Analysis of glyoxal, methylglyoxal and diacetyl in soy sauce

In this study, an analytical method for the determination of alpha-dicarbonyl compounds (alpha-DCs), including glyoxal (GO), methylglyoxal (MGO) and diacetyl (DA), in soy sauce was validated using gas chromatography-nitrogen-phosphorus detection. Through Maillard reaction various alpha-DCs, including GO, MGO and DA have been found in fermented food, dairy products and beverages. The analysis of alpha-DC was carried out by a derivatisation with o-phenylenediamine. The limit of detection and limit of quantitation were 0.04 and 0.12 mu g/kg for GO, 0.04 and 0.13 mu g/kg for MGO, and 0.07 and 0.22 mu g/kg for DA. The intra- and inter-day accuracy ranged from 92.8 to 109% for GO, from 99.5 to 113% for MGO and from 93.6 to 102% for DA. The intra- and inter-day precision ranged from 3.38 to 12.1% for GO, from 0.67 to 7.65% for MGO and from 1.27 to 9.35% for DA. In 20 commercial soy sauces, alpha-DCs were found in concentration ranges of 5.60-31.7 mu g/mL for GO, 14.4-116 mu g/mL for MGO and 0.47-5.48 mu g/mL for DA. The developed analytical method could be applied for the determination of alpha-DCs in soy sauce and motivate investigations related to reducing the content of alpha-DCs in soy sauce.

Automated summary

This study validated an analytical method for determining alpha-dicarbonyl compounds (alpha-DCs) in soy sauce and found various alpha-DCs, including GO, MGO, and DA, in fermented foods. The developed method successfully analyzed the concentration ranges of alpha-DCs in 20 commercial soy sauces, indicating potential for further investigations on reducing alpha-DC content in soy sauce.