A simple procedure for extracting and purifying sinigrin from Oriental mustard (Brassica juncea) meal using cold water was developed. Subsequently, the chemical degradation of sinigrin due to enzymatic activity was monitored using (1)H NMR spectroscopy over the course of 30 h. The experimental findings show that sinigrin has been positively identified from B. juncea using (1)H NMR spectroscopy and the prescribed preparation procedure. The results that have been presented also offer unambiguous evidence that (1)H NMR spectroscopy can be used to detect changes in sinigrin concentration over time.