Elsevier

Journal of Cereal Science

Volume 60, Issue 2, September 2014, Pages 352-355
Journal of Cereal Science

Variation in vitamin E level and aflatoxins contamination in different rice varieties

https://doi.org/10.1016/j.jcs.2014.05.012Get rights and content

Highlights

  • The contamination of aflatoxins and vitamin E level have been studied in different rice varieties.

  • The rice varieties have shown significant amount of AFs contamination.

  • The results indicated that higher the level of vitamin E content, lower the AFs contamination.

Abstract

In the present study, a total of 380 samples of 5 rice varieties were investigated for the presence of aflatoxins (AFs) and tocopherols (Vitamin E) using HPLC, equipped with a fluorescence detector. The data revealed that super basmati rice has the highest mean level of total AFs (12.45 μg/kg) followed by KS-282 (11.2 μg/kg), basmati PK-385 (9.8 μg/kg), Irri-6 (9.7 μg/kg) and the lowest mean level was found in Irri-9 (8.9 μg/kg). Furthermore, the results have shown that the variety with lowest level of AFs has the highest level of tocopherol content; i.e. Irri-9 (53.2 mg/100 g), basmati PK-385 (45.9 mg/100 g), Irri-6 (45.3 mg/100 g), KS-282 (40.4 mg/100 g) and super basmati rice (40.2 mg/100 g). The data has shown correlation (r = −0.62, p < 0.05) between vitamin E content and AFs concentration in different rice varieties. The results are interesting and need further study to investigate the mechanistic background of vitamin E content and its effect on aflatoxins contamination.

Introduction

Rice is one of the most important cereal crop, which is consumed worldwide and is the staple food for more than half of the world's population. To highlight the importance of rice, United Nations had declared 2004 as the international year of rice (US Department of State, 2003). Asian countries are the major producers as well as the major consumers of rice per capita per year. According to the FAO, the production of rice in Asia during 2012 was 650 million tonnes (FAO, 2012). Pakistan produces 9.4 million tonnes of rice and exports 3.7 million tonnes and thus brings Pakistan as one of the world's leading rice exporters (Anonymous, 2012). Rice is generally dried after harvesting. It can be an ideal substrate for mycotoxins producing fungi due to inappropriate storage conditions. Previous studies have shown that climate and storage conditions influence the fungal attack on crops and thus subsequently, the production of mycotoxins. The contamination of fungal attack on the crops may occur during field (pre-harvest) or after harvest (during storage, post-harvest). The studies have shown that various insects are also associated to distribute mycotoxigenic fungi (Cotty and Jaime-Garcia, 2007, Reiter et al., 2010).

Mycotoxins are a group of natural toxins produced as a result of fungal attack. Aflatoxins (AFs) are toxic groups of mycotoxins (Iqbal et al., 2013). AFs are produced by certain species of Aspergillus (A.) namely A. flavus and A. parasiticus (Iqbal et al., 2014). Different types of AFs are produced in nature belonging to a group called the di-furanocoumarins but only four, aflatoxin B1 (AFB1), aflatoxin B2 (AFB2), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) are naturally found in foodstuffs (Sweeney and Dobson, 1998, Iqbal et al., 2014a). AFB1 is the most toxic, potent and carcinogenic in humans (Eaton et al., 1994) and therefore, it has been classified by the International Agency for Research on Cancer (IARC) as group I carcinogenic to humans (International Agency for Research on Cancer (IARC), 1993, Iqbal et al., 2014b).

Rice has significant amounts of tocopherols (Vitamin E). It occurs in the form of eight stereoisomers, four tocopherols (α, β, γ, δ), and four tocotrienols. However, the most abundant tocols found in rice are: α-tocopherol, α-tocotrienol and γ-tocopherol (Heinemann et al., 2008). Tocopherols are recognized to show potential antioxidant activity, to reduce lipid peroxidation, display cardiovascular protective effects and anti-inflammatory properties (Pascual et al., 2013).

Previous studies have revealed the occurrence of AFs in rice and rice products from different countries (Liu et al., 2006, Mazaheri, 2009, Reiter et al., 2010, Iqbal et al., 2012, Zhu et al., 2013, Majeed et al., 2013, Ruadrew et al., 2013). However, there is no report to highlight the effect of different varieties on the contamination of AFs in rice. The present study is designed to investigate the level of AFs contamination and their correlation with the level of tocopherol content in different rice varieties. The study is innovative and focuses the attention to discover or improve the existing rice varieties and it will be helpful to introduce new rice varieties, which will be more resistant against mycotoxigenic fungi and thus subsequently avoid or reduce the level of these toxins.

Section snippets

Sampling

The unpacked samples of different rice varieties (total 380) were collected from major central areas, venders, super stores and processing mills from Sialkot, Gujrat and Hafizabad cities of Punjab, Pakistan. The rice varieties have been confirmed in the Division of Plant Protection, Nuclear Institute of Agriculture and Biology Faisalabad, Pakistan. These varieties included super basmati rice (67), basmati PK-385 (86), Irri-6 (93), Irri-9 (56) and KS-282 (78) and the majority of the samples were

Results and discussion

In the present study, the incidence and contamination of AFB1 and total AFs in different varieties of rice is presented in Table 3. The results have shown that the highest mean level of total AFs was found in super basmati rice variety, i.e. 12.45 μg/kg. The lowest mean level of total AFs was found in Irri-9 rice variety. The results have shown that AFB1 was found in highest concentration followed by AFG1; AFG2 was only found in super basmati rice variety (as shown in Fig. 1). Total aflatoxin

Conclusions

The study highlights the relationship between vitamin E level and AFs contamination in different varieties of rice. The results have shown a negative correlation between vitamin E content and AFs contamination in different rice varieties. Further studies are desirable at genetic and molecular levels to investigate the mechanistic background.

Acknowledgement

The authors are thankful for the financial assistance provided by Higher Education Commission Islamabad, Pakistan.

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