuring the validity of the future
385
studies, previously to the implementation of the developed methods in the industry: (i) all the
386
possible sources of variability, such as changes caused by intra-species differences or food
387
processing, should have to be controlled; (ii) power analysis should be performed to check
388
statistical validity of the results; (iii) inter-laboratory comparisons should be addressed in
389
order to guarantee that comparable analytical results are provided; (iv) certified reference
390
materials and operation procedures should be developed and made available for method
391
standardization.
392 393
REFERENCES
394
(1)
98167.pdf.
395 396
Perks, B. http://www.rsc.org/images/FightingFoodFraudWithScience_tcm18-
(2)
Johnson, R. Food fraud and “economically motivated adulteration” of food and food
ACS Paragon Plus Environment
16
Page 17 of 37
Journal of Agricultural and Food Chemistry
397
ingredients. Congressional Research Service Report 2014, R43358 (accessed March
398
14 2019).
399
(3)
Ortea, I.; Pascoal, A.; Cañas, B.; Gallardo, J. M.; Barros-Velázquez, J.; Calo-Mata, P.
400
Food Authentication of Commercially-Relevant Shrimp and Prawn Species: From
401
Classical Methods to Foodomics. Electrophoresis 2012, 33, 2201–2211.
402
(4)
U.S. Food and Drug Administration. US Federal Food, Drug, and Cosmetic Act.
403
Chapter IV: Food
404
https://www.fda.gov/regulatoryinformation/lawsenforcedbyfda/federalfooddrugandco
405
smeticactfdcact/fdcactchapterivfood/default.htm (accessed March 14, 2019).
406
(5)
European Parliament & European Council. Regulation (EC) No 178/2002 of the
407
European Parliament and of the Council of 28 January 2002 Laying down the
408
General Principles and Requirements of Food Law, Establishing the European Food
409
Safety Authority and Laying down Procedures in Matters of Food Saf. Off. J. Eur.
410
Communities 2002, 31, 1–24.
411
(6)
Salihah, N. T.; Hossain, M. M.; Lubis, H.; Ahmed, M. U. Trends and Advances in
412
Food Analysis by Real-Time Polymerase Chain Reaction. J. Food Sci. Technol. 2016,
413
53 (5), 2196–2209.
414
(7)
PCR-Based Methods. Eur. Food Res. Technol. 2007, 227 (3), 649–665.
415 416
(8)
Ortea, I.; O’Connor, G.; Maquet, A. Review on Proteomics for Food Authentication. J. Proteomics 2016, 147.
417 418
Mafra, I.; Ferreira, I. M. P. L. V. O.; Oliveira, M. B. P. P. Food Authentication by
(9)
Di Pinto, A.; Bottaro, M.; Bonerba, E.; Bozzo, G.; Ceci, E.; Marchetti, P.; Mottola,
419
A.; Tantillo, G. Occurrence of Mislabeling in Meat Products Using DNA-Based
420
Assay. J. Food Sci. Technol. 2014, 52 (4), 2479–2484.
421
(10)
Tantillo, G.; Marchetti, P.; Marchetti, P.; Mottola, A.; Mottola, A.; Terio, V.; Terio,
ACS Paragon Plus Environment
17
Journal of Agricultural and Food Chemistry
422
V.; Bottaro, M.; Bottaro, M.; Bonerba, E.; et al. Occurrence of Mislabelling in
423
Prepared Fishery Products in Southern Italy. Ital. J. Food Saf. 2015, 4 (3), 5358.
424
(11)
Page 18 of 37
Kane, D. E.; Hellberg, R. S. Identification of Species in Ground Meat Products Sold
425
on the U.S. Commercial Market Using DNA-Based Methods. Food Control 2016, 59,
426
158–163.
427
(12)
Pascoal, A.; Barros-Velázquez, J.; Cepeda, A.; Gallardo, J. M.; Calo-Mata, P. Survey
428
of the Authenticity of Prawn and Shrimp Species in Commercial Food Products by
429
PCR-RFLP Analysis of a 16S rRNA/tRNAVal Mitochondrial Region. Food Chem.
430
2008, 109 (3), 638–646.
431
(13)
Di Pinto, A.; Terio, V.; Marchetti, P.; Bottaro, M.; Mottola, A.; Bozzo, G.; Bonerba,
432
E.; Ceci, E.; Tantillo, G. DNA-Based Approach for Species Identification of Goat-
433
Milk Products. Food Chem. 2017, 229, 93–97.
434
(14)
Böhme, K.; Barros-Velázquez, J.; Calo-Mata, P.; Gallardo, J. M.; Ortea, I. Seafood
435
Authentication Using Foodomics. Genomics, Proteomics and Metabolomics in
436
Nutraceuticals and Functional Foods. John Wiley & Sons, Ltd 2015, pp 14–30.
437
(15)
Böhme, K.; Calo-Mata, P.; Barros-Velázquez, J.; Ortea, I. Recent Applications of
438
Omics-Based Technologies to Main Topics in Food Authentication. TrAC - Trends
439
Anal. Chem. 2019, 110, 221–232.
440
(16)
Saiki, R. K.; Gelfand, D. H.; Stoffel, S.; Scharf, S. J.; Higuchi, R.; Horn, G. T.;
441
Mullis, K. B.; Erlich, H. A. Primer-Directed Enzymatic Amplification of DNA with a
442
Thermostable DNA Polymerase. Science (80-. ). 1988, 239 (4839), 487–491.
443
(17)
Dai, Z.; Qiao, J.; Yang, S.; Hu, S.; Zuo, J.; Zhu, W.; Huang, C. Species
444
Authentication of Common Meat Based on PCR Analysis of the Mitochondrial COI
445
Gene. Appl. Biochem. Biotechnol. 2015, 176 (6), 1770–1780.
446
(18)
Xue, C.; Wang, P.; Zhao, J.; Xu, A.; Guan, F. Development and Validation of a
ACS Paragon Plus Environment
18
Page 19 of 37
Journal of Agricultural and Food Chemistry
447
Universal Primer Pair for the Simultaneous Detection of Eight Animal Species. Food
448
Chem. 2017, 221, 790–796.
