Quality dynamics of fresh Chimonobambusa utilis bamboo shoots under the liquid nitrogen quick-frozen storage condition
[Objective]Fresh Chimonobambusa utilis shoots from Jinfoshan mountain were processed by the technique of liquid nitrogen quick-freezing-vacuum packing-frozen storage.The dynamics(hardness,color,nutritional quality and enzyme activity)during storage were investigated with the increasing the frozen storage time,and thus providing a theoretical support for the industrial production and quality control of fresh C.utilis shoots under the liquid nitrogen quick-frozen storage condition.[Method]C.utilis shoots with shells were used to produce quick-frozen bamboo shoots by the processes of liquid nitrogen quick-freezing and vacuum packaging.At a frozen storage process(-18℃,0-180 d),the main quality indicators of the quick-frozen shoots were determined in terms of hardness,color,protein and amino acids,crude fiber,total sugar,fat,vitamin C,and selenium.The enzymatic activities(POD,PPO and PAL)of the quick-frozen shoots at different storage time were also analyzed.[Result]The hardness and color of fresh C.utilis shoots under the liquid nitrogen quick-frozen storage condition were affected by the frozen storage time.When the frozen storage time was ≥90 d,the hardness increased slightly,while their L*,a*and b*values decreased a little.With the increasement of storage time,the contents of water,protein,total amino acids,total sugar and vitamin C gradually decreased,while the content of crude fiber gradually increased.These contents tended to be stable at 90-180 d.The contents of fat,selenium and tannin were basically stable in the storage time.When the frozen storage time was at 180 d,the contents of water,protein,crude fiber,total sugar,fat,essential amino acid,vitamin C and selenium were respectively 91.24％,2.51％,2.82％,0.93％,0.27％,552.96×10-3％,13.14×10-3％,0.785× 10-6％,with good quality.The activities of PAL,PPO and POD decreased significantly during 0-90 d,and they were stable at 90-180 d.The quality of C.utilis shoots was affected little by enzymatic activity at the storage time(90-180 d).[Conclusion]Finally,the liquid nitrogen quick-freezing-vacuum packing-frozen storage technology had achieved a preservation of 6 months for fresh C.utilis shoots under the liquid nitrogen quick-frozen storage condition.Thus,it is a feasible method for the preservation of fresh bamboo shoots.
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