Preparation process optimisation, structural characterisation and stability analysis of sika deer blood–selenium chelate

Abstract

Context Selenium deficiency occurs all over the world. Therefore, the research and development of selenium supplements has been a focus for relevant scholars. Organic selenium is safer and more efficient than is inorganic selenium. In fact, China’s sika deer resources are of high quality, but the utilisation rate of deer blood is very low. Research has found that deer blood is a reasonable peptide source for the preparation of selenium-chelate supplements. The abundance of deer blood resources provided conditions for this study. Aim To provide new selenium supplements for humans, and further develop and utilise China’s sika deer industry, which to some extent also improves the utilisation rate of deer blood resources. Methods Peptides were hydrolysed by protease, and the best hydrolysates were screened. Single-factor experiments and response-surface methodology were used to study the effects of pH, temperature, time and peptide:selenium mass ratio on selenium-chelating activity. The sika deer blood polypeptide–selenium was characterised and analysed through ultraviolet spectrum, infrared spectrum, amino acid analysis, molecular-weight determination, scanning electron microscopy, and particle-size and potential analysis. Also, thermal-stability and acid–base-stability tests were conducted. Key results The chelating activity of alkaline protease hydrolysate was the highest, being 73.1 ± 0.16%. The pH value, temperature, time and peptide:selenium mass ratio had influence on selenium-chelating activity. Because of the cross-linking of selenium ions, the chelated selenium aggregates into larger particles with a more compact structure. The determination of amino acid and molecular weight showed that the metal-chelating activity of small-molecular peptides was very strong. Glutamic acid (Glu) and aspartic acid (Asp) play an important role in the binding of selenium ions. At the same time, the chelated SDBP–selenium had acid–base stability and thermal stability. Conclusion Studies depicted that SDBP–selenium is suitable as a new type of selenium supplement. Implications The preparation of deer blood polypeptide-chelated selenium provides a scientific basis for the development of new selenium supplements and the practical application of deer blood resources.