The Effect Of Light Intensity On Bitter And Astringent Taste Compound Contents In Different Patrs Of Bamboo Shoots Of Three Species

Bamboo shoots of three species, i.e. Dendrocalamus latiflorus, Bambusa oldhami, andPhyllostachys edulis were studied under6different light intensities, including complete shade(T1),5%intensity (T2),20%(T3),40%(T4),60%(T5) and natural light (CK). Bitter andastringent taste substance contents in different parts of three shoots species were measured inorder to unravel the impact of light on the taste of bamboo shoots. Meanwhile, bitter andastringent taste substances in bamboo shoots after removing sheath ear were compared withthose under the natural sun light. The results show as follows:(1) Bitter-taste amino acids and flavonoid influence bamboo shoot edible flavour.Thecontents of bitter-taste substances of three shoot species under the shading conditions are lowerthan CK (P<0.05). The amount of bitter-taste amino acids in the shoots of Dendrocalamuslatiflorus is lowest at60%light intensity, while Bambusa oldhami at40~60%, andPhyllostachys edulis at20%. The bitter amino acids are decreased from the top to the bottom inall three bamboo species. The content of flavonoid is dropped sharply at60%intensity, anddecreased to the lowest under complete shade. The flavonoid content is increased from the topto the bottom of the shoots. Therefore, reducing the light intensity can decrease the contents ofbitter-taste substances in bamboo shoots.(2) Shading has a huge impact on the contents of tannin and oxalic acid. As the lightintensity decreases, the levels of tannin and oxalic acids in all three shoot species decreasesgradually. The tannin content is positively proportional to the light intensity (P<0.05), it isminimized under complete shade in all three bamboo species. Within the shoot body, the tanninlevel is gradually increased from the bottom to the top. The amount of oxalic acids is increasedinitially, and decreased later as the light intensity is reduced. The level of oxalic acids inDendrocalamus latiflorus and Bambusa oldhami at40~60%is higher than that under CK, andit becomes lowest at5%intensity. However, there is no significantly change in Phyllostachys edulis. The oxalic acids content is varied along the shoot body in all three bamboo species（P<0.05）. The level of oxalic acids at the middle portion of the shoot is higher than both thetop and the bottom parts. These indicate that the low light intensity can greatly reduce theastringent taste substances such as tannin and oxalic acids.(3) Removing the sheath ear has a significant impact on the content of bitter andastringent taste substances in bamboo shoots （P<0.05）. Compared to CK, the contents ofhydrolyzed amino acids and tannin are decreased once the sheath ear are removed away, whilethe oxalic acids level is increased. The content of flavonoid drops after taking away the sheathear except for Dendrocalamus latiflorus, while the level of anthocyanin is decreased except forBambusa oldhami. The effect of picking up sheath ear on the reduction of the bitter andastringent taste substances is similar to that of shading treatment, and it is comparable to that at5%~20%(T2-T3) shading condition, which proves that both sheath ear removal and lightintensity reduction can decrease the content of bitter-taste substances in bamboo shoots.