449
(19)
Amaral, J. S.; Santos, C. G.; Melo, V. S.; Oliveira, M. B. P. P.; Mafra, I.
450
Authentication of a Traditional Game Meat Sausage (Alheira) by Species-Specific
451
PCR Assays to Detect Hare, Rabbit, Red Deer, Pork and Cow Meats. Food Res. Int.
452
2014, 60, 140–145.
453
(20)
Amaral, J. S.; Santos, C. G.; Melo, V. S.; Costa, J.; Oliveira, M. B. P. P.; Mafra, I.
454
Identification of Duck, Partridge, Pheasant, Quail, Chicken and Turkey Meats by
455
Species-Specific PCR Assays to Assess the Authenticity of Traditional Game Meat
456
Alheira Sausages. Food Control 2015, 47, 190–195.
457
(21)
Ahamad, M. N. U.; Ali, M. E.; Hossain, M. A. M.; Asing, A.; Sultana, S.; Jahurul, M.
458
H. A. Multiplex PCR Assay Discriminates Rabbit, Rat and Squirrel Meat in Food
459
Chain. Food Addit. Contam. Part A 2017, 34 (12), 2043–2057.
460
(22)
Rahman, M. M.; Ali, M. E.; Hamid, S. B. A.; Mustafa, S.; Hashim, U.; Hanapi, U. K.
461
Polymerase Chain Reaction Assay Targeting Cytochrome B Gene for the Detection
462
of Dog Meat Adulteration in Meatball Formulation. Meat Sci. 2014, 97 (4), 404–409.
463
(23)
Prado, M.; Boix, A.; von Holst, C. Novel Approach for the Simultaneous Detection
464
of DNA from Different Fish Species Based on a Nuclear Target: Quantification
465
Potential. Anal. Bioanal. Chem. 2012, 403 (10), 3041–3050.
466
(24)
Ririe, K. M.; Rasmussen, R. P.; Wittwer, C. T. Product Differentiation by Analysis of
467
DNA Melting Curves during the Polymerase Chain Reaction. Anal. Biochem. 1997,
468
245 (2), 154–160.
469
(25)
Druml, B.; Grandits, S.; Mayer, W.; Hochegger, R.; Cichna-Markl, M. Authenticity
470
Control of Game Meat Products – A Single Method to Detect and Quantify
471
Adulteration of Fallow Deer (Dama dama), Red Deer (Cervus elaphus) and Sika
ACS Paragon Plus Environment
19
Journal of Agricultural and Food Chemistry
Deer (Cervus nippon) by Real-Time PCR. Food Chem. 2015, 170, 508–517.
472 473
(26)
Druml, B.; Mayer, W.; Cichna-Markl, M.; Hochegger, R. Development and
474
Validation of a TaqMan Real-Time PCR Assay for the Identification and
475
Quantification of Roe Deer (Capreolus capreolus) in Food to Detect Food
476
Adulteration. Food Chem. 2015, 178, 319–326.
477
(27)
Kaltenbrunner, M.; Hochegger, R.; Cichna-Markl, M. Development and Validation of
478
a Fallow Deer (Dama dama)-Specific TaqMan Real-Time PCR Assay for the
479
Detection of Food Adulteration. Food Chem. 2018, 243, 82–90.
480
(28)
Kaltenbrunner, M.; Hochegger, R.; Cichna-Markl, M. Sika Deer (Cervus nippon)-
481
Specific Real-Time PCR Method to Detect Fraudulent Labelling of Meat and Meat
482
Products. Sci. Rep. 2018, 8, 7236.
483
Page 20 of 37
(29)
Karabasanavar, N. S.; Singh, S. P.; Kumar, D.; Shebannavar, S. N. Detection of Pork
484
Adulteration by Highly-Specific PCR Assay of Mitochondrial D-Loop. Food Chem.
485
2014, 145, 530–534.
486
(30)
Sakalar, E.; Ergun, S. O.; Akar, E. A Simultaneous Analytical Method for Duplex
487
Identification of Porcine and Horse in the Meat Products by EvaGreen Based Real-
488
Time PCR. Korean J. Food Sci. Anim. Resour. 2015, 35 (3), 382–388.
489
(31)
Liu, S.; Xu, K.; Wu, Z.; Xie, X.; Feng, J. Identification of Five Highly Priced Tuna
490
Species by Quantitative Real-Time Polymerase Chain Reaction. Mitochondrial DNA
491
2016, 27, 3270-3279.
492
(32)
(qxPCR) Assay for Adulteration in Dairy Products. Food Chem. 2015, 187, 58–64.
493 494
Agrimonti, C.; Pirondini, A.; Marmiroli, M.; Marmiroli, N. A Quadruplex PCR
(33)
Di Domenico, M.; Di Giuseppe, M.; Wicochea Rodríguez, J. D.; Cammà, C.
495
Validation of a Fast Real-Time PCR Method to Detect Fraud and Mislabeling in Milk
496
and Dairy Products. J. Dairy Sci. 2017, 100 (1), 106–112.
ACS Paragon Plus Environment
20
Page 21 of 37
497
Journal of Agricultural and Food Chemistry
(34)
Guo, L.; Qian, J.-P.; Guo, Y.-S.; Hai, X.; Liu, G.-Q.; Luo, J.-X.; Ya, M. Simultaneous
498
Identification of Bovine and Equine DNA in Milks and Dairy Products Inferred from
499
Triplex Taq Man Real-Time PCR Technique. J. Dairy Sci. 2018, 101 (8), 6776–
500
6786.
501
(35)
Holst, C. von; Boix, A.; Marien, A.; Prado, M. Factors Influencing the Accuracy of
502
Measurements with Real-Time PCR: The Example of the Determination of Processed
503
Animal Proteins. Food Control 2012, 24 (1–2), 142–147.
504
(36)
Aldeguer, M.; López-Andreo, M.; A. Gabaldón, J.; Puyet, A. Detection of Mandarin
505
in Orange Juice by Single-Nucleotide Polymorphism qPCR Assay. Food Chem.
