The effect of pH and temperature on the degree of hydrolysis and antioxidant activity of Spirulina cell extract

BACKGROUND AND ABJECTIVEIncreasing the consumption of natural materials has increased the request for biological sources such as Spirulina. Spirulina is considered one of the healthiest foods because of its high protein content, vitamins, minerals, carotenoids, essential fatty acids antioxidants, and phycocyanin. It has high nutritional value and promising health benefits such as antioxidant, immunomodulatory, and anti-inflammatory activities that have already been explained. The aim of this study was to investigate the effects of pH and temperature on the degree of hydrolysis (DH) and potent antioxidant properties of Spirulina cell extract.MATERIALS AND METHODSFor this purpose, Zarrouk medium was used to culture Spirulina. Spirulina cells were disrupted with ultrasonication. The resulting cell extract was lyophilized. The protein value of cell extract was evaluated with the Lowry method. The degree of hydrolysis was measured by ortho-phthalaldehyde (OPA) test. The antioxidant activity was evaluated by assessing ۲,۲-diphenyl-۱-picrylhydrazy (DPPH) radical scavenging activity.RESULTS AND DISCUSSIONResults demonstrate that the degrees of hydrolysis in different hours at pH= ۸ and ۳۷oC do not differ significantly (P≤۰.۰۵). The results at pH= ۸ and ۵۵oC also showed the same results (P≤۰.۰۵). There were no statistically considerable differences in DH at different times on ۳۷oC and pH=۲. Comparing the degree of hydrolysis in different conditions (pH= ۲ and ۳۷oC, pH= ۸ and ۳۷oC, pH= ۸ and ۵۵oC) showed that the highest degree of hydrolysis was obtained at pH=۲ and ۳۷oC (۱۷.۶۵۵ ± ۰.۴۲۸). The lowest DPPH radical scavenging activity was obtained at pH= ۸ and ۵۵oC, which were not significantly different from each other. The highest DPPH radical scavenging activity was obtained at pH= ۲ and ۳۷oC (۶۵.۴۸۳ ± ۲.۵۲۱ μM TE/mg protein). The higher degree of hydrolysis obtained at pH=۲ and temperature of ۳۷oC showed more antioxidant activity than the other conditions mentioned above.CONCLUSIONThis study has demonstrated that pH= ۲ and ۳۷oC have caused Spirulina proteins are more hydrolyzed and produced bioactive peptides that have a greater ability to scavenge the DPPH radicals. It has been suggested that Spirulina cell extract is more reductant at pH= ۲ than pH= ۸ at ۳۷oC. Spirulina cell extract can be used as a functional food. They can prevent various diseases and disorders.

کلیدواژه ها:

Spirulina ، cell extract ، degree of hydrolysis ، antioxidant activity