卵磷脂與麥芽糊精對奈米/次微米纖維素懸浮液穩定性及其凍乾粉末復水性之研究

Abstract

纖維素是自然界中分布最廣、含量最多的多醣，絕大多數存在於植物體內，且廣泛存在於食品中，屬於非水溶性膳食纖維的一種。膳食纖維已被證實可促進人體健康，例如：促進腸胃蠕動、預防便秘及結腸癌、降低膽固醇、穩定血糖及減重。本論文之目的在探討纖維素微粒於水中之懸浮穩定性，及其凍乾粉末之復水性。藉由添加卵磷脂作為乳化劑，改善經介質研磨後奈米/次微米纖維素懸浮液之穩定性；添加麥芽糊精作為賦形劑，改善其凍乾粉末之復水性。經由物性分析、顯微觀察確認其穩定性及復水效果。 纖維素20 g加入400 mL去離子水混勻，添加不同比例之卵磷脂及麥芽糊精，研磨90分鐘。結果顯示，未添加卵磷脂的樣品，體積平均粒徑下降至0.66 µm，奈米/次微米之微粒佔總體積的78.9%，比表面積與表面能大幅提升，微粒間的聚集現象嚴重，物性皆不穩定。有添加卵磷脂的樣品，濁度變化都在± 1%以內，表面電位均小於-30 mV，無離水現象，呈穩定狀態，其中添加1.25%的樣品保水性最好。以添加1.25%卵磷脂的樣品添加麥芽糊精進行復水性實驗，結果顯示，將研磨樣品之凍乾粉末復水後，未添加麥芽糊精的樣品，已無奈米/次微米微粒存在，濁度變化高達-89%，離水嚴重，極不穩定；而添加50及100%麥芽糊精的樣品，奈米/次微米微粒分別佔總體積的7%及10%，濁度變化為-8%及33%，表面電位為-17及-12 mV，有輕微離水，整體物性比未添加麥芽糊精的樣品穩定。 適量添加卵磷脂可促進奈米/次微米纖維素懸浮液之穩定性，其中又以添加1.25%的樣品效果最好。添加麥芽糊精雖然使穩定性下降，卻可提升奈米/次微米纖維素凍乾粉末之復水性，且有效減緩凍乾前及凍乾復水後樣品之物性變化，其中添加50%的樣品穩定性較好，而添加100%的樣品復水性較佳。此外，經實驗證明適量添加卵磷脂可幫助麥芽糊精提升奈米/次微米纖維素懸浮液之復水性。

Cellulose is the most broadly-distributed and abundant polysaccharide in nature. It is also known as dietary fiber in food. It has been proved that dietary fiber can improve human health, such as promoting gastrointestinal peristalsis, preventing constipation and colon cancer, reducing cholesterol, stabilizing blood sugar level and reducing weight. In this study, the stability of nano/submicron cellulose particles suspending in water and the rehydration ability of the lyophilized powder were investigated. Addition of lecithin worked as an emulsifier improved the stability of nano/submicron cellulose suspension, while the addition of maltodextrin worked as an excipient to improve the rehydration ability of the lyophilized powder. Samples of nano/submicron cellulose particles adding different amount of lecithin and maltodextrin were milled for 90 min. Suspension without the addition of lecithin was unstable because of the increase in specific surface area and surface energy, which resulted in the aggregation of particles. For samples with the addition of lecithin, stability over time was observed, turbidity variations were all within ± 1%, no syneresis was found, and zeta potentials were under -30 mV. The addition of 1.25% lecithin performed the best water holding capacity, and this condition was chose to proceed with the experiments of rehydration ability. After rehydrating the lyophilized powder without the addition of maltodextrin, no nano/submicron cellulose particles was found in the sample and the suspensions was very unstable. For the samples with the addition of 50% and 100% maltodextrin to the cellulose suspension with 1.25% lecithin, 7% and 10% nano/submicron particles were present in the samples, turbidity variations were -8% and 33%, and zeta potentials were -17 and -12 mV, respectively. Slight syneresis occurred but the samples were more stable than the ones without the addition of maltodextrin. Adding appropriate amount of lecithin enhanced the stability of nano/submicron cellulose suspension; sample with 1.25% lecithin was found to be the most stable. The addition of maltodextrin improved the rehydration ability of nano/submicron cellulose lyophilized powder, but decreased the stability. It can effectively delay the change in physical characteristics after lyophilizing. The addition of 50% maltodextrin showed better stability and the rehydration ability with 100% maltodextrin performed well. The addition of lecithin can enhance stability and the addition of maltodextrin can improve rehydration.