506
2014, 145, 1086–1091.
507
(37)
López-Calleja, I. M.; de la Cruz, S.; Pegels, N.; González, I.; García, T.; Martín, R.
508
High Resolution TaqMan Real-Time PCR Approach to Detect Hazelnut DNA
509
Encoding for ITS rDNA in Foods. Food Chem. 2013, 141 (3), 1872–1880.
510
(38)
Baker, M. Digital PCR Hits Its Stride. Nat. Methods 2012, 9, 541–544.
511
(39)
Floren, C.; Wiedemann, I.; Brenig, B.; Schütz, E.; Beck, J. Species Identification and
512
Quantification in Meat and Meat Products Using Droplet Digital PCR (ddPCR). Food
513
Chem. 2015, 173, 1054–1058.
514
(40)
Furutani, S.; Hagihara, Y.; Nagai, H. On-Site Identification of Meat Species in
515
Processed Foods by a Rapid Real-Time Polymerase Chain Reaction System. Meat
516
Sci. 2017, 131, 56–59.
517
(41)
Lin, C. C.; Fung, L. L.; Chan, P. K.; Lee, C. M.; Chow, K. F.; Cheng, S. H. A Rapid
518
Low-Cost High-Density DNA-Based Multi-Detection Test for Routine Inspection of
519
Meat Species. Meat Sci. 2014, 96 (2), 922–929.
520 521
(42)
Wang, W.; Zhu, Y.; Chen, Y.; Xu, X.; Zhou, G. Rapid Visual Detection of Eight Meat Species Using Optical Thin-Film Biosensor Chips. J. AOAC Int. 2015, 98 (2),
ACS Paragon Plus Environment
21
Journal of Agricultural and Food Chemistry
410–414.
522 523
(43)
Kitpipit, T.; Sittichan, K.; Thanakiatkrai, P. Direct-Multiplex PCR Assay for Meat Species Identification in Food Products. Food Chem. 2014, 163, 77–82.
524 525
(44)
Song, K.-Y.; Hwang, H. J.; Kim, J. H. Ultra-Fast DNA-Based Multiplex Convection
526
PCR Method for Meat Species Identification with Possible on-Site Applications.
527
Food Chem. 2017, 229, 341–346.
528
(45)
Taboada, L.; Sánchez, A.; Pérez-Martín, R. I.; Sotelo, C. G. A New Method for the
529
Rapid Detection of Atlantic Cod (Gadus morhua), Pacific Cod (Gadus
530
macrocephalus), Alaska Pollock (Gadus chalcogrammus) and Ling (Molva molva)
531
Using a Lateral Flow Dipstick Assay. Food Chem. 2017, 233, 182–189.
532
(46)
Armani, A.; Giusti, A.; Castigliego, L.; Rossi, A.; Tinacci, L.; Gianfaldoni, D.; Guidi,
533
A. Pentaplex PCR As Screening Assay for Jellyfish Species Identification in Food
534
Products. J. Agric. Food Chem. 2014, 62 (50), 12134–12143.
535
(47)
(48)
Roslin, T.; Majaneva, S. The Use of DNA Barcodes in Food Web Construction— terrestrial and Aquatic Ecologists Unite! Genome 2016, 59 (9), 603–628.
538 539
Hebert, P. D. N.; Cywinska, A.; Ball, S. L.; DeWaard, J. R. Biological Identifications through DNA Barcodes. Proc. R. Soc. London. Ser. B Biol. Sci. 2003, 270, 313–321.
536 537
(49)
Shokralla, S.; Hellberg, R. S.; Handy, S. M.; King, I.; Hajibabaei, M. A DNA Mini-
540
Barcoding System for Authentication of Processed Fish Products. Sci. Rep. 2015, 5
541
(1).
542
(50)
Adamowicz, S. J. International Barcode of Life: Evolution of a Global Research Community. Genome 2015, 58 (5), 151–162.
543 544
Page 22 of 37
(51)
Di Pinto, A.; Di Pinto, P.; Terio, V.; Bozzo, G.; Bonerba, E.; Ceci, E.; Tantillo, G.
545
DNA Barcoding for Detecting Market Substitution in Salted Cod Fillets and Battered
546
Cod Chunks. Food Chem. 2013, 141 (3), 1757–1762.
ACS Paragon Plus Environment
22
Page 23 of 37
547
Journal of Agricultural and Food Chemistry
(52)
Di Pinto, A.; Mottola, A.; Marchetti, P.; Bottaro, M.; Terio, V.; Bozzo, G.; Bonerba,
548
E.; Ceci, E.; Tantillo, G. Packaged Frozen Fishery Products: Species Identification,
549
Mislabeling Occurrence and Legislative Implications. Food Chem. 2016, 194, 279–
550
283.
551
(53)
of Seafood Accuracy in Washington, D.C. Restaurants. PeerJ 2017, 5, e3234.
552 553
Stern, D. B.; Castro Nallar, E.; Rathod, J.; Crandall, K. A. DNA Barcoding Analysis
(54)
Piras, P.; Sardu, F.; Meloni, D.; Riina, M. V.; Beltramo, C.; Acutis, P. L. A Case
554
Study on the Labeling of Bottarga Produced in Sardinia from Ovaries of Grey
555
Mullets (Mugil cephalus and Mugil capurrii) Caught in Eastern Central Atlantic
556
Coasts. Ital. J. Food Saf. 2018, 7 (1), 6893.
557
(55)
Rath, S.; Kumar, V.; Kundu, S.; Tyagi, K.; Singha, D.; Chakraborty, R.; Chatterjee,
558
S. DNA Testing of Edible Crabs from Seafood Shops on the Odisha Coast, India.
559
Biomol. Concepts 2018, 9 (1), 12–16.
