A survey was made of residual free and combined or total sulfur dioxide in Thai noodles. Included were 11 samples of Keau-teo, 24 samples of Wun-sen and 9 samples of Sen-mee, which were dried noodles made of rice flour or mung bean flour. Sulfur dioxide was detected by the modified Rankin method. One sample of Keau-teo contained 136 ppm of SO2, whereas the SO2 contents of Wun-sen ranged from 0 – 157 ppm. The Sen-mee contained from 0 – 285 ppm of SO2. The total SO2 content of all Thai noodles tested was within the permissible limit of 500 ppm in Thailand. In addition, the SO2 content of noodles before and after cooking was determined using 11 samples of Wun-sen, 2 of Keau-teo and 3 of Sen-mee. The SO2 in noodles decreased about 70% during cooking.
1Ministry of Public Health, Thailand.
2National Institute of Hygienic Sciences, Japan.