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Enzymatic characterization of a laccase from lychee pericarp in relation to browning reveals the mechanisms for fruit color protection
Author(s) -
Zhang Xuelian,
Fang Fang,
He Quan,
Zhang Xin,
Shi Ningbo,
Song Jun,
Zhang Zhaoqi,
Pang Xuequn
Publication year - 2018
Publication title -
journal of food processing and preservation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.511
H-Index - 48
eISSN - 1745-4549
pISSN - 0145-8892
DOI - 10.1111/jfpp.13515
Subject(s) - browning , laccase , chemistry , kojic acid , food science , enzyme , phytic acid , postharvest , enzyme assay , cysteine , biochemistry , botany , tyrosinase , biology
An anthocyanin degradation‐related laccase (LcADE/LAC) from lychee fruit was found to be responsible for the pericarp browning. In this study, LcADE/LAC was purified and characterized for better control of laccase‐based browning. The optimum pH for LcADE/LAC activities was 5.0–6.0, with less than 20% of the activity retained at pH 3.0. The optimum temperature is 45 °C, and the activity is thermostable at this temperature. The enzyme was inhibited by 1 mM Fe 2+ , but induced by 0.1 mM Fe 3+ . Na 2 SO 3 and l ‐cysteine highly inhibited the activity at 0.1 mM, while kojic and phytic acids inhibited 40 and 43%, respectively, at 1 mM. Na 2 SO 3 inhibited the activity in a noncompetitive model with a K i value of 33.1 μM, and the inhibition increased when pH decreased to 3.5. In postharvest fruit, the enzyme activity and LcADE/LAC gene expression were strongly inhibited by SO 2 ‐HCl treatment. Practical applications The present study systematically characterizes a pericarp browning related laccase (LcADE/LAC) from lychee. The high sensitivity of the enzyme to low pH and several inhibitors, such as SO 2 , l ‐cysteine, and kojic acid and phytic acids, will help in the development of more efficient strategies for browning control of lychee pericarp or other laccase‐based food browning.