{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,29]],"date-time":"2026-09-29T23:40:31Z","timestamp":1790725231009,"version":"4.1.0"},"reference-count":43,"publisher":"MDPI AG","issue":"9","license":[{"start":{"date-parts":[[2021,9,21]],"date-time":"2021-09-21T00:00:00Z","timestamp":1632182400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/100000001","name":"National Science Foundation","doi-asserted-by":"publisher","award":["1563924"],"award-info":[{"award-number":["1563924"]}],"id":[{"id":"10.13039\/100000001","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Foods"],"abstract":"<jats:p>Dyeing vegetables with harmful compounds has become an alarming public health issue over the past few years. Excessive consumption of these dyed vegetables can cause severe health hazards, including cancer. Copper sulfate, malachite green, and Sudan red are some of the non-food-grade dyes widely used on vegetables by untrusted entities in the food supply chain to make them look fresh and vibrant. In this study, the presence and quantity of dye-based adulteration in vegetables are determined by applying 1H-nuclear magnetic resonance (NMR) relaxometry. The proposed technique was validated by treating some vegetables in-house with different dyes and then soaking them in various solvents. The resulting solutions were collected and analyzed using NMR relaxometry. Specifically, the effective transverse relaxation time constant, T2,eff, of each solution was estimated using a Carr\u2013Purcell\u2013Meiboom\u2013Gill (CPMG) pulse sequence. Finally, the estimated time constants (i.e., measured signatures) were compared with a library of existing T2,eff data to detect and quantify the presence of unwanted dyes. The latter consists of data-driven models of transverse decay times for various concentrations of each water-soluble dye. The time required to analyze each sample using the proposed approach is dye-dependent but typically no longer than a few minutes. The analysis results can be used to generate warning flags if the detected dye concentrations violate widely accepted standards for food dyes. The proposed low-cost detection approach can be used in various stages of a produce supply chain, including consumer household.<\/jats:p>","DOI":"10.3390\/foods10092232","type":"journal-article","created":{"date-parts":[[2021,9,21]],"date-time":"2021-09-21T08:04:23Z","timestamp":1632211463000},"page":"2232","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":17,"title":["Detecting Dye-Contaminated Vegetables Using Low-Field NMR Relaxometry"],"prefix":"10.3390","volume":"10","author":[{"given":"Sumaiya","family":"Shomaji","sequence":"first","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Florida, 216 Larsen Hall, P.O. Box 116200, Gainesville, FL 32611, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7691-5560","authenticated-orcid":false,"given":"Naren Vikram Raj","family":"Masna","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Florida, 216 Larsen Hall, P.O. Box 116200, Gainesville, FL 32611, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"David","family":"Ariando","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Florida, 216 Larsen Hall, P.O. Box 116200, Gainesville, FL 32611, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6138-4592","authenticated-orcid":false,"given":"Shubhra","family":"Deb Paul","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Florida, 216 Larsen Hall, P.O. Box 116200, Gainesville, FL 32611, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0431-2306","authenticated-orcid":false,"given":"Kelsey","family":"Horace-Herron","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Florida, 216 Larsen Hall, P.O. Box 116200, Gainesville, FL 32611, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Domenic","family":"Forte","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Florida, 216 Larsen Hall, P.O. Box 116200, Gainesville, FL 32611, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9070-2337","authenticated-orcid":false,"given":"Soumyajit","family":"Mandal","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Florida, 216 Larsen Hall, P.O. Box 116200, Gainesville, FL 32611, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Swarup","family":"Bhunia","sequence":"additional","affiliation":[{"name":"Department of Electrical and Computer Engineering, University of Florida, 216 Larsen Hall, P.O. Box 116200, Gainesville, FL 32611, USA"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,9,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"139","DOI":"10.1002\/ajhb.22202","article-title":"What\u2019s NOT to eat\u2014food adulteration in the context of human biology","volume":"24","author":"Schell","year":"2012","journal-title":"Am. J. Hum. Biol."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"R118","DOI":"10.1111\/j.1750-3841.2012.02657.x","article-title":"Development and application of a database of food ingredient fraud and economically motivated adulteration from 1980 to 2010","volume":"77","author":"Moore","year":"2012","journal-title":"J. Food Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"1174","DOI":"10.1080\/10408398.2014.967834","article-title":"Food adulteration: Sources, health risks, and detection methods","volume":"57","author":"Bansal","year":"2017","journal-title":"Crit. Rev. Food Sci. Nutr."