To investigate the effect of thawing method on the quality of frozen Phyllostachys praecox(P.praecox)shoots,fresh P.praecox shoots frozen by liquid nitrogen freezing were vacuum packaged and placed in a freezer at-18 ℃ for 4 weeks.Five thawing methods(flowing water,cold storage,variable temperature,gradient temperature and ultrasound)were used to thaw the frozen P.praecox shoots,respectively,to determine the thawing efficiency,drip loss,relative electrical conductivity,hardness,color,soluble compounds and total phenolic contents,and to observe total viable count and microscopic structure.The results showed that ultrasonic and flowing water thawing were faster than cold storage,variable and gradient temperature thawing;among cold storage,variable and gradient temperature thawing,gradient temperature thawing was the most efficient.Compared to flowing water thawing,ultrasound thawing could improve the thawing efficiency,and the quality of P.praecox shoots was also better,while cold storage,variable temperature and gradient temperature thawing had more significant effects on the decrease of drip loss,the increase of relative electrical conductivity,the maintenance of soluble compounds and total phenolic contents and the preser-vation of hardness and microscopic structure of P.praecox shoots.There was not significant difference in relative e-lectrical conductivity,soluble compounds and total phenolic contents and microscopic structure among ultrasound,cold storge and variable temperature thawing.The total viable count of ultrasound and flowing water thawing was lower than that of cold storage,variable temperature and gradient temperature thawing.However,the total viable count of all five thawing methods was maintained at a low level,and the impact on the quality attributes of P.prae-cox shoots was not significant.Based on the aforementioned results,the best thawing method of frozen P.praecox shoots is ultrasound thawing.This work can provide technical support for the processing of frozen P.praecox shoots.
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