560
(56)
Paracchini, V.; Petrillo, M.; Lievens, A.; Puertas Gallardo, A.; Martinsohn, J. T.;
561
Hofherr, J.; Maquet, A.; Silva, A. P. B.; Kagkli, D. M.; Querci, M.; et al. Novel
562
Nuclear Barcode Regions for the Identification of Flatfish Species. Food Control
563
2017, 79, 297–308.
564
(57)
Pawar, R.; Handy, S.; Cheng, R.; Shyong, N.; Grundel, E. Assessment of the
565
Authenticity of Herbal Dietary Supplements: Comparison of Chemical and DNA
566
Barcoding Methods. Planta Med. 2017, 83 (11), 921–936.
567
(58)
Angers-Loustau, A.; Petrillo, M.; Paracchini, V.; Kagkli, D. M.; Rischitor, P. E.;
568
Puertas Gallardo, A.; Patak, A.; Querci, M.; Kreysa, J. Towards Plant Species
569
Identification in Complex Samples: A Bioinformatics Pipeline for the Identification
570
of Novel Nuclear Barcode Candidates. PLoS One 2016, 11 (1), e0147692.
571
(59)
Mosa, K. A.; Soliman, S.; El-Keblawy, A.; Ali, M. A.; Hassan, H. A.; Tamim, A. A.
ACS Paragon Plus Environment
23
Journal of Agricultural and Food Chemistry
Page 24 of 37
572
B.; Al-Ali, M. M. Using DNA Barcoding to Detect Adulteration in Different Herbal
573
Plant- Based Products in the United Arab Emirates: Proof of Concept and Validation.
574
Recent Pat. Food. Nutr. Agric. 2018, 9 (1), 55–64.
575
(60)
Mezzasalma, V.; Ganopoulos, I.; Galimberti, A.; Cornara, L.; Ferri, E.; Labra, M.
576
Poisonous or Non-Poisonous Plants? DNA-Based Tools and Applications for
577
Accurate Identification. Int. J. Legal Med. 2016, 131 (1), 1–19.
578
(61)
De Castro, O.; Comparone, M.; Di Maio, A.; Del Guacchio, E.; Menale, B.; Troisi, J.;
579
Aliberti, F.; Trifuoggi, M.; Guida, M. What Is in Your Cup of Tea? DNA Verity Test
580
to Characterize Black and Green Commercial Teas. PLoS One 2017, 12 (5),
581
e0178262.
582
(62)
Parvathy, V. A.; Swetha, V. P.; Sheeja, T. E.; Sasikumar, B. Detection of Plant-Based
583
Adulterants in Turmeric Powder Using DNA Barcoding. Pharm. Biol. 2015, 53 (12),
584
1774–1779.
585
(63)
Uncu, A. T.; Uncu, A. O.; Frary, A.; Doganlar, S. Barcode DNA Length
586
Polymorphisms vs Fatty Acid Profiling for Adulteration Detection in Olive Oil. Food
587
Chem. 2017, 221, 1026–1033.
588
(64)
Wu, Y.; Li, M.; Yang, Y.; Jiang, L.; Liu, M.; Wang, B.; Wang, Y. Authentication of
589
Small Berry Fruit in Fruit Products by DNA Barcoding Method. J. Food Sci. 2018,
590
83 (6), 1494–1504.
591
(65)
Bruni, I.; Galimberti, A.; Caridi, L.; Scaccabarozzi, D.; De Mattia, F.; Casiraghi, M.;
592
Labra, M. A DNA Barcoding Approach to Identify Plant Species in Multiflower
593
Honey. Food Chem. 2015, 170, 308–315.
594
(66)
Prosser, S. W. J.; Hebert, P. D. N. Rapid Identification of the Botanical and
595
Entomological Sources of Honey Using DNA Metabarcoding. Food Chem. 2017,
596
214, 183–191.
ACS Paragon Plus Environment
24
Page 25 of 37
597
Journal of Agricultural and Food Chemistry
(67)
Educ. Pract. Ed. 2013, 98 (6), 236–238.
598 599
Behjati, S.; Tarpey, P. S. What Is next Generation Sequencing? Arch. Dis. Child.
(68)
Abbadi, M.; Marciano, S.; Tosi, F.; De Battisti, C.; Panzarin, V.; Arcangeli, G.;
600
Cattoli, G. Species Identification of Bivalve Molluscs by Pyrosequencing. J. Sci.
601
Food Agric. 2016, 97 (2), 512–519.
602
(69)
De Battisti, C.; Marciano, S.; Magnabosco, C.; Busato, S.; Arcangeli, G.; Cattoli, G.
603
Pyrosequencing as a Tool for Rapid Fish Species Identification and Commercial
604
Fraud Detection. J. Agric. Food Chem. 2013, 62 (1), 198–205.
605
(70)
Giusti, A.; Armani, A.; Sotelo, C. G. Advances in the Analysis of Complex Food
606
Matrices: Species Identification in Surimi-Based Products Using Next Generation
607
Sequencing Technologies. PLoS One 2017, 12 (10), e0185586.
608
(71)
Bertolini, F.; Ghionda, M. C.; D’Alessandro, E.; Geraci, C.; Chiofalo, V.; Fontanesi,
609
L. A Next Generation Semiconductor Based Sequencing Approach for the
610
Identification of Meat Species in DNA Mixtures. PLoS One 2015, 10 (4), e0121701.
611
(72)
Ribani, A.; Schiavo, G.; Utzeri, V. J.; Bertolini, F.; Geraci, C.; Bovo, S.; Fontanesi,
612
L. Application of next Generation Semiconductor Based Sequencing for Species
613
Identification in Dairy Products. Food Chem. 2018, 246, 90–98.
614
(73)
Montgomery, J. L.; Sanford, L. N.; Wittwer, C. T. High-Resolution DNA Melting
615
Analysis in Clinical Research and Diagnostics. Expert Rev. Mol. Diagn. 2010, 10 (2),
616
219–240.
617
(74)
Lopez-Oceja, A.; Nuñez, C.; Baeta, M.; Gamarra, D.; de Pancorbo, M. M. Species
618
Identification in Meat Products: A New Screening Method Based on High Resolution
619
Melting Analysis of Cyt B Gene. Food Chem. 2017, 237, 701–706.
