以聚醣類高分子包覆之乳酸菌於模擬胃腸環境中耐受 性及釋放性質探討

Abstract

本研究利用兩種天然耐酸性材料，褐藻酸鈉與醋酸鄰苯二甲酸纖維素(CAP)，以及耐鹼性材料－幾丁聚醣包覆乳酸(Lactobacillus plantarum)，製成乳酸菌複合顆粒及乳酸菌粉。調整包覆製程條件，找尋最佳保護效果，以減少乳酸菌受到胃部酸性環境及腸道膽汁的損害，增進乳酸菌產品效能。 以褐藻酸鈉、幾丁聚醣及氯化鈣製備褐藻酸鈣/幾丁聚醣複合顆粒包覆乳酸菌，探討不同製程條件之複合顆粒對乳酸菌保護效果的影響。實驗結果發現若使顆粒中包覆的乳酸菌濃度過高，反而會造成存活率降低，以30 倍濃縮菌液為最佳包覆乳酸菌數。單層包覆之褐藻酸鈣顆粒，在經pH 2 人工胃液耐酸性測試後，包覆之乳酸菌存活率約為15%，再經褐藻酸鈉二重包覆後，可提升存活率至70%。以包覆法製備複合顆粒能夠有效增加顆粒中幾丁聚醣含量，其中又以使用重量平均分子量6 萬的幾丁聚醣製成複合顆粒有最佳的保護效果，此顆粒再經二重包覆複合顆粒，經pH 2 人工胃液處理兩小時，再於人工膽汁中經一小時後，仍有30%以上的存活率。使用較高濃度的氯化鈣溶液硬化顆粒，也可提升乳酸菌存活率。包覆乳酸菌之複合顆粒於人工腸液中經6~10 小時可將乳酸菌完全釋放，達到提升乳酸菌效能目的。 另一種包覆方法為利用褐藻酸鈉、CAP 及幾丁聚醣製成乳酸菌粉。實驗結果發現CAP 及幾丁聚醣皆可幫助乳酸菌沉降，提升乳酸菌收率。以褐藻酸鈉或CAP於外層包覆製備乳酸菌粉，兩種耐酸性包覆材料皆可有效提升乳酸菌粉耐酸性，其中以褐藻酸鈉包覆有較佳的保護效果，於人工胃液中經二小時後，約有68%的存活率。增加外層CAP 包覆濃度，也可提升菌粉耐酸性保護效果。在耐膽鹽性方面，以幾丁聚醣幫助乳酸菌離心之菌粉有較佳的耐膽鹽保護效果，如外層再以褐藻酸鈉進行包覆，此菌粉經耐膽鹽性測試三小時後，仍有5%以上存率。乳酸菌粉在人工腸液中4~6 小時即可完全釋放，藉此增進乳酸菌效能。

In this study, sodium alginate, cellulose acetate phthalate (CAP) and chitosan wereused for encapsulating Lactobacillus plantarum, one species of the lactic acid bacteria(LAB). Survival ratio of the encapsulated LAB in simulated gastric fluid and intestinalenvironments were examined. Improvements of survival ratio were expected from encapsulation of LAB. There were two types of encapsulated products. One was calcium alginate-chitosancomplex beads. The effects of cell load, beads with alginate double coating, different encapsulating methods, different molecular weight of chitosan and concentrations of calcium chloride were investigated. It was noted that raising in cell load could increase the number of survival LAB after 2 hour incubation in simulated gastric condition, but the survival ratio would decrease. If the encapsulated beads were coated with one more alginate layer, viability of encapsulated LAB could further increase. The calcium alginate beads coated with chitosan could significantly add chitosan in the beads, so LAB encapsulated in these beads would have higher viability after incubated in simulated bile solution. The different concentrations of calcium chloride would also affect the survival ratio of encapsulated LAB after gastric and bile test. The encapsulated LAB in all types of beads would release in intestinal environment after about 6 to 10 hours. The other type of encapsulated products was double-layer powder. The inner layer of powder was used CAP or chitosan, and the outer layer was CAP or sodium alginate. The sedimentation abilities of inner layer materials, CAP and chitosan, were investigated, and the survival ratio of encapsulated bacteria was evaluated under simulated gastric and intestinal environments. The result showed CAP and chitosan could also coprecipitate with bacteria, increasing the load of LAB in powder. The increment of concentration of coating CAP could increase the survival ratio after 2 hour incubation in simulated gastric fluid. Moreover, sodium alginate, which was the same as CAP, could also protect encapsulated LAB in gastric environment, and the sodium alginate had better result than CAP. After 2 hour in simulated bile solution, the powder used chitosan as inner layer had better survival results of encapsulated LAB. In addition, the encapsulated LAB could release in simulated intestinal solution after 4 to 6 hours.