ABSTRACT: 

Rice was the staple food for global population. Southeast Asia is one of the main rice producers to supply the global demand. With increasing consumption of rice for the last ten years, deoxynivalenol (DON), aflatoxin B1 (AFB1), ochratoxin A (OTA), fumonisin B1 (FB1) and zearalenone (ZEA) were mycotoxins that can be contaminated in rice. In this study, an analytical method for simultaneous determination of six regulated mycotoxins (DON, AFB1, OTA, FB1, ZEA and T-2 toxin (T-2)) in rice was developed using dilute and shoot (DnS) approach followed by LC-QQQ-MS/MS detection. Methanol:water (70:30, v/v) acidified with acetic acid (pH3) was the optimal solvent for extraction of mycotoxins in rice. Analytical performance was validated giving acceptable recovery (73% – 118%) and precision (2.1% – 11.3%) with LOD and LOQ ranging from 0.1 – 1 ng/g and 0.5 – 10 ng/g, respectively. The developed method was successfully applied for occurrence analysis of 282 rice samples. The rice samples were collected from both Thailand and Cambodia with different varieties, processing types and geographical regions. Result revealed that, 38 of 282 samples showed positive for at least one of these mycotoxins (DON, AFB1, FB1, T-2, and OTA). FB1 was the most frequently found in rice samples (36 of 282 samples, 12.77%) with a concentration range of 5.96–74.94 ng/g. However, there were no samples exceeding the maximum regulatory limits (1,000 ng/g) for FB1 in cereal intended for direct human consumption according to the European Commission. On the other hands, AFB1 was detected in 5 of 282 samples (1.77 %) with exceeding the maximum regulatory limits (2 ng/g) for AFB1 in rice according to the European Commission. Focusing on positive samples, Riceberry (35.71%) and RD6 (19.12%) showed the highest incidence of mycotoxins contamination compared to other rice varieties. Among the geographical regions, rice samples cultivated from South region (25.71%) was more susceptible to mycotoxins contamination than those from North, Central and Northeast regions, implying that high humidity might be a key factor for the fungal growth leading to enhance the mycotoxin contamination. Interestingly, the positive rate of mycotoxin contamination in white rice (3.23%) was significantly lower than that in brown rice (24.41%), suggesting that a polishing process could reduce the mycotoxin contamination. These findings pinpointed the effect of variety, geographical region and processing type on the occurrence of mycotoxins contamination in rice, which could be further applied to agricultural practice as well as for risk assessment. 

Abbreviated title: Multiple mycotoxins detection method in rice 

KEYWORDS: Mycotoxins contamination, occurrences, multi-mycotoxin analysis, processing type, rice variety