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This paper (open access) reviews the history and exportation of turmeric in Africa and the safety issues of some toxic adulterants.

Priority adulterants were determined from global food safety alerts. A systematic bibliographic search was performed to identify appropriate methods and techniques for authentication and safety testing. The quality of each study was assessed according to PRISMA guidelines/protocol.

The authors report that African turmeric exportation is on the rise due to recent insights into the suitability of local cultivars, soil and climate for growing high-quality turmeric. There are limited data on turmeric adulteration for domestic consumption and export markets..

Global alert databases revealed lead chromate as the top hazard identified of all adulterants. Current techniques to detect adulterants are laboratory-based, and while efficient, there is a need for more rapid, field-friendly, non-destructive analytical tools.  The authors consider that – if lead chromate is considered to be the main tisk - then pXRF would be ideally suited as a field-based test in Africa. In the hope that it could be further developed and calibrated to detect below the regulatory level of 1.5 mg/kg lead in turmeric powder. There would be a need to cross-check pXRF screening results against a validated and accredited ICP-MS method as a reliable confirmatory tool.

Photo by Md Shakil Photography on Unsplash

Adulteration is a growing food safety concern worldwide. Previous studies have implicated turmeric as a source of lead (Pb) exposure due to the addition of lead chromate (PbCrO4), a yellow pigment used to enhance brightness. This study aimed to assess the practice of adding yellow pigments to turmeric and producer- consumer- and regulatory-factors affecting this practice across the supply chain in Bangladesh.

Nine major turmeric-producing districts of Bangladesh, as well as two districts with minimal turmeric production, were identified and visited. In each district, semi-structured interviews were conducted and informal observations were made with individuals involved in the production, consumption, and regulation of turmeric. Perceptions of and preferences for turmeric quality.

Samples of yellow pigments and turmeric were collected from the most-frequented wholesale and retail markets. Samples were analysed for Pb and chromium (Cr) concentrations via inductively coupled plasma mass spectrometry and x-ray fluorescence.

The study found evidence of PbCrO4-based yellow pigment adulteration in 7 of the 9 major turmeric-producing districts.

Turmeric wholesalers reported that the practice of adding yellow pigments to dried turmeric root during polishing began more than 30 years ago and continues today, primarily driven by consumer preferences for colourful yellow curries.

The results from this study indicate that PbCrO4 is being added to turmeric by polishers, who are unaware of its neurotoxic effects, in order to satisfy wholesalers who are driven by consumer demand for yellow roots. The study recommends immediate intervention that engages turmeric producers and consumers to address this public health crisis and ensure a future with Pb-free turmeric.

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