Screening of antioxidant and tyrosinase inhibition activities of spicy vegetables in Vietnam and application of Persicaria odorata leaf extract to preservative white leg shrimp (Litopenaus vannamei).

Dao T.A Phan

doi:10.1590/0001-3765202120191341

Abstract

In this study, we aimed to exploit natural extracts from the spicy vegetables, which are rich in phenolic compounds as an initial treatment step in the cold storage process for shrimp. Firstly, 40 extracts from 10 types of spicy vegetables in Vietnam were prepared and tested for their bioactivities. Among samples, the extract from Persicaria Odorata leaves (E-4) exhibited the highest potential of scavenging DPPH free radical (IC50 of 7.54 µg.mL-1) and decreasing tyrosinase activity with the inhibition percentage of 54.2 % at the concentration of 100 mg/mL. Twenty-two out of a total of 36 chemical compounds in the E-4 extract identified using HPLC-MS technique were phenolic compounds, in which four compounds (morin, quercetin, fisetin, astragalin) are flavonoids. Shrimp (Litopenaus vannamei) samples were treated with the E-4 extract having lower gray values, lipid peroxidation values, and microbiological counts than those of the control samples after 7 days of storage at 2 oC. These results show the potential of using the natural extract as a safe and effective alternative for commercial chemical-derived preservatives in the shrimp storage process.

Highlights

Shrimp and shrimp products have occupied a significant portion of the exported seafood products
White leg shrimps (L. vannamei) with the size of 30-40 shrimps/kg were purchased from Thu Duc market, Ho Chi Minh City, Vietnam, in March 2018
Twelve extracts that showed vigorous antioxidant activities prepared from three spice vegetables, including Persicaria Odorata, Artemisia Vulgaris, Houttuynia Cordata

Summary

Introduction

Shrimp and shrimp products have occupied a significant portion of the exported seafood products. It is challenging to preserve shrimps because their spoilage begins soon after death and in the storage process. The current storage technology focuses on using the cold/ heat treatment or adding additives, these methods face with the challenges of melanosis development, lipid oxidation, microbial spoilage over time and toxicity (Bhobe & Pai 1986, Montero et al 2001, Pedale et al 2012). The development of a safe storage method for shrimps has been paid attention a significant number of research attentions. The spoilage of shrimps has correlated the compound called tyrosine, which undergoes the oxidation process by the assist of the tyrosinase in shrimps after death. The convert of phenol moiety in tyrosine to quinones by tyrosinase activates the melanosis process via a biochemical mechanism (Norman & Benjamin 2000). The melanosis development is followed by non-enzymatic polymerization and

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