Method For Determination Of Azodicarbonamide And Semicarbazide And Investigation Of Variation In Processing Of Flour Products

With the development of people's living standards, food industry has been rapid developed and food additives have became an indispensable materials in food processing. Wheat is one of major crops in the world. As the major product of wheat, flour has a large proportion in people's diet. People is now concerned about the problem of the use of food additives in flour. It mainly shows in two aspects: (1) Excessive additives and the use of food additives which are banned makes food safety an increasingly in doubt. (2) Eliminate nutritional deficiencies of flour, improve the use of flour enhancer of quality in people's diet.Azodicarbonamide (ADA) was early used in the production of polyethylene foam material. Recently, most of azodicarbonamide is used for food additive. Azodicarbonamide (ADA), a bleaching agent and improving agent, is a permitted food additive in certain countries and it is commonly used as a flour additive up to a maximum of 45 mg/kg in flour. ADA, as a new improving agent, can improve the physical properties and organization structure of flour products, which has widely applied overseas. In terms of treatment in the flour, it can oxidation the cysteine in wheat flour so that it can increase the tendons degree of flour and improves the amount of retaining of dough. In addition, it also can increase the elasticity and tenacity of bakery products and improves the operability and orderliness of flour.Azodicarbonamide in flour was extracted with acetone. The extract was then concentrated under nitrogen and diluted with 20 mmol/L ammonium acetate aqueous solution. After removed the lipid by hexane, it can be determined by HPLC.However, azodicarbonamide is very instability and it partially degrades with the heat of processing to form trace amounts of semicarbazide (SEM). The main conversion process is that ADA can quickly and completely convert into biurea with the condition of humidification. Biurea has the same structure with SEM, so it can convert into SEM in the condition of acidity. Semicarbazide is a known metabolite of the veterinary drug nitrofurazone and has strong carcinogenicity, teratogenicity, mutagenicity and other side effects.As semicarbazide does not be absorbed in the UV range of the spectrum, the contents of semicarbazide in azodicarbonamide-treated flour were determined by isotope dilution (¹³C, ¹⁵N₂-semicarbazide) liquid chromatography electrospray tandem mass spectrometry (LC-MS/MS). The quantification was obtained utilizing the homologous internal standard. The limits of detection were 1 mg/kg for azodicarbonamide and 0.5μg/kg for semicarbazide. The recovery rates were 87.97%¹01.4% for azodicarbonamide and 77.77%¹09.5% for semicarbazide.In addition, to better evaluate the property of semicarbazide, statistical analysis of the data indicated its variation by preparing four types of flour products. The levels of semicarbazide in all types of flour products are higher than that in flour and the levels of semicarbazide of outside of all flour products are higher than that inside.As the problem of food safety hazard aggravates daily, we should be more concerned about food security and human health.