百里香精油−幾丁質薄膜物理性質與抗菌性

Abstract

每年塑膠使用量超過 2 億萬噸，且仍在逐年增加中，石化材料無法完全被回收且無法被分解，對環境造成極大的負擔。近年來，許多學者與業者著力於開發具有可再生性、生物降解性、低成本、非石油來源和低二氧化碳排放的複合材料。以生物可分解聚合物作為活性包材具有開發價值，幾丁質為世界上含量第二豐富的高分子聚合物，其優點是年產量大、容易取得等，但不溶於水或良性溶劑中，為利用幾丁質的問題。本研究為濕式研磨，以物理性作用力改變材料結構，不使用溶劑：DMAc、LiCl、N-methyl-2-pyrrolidone，只使用水作為溶劑，是一種環境友善的加工方式。另一方面，近年來有許多文獻將植物精油 (Essential oil) 加入幾丁聚醣膜中，利用精油的抗菌、抗氧化特性產生具功能性的包材，以作為食品抗菌膜。本研究將研磨 30、60、90 分鐘之幾丁質漿液混合百里香精油以陶鑄法 (Casting method) 於濕度 75%、溫度 25 ℃ 下乾燥形成薄膜。探討含有百里香精油之幾丁質薄膜物理性質及其抗菌性的的改變。隨著百里香精油添加量增加，薄膜總吸光值、厚度增加。掃描式電子顯微鏡 (SEM) 影像顯示，隨著精油添加量增加，薄膜表面的孔洞增加，薄膜的截面具有層層堆疊之結構，精油增加使層與層之間較分散、孔隙增多。固定精油添加量下，抗張強度的變化皆為研磨 30 分鐘薄膜 > 研磨 60 分鐘薄膜 > 研磨 90 分鐘薄膜。薄膜延展性未隨著精油量增加而提升。X光繞射儀 (XRD) 結果顯示，與幾丁質原料比較，並無任何新的結晶產生，各組薄膜之 12.6° 結晶峰消失，26.3° 結晶峰有上升的趨勢。精油添加量達到 1、1.25g 時，薄膜對金黃葡萄球菌、大腸桿菌產生明顯抑菌圈。

The current global consumption petroleum plastics is more than 200 million tonnes, and is still increasing. Petrochemical-based materials are not environmental-friendly. Recent years, many scholars and industries have focused on the development of composites with renewable, biodegradability, low cost, non-petroleum sources and low carbon dioxide emissions. The biodegradable polymer has potential to be the active packaging material. Chitin is the second abundant macromolecular polymer in the world, with the advantages of low cost and feasible. However, it can only dissolved in special solvent, which limits the applications. In this study, media-milling was used, instead of solvents: DMAc, LiCl and N-methyl-2-pyrrolidone, with water as a solvent for processing chitin, which is an environment-friendly processing method. To enhance the anti-bacterial effect, essential oil had been used in chitosan film for food packaging. In this study, thyme oil (0, 0.5, 0.75, 1, 1.25g) was added to chitin suspension (30, 60, 90 milled). The physical properties of chitin films containing thyme oil and their antibacterial properties were investigated. As the addition of thyme oil increases, the total absorbance and the thickness of the films increase. SEM showed the cross-section of the films had layered structures. The addition of thyme oil increased the gap between layers. The changes of tensile strength are 30 min-milled > 60 min-milled > 90 min-milled chitin films with same addition of thyme oil. The elongation at break of the film does not increase as the amount of the thyme oil increases. XRD showed that 2