The impact of flours and product storage on the thiamin content of Asian noodles

Thiamin is essential for human health and wheat foods are generally considered to be a good source of thiamin. However, dietary levels may be limited because of losses during processing. The aim of this study was to investigate the level of thiamin in a variety of wheat flour products along with the factors impacting on the thiamin content of Asian noodles particularly during storage. A standard fluorometric procedure was selected for the determination of thiamin in flours and noodle samples. White salted, yellow alkaline and instant noodles were prepared and the impact of storage conditions on thiamin levels analysed. Noodle pH appeared to be directly related to the amount of alkaline salt added and this in turn influenced the thiamin stability. The losses varied between the different styles with the greatest decreases occurring in the fresh yellow alkaline noodles. Prolonged drying at 40 °C for up to 9 days had no adverse influence on the ultimate thiamin status of these products. Storage of dried noodles for up to 4 months did not result in any further loss of thiamin. It is concluded that the potential of Asian noodles to contribute to dietary thiamin intakes appears to be limited in those where alkaline salts are included in the formulation.