Semicarbazide universality study and its speculated formation pathway

Semicarbazide (SEM) was used as a metabolic marker to indicate the use (abuse) of the antibiotic nitrofurazone. It can be generated from azodicarbonamide and also had been observed from other unrelated sources. The purpose of this study is to evaluate the existence of SEM in different foods and conjecture the producing pathway. In this article, a LC–MS/MS method for the detection of SEM in different food products had been validated, and the limit of detection was 0.5 μg/kg. Several different sample pretreatment methods had been developed and 31 samples had been evaluated, 80.03–120.15% recoveries of the spiked samples were obtained. It was shown that SEM was detected in various foods. Different types of food might have different mechanisms for retaining SEM, and blank shrimp flesh had been chosen to further study. Several processing methods were performedand the concentration of SEM in processed shrimps was higher than that in unprocessed shrimps, and temperature, moisture, oil, may influence the formation of SEM. Meanwhile, the simulation experiment proved that SEM was produced by amino acids under high temperature. It was shown that the excessive level of SEM in shrimp was endogenous, presumably, it also can be found in rich‐protein food after processing. Practical applications This study reflected the SEM universality in different food. In previous studies where using LC–MS to detect SEM in different foods, the pretreatments of different substrate foods rarely varied, this would easily lead to experimental error and solvent waste, this study carried out sample pretreatment classification for the main components of different foods, which provided a reference for the subsequent SEM detection. In view of the endogenous SEM, the possible formation pathways of endogenous SEM were analyzed from the aspects of processing methods and amino acid compositions, providing a theoretical basis for the future study of endogenous SEM.