620 621
(75)
Soares, S.; Grazina, L.; Mafra, I.; Costa, J.; Pinto, M. A.; Duc, H. P.; Oliveira, M. B. P. P.; Amaral, J. S. Novel Diagnostic Tools for Asian (Apis cerana) and European
ACS Paragon Plus Environment
25
Journal of Agricultural and Food Chemistry
(Apis mellifera) Honey Authentication. Food Res. Int. 2018, 105, 686–693.
622 623
(76)
Jaakola, L.; Suokas, M.; Häggman, H. Novel Approaches Based on DNA Barcoding
624
and High-Resolution Melting of Amplicons for Authenticity Analyses of Berry
625
Species. Food Chem. 2010, 123 (2), 494–500.
626
Page 26 of 37
(77)
Ganopoulos, I.; Bazakos, C.; Madesis, P.; Kalaitzis, P.; Tsaftaris, A. Barcode DNA
627
High-Resolution Melting (Bar-HRM) Analysis as a Novel Close-Tubed and Accurate
628
Tool for Olive Oil Forensic Use. J. Sci. Food Agric. 2013, 93 (9), 2281–2286.
629
(78)
Fernandes, T. J. R.; Silva, C. R.; Costa, J.; Oliveira, M. B. P. P.; Mafra, I. High
630
Resolution Melting Analysis of a COI Mini-Barcode as a New Approach for
631
Penaeidae Shrimp Species Discrimination. Food Control 2017, 82, 8–17.
632
(79)
Approach for the Discrimination of Hake Species. Fish. Res. 2018, 197, 50–59.
633 634
Fernandes, T.; Costa, J.; Oliveira, M.; Mafra, I. COI Barcode-HRM as a Novel
(80)
Liu, Y.; Xiang, L.; Zhang, Y.; Lai, X.; Xiong, C.; Li, J.; Su, Y.; Sun, W.; Chen, S.
635
DNA Barcoding Based Identification of Hippophae Species and Authentication of
636
Commercial Products by High Resolution Melting Analysis. Food Chem. 2018, 242,
637
62–67.
638
(81)
Osathanunkul, M.; Ounjai, S.; Osathanunkul, R.; Madesis, P. Evaluation of a DNA-
639
Based Method for Spice/herb Authentication, so You Do Not Have to Worry about
640
What Is in Your Curry, Buon Appetito! PLoS One 2017, 12 (10), e0186283.
641
(82)
Pereira, L.; Gomes, S.; Castro, C.; Eiras-Dias, J. E.; Brazão, J.; Graça, A.; Fernandes,
642
J. R.; Martins-Lopes, P. High Resolution Melting (HRM) Applied to Wine
643
Authenticity. Food Chem. 2017, 216, 80–86.
644
(83)
Tomita, N.; Mori, Y.; Kanda, H.; Notomi, T. Loop-Mediated Isothermal
645
Amplification (LAMP) of Gene Sequences and Simple Visual Detection of Products.
646
Nat. Protoc. 2008, 3, 877–882.
ACS Paragon Plus Environment
26
Page 27 of 37
647
Journal of Agricultural and Food Chemistry
(84)
Sheu, S.-C.; Tsou, P.-C.; Lien, Y.-Y.; Lee, M.-S. Development of Loop-Mediated
648
Isothermal Amplification (LAMP) Assays for the Rapid Detection of Allergic Peanut
649
in Processed Food. Food Chem. 2018, 257, 67–74.
650
(85)
Lee, M.-S.; Su, T.-Y.; Lien, Y.-Y.; Sheu, S.-C. The Development of Loop-Mediated
651
Isothermal Amplification (LAMP) Assays for the Rapid Authentication of Five
652
Forbidden Vegetables in Strict Vegetarian Diets. Sci. Rep. 2017, 7 (1).
653
(86)
Garrido-Maestu, A.; Azinheiro, S.; Fuciños, P.; Carvalho, J.; Prado, M. Highly
654
Sensitive Detection of Gluten-Containing Cereals in Food Samples by Real-Time
655
Loop-Mediated Isothermal AMPlification (qLAMP) and Real-Time Polymerase
656
Chain Reaction (qPCR). Food Chem. 2018, 246, 156–163.
657
(87)
Deb, R.; Sengar, G. S.; Singh, U.; Kumar, S.; Alyethodi, R. R.; Alex, R.; Raja, T. V;
658
Das, A. K.; Prakash, B. Application of a Loop-Mediated Isothermal Amplification
659
Assay for Rapid Detection of Cow Components Adulterated in Buffalo Milk/Meat.
660
Mol. Biotechnol. 2016, 58 (12), 850–860.
661
(88)
Yang, L.; Fu, S.; Peng, X.; Li, L.; Song, T.; Li, L. Identification of Pork in Meat
662
Products Using Real-Time Loop-Mediated Isothermal Amplification. Biotechnol.
663
Biotechnol. Equip. 2014, 28 (5), 882–888.
664
(89)
Azam, N. F. N.; Roy, S.; Lim, S. A.; Uddin Ahmed, M. Meat Species Identification
665
Using DNA-Luminol Interaction and Their Slow Diffusion onto the Biochip Surface.
666
Food Chem. 2018, 248, 29–36.
667
(90)
Cho, A.-R.; Dong, H.-J.; Cho, S. Meat Species Identification Using Loop-Mediated
668
Isothermal Amplification Assay Targeting Species-Specific Mitochondrial DNA.
669
Korean J. Food Sci. Anim. Resour. 2014, 34 (6), 799–807.
670 671
(91)
Xu, Y.; Xiang, W.; Wang, Q.; Cheng, N.; Zhang, L.; Huang, K.; Xu, W. A Smart Sealed Nucleic Acid Biosensor Based on Endogenous Reference Gene Detection to
ACS Paragon Plus Environment
27
Journal of Agricultural and Food Chemistry
Screen and Identify Mammals on Site. Sci. Rep. 2017, 7 (1), 43453.
