Studies On The Mechanism Of Quality Deterioration Of Postharvest Big Task Hemp Bamboo Shoots

With big task hemp bamboo shoots (Sinocalamus latiflorus (Munro) Mcclure) as test material, effects of postharvest treatment on organoleptic quality and quality related physiological and biochemical indicators of big task hemp bamboo shoots (Sinocalamus latiflorus (Munro) Mcclure), and the effect on quality deterioration were studied in this paper. The principle of quality deterioration of postharvest big task hemp bamboo shoots and possible regulation methods for quality deterioration are proposed. Results are as follows:1. Influence on organoleptic quality:The color of big task hemp bamboo shoots both take on the trend of "yellow and green→slightly yellow→slightly brown". Its body becomes harden, and its texture becomes worse. The color, texture, and total organoleptic quality of bamboo shoots storing at 23℃are all better than that stored at 33℃. On the 2^nd day, the texture of GA₃ group is crisper than that of alcohol group, with the order GA₃> alcohol > control group.2. Influence on moisture and sugar content:Moisture and sugar contents of bamboo shoots decrease gradually during storage. On the 4^th day, moisture and sugar contents at 33℃and 23℃are 86.33% and 88.14% respectively, with extremely significant difference of the results (p<0.01). On the 3^rd day, total sugar content at 23℃is 85.5% higher than that at 33℃, with extremely significant difference (p<0.01). On the 4^th day, moisture content of GA₃ group and alcohol group is 91.14% and 90.67%, 3.0% and 2.53% higher than that of the control group. On the 3^rd& 4^th day, moisture content of GA₃ group are all significantly higher than that of alcohol group (p<0.05). On the 3^rd day , soluble sugar content of GA₃ group are significantly higher than that of alcohol group and control group (p<0.05).3. Influence on the content of lignin and cellulose:The contents of lignin and cellulose increase gradually during the storage period. On the 4^th day, the content of lignin stored at 23℃and 33℃are 19.37% and 21.70% respectively; for cellulose content, 8.99% and 11.92% respectively. The content of lignin of GA₃ group and alcohol group are 18.41% and 17.46% respectively, and 8.59% and 8.11% for cellulose content, both are lower than those of control group with extremely significant difference (p<0.01) among each treatment.4. Influence on enzyme activity of related enzyme:The activity of PAL, POD and PPO of big task hemp bamboo shoots are all first increase and then decrease. The activity of PPO reach maximum value on the 1^st day, 3.9U/g·h and 4.8 U/g·h at 23℃and 33℃with extremely significant difference (p<0.01); PPO activity of GA₃ group, alcohol group and the control group are 3.3 U/g·h, 3.8 U/g·h and 3.9 U/g·h, with GA₃ group significantly lower than that of the control group. The activity of PAL reaches maximum on the 3^rd day, 16.4 U/g·h and 20.8 U/g·h at 23℃and 33℃with extremely significant difference (p<0.01); PAL activity of GA₃ group, alcohol group and the control group are 6.8 U/g·h, 13.6 U/g·h and 16.4 U/g·h, with extremely significant difference (p<0.01) among the three groups. The activity of POD reaches maximum On the 3^rd day, 2.7U/g·min and 6.5 U/g·min at 23℃and 33℃with extremely significant difference (p<0.01);POD activity of GA₃ group, alcohol group and the control group are 2.6U/g·min 2.5U/g·min and 2.7 U/g·min, with extremely significant difference (p<0.01) between the GA₃ group and control group.5. Influence on metabolism of active oxygen:The content of H₂O₂ increases gradually during storage. On the 3^rd day, H₂O₂ content at 23℃and 33℃reach 0.1226 mmol/g and 0.1408 mmol/g respectively. The content of H₂O₂ increases gradually and reaches peak value on the 4^th day. The activity of CAT is first to increase and then decrease, reaching maximum value on the 3^rd day with not significant difference between different temperatures. The group treated by GA₃ and alcohol both inhibit the increase of content of O₂^-·and H₂O₂) and O₂^-·content of GA₃ group is significantly lower than that of alcohol group. Activity of CAT reach maximum value on the 3^rd day, 3.0 U/g·min for GA₃ treatment, 3.1 U/g·min for alcohol treatment and 3.6U/g·min for the control group. Among them, the activity of GA₃ treatment is significantly lower than that of the control group (p<0.05).6. Influence of different treatments on the content of cytoderm polycose and phenolic acid:During storage, the content of glucose residue from cellulose, xylose residue and rhodeose residue from hemicellulose increase gradually, which is consistent with changes of several antecedents in the composition of lignin. Decrease rate of phenol content at 33℃is larger than that at 23℃. Phenol content after treatment is: GA₃ treatment < alcohol treatment < control group. Fluorescence emission spectrum analysis indicates that the content of p-coumaric acid increases along with the lignin content ascension, but the ferulaic acid content reduces .To sum up, storage temperature has relationship with that of the process of aging and quality deterioration of postharvest big task hemp bamboo shoots. Compared with 33℃, 23℃is more profit for its storage. Treated by GA₃ and alcohol can both delay the two processes, and the effect of GA₃ is better than that of alcohol.The possible mechanism of quality deterioration of post-harvest big task hemp bamboo shoots is inferred in terms of the measure of related physiological biochemical indicator of big task hemp bamboo shoots.