Evaluation of inhibitory activity of a polyoxometallate on polyphenol oxidase and its application in the preservation of Litopenaeus vannamei

Abstract

Objective: To design new and effective polyphenol oxidase （PPO） inhibitors and expand their application in the field of aquatic product preservation. Methods: The synthesized H8[P2Mo17Ni（OH2）O61] （P2Mo17Ni） structure was characterized by ultraviolet and infrared spectrum. The inhibitory effect, type and mechanism of P2Mo17Ni on the relative activity of mushroom PPO in vitro was clarified. Then, the preservation effects of P2Mo17Ni on Litopenaeus vannamei Boone were evaluated through studying the index change of shrimps treated with P2Mo17Ni stored at 4 ℃, in which included the sensory score, the value of chromatic aberration L*, the value of total chromatic aberration （ΔE）, the total number of colonies, the value of pH and the value of total volatile basic nitrogen （TVB-N）. Results: The results showed that P2Mo17Ni was synthesized successfully. P2Mo17Ni inhibited the activity of PPO from mushroom in vitro with semi-inhibitory concentration （IC50） of （0.377±0.004） mmol/L. P2Mo17Ni inhibited mushroom PPO in a competitive reversible manner, and the inhibition constant KI was 0.185 mmol/L. Under the cold storage condition of 4 ℃, compared with the control group, P2Mo17Ni could effectively delay the decline of sensory score and the increase of L* and ΔE value in shrimps treated with P2Mo17Ni, and the inhibitory effect was significant. P2Mo17Ni could significantly inhibit the increase of total number of colonies, pH value and TVB-N value. P2Mo17Ni could extend the shelf life of shrimps for 4~5 days. Conclusion: P2Mo17Ni can slow down the blackening of shrimps and prevent its spoilage. P2Mo17Ni possesses a good preservation effect on L. vannamei and can be used in the preservation industry of aquatic products.

Keywords

• polyoxomethoate
• polyphenol oxidase
• inhibitor
• litopenaeus vannamei boone
• preservation