672 673
(92)
Rasmussen, R. S.; Morrissey, M. T. DNA-Based Methods for the Identification of
674
Commercial Fish and Seafood Species. Compr. Rev. Food Sci. Food Saf. 2008, 7,
675
280–295.
676
Page 28 of 37
(93)
Kumar, A.; Kumar, R. R.; Sharma, B. D.; Gokulakrishnan, P.; Mendiratta, S. K.;
677
Sharma, D. Identification of Species Origin of Meat and Meat Products on the DNA
678
Basis: A Review. Crit. Rev. Food Sci. Nutr. 2015, 55 (10), 1340–1351.
679
(94)
Saiki, R. K.; Scharf, S.; Faloona, F.; Mullis, K. B.; Horn, G. T.; Erlich, H. A.;
680
Arnheim, N. Enzymatic Amplification of Beta-Globin Genomic Sequences and
681
Restriction Site Analysis for Diagnosis of Sickle Cell Anemia. Science 1985, 230
682
(4732), 1350–1354.
683
(95)
Sivaraman, B.; Jeyasekaran, G.; Jeya Shakila, R.; Alamelu, V.; Wilwet, L.; Aanand,
684
S.; Sukumar, D. PCR-RFLP for Authentication of Different Species of Processed
685
Snappers Using Mitochondrial D-Loop Region by Single Enzyme. Food Control
686
2018, 90, 58–65.
687
(96)
Zeng, L.; Wen, J.; Fan, S.; Chen, Z.; Xu, Y.; Sun, Y.; Chen, D.; Zhao, J.; Xu, L.; Li,
688
Y. Identification of Sea Cucumber Species in Processed Food Products by PCR-
689
RFLP Method. Food Control 2018, 90, 166–171.
690
(97)
Abdullah, A.; Rehbein, H. The Differentiation of Tuna (Family: Scombridae)
691
Products through the PCR-Based Analysis of the Cytochrome B Gene and
692
Parvalbumin Introns. J. Sci. Food Agric. 2015, 96 (2), 456–464.
693
(98)
Ali, M. E.; Al Amin, M.; Hamid, S. B. A.; Hossain, M. A. M.; Mustafa, S. Lab-on-a-
694
Chip-Based PCR-RFLP Assay for the Confirmed Detection of Short-Length Feline
695
DNA in Food. Food Addit. Contam. Part A 2015, 32 (9), 1373–1383.
696
(99)
Herrmann, L.; Felbinger, C.; Haase, I.; Rudolph, B.; Biermann, B.; Fischer, M. Food
ACS Paragon Plus Environment
28
Page 29 of 37
Journal of Agricultural and Food Chemistry
697
Fingerprinting: Characterization of the Ecuadorean Type CCN-51 of Theobroma
698
Cacao L. Using Microsatellite Markers. J. Agric. Food Chem. 2015, 63 (18), 4539–
699
4544.
700
(100) Manechini, J. R. V.; da Costa, J. B.; Pereira, B. T.; Carlini-Garcia, L. A.; Xavier, M.
701
A.; Landell, M. G. de A.; Pinto, L. R. Unraveling the Genetic Structure of Brazilian
702
Commercial Sugarcane Cultivars through Microsatellite Markers. PLoS One 2018, 13
703
(4), e0195623.
704 705 706
(101) Kashi, Y.; King, D.; Soller, M. Simple Sequence Repeats as a Source of Quantitative Genetic Variation. Trends Genet. 1997, 13 (2), 74–78. (102) Palumbo, F.; Galla, G.; Barcaccia, G. Developing a Molecular Identification Assay of
707
Old Landraces for the Genetic Authentication of Typical Agro-Food Products: The
708
Case Study of the Barley 'Agordino'. Food Technol. Biotechnol. 2017, 55 (1), 29-39.
709
(103) Horacek, M.; Hansel-Hohl, K.; Burg, K.; Soja, G.; Okello-Anyanga, W.; Fluch, S.
710
Control of Origin of Sesame Oil from Various Countries by Stable Isotope Analysis
711
and DNA Based Markers—A Pilot Study. PLoS One 2015, 10 (4), e0123020.
712
(104) Gupta, P. K.; Roy, J. K.; Prasad, M. Single Nucleotide Polymorphisms: A New
713
Paradigm for Molecular Marker Technology and DNA Polymorphism Detection with
714
Emphasis on Their Use in Plants. Curr. Sci. 2001, 80 (4), 524–535.
715
(105) Kalogianni, D. P.; Bazakos, C.; Boutsika, L. M.; Targem, M. Ben; Christopoulos, T.
716
K.; Kalaitzis, P.; Ioannou, P. C. Olive Oil DNA Fingerprinting by Multiplex SNP
717
Genotyping on Fluorescent Microspheres. J. Agric. Food Chem. 2015, 63 (12), 3121–
718
3128.
719
(106) Wu, J.; Kodzius, R.; Cao, W.; Wen, W. Extraction, Amplification and Detection of
720
DNA in Microfluidic Chip-Based Assays. Microchim. Acta 2014, 181, 1611–1631.
721
(107) Tian, Q.; Mu, Y.; Xu, Y.; Song, Q.; Yu, B.; Ma, C.; Jin, W.; Jin, Q. An Integrated
ACS Paragon Plus Environment
29
Journal of Agricultural and Food Chemistry
Page 30 of 37
722
Microfluidic System for Bovine DNA Purification and Digital PCR Detection. Anal.
723
Biochem. 2015, 491, 55–57.
724 725 726
(108) Rane, T. D.; Chen, L.; Zec, H. C.; Wang, T. H. Microfluidic Continuous Flow Digital Loop-Mediated Isothermal Amplification (LAMP). Lab Chip 2015, 15 (3), 776–782. (109) Gómez-Arribas, L. N.; Enito-Peña, E.; Hurtado-Sánchez, M. del C.; Moreno-Bondi,
727
M. C. Biosensing Based on Nanoparticles for Food Allergens Detection. Sensors
728
(Basel) 2018, 18 (4), 1087.
