研磨去枝玉米澱粉製備皮克林乳液之物化性質探討及其作為薑黃素載體之潛力

Abstract

皮克林乳液 (Pickering emulsions) 是藉由固體顆粒作為乳化劑所形成的乳液系統，具有良好穩定性且具有作為生物活性化合物載體之潛力。本篇研究使用三種不同直/枝鏈比例之玉米澱粉 (糯性玉米澱粉、普通玉米澱粉及高直鏈玉米澱粉 (Hylon VII))，將其以酵素性去枝修飾後，再進行物理性介質研磨處理，以製備出奈米/次微米澱粉顆粒。隨後再將這些線性糊精作為水包油型皮克林乳液之穩定劑，並評估其作為薑黃素載體之潛力。三種玉米澱粉在經過去枝及介質研磨處理後，數目平均粒均下降至 0.1 微米；此外，視直鏈澱粉含量提高，且水合性質提升，而漿液外觀變為不透明。研磨去枝普通澱粉 (MDN) 具有最佳乳化能力，其次為研磨去枝糯性澱粉 (MDW)，研磨去枝高直鏈玉米澱粉 (MDH7) 則無法形成穩定乳液，澱粉直/枝鏈比例、粒徑大小及溶解度皆會影響乳化能力。此外，液滴尺寸會受到油相質量分率 (φ)、水相中澱粉濃度、離子強度及酸鹼值影響。當水相中 MDN 濃度越高，液滴粒徑越小，會增強乳液穩定性。然而，在添加氯化鈉後會因為靜電排斥粒下降造成乳液油水分離；在中性及弱鹼性環境下具有較佳乳液穩定性。由實驗結果得知，當 φ = 0.5，MDN 於水相中濃度為 3.8% 且 pH 為 7 時，具有最佳乳液安定性，甚至可維持一個月之久。後續將以此條件製備負載薑黃素皮克林乳液，並進行體外消化試驗。結果顯示，MDN 皮克林乳液 (MDNPE) 的脂質消化程度高於 Tween 20 乳液 (TE) 及 Bulk oil 系統。另外，MDNPE 薑黃素生物可及性 (26.60%) 略低於 TE (28.55%)，但顯著高於 Bulk oil 組別 (10%)。總結來說，MDN 皮克林乳液具有作為油溶性生物活性物質之載體的潛力。

Pickering emulsions (PE) are emulsion systems formed by utilizing solid particles as emulsifiers, exhibiting excellent stability and the potential to serve as carriers for bioactive compounds. In this study, we enzymatically debranched three corn starches (waxy cornstarch, normal cornstarch, and high-amylose cornstarch) with varying amylose/amylopectin ratios and subsequently subjected them to media milling to create nano/submicron particles. These linear dextrins were employed as stabilizers for oil-in-water PE, which were subsequently utilized to assess the potential for curcumin delivery. Following debranching and milling (MD), the number average sizes of three types of MD starch decreased to 0.1 micron. MD starch also exhibited an increase in the content of apparent amylose and improved hydration properties, resulting in a relatively opaque slurry morphology. MD-normal starch (MDN) demonstrated the highest emulsifying capacity, followed by MD-waxy starch, with both of them outperforming MD-high amylose starch. The droplet size of the emulsions was affected by the oil fraction, the initial starch concentration, ionic strength, and pH level. Higher MDN concentrations resulted in the production of smaller droplets, enhancing emulsion stability. However, the introduction of NaCl had a destabilizing effect on the Pickering emulsions due to electrostatic repulsion. Better emulsion stability is observed under neutral and weak alkaline conditions. In summary, optimal emulsion stability was attained at the oil ratio (φ) of 0.5, MDN concentration of 3.8% in the aqueous phase, and pH of 7, which maintained good stability for up to one month of storage. Following this, we performed in vitro digestion tests on curcumin encapsulated in Pickering emulsions under these conditions. The findings revealed that the MDN Pickering emulsion (MDNPE) showed higher lipid digestion compared to Tween 20 emulsion (TE) and bulk oil system. Additionally, curcumin bioaccessibility in the MDNPE (26.60%) was slightly lower than TE (28.55%) but significantly higher than bulk oil system (10%). In conclusion, this study demonstrates that MDN Pickering emulsions have the potential to serve as effective delivery vehicles for oil-soluble bioactive substances.