鲜切竹笋冷藏过程中生理和生化变化的研究

Study on the Physiological and Biochemical Changes of Fresh-cut Bamboo Shoot during Cold Storage

研究了最少化加工(MP)对竹笋呼吸强度的影响及MP竹笋贮藏期间呼吸强度的变化。测定了4℃下不同部位的竹笋的总糖、还原糖、总酚、木质素、纤维素、丙二醛(MDA)含量及苯丙氨酸解氨酶(PAL)和多酚氧化酶(PPO)活性的变化。结果表明:加工造成的机械损伤导致了竹笋呼吸强度的迅速增加,在随后的贮藏过程中又逐步减弱。竹笋尖部和中部的总糖和还原糖的含量贮藏前期下降、后期增加,而基部的总糖呈上升趋势。竹笋尖部和中部的总酚含量先减少后上升,之后再减少,而基部的总酚含量没有大的变化。纤维素和木质素含量贮藏前期从尖部的到基部的逐渐增加,贮藏中期从尖部的到基部的有不同程度的下降,贮藏后期有不同程度的增加。各部位MP竹笋的MDA含量在贮藏初期急剧上升,随后维持在高水平状态。尖部的PAL和PPO的活性高于中部和基部的。各部位的PAL活性贮藏前期上升,中期下降,后期又上升。尖、中部的PPO活性贮藏前期上升,后期下降,但仍维持在较高水平,而基部的PPO活性一直下降。

Effect of minimal processing on respiration rate of bamboo shootsPhyllostachys heterocycla var. pubescensand changes of respiration rate of minimally processed bamboo shoots during storage at 4℃ were studied. Different sections of minimally processed bamboo shoots along the length of the shoots were used to study the changes of total sugar, reducing sugar, total phenol, lignin, cellulose and malondialdehydeMDAand the activities of phenylalanine ammonia-lyasePALand polyphenoloxidasePPOduring storage at 4℃. Respiration rate increased after mechanical stress resulted from cutting, but decreased step-by-step during the storage. The content of total sugar and reducing sugar in the apical and middle parts decreased during the first part of storage and increased during the later storage, while the content of total sugar in the baseparts increased during the whole storage. Total phenol in the apical and middle parts raised after a period of lowering and decreased thereafter, while that in the basal part changed little. The content of cellulose and lignin increased gradually from the apical to the basal. Both decreased in different rates during the middle of storage, then increased in different rates during the later storage. MDA in different sections of minimally processed bamboo shoots raised markedly at the beginning of storage and kept at high lever thereafter. PAL activity and PPO activity were higher in the apical section than those in the middle and basal sections of bamboo shoot. PAL activity in three parts rose during the first period, lowered during the middle period and raised again during the later period of storage. PPO activity in the apical and middle parts rose and remained higher level, while that in the basal decreased successively during the storage.