Moulds and mycotoxins in rice from the Swedish retail market

Abstract

A survey of moulds and mycotoxins was performed on 99 rice samples taken from the Swedish retail market. The main objective was to study the mould and mycotoxin content in basmati rice and rice with a high content of fibre. Samples of jasmine rice as well as long-grain rice were also included. The samples were analysed for their content of ochratoxin A (high-performance liquid chromatography (HPLC)), aflatoxin B₁, B₂, G₁, and G₂ (HPLC, RIDA®QUICK), and mould (traditional cultivation methods in combination with morphological analysis). The majority of samples were sampled according to European Commission Regulation 401/2006. Subsamples were pooled and mixed before milling and both mould and mycotoxin analyses were performed on milled rice. The results showed that the majority of basmati rice (71%) and many jasmine rice samples (20%) contained detectable levels of aflatoxin B₁ (level of quantification = 0.1 µg aflatoxin kg⁻¹ rice). Two samples of jasmine rice and ten basmati rice samples contained levels over the regulated European maximum limits of 2 µg kg⁻¹ for aflatoxin B₁ or 4 µg kg⁻¹ for total aflatoxins. Aspergillus was the most common mould genus isolated, but also Penicillium, Eurotium, Wallemia, Cladosporium, Epicoccum, Alternaria, and Trichotecium were found. The presence of Aspergillus flavus in 21% of the samples indicates that incorrect management of rice during production and storage implies a risk of mould growth and subsequent production of aflatoxin. Rough estimates showed that high rice consumers may have an intake of 2–3 ng aflatoxin kg⁻¹ bodyweight and day⁻¹ from rice alone. This survey shows that aflatoxin is a common contaminant in rice imported to Europe.

Keywords:

• basmati rice
• aflatoxin
• ochratoxin A
• jasmine rice
• retail
• Aspergillus flavus
• mould

Acknowledgement

The authors acknowledge Food Diagnostics, Gothenburg, Sweden, for good collaboration on the RIDA®QUICK Aflatoxin kit from R-Biopharm AG.