蝦蟹類是台灣重要的水產加工原料,其廢棄物中之幾丁質利用是項值得研究開發之素材,世界各國也對幾丁質和幾丁聚醣之利用正在積極研究中,幾丁質與幾丁聚醣的應用很廣泛,已知具有膳食纖維功能,可降低血中三酸甘油酯和膽固醇,其衍生物可製人工血管,具抗血栓性質;可作為藥物膠囊材料而減緩藥物之釋出速率以及具抗腫瘤作用,可做為膳食成分或食品機能性成分,因此其作為食用化之安全添加量急須加以探討。 另外台灣之海域受銅汙染嚴重,且因重金屬汙染而引起的職業傷害亦常有所聞。而已知幾丁聚醣帶多價陽離子,具有吸附之作用,可作為金屬螯合劑。為知其在生物體內是否具有降解重金屬之毒害,乃以老鼠為實驗對象,於飼料中添加幾丁聚醣,探討幾丁聚醣對銅在老鼠毒性之影響,並觀察其是否具有降低重金屬毒害之癒後效果及預防效果。 實驗一以老鼠為實驗對象,餵食不同含量的幾丁質和幾丁聚醣,由實驗結果得知5%以下的幾丁聚醣和10%以下的幾丁質對老鼠之成長、血液學、生化學沒有不利的影響,而且具有降低血漿中膽固醇和三酸甘油酯之功能。但10%之幾丁聚醣,經老鼠長期攝食後,其血液中之血比容和血紅素會下降,血漿鐵之濃度亦會下降,但對老鼠之成長和肝腎功能等並無不良影響。顯示幾丁質和幾丁聚醣做為食品使用,10%以下之幾丁質和5%以下之幾丁聚醣應無安全性之顧慮。 由實驗二結果得知,在同時給予銅和幾丁聚醣之實驗結果顯示,幾丁聚醣對銅所造成老鼠之生長遲緩、肝體化、腎體比、飼料轉換率及血漿中尿素氮之上升和肌酸酐之降低的情形,沒有顯著改善效果,然而其對銅所造成之紅血球增加、血漿中AST與ALT之酵素活性的提高及肝臟銅含量增加的情形有顯著改善效果,綜合上述結果顯示同時給予銅和幾丁聚醣時,幾丁聚醣稍具有降解銅對老鼠之毒害作用。 在癒後實驗部分,幾丁聚醣對銅所造成老鼠之生長遲緩、飼料轉換率及血漿中尿素氮之上升和肌酸酐之降低的情形,沒有顯著改善效果,然而其對銅所造成之肝體比、腎體比、血漿中AST與ALT之酵素活性及肝臟銅含量增加的情形有顯著改善效果,綜合上述結果顯示幾丁聚醣稍具有癒後效果。 在預防實驗部分,幾丁聚醣只對銅所造成老鼠之肝體比、腎體比的增加稍具恢復情形,其他如老鼠之生長遲緩、飼料轉換率及血漿中尿素氮之上升,和血漿中肌酸酐之降低的情形,沒有顯著改善效果,綜合上述結果顯示幾丁聚醣在銅對老鼠之毒害作用的預防效果不佳。 綜合上述結果得知,顯示幾丁質和幾丁聚醣做為食品使用,10%以下之幾丁質和5%以下之幾丁聚醣應無安全性之顧慮。另外幾丁聚醣對銅在老鼠所引起之毒性稍具癒後效果,但在預防上無顯著效果。 Crustaceans shrimp and crab are very important species of fishery in the world. The outer shells are produced in a large scale as waste residues from their utilization. The major component of crustacean shell is well known as chitinous compound. Nowadays, the applications of chitinous products have been developed in many countries. One of them is used as healthy food or food additive. To certify the edible safety of chitinous products for human the animal test was then carried out. The male Wistar rats were fed diets with different levels (0-10%) of chitin and chitosan for 8 weeks. The results indicated that edible safety limit of chitin and chitosan was below 10% and 5%, respectively. All of tested groups, chitin and chitosan showed no harmful effects on the growth, liver and kidney function, relative liver and kidney weights, and feed coefficient ratio in the rats, but 10% chitosan exhibited to decrease the level of hemacrit, hemoglobin and plasma iron in the rats. Moreover, chitosan presented significantly physiological function to decrease cholesterol and triglycerides in the blood of rats. On the other hand, chitosan is often used as a coagulant or chelating agent to clear out heavy metals. This prompted us to study the effect of chitosan on the toxicity of copper in male Wistar rats. After feeding diet with 500ppm copper and 5% chitosan at the same time, chitosan could not improve the decrease of the growth and the plasma creatinine and the increase of the hepatosomatic index, relatitive kidney weight, feed coefficient ratio and plasma urea nitrogen in the rats caused by copper. But it could improve the increase of red blood cell, the activities of aspartate transminase and alanine transminase in the plasma and the level of copper in the liver of rats caused by copper. Judging from these data, chitosan may be able to reduce the toxic effect of copper in the rats. Furthermore, chitosan also showed some healing effect on the toxicity of copper in the rats, but its preventive function was not found. Based on above data, the respective level of chitosan and chitin, being under 5% and 10% in the diet, is acceptable for edible safety. Chitosan may be as a good agent for use in reducing the level of cholesterol and triglycerides and deletting the harmful effect of copper in copper.