以靈芝菌絲進行西洋參生物轉化過程固醇類化合物之組成變化

Abstract

西洋參是常用的保健食品與中藥材料，隨著人參產品的銷售量增加，食品加工產業產生數量可觀的人參萃取殘渣，此人參渣仍殘留有許多生物活性成分，如植物固醇，為了更有效的利用這些成分，本研究藉由接種靈芝菌絲體於西洋參渣進行生物轉化，來增加植物固醇的釋出，同時轉化植物固醇之形式，並產生真菌固醇類化合物麥角固醇。所使用的西洋參渣試驗材料之植物固醇含量為72.32 mg/ 100 g，相較於西洋參原料高出30%，以β-sitosterol、stigmasterol與campesterol為主要的固醇，植物固醇總量中其游離、酯化與醣苷型態之比率為36%、24%與39%。分別接種1%與10%靈芝菌絲於4、8、14與30天後，取樣分析。結果顯示隨著靈芝菌絲的生長，麥角固醇含量也隨之上升，於培養30天後可達36.52- 77.31 mg/ 100 g。且隨著靈芝菌絲的生長，西洋參渣植物固醇總含量只有些微變化，但型態上卻有顯著的變化，醣苷態從39%顯著的減少為5- 23%，而游離態顯著從36%增加為46- 81%，酯化態則變化幅度較小，含量在13- 33%範圍之間; 各組別在接種後第四或第八天就可觀察到顯著的變化，此變化時間與靈芝菌絲體在接種後第八天產生最高的β-glucosidase活性之趨勢有一致性，顯示游離態植物固醇的增加，是由靈芝菌絲體產生的β-glucosidase水解醣苷態植物固醇之轉化生成。接種菌絲若先經過含西洋參渣基質的馴化，則轉化程度較高; 接種量1%的組別，雖然菌絲覆蓋西洋參渣的速度較慢，但對於植物固醇的生物轉化效果卻與接種量10%的組別相近。根據以上結果，西洋參-靈芝菌絲發酵培養產物與原先之西洋參渣相比含有較多游離態植物固醇與額外增加之維生素D前驅物─麥角固醇。

American ginseng (Panax quinquefolius L.) is a popular ingredient of products of functional food and Traditional Chinesse Medicine. Considerable amount of water-extracted residue was generated as the increase of consumption on ginseng-related health food products. The ginseng residue still contains a great amount of bioactive substances, such as phytosterols. In this study, Lingzhi (Ganoderma lucidum) mycelia were applied to degrade cellulose and lignin in cell walls of the ginseng residue and to release and to bioconverse phytosterols. The growth of Lingzhi mycelium brings the mushroom bioactive ergosterol into the fermentation product. The ginseng residue used as fermentation medium contained 72.32 mg/ 100 g (on dry basis) of phytosterols that was 30% higher than original ginseng raw material. The major phytosterols were β-sitosterol, stigmasterol and campesterol in the order of their contents. The ratios of free, ester and glycoside forms of the phytosterols were 36%, 24% and 39%. To observe the changes of steroidal composition during the growth of Lingzhi mycelium, 1% and 10% mycelia were inoculated on ginseng residue for 4, 8, 14 and 30 days. Our results indicated that, the content of ergosterol increased as the mycelium grew, the content reached 36.52- 77.31 mg/ 100 g at 30th day. Total content of phytosterols only slightly changed by the mycelia but the forms of phytosterols significantly altered. The contents of glycosides sigmificantly decreased from 38% to 5- 23% and the content of free form increased from 36% to 46- 81%; the content of esters mild changed in the range 13- 33%. The changes could be observed at first and second sampling points, 4th and 8th day, and the timing was in accordance with the changes of β-glucosidase activity. The groups of those mycelia being adapted to ginseng before inoculation showed higher conversion ratio than those un-adapted groups. The conversion ratios of those groups of 1% mycelium inoculation was similar with 10% groups, although the growth of mycelium was slower. Our results indicated that the fermentation composite of American ginseng-Ganoderma mycelium contained higher free form of phytosterols than original ginseng with additional ergosterol, a vitamin D precursor.