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1016\/j.chs.2005.01.012","article-title":"Pesticide residue in organic and conventional food-risk analysis","volume":"13","author":"Naik","year":"2006","journal-title":"J. Chem. Health Saf."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"220","DOI":"10.1179\/1077352512Z.00000000034","article-title":"Toxicology of food dyes","volume":"18","author":"Kobylewski","year":"2012","journal-title":"Int. J. Occup. Environ. Health"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"524","DOI":"10.1080\/10408398.2014.889652","article-title":"Food colors: Existing and emerging food safety concerns","volume":"57","author":"Elliott","year":"2017","journal-title":"Crit. Rev. Food Sci. Nutr."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"3877","DOI":"10.1002\/jsfa.8364","article-title":"Modern analytical methods for the detection of food fraud and adulteration by food category","volume":"97","author":"Hong","year":"2017","journal-title":"J. Sci. Food Agric."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"437","DOI":"10.1093\/jaoac\/90.2.437","article-title":"Fast cleanup method for the analysis of Sudan IIV and para red in various foods and paprika color (oleoresin) by high-performance liquid chromatography\/diode array detection: Focus on removal of fat and oil as fatty acid methyl esters prepared by transesterification of acylglycerols","volume":"90","author":"Uematsu","year":"2007","journal-title":"J. AOAC Int."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"55","DOI":"10.1016\/S0027-5107(02)00152-5","article-title":"Mutagenicity and carcinogenicity in relation to DNA adduct formation in rats fed leucomalachite green","volume":"506","author":"Culp","year":"2002","journal-title":"Mutat. Res. \/Fundam. Mol. Mech. Mutagenesis"},{"key":"ref_10","first-page":"1","article-title":"Application of nuclear magnetic resonance spectroscopy in food adulteration determination: The example of Sudan dye I in paprika powder","volume":"7","author":"Hu","year":"2017","journal-title":"Sci. Rep."},{"key":"ref_11","unstructured":"Jolene (2020, March 05). Indian Farmers Dye and Inject Vegetables To Make Them Look \u2018Fresher and Bigger. Available online: https:\/\/www.worldofbuzz.com\/indian-farmer-dye-inject-vegetables-make-look-fresh-big\/."},{"key":"ref_12","unstructured":"Julia Glotz (2020, March 05). New Copper Sulphate Scam on The Rise in Fruit & Veg Sector. Available online: https:\/\/www.thegrocer.co.uk\/food-safety\/new-copper-sulphate-scam-on-the-rise-in-fruit-and-veg-sector\/544132.article."},{"key":"ref_13","unstructured":"India Today (2020, March 05). Common Food Adulterants in India. Available online: https:\/\/www.indiatoday.in\/education-today\/gk-current-affairs\/story\/common-food-adulterants-in-india-1370601-2018-10-19."},{"key":"ref_14","unstructured":"NDTV Food (2020, March 05). Is Your Turmeric Real or Fake? Use These Smart Tricks to Find Out. Available online: https:\/\/food.ndtv.com\/food-drinks\/is-your-turmeric-real-or-fake-use-these-smart-tricks-to-find-out-1709273."},{"key":"ref_15","unstructured":"Anasazi Instruments, Inc. (2021, September 08). Cryogen Free NMR Spectrometers for Education and Industry. Available online: https:\/\/www.aiinmr.com\/."},{"key":"ref_16","unstructured":"Magritek (2021, September 08). Discover the Spinsolve Desktop NMR Spectrometer Family. Available online: https:\/\/magritek.com\/products\/spinsolve\/."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"5706","DOI":"10.1039\/c2cs35138b","article-title":"Fingerprinting food: Current technologies for the detection of food adulteration and contamination","volume":"41","author":"Ellis","year":"2012","journal-title":"Chem. Soc. Rev."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"12","DOI":"10.1109\/MCE.2018.2867969","article-title":"Eat, but verify: Low-cost portable devices for food safety analysis","volume":"8","author":"Masna","year":"2018","journal-title":"IEEE Consum. Electron. Mag."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"189","DOI":"10.1111\/1541-4337.12408","article-title":"Nuclear magnetic resonance (NMR) spectroscopy in food science: A comprehensive review","volume":"18","author":"Hatzakis","year":"2019","journal-title":"Compr. Rev. Food Sci. Food Saf."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"101684","DOI":"10.1016\/j.ssnmr.2020.101684","article-title":"A method for fast field settling in cryogen-free superconducting magnets for NMR","volume":"109","author":"Kryukov","year":"2020","journal-title":"Solid State Nucl. Magn. Reson."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Fukushima, E., and Roeder, S.B. (2018). Experimental Pulse NMR: A Nuts and Bolts Approach, CRC Press.","DOI":"10.1201\/9780429493867"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1016\/j.trac.2016.04.020","article-title":"Compact NMR relaxometry of human blood and blood components","volume":"83","author":"Cistola","year":"2016","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_23","unstructured":"(2021, September 08). NMR Relaxation. Available online: http:\/\/chem.ch.huji.ac.il\/nmr\/techniques\/other\/t1t2\/t1t2.html."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"941","DOI":"10.1070\/RC1988v057n10ABEH003403","article-title":"NMR spectroscopy of azo dyes","volume":"57","author":"Fedorov","year":"1988","journal-title":"Russ. Chem. Rev."