Rice Science

Rice Science

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Stability of Vitamins and Minerals in Coated and Extruded Fortified Rice Kernels Stored under Real-Life Conditions over Two Years and Implications for Standards

  1. Eurofins Dr. Specht Express Testing and Inspection GmbH, Hamburg 21079, Germany; UN World Food Programme, Rome 00148, Italy; 3Eurofins Vitamin Testing Denmark, Vejen 6600, Denmark
  • Contact: Werner NADER
  • Supported by:

    This study was supported by Analysis of Fortified Rice Kernels and Fortified Rice Within A Shelf-Life Study, the United Nations World Food Programme (Grant No. HQ22NF111). We thank LT Foods Ltd. In Mandideep, India, for their continuous support of the project, in particularly mixing of fortified rice, providing storage capacity, sampling and temperature monitoring. We furthermore thank the World Food Programme for providing the funding and organisation of the project. We are also grateful to the Wright Group and DSM Nutritional Products Ltd. for providing the premix kernels.

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Abstract: Rice fortification is a cost-effective intervention to address and prevent micronutrient deficiencies in contexts where rice is a staple food. The stabilty of such added micronutrients is of critical importance, especially when rice is stored in harsh storage conditions. Coated and extruded fortified rice kernels (FRK) containing vitamins A, B1, B3, B6, B9, and B12, zinc and iron, and bulk rice fortified with these kernels were stored in different packaging materials over a period of 24 and 26 months, respectively. Blending, final packaging and storage was done in Madhya Pradesh, in central India, which experiences subtropical monsoon climate conditions. Large variations in the analytical results were observed for the fortified rice samples, mostly due to non-homogenous distribution of the FRK within the bulk rice. Consequently, to reduce analytical variation, results were correlated to the concentration of vitamin B3 as an internal standard. Vitamins B3, B6, B9, and B12, zinc and iron remained stable in both coated and extruded FRK throughout storage while vitamin B1 stability was more pronounced in coated FRK, with results consistent across packaging materials. The decay of vitamin B1 followed a zero order kinetics in extruded premix kernels stored in metallized paper bags and rice fortified with these in all packaging types, with half-lives of 20 and 34 months, respectively. Vitamin A decay followed a first order reaction in both rice fortified with coated and extruded kernels with half-lives of 6.8 and 15.1 months, respectively. In FRK, vitamin A decay was best described by mixed-order kinetics, with half-lives of 6.5 months (coated) and 5.5 months (extruded). The study informed major revisions to WFP’s fortified rice specifications, including the removal of vitamin A due to its instability during storage, while confirming the stability of B vitamins, zinc, and iron, and highlighting the critical role of blending and analytical control practices.

Key words: vitamin A, B vitamins, zinc, iron, industrial blending, coated fortified rice kernels, extruded fortified rice kernels, World Food Programme