729
(110) Nikoleli, G.-P.; Nikolelis, D. P.; Siontorou, C. G.; Karapetis, S.; Varzakas, T. Novel
730
Biosensors for the Rapid Detection of Toxicants in Foods. Adv. Food Nutr. Res.
731
2018, 84, 57–102.
732
(111) Valentini, P.; Galimberti, A.; Mezzasalma, V.; De Mattia, F.; Casiraghi, M.; Labra,
733
M.; Pompa, P. P. DNA Barcoding Meets Nanotechnology: Development of a
734
Universal Colorimetric Test for Food Authentication. Angew. Chemie Int. Ed. 2017,
735
56 (28), 8094–8098.
736
(112) Carvalho, J.; Puertas, G.; Gaspar, J.; Azinheiro, S.; Diéguez, L.; Garrido-Maestu, A.;
737
Vázquez, M.; Barros-Velázquez, J.; Cardoso, S.; Prado, M. Highly Efficient DNA
738
Extraction and Purification from Olive Oil on a Washable and Reusable Miniaturized
739
Device. Anal. Chim. Acta 2018, 1020, 30–40.
740
(113) Carvalho, J.; Negrinho, R.; Azinheiro, S.; Garrido-Maestu, A.; Barros-Velázquez, J.;
741
Prado, M. Novel Approach for Accurate Minute DNA Quantification on
742
Microvolumetric Solutions. Microchem. J. 2018, 138, 540–549.
743 744 745 746
ACS Paragon Plus Environment
30
Page 31 of 37
Journal of Agricultural and Food Chemistry
747
FIGURE CAPTIONS
748
Figure 1. Current challenges associated with food authenticity and main DNA-based
749
technologies that are being used to study them. Adapted from Ortea et al. (2016),
750
doi:10.1016/j.jprot.2016.06.033, available under the Creative Commons Attribution License
751
(CC BY) (https://creativecommons.org/licenses/by/4.0/). Bar-HRM, DNA barcoding high-
752
resolution melting; ddPCR, droplet digital PCR; HRM, high resolution melting; LAMP, loop-
753
mediated isothermal amplification; NGS, next-generation sequencing; PCR, polymerase
754
chain reaction; PDO, protected designation of origin; qPCR, real-time PCR; RFLP, restriction
755
fragment length polymorphism.
756
ACS Paragon Plus Environment
31
Journal of Agricultural and Food Chemistry
757
Page 32 of 37
TABLES
758 759
Table 1. Recent representative studies applying standard PCR and qPCR to food authentication Food group Meat
Purpose of analysis
Main Technique
Ref.
COI gene
17
Cyt b, COI and 12S rRNA genes
43
Duplex PCR
mtDNA sequence
18
Multiplex PCR with optical microarray biosensor
mt DNA regions
42
ddPCR
Nuclear gene
39
0.01-50% mixtures of minced cooked beef, pork, and horsemeat.
Cyt b gene
44
Raw beef, lamb, and pork meat samples from Korean markets.
PCR + specific hybridisation
COI gene
41
Meat samples from dog, dog, mouse, horse, pork, lamb and beef.
Multiplex PCR
Cyt b and ATP6 genes
21
81 reference rabbit, squirrel and rat meat samples.
Mitochondrial genes
19,20
Reference meat samples (pork, chicken, turkey, partridge, pheasant, wild duck and quail).
Binary mixtures (0.01-20%), and 18 commercial samples
0.01% addition of each of the species.
Mitochondrial D-loop region
29
34 pork meat and blood samples from local markets.
Cooked, autoclaved, and microoven cooked pork samples. Selectivity: 23 other animal species.
10 pg pig DNA; 0.1% pork content in meat mixtures.
Cyt b gene
22
Ternary mixtures and cooked meatballs, plus 10 other animal and three plant species.
Commercial meatballs (five halal brands).
0.1% (in ternary mixtures), 0.2% (in cooked meatballs) dog meat.
Multiplex PCR
Multi-species detection
Convection PCR
Discrimination of rabbit, squirrel and rat meat Authentication traditional products
Palm
of meat
Detection/quantification of pork meat adulteration Detection of dog meat adulteration
Target species and type of samples tested Reference meats of horse, beef, mutton, pork, dog, chicken and mice.
Target
Species-specific PCR assays
F2
Reference meats of chicken, beef, pork, horse, mutton and ostrich, Meat samples from eight species (goat, sheep, deer, buffalo, cattle, yak, pig and camel). Meat samples from deer, rabbit, duck, chicken, beef, horse, sheep, and pork from local Chinese supermarkets.
ACS Paragon Plus Environment
Validation
Detection limits
Binary pork-mutton meat mixtures, and processed foods 115 processed foods from Thailand markets. Specificity: 13 other animal species. 170 commercial meat products. Specificity: nine other animal species.
1 pg DNA, 0.05% (pork content in mixtures).
Five retail samples for validation. Calf liver sausages and processed meat products. Specificity 14 other species and 49 different breeds. Thermally processed samples and processed food products (ham and sausage). Specificity: 10 other mammal or bird species. 72 meatball samples. Stability: boiled, autoclaved and micro-oven cooked samples.
7 fg. 6-20 pg. 0.5 pg deer/beef DNA, 0.001% (w/w) deer/beef. 0.001%. 1 pg DNA; 1% meat adulteration. 5 pg DNA. 0.01 ng DNA in pure meat samples and 0.1% in meatballs.
32
Page 33 of 37
Journal of Agricultural and Food Chemistry
COI gene
40
Ground meat samples of beef, pork, chicken, rabbit, horse, and mutton.
Binary mixtures (chicken meat in pork) and four commercial processed foods (hamburgers, nugget, and sausage).
0.1% chicken content in a processed food.
Determination of deer content in meat products
MC1-R gene; kappa-casein precursor gene
27,28
Game meat obtained from Austrian institutions.
Mixtures, model game sausages, and processed foods. Specificity: 19 animal and 50 plant species.
0.1% (fallow deer), 0.3% (sika deer).
