Effect of mango seed kernel extract on polyphenol oxidase inhibition and shelf life of shrimp during iced storage

Abstract

The effects were examined of mango seed kernel extract (MSKE) on the inhibition of polyphenol oxidase (PPO) activity and the quality of white shrimp during iced storage for 12 d. The molecular weight of PPO from the Pacific white shrimp (Litopenaeus vannamei) cephalothorax was 220 kDa. PPO activity from the shrimp was inhibited in a dose-dependent manner by MSKE. The effective final concentration of MSKE which inhibited the PPO activity by 90% was 5,000 mg/kg. Immersion in MSKE solution could appreciably retard the melanosis score of the shrimp (p < 0.05). The shrimp immersed in MSKE solution at 1,000 mg/kg and 5,000 mg/kg had significantly (p < 0.05) lower values for total volatile basic nitrogen and thiobarbituric acid reactive substances (57.43±1.28 to 57.99±2.70 mg N/100 g sample and 0.98±0.11 to 1.22±0.05 mg malanoaldehyde/kg sample, respectively) compared with the control (79.64±2.79 mg N/100 g sample and 1.38±0.11 mg malanoaldehyde/kg sample, respectively) at the 12 d. The shrimps treated with MSKE had lower psychrophilic bacterial counts than the control throughout the 12 d of iced storage. Thus, MSKE has potential to be a natural melanosis-inhibiting agent to prevent black spot and to extend the shelf-life of the shrimp during iced storage.