Analytical Control of the Total Volatile Bases Nitrogen in Fish Products

Abstract

Comparative studies of the content of total nitrogen of volatile bases (ALO) in fish raw materials, as an objective indicator of quality, were carried out by direct distillation of the sample and by distillation of acid extract. It was found that the method based on direct distillation of the sample results in 25-30% higher values than the method of acid extract distillation due to alkaline hydrolysis of the sample protein. A comparison of the reproducibility of the two methods using the Fisher statistical criterion showed the heterogeneity of the variances and the impossibility of attributing them to a single general population. For the gradation of the quality of fish raw materials, the method of distilling acid extract is recommended. The objects of three different categories are studied, grouped according to the proposed three degrees of quality, based on the maximum permissible levels of nitrogen content of volatile bases. The reliability of the results is shown and a conclusion is made about the use of the ALO content as an indicator characterizing both the initial state of fish raw materials and the dynamics of the storage process and the establishment of the moment of spoilage. A method for measuring the mass fraction of total nitrogen of volatile bases has been developed and certified (certificate of certification No. 0168/ROSS RU.0001.310430/2020).