Studies On Changes Of Biogenic Amines During The Storage And Mechanism Of Histamine Formation In Seafood

Biogenic amines (BAs) are low molecular weight nitrogenous compounds, including tyramine, putrescine, cadaverine, histamine, agmatine, spermidine and spermine. BAs are detected in many foods, and high amounts of them may cause food borne intoxication. In recent years, BAs poisoning incidents occurred many times and many countries are doing much research on BAs, especially histamine, including technology, toxicology and other relative fields, in order to control and reduce the formation of BAs. Histamine, which is considered as the most toxic BAs, has been paid more attention. Though histamine was researched in many fields, the current theory of mechanism of histamine formation cannot explain some phenomenon in foods. So, a new theory should be established. The method for determination of BAs by reversed-phase high performance liquid chromatography (HPLC) and post-column derivatization with o-Phthalaldehyde (OPA) was used to research BAs, and the law of changes, the effects of processes, the details of formation were studied in order to establish a new theory on the mechanism of histamine formation in aquatic products.1. Changes of BAs during the storage at different temperature (0℃, 4℃, 20℃) were studied in some classical seafood, such as Scomberomorus niphonius, Thunnus albacares, Paralichthys olivaceus, Penaeus chinensis, Trachypenaeus curvirostris, Eriocheir sinensis, Ruditapes variegate and Haliotis diversicolor. The formulae of BAs in the eight aquatic products at 20℃were summarized. Results show that tyramine, putrescine, cadaverine, and histamine, which are the main BAs of seafood, have great changes at different temperature. On the contrary, agmatine, spermidine and spermine have little changes at all temperature. Meanwhile, no histamine and little BAs are detected in the fresh seafood. Low-temperature can prevent the formation of biogenic amines effectively.2. Effects of different processes to BAs were studied. None of BAs was destroyed by ultrasonic, microwave and heating. The inhibition rates of ultrasound and potassium sorbate on BAs in Spanish mackerel were 45.89% and 58.36%, respectively. And the removal rates of acetic acid and pickle juice were 17.59% and 27.76%, respectively.3. Changes on physical, chemical, and microbiological aspects of Spanish mackerel were studied during the storage at 20℃and BAs bacteria were isolated and identified. From physical point of view, gradient concentrations of histamine were detected in tuna block. From chemical point of view, results showed that no histamine was formed at autolysis phase. With the increase of pH, the growth of TVBN, the sharp decline of free histadine, and the reproductions of bacteria ,histamine began to form at the corruption phase. However, only 10.42% histadine were converted to histamine, most free histadine catabolism must be mainly to other nitrogenous substances. During the process of bacteria growth, histamine was appeared at the late logarithmic phase, and increased at stationary phase. Eight histamine-forming strains were isolated by trypticase soy broth (TSB) supplemented with 1% l-histidine (TSBH) and identified as Escherichia coli (two strains), Pseudomonas fluorescens, Pasteurella pneumotropica, Brevundimonas vesicularis, Serratia fonticola, Burkholderia pseudomallei and Aeromonas salmonicida. All strains are mesophilic bacteria consisted in the environment and many conditions of bacteria growth, such as carbon, nitrogen, temperature, moisture, oxygen, can affect the formation of histamine. In conclusion, the histamine, which caused histamine poisoning, was from decarboxylation of histidine decarboxylase producted by bacteria rather than organism itself. So preventing bacterial contamination is an important method to inhibit histamine formation effectively.