Determination of Vanillin in Thai Hom Mali Rice Production Chain by LC-MS/MS Technique

Abstract

China is a major importer of Thai Hawm Mali rice from Thailand and earns high income for our country. However, the detection of vanillin in exported Hawm Mali rice from Thailand has been reported since April, 2021 which caused random sampling and recalled rice products. This study aims to survey and analyze vanillin concentration in Thai Hawm Mali rice samples in rice production chain from foundation seed fields, farmer fields, mills until exporters. Rice Department has developed a method for vanillin analysis referred from China (BJS 201705) using liquid chromatography tandem-mass spectrometry (LC-MS/MS) technique. The limit of quantitation (LOQ) of this measurement is 40.00 µg·kg^-1. The vanillin concentration from 223 rice samples (13 Rice research centers, 120 farmer fields, 40 mills (both paddy and white rice samples), 5 community enterprises, and 5 packaged rice samples from supermarkets) ranged from < 40.00-378.90 µg·kg^-1 and the highest content was found in a packaged Hawm Mali rice from the supermarket. However, Thai Hawm Mali foundation seeds which are physically and genetically pure seeds showed 107.46 µg·kg^-1 of vanillin while rice samples from farmer fields that only a drying process is applied showed the highest vanillin concentration at 364.57 µg·kg^-1. This can be implied that vanillin can be naturally found in Thai Hawm Mali rice, in addition, there were no peaks of ethyl vanillin and methyl vanillin which are used as synthetic vanillin markers found in any samples.