This study (open access) examined how variations in δ2H and δ18O values of cooking water affect the isotopic fingerprint of noodles with different gluten-to-starch formulations.
Eight differently formulated noodles were boiled using waters with six distinct isotopic compositions ranging from of −160‰ to +50‰ for δ2H and from −22.9‰ to +99.9‰ for δ18O, respectively.
It was found that formulation and water isotopic composition significantly affected the δ2H in cooked noodles. Additionally, the δ2H values of noodles changed with the isotopic signatures of the cooking water. Conversely, δ18O in the noodles remained stable despite boiling processing and was also not changed by the water's isotopic signature.
The authors derived an equation for determining the exchange factor (f(H)ex) between noodles and cooking water. The fraction of hydrogen atoms in different noodles for exchange was highest at 19.3% in noodles with the formulation of 45:55(gluten-to-starch) and the lowest at 11.1% in noodles with 100% gluten.
The authors conclude that cooking water systematically alters the isotopic signatures of noodles, underscoring the necessity of considering this type of effect in food authentication and traceability practices.
