噴霧乾燥製備植物基油凝膠之開發

Abstract

全球糧食系統對氣候變遷具有顯著影響，約佔全球溫室氣體排放量的25%，其中以動物性產品的生產為主要排放來源之一。為減緩環境衝擊並推動永續發展，植物性替代產品的研發已成為重要趨勢。儘管相關領域已有初步進展，脂肪替代的技術仍相對不足。在眾多創新技術中，利用高分子量油凝膠劑(high molecular weight oleogelator, HMWOG)製備油凝膠(oleogel)，能夠達到優異的油結合能力、熱穩定性與機械穩定性，並在保留植物油營養價值的同時模擬動物脂肪的結構特性。然而，該技術於食品產業應用上仍面臨諸多挑戰，包括修飾纖維素引發的健康疑慮、乾燥效率不佳，以及製程複雜與成本高昂等問題。 本研究主要探討天然纖維素作為油凝膠劑的可行性，以應對修飾纖維素的安全性疑慮，並藉由噴霧乾燥(spray drying)技術，改善油凝膠於乾燥效率以及均勻穩定性等限制。實驗結果顯示，以大豆分離蛋白(soybean protein isolate, SPI)能與卡德蘭膠和棉花纖維素於總固體顆粒濃度4.9%以及70℃下熱交聯一小時，形成具有良好流動性與穩定性的水凝膠。此外，將SPI進行預熱處理後(95℃,15分鐘)，於入口溫度180℃以及霧化氣體流量600 L/h的噴霧乾燥參數下，可形成具有優異水合能力且產率高達48.44%的水凝膠粉末。同時，將SPI進行後熱處理並以高速均質(12000 rpm, 5分鐘)以及超音波(20 kHz, 5分鐘)處理後能形成穩定的乳化系統，並在相同乾燥條件下形成含油量為76.03%、流動性佳，且產率為20.61%的乳液粉末。 將兩種粉末製備成油凝膠後，可在流變性質以及油煎試驗上達到與傳統油凝膠一致的結構性質且未產生任何負面影響。此外，水凝膠粉末能夠在三次凍融循環下維持其結構穩定性，並呈現較高的硬度與咀嚼性，適用於香腸與肉排等肉製品中作為脂肪模擬物；乳液粉末則呈現良好熱穩定性而避免高溫下的結構破壞，其柔軟的質地亦使其適用於烘焙餡料以及抹醬等食品應用中。綜上所述，本研究成功以噴霧乾燥以及熱處理技術，製備出符合綠色製程的天然纖維素油凝膠，並藉由水凝膠和乳液系統克服過去傳統油凝膠在使用與儲存上的限制，從而成功拓展產品的應用範圍。

The global food system contributes substantially to climate change, accounting for approximately 25% of total greenhouse gas emissions, with animal-based product production being a primary source. To mitigate environmental impact and enhance sustainability, plant-based alternatives have gained increasing attention. Despite this progress, fat substitution remains underexplored. Among emerging strategies, oleogelation using high-molecular-weight oleogelator (HMWOG) offers notable advantages, including enhanced oil-binding capacity, thermal and mechanical stability, and structural mimicry of conventional fats, while retaining the nutritional benefits of vegetable oils. However, industrial application faces significant barriers, such as health concerns associated with modified cellulose-based HMWOG, suboptimal drying performance, and complex, cost-intensive processing. This study primarily investigates the feasibility of using natural cellulose as an oleogelator to address safety concerns associated with chemically modified cellulose. To overcome limitations related to drying performance and uniformity, spray drying was employed to improve efficiency and enhance product stability. Experimental results demonstrated that hydrogels composed of soybean protein isolate (SPI), combined with curdlan and cellulose at a total solid concentration of 4.9%, and thermally cross-linked at 70 °C for 1 hour, exhibited excellent flowability and stability. Furthermore, heat treatment SPI (95 °C for 15 minutes), spray-dried at an inlet temperature of 180 °C and a gas flow rate of 600 L/h, produced hydrogel powders with favorable rehydration properties and a production yield of 48.44%. Additionally, postheat treatment SPI, subjected to high speed homogenization(12,000 rpm for 5 minutes)and ultrasonication (20 kHz for 5 minutes), formed stable emulsion systems. Under the same spray drying conditions, these emulsions yielded oil powders with a high oil content (76.03%), good flowability, and a production yield of 20.61%. Upon reconstitution, both powder types formed oleogels exhibiting rheological and pan-frying characteristics comparable to conventional oleogels, without any adverse effects. The hydrogel powder showed structural stability over three freeze-thaw cycles and demonstrated enhanced hardness and chewiness, making it suitable for incorporation into meat products such as sausages and patties as a fat mimetic. The emulsion powder exhibited strong thermal stability, maintaining its structure under high temperatures, and its soft texture renders it suitable for applications in baked fillings and spreads. Overall, this study successfully demonstrates the preparation of natural cellulose-based oleogels using spray drying and thermal treatment, overcoming previous challenges in conventional oleogel applications and storage, and expanding their potential uses in food systems.