Detection of pork and horse meat adulteration
12S and 16S rRNA genes
30
Specificity: six different meat and six plant species.
0.0001% horse and 0.001% pork meat in model sausages.
31 commercial fish products from local markets (22.58% mislabeling found).
50 pg DNA.
Multi-species detection
Seafood
Fruit juices
Model pasteurized sausages (with beef, chicken, soybean proteins and additives) with different proportion of horse and pork meat. Two cod species (Gadus morhua, n=15, and G. macrocephallus, n=7), Pollock (n=15) and ling (n=15), 17 specimens of other fish species.
Detection of cod, Pollock and ling in seafood products
4-plex PCR + LFD
Cyt b gene
45
Identification jellyfish species fishery products
Pentaplex PCR
COI gene
46
57 jellyfish reference samples.
78 market samples.
-
qPCR
16S rRNA gene and mitochondrial control region
31
Reference samples from five appreciated tuna species (Thunnus maccoyii, T. obesus, T. albacares, T. alalunga, and Katsuwonus pelamis), and other five tuna or tuna-like species.
Mislabeling was found in 5 out of 9 commercial samples assessed.
-
32
Cow, buffalo, goat, and sheep milk and meat were used.
33
Reference cow, buffalo, sheep, and goat milks from farms.
Identification tuna species Milk and dairy products
Portable qPCR
of
of in
five
Detection of cow, buffalo, sheep, and goat milk in dairy products Detection of cow, buffalo, sheep, and goat milk in dairy products Detection of cow and horse milk in dairy products Detection of mandarine in orange juice
4-plex qPCR Cyt b and 12S rRNA genes Multiplex qPCR 3-plex qPCR
12S gene
rRNA
qPCR
trnL-trnF intergenic region
34
36
Cow milk, mare milk, yogurt, koumiss, and sour soup (n=5 each) from Mongolia. Leaves from nine orange and 13 mandarin commercial varieties, model juices from one orange and one mandarin variety.
28 commercial samples (cheeses, yogurts, creams). Sensitivity and accuracy: binary mixture cheeses. Binary mixtures and 18 commercial dairy samples (milks and cheeses). Meat samples (beef, horse, mutton, pork, chicken, duck, goose, dog, rabbit, cat, and carp). Two commercial juices.
multi-fruit
1% cow DNA in milk mixes and cheeses. 1%. 1 pg (cow milk, yogurt, mare milk); 5 pg (sour soup, koumiss). 5% mandarine in orange juice.
760
ddPCR, droplet digital polymerase chain reaction; EGF, epidermal growth factor; LFD, lateral flow dipstick; mtDNA, mitochondrial DNA; PCR,
761
polymerase chain reaction ; qPCR, real-time polymerase chain reaction.
ACS Paragon Plus Environment
33
Journal of Agricultural and Food Chemistry
762
Page 34 of 37
Table 2. Summary of the application of recent classical DNA markers to food authentication. Food group Meat
Seafood
Main Technique
Purpose of analysis Detection of adulteration
cat
meat
Differentiation snapper species
of
nine
Lab-on-a-Chip RFLP assay
RFLP assay
Differentiation of 16 sea cucumber species Differentiation of five tuna species Plant origin
Differentiation varieties
of
cocoa
Validation
Other details
Cyt b gene
98
Cat meat samples (three specimens).
Binary and ternary mixtures and meatballs. Specificity: nine other animal and seven plant species.
Detection limit: 0.01% feline meat
Mitochondrial D-loop region
95
24 specimens from each nine snapper species in several processing forms.
20 commercial samples.
16S rRNA gene
96
Parvalbumin and cyt b genes
97
Ref.
10 nuclear SSRs
99
12 SSRs
100
Identification of local varieties of Agordino barley
Seven SSR loci
102
Differentiation among different geographical origins of sesame oils
Nine nuclear and one chloroplast SSR
103
Three SNPs
105
Differentiation of Brazilian sugarcane cultivars
Oils
RFLP and SSCP assays
Target species and type of samples tested
Target
Identification of Greek olive oil cultivars
Microsatellite marker analysis
SNP genotyping by fluorescent microspheres
16 sea cucumber species (6 fresh specimens each). 27 fish samples from five Thunnus and other scombrids from Indian and Pacific Oceans. Eight CCN-51 cocoa leaf (n=8) and bean (n=2) samples, together with Arriba cocoa (n=2) and Criollo cocoa (n=2) leaf samples. 137 genotypes from 81 Brazilian commercial sugarcane cultivars and 56 germplasm accessions, leaves or leaf roll tissue. 60 samples of the Italian barley landrace Agordino, together with 35 samples from 21 other commercial varieties from the Veneto region. 38 sesame seed samples from different countries (from Europe, Africa, Asia, and America) and the oil derived from them. Monovarietal olive oil samples, leaves and fruits from five common Greek olive cultivars.
19 frozen and commercial products.
dried
Tuna fillets from Germany.
-
-
Two out of the nine species could not be distinguished. 48% mislabeling found. Differences were found between the three varieties, and even within CCN-51 samples. 285 allele markers found could distinguish the genetic cultivar and germplasm accessions.
-
-
-
-
-
-
763
cyt b, cytochrome b; DL, detection limits; RFLP, restriction fragment length polymorphism; rRNA, ribosomal RNA.; SNP, single-nucleotide
764
polymorphism; SSCP, single-strand conformation polymorphism; SSR, simple sequence repeats.
ACS Paragon Plus Environment
34
Page 35 of 37
765
Journal of Agricultural and Food Chemistry
FIGURE GRAPHICS
766 767
Figure 1.
768
769 770 771 772 773 774 775 776 777 778
ACS Paragon Plus Environment
35
Journal of Agricultural and Food Chemistry
779
Page 36 of 37
Graphic for table of contents
780 781 782 783 784
ACS Paragon Plus Environment
36
Page 37 of 37
Journal of Agricultural and Food Chemistry
qPCR Species authentication
FOOD AUTHENTICITY
Variety/cultivar identification
DNA barcoding ACS Paragon Plus Environment