| Water bamboo shoot (Zizania caduciflora L., WBS) is a unique aquatic vegetable in China. It is very popular for its tender texture, delicious flavor and rich nutrition. WBS is obtained in May to June and August to October with high temperature seasons. After harvested, the vegetable is susceptible to Yellowing, hollowness and lignification, limiting the postharvest life to3-5days under ambient temperature. Rapid lignification is a major problem of FFW that limits its market ability.Four categories of water bamboo shoot were studied in terms of the storage characteristics to screen out the best storage-resistant one in the present study. The mechanism of lignification, senescence, effects of modified atmosphere package (MAP) treatment on the senescence as well as its mechanism under2℃,10℃and20℃in water bamboo shoot after harvested were also studied from the aspects on examining the reactive oxygen species metabolism, cell wall material metabolism and activities of relevant enzymes, lignin biosynthesis and the activities of relevant enzymes. In addition, the effect of hypobaric on storage in water bamboo shoot after harvest was investigated. The results were as follows:(1) Compared with the other three categorie (’Suozijiao’,’Zhejiao911’and’Zhejiao2’),’Longjiao2’showed the best characteristics on good sensory quality, tender texture, high contents of total soluble sugar and vitamin C during the whole storage period. It showed that the growth characteristics of’Longjiao2’remained relatively good, so the results indicated that’Longjiao2’was more suitable for long time storage and preservation.(2) The study showed that the production rate of superoxide anion (O2) and content of hydrogen peroxide (H2O2) gradually increased, while the activity of catalase (CAT), superoxide dismutase (SOD) and ascorbate peroxidase (APX) decreased during the period of storage of water bamboo shoot, and the decrease in activities of cell wall-degrading enzymes (PME, PG, CX), abnormal metabolism of cell wall material, increase in activities of lignin synthesis-related enzymes (PAL, POD, CAD), which relatively registered as the reduction of content of water soluble pectin increase of contents of protopectin> fiber and lignin, increase of content of lignin. MAP treatments under three different temperatures could inhibit the decline of SOD, CAT and APX activity, resist the increase of production rate of O2-and the content of H2O2, and prevented the decrease of activities of PME, PG, and CX and the increase of activities of PAL, POD, CAD, and the contents of protopectin, fiber and lignin were significantly lower than those obtained from the control group. Consequently, MAP treatment could inhibit the decrease of active oxygen scavenging enzymes activity, reduce the accumulation of reactive oxygen species, and then avoid cellular oxidative damage, delay the senescence of WBS after harvest, and the reduction in the reverse accumulation of protopectin and cellulose as well as the formation of lignin could be decreased as the reduction of cell wall-degrading enzymes activities and the increase of lignin synthesis-related enzymes activities under MAP treatment which then delayed the lignification of WBS after harvested. The abnormal metabolism of cell wall material was related closely to lignification, which was also one of the causes for lignification that provided theoretical basis for explain lignification mechanism. It showed the best results under2℃.(3) The hypobaric storage of harvested WBS could maintain its appearance quality remarkably, delay the degradation of total soluble sugar and Vc, inhibit the rise of the content of lignin in postharvest WBS, and delay the process of lignification. Compared with storage under40-50kPa, the storage of WBS under70-80kPa maintained better appearance quality and higher level of total soluble sugar and Vc after2months storage, under which, lignification was less obvious, and the unique commodity value was maintained well. |
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