Detecting Dye-Contaminated Vegetables Using Low-Field NMR Relaxometry

Abstract

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–Purcell–Meiboom–Gill (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.

Classification of Organic and Conventional Vegetables Using Machine Learning: A Case Study of Brinjal, Chili and Tomato

“…The use of dyeing agents on food items to make them look fresh and prolong the storage period was analyzed, as this practice harms individuals. 1 H NMR relaxometry [ 8 ] was deployed to determine the presence of Sudan dye, malachite green and copper sulfate on red chili, peas and okra. Homegrown vegetable samples were utilized by spraying the dyes and soaking the vegetables in different solvents.…”

Implementation of Chemometrics and Other Techniques as Means of Authenticity and Traceability to Detect Adulteration in Foods for the Protection of Human Health

“…Shomaji et al [5] reported the use of low-field 1 H-nuclear magnetic resonance (NMR) relaxometry to determine dye contamination on vegetables. It is very well known that non-food-grade dyes could be very toxic.…”

Electrochemical Sensing Platform for the Detection and Degradation Studies of Metanil Yellow

“…17 It is used to adulterate turmeric powder and Arhar Dal/Pulse (a commonly prepared dish in Indian households) to attract consumers in spite of the fact that it is not permitted by the prevention of food adulteration committee of India. 18 It is reported that the turmeric powder although is valued for its therapeutic properties, can cause serious health consequences when consumed for longer times as a result of the dye contamination. 14,15,[19][20][21] The dye causes oxidative stress in different organs of body including heart, kidney, and liver and damages the neurological systems.…”