| Bamboo shoot is one kind of green protective food which had high protein, low fat, low sugar and high fiber. People like it very much because of its plentiful nutrition, but as the bud of bamboo, the bamboo shoot was easily lignified after picking and lost its edible value when stored in normal temperature for one to two days, moreover the bamboo shoot was produced in a focus time and had a limited process capability, so studying a preserve method to defer the lignification of bamboo shoot and keep a good quality had important meaning.GA could regulate the development, improve the quality, prolong the storage and defer consenescence. Heat treatment was widely used in postharvest storage because of its specially characterist such as restraining bacteria, retarding the physiological activity, no chemistry remain, safety, simpleness and convenience. Chitosan was safety, non-toxic, edible and had high biologic activity. Chitosan coating could form a miniature modified-atmosphere circumstance of low O2 and high CO2, which was widely used in postharvest storage. But now the three treatments were rarely used in controlling the lignification and keeping the quality of bamboo shoots.This experiment studied on the effect of lignification and storage quality of ma bamboo shoots by different treatments. According to this experiment, we expected to provide theoretical reliance and technical support for preserving of bamboo shoots. The bamboo shoots were handled by different methods including diverse concentration GA treatment (50mg/L and 100mg/L) combined with low temperature, heat treatment with different temperature (45℃,55℃,65℃,75℃,80℃), chitosan coating (1%. 1.5%, 2%) combined with low temperature, and compound treatment (55℃heat treatment plus 100mg/L GA and 1.5% chitosan coating). The experiment results indicated as follows:1. The effect of GA on postharvest lignification and quality of bamboo shootsGA treatment could retard the increasing of PAL, POD and PPO activity, ease off the ascending rate of lignin and fiber. The soluble sugar, soluble protein, soluble solid and Vc content of bamboo shoots declined during storage period, the quality pejorated gradually but GA treatment could inhibit the tendency of degression and keep a better quality than the contrast. Senescence process was the process of decompensation and accumulation of H2O2 and -O2. content, but GA treatment reduced the increase of H2O2 and -O2. content. Generally speaking, the 100mg/L GA had a better effect than 50mg/L GA, GA treatment could reduce the lignification and keep a good quality of bamboo shoots.2.The effect of heat treatment on appearance and quality of bamboo shootsHeat treatment could kill the zyme and passivate the enzyme of bamboo shoots. The experiment results indicated that 45℃and 55℃heat treatment had good effects in preservation, but after a long-time storage, the bamboo shoots quality of 45℃heat treatment was not better than 55℃heat treatment and the weight loss was bigger than the weight loss of 55℃heat treatment but the both effects were better than the contrast. Under 65℃,75℃and 80℃heat treatment, the bamboo shoots had slaked flavor, contracted, softened, decayed easily and brought about heat damage. The storage quality of bamboo shoots was the best by 55℃heat treatment.3.The effect of chitosan coating on storage quality of bamboo shootsChitosan coating could inhibit the increase of the lignin and fiber content of bamboo shoots, defer the appearance of senescence, decrease the water loss and decay index, retard the change of soluble solid, soluble protein and Vc content during storage period. The experiment results indicated that the effect of 1.5% chitosan coating was the best one, the effect of 1% chitosan was not clear because of low concentration and bad film, the 2% chitosan caused damage because of high concentration and no oxygen respiration.4.The effect of compound treatment on storage quality of bamboo shootsThe compound treatment was that we used 55℃heat treatment for 1min firstly, after the water was dried in the air, we put the bamboo shoots into the 1.5% chitosan coating and 100mg/L GA solution for lmin at last. The results indicated that compared with the contrast, this treatment defered the increase of lignin and fiber, decreaded weight loss and decay index, inhibited the decrease of soluble solid, soluble protein, Vc content and retained good quality. We studied the effect of different treatments on lignification and storage quality of bamboo shoots and found reasonable preserve method in order to provide some theoretical reliance and technical support for controlling lignification and increasing storage quality of bamboo shoots (The thesis contained 27 figures, 5 tables, 91 reference literatures)Chongqing Science Committee Natural Science Fund Subsidize ItemItem Number: 05-9063... |