},{"key":"ref_25","unstructured":"Allisy-Roberts, P.J., and Williams, J. (2007). Farr\u2019s Physics for Medical Imaging, Elsevier Health Sciences."},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"5","DOI":"10.1016\/j.trac.2012.02.007","article-title":"Quantitative 1H NMR spectroscopy","volume":"35","author":"Bharti","year":"2012","journal-title":"TrAC Trends Anal. Chem."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"261","DOI":"10.1006\/jmre.2001.2474","article-title":"T1\u2013T2 correlation spectra obtained using a fast two-dimensional Laplace inversion","volume":"154","author":"Song","year":"2002","journal-title":"J. Magn. Reson."},{"key":"ref_28","unstructured":"Tadepalli, S. (2021, September 08). Green Veggies Made Greener with Lethal Copper Sulphate. Available online: https:\/\/times9ofindia.indiatimes.com\/city\/hyderabad\/Green-veggies-made-greener-with-lethal-copper-sulphate\/articleshow\/48599444.cms."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1186\/1745-6673-6-34","article-title":"Complications and management of acute copper sulphate poisoning; a case discussion","volume":"6","author":"Gamakaranage","year":"2011","journal-title":"J. Occup. Med. Toxicol."},{"key":"ref_30","unstructured":"National Center for Biotechnology Information (2020, February 26). PubChem Database. Malachite Green, CID=11294, Available online: https:\/\/pubchem.ncbi.nlm.nih.gov\/compound\/Malachite-green."},{"key":"ref_31","unstructured":"National Center for Biotechnology Information (2020, February 26). PubChem Database. Sudan III, CID=62331, Available online: https:\/\/pubchem.ncbi.nlm.nih.gov\/compound\/Sudan-III."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"2566","DOI":"10.1039\/c0an00232a","article-title":"Preparation of anti-Sudan red monoclonal antibody and development of an indirect competitive enzyme-linked immunosorbent assay for detection of Sudan red in chilli jam and chilli oil","volume":"135","author":"Xu","year":"2010","journal-title":"Analyst"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"461","DOI":"10.1093\/chromsci\/43.9.461","article-title":"Simultaneous determination of Sudan dyes and carotenoids in red pepper and tomato products by HPLC","volume":"43","author":"Daood","year":"2005","journal-title":"J. Chromatogr. Sci."},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"44","DOI":"10.1016\/j.jmr.2018.06.011","article-title":"Automated classification of food products using 2D low-field NMR","volume":"294","author":"Greer","year":"2018","journal-title":"J. Magn. Reson."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"106591","DOI":"10.1016\/j.jmr.2019.106591","article-title":"An easily reproducible, hand-held, single-sided, MRI sensor","volume":"308","author":"Greer","year":"2019","journal-title":"J. Magn. Reson."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1016\/0022-2364(76)90233-X","article-title":"The signal-to-noise ratio of the nuclear magnetic resonance experiment","volume":"24","author":"Hoult","year":"1976","journal-title":"J. Magn. Reson. (1969)"},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"630","DOI":"10.1103\/PhysRev.94.630","article-title":"Effects of diffusion on free precession in nuclear magnetic resonance experiments","volume":"94","author":"Carr","year":"1954","journal-title":"Phys. Rev."},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"688","DOI":"10.1063\/1.1716296","article-title":"Modified spin-echo method for measuring nuclear relaxation times","volume":"29","author":"Meiboom","year":"1958","journal-title":"Rev. Sci. Instrum."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1038\/s41598-018-33362-6","article-title":"Application of spin-crossover water soluble nanoparticles for use as MRI contrast agents","volume":"8","author":"Tsukiashi","year":"2018","journal-title":"Sci. Rep."},{"key":"ref_40","unstructured":"(2021, September 08). T2 Relaxation. Available online: https:\/\/radiopaedia.org\/articles\/t2-relaxation."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"478","DOI":"10.1002\/mrm.1910010407","article-title":"Relaxation of solvent protons by paramagnetic ions and its dependence on magnetic field and chemical environment: Implications for NMR imaging","volume":"1","author":"Koenig","year":"1984","journal-title":"Magn. Reson. Med."},{"key":"ref_42","doi-asserted-by":"crossref","unstructured":"Kimmich, R. (2018). Field-Cycling NMR Relaxometry: Instrumentation, Model Theories and Applications, Royal Society of Chemistry.","DOI":"10.1039\/9781788012966"},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"74","DOI":"10.1016\/j.jmr.2018.12.007","article-title":"An autonomous, highly portable NMR spectrometer based on a low-cost System-on- Chip (SoC)","volume":"299","author":"Ariando","year":"2019","journal-title":"J. Magn. Reson."}],"container-title":["Foods"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2304-8158\/10\/9\/2232\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T07:02:38Z","timestamp":1760166158000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2304-8158\/10\/9\/2232"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,9,21]]},"references-count":43,"journal-issue":{"issue":"9","published-online":{"date-parts":[[2021,9]]}},"alternative-id":["foods10092232"],"URL":"https:\/\/doi.org\/10.3390\/foods10092232","relation":{},"ISSN":["2304-8158"],"issn-type":[{"value":"2304-8158","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,9,21]]}}}