薄荷香精微胶囊的内乳化凝胶法制备及性能研究

Characteristics of Mint Essence Microcapsule Prepared by Emulsification-internal Ionotropic Gelation

薄荷香精在食品生产中应用广泛,但是由于其易挥发性和对环境敏感的特性,致使留香时间不长,货架期较短。目前,喷雾干燥是最广泛使用的微胶囊制备方法,但是由于喷雾后的高温干燥处理会导致香精的部分损失,所以需要探索一种在常温下制备香精微胶囊的方法。本文以海藻酸钙为壁材,薄荷香精为芯材,采用内乳化凝聚法来制备薄荷香精微胶囊,在常温下可获得球形好、粒径分布均一的微胶囊。通过傅立叶红外光谱定性验证香精是否被海藻酸钠包埋。由单因素实验和正交实验对包埋率和粒径分布进行考察,得到制备的最佳工艺参数。最佳的工艺条件为:芯材与海藻酸钠质量比1:3,海藻酸钠质量分数为4%,Span-80添加量2%,冰醋酸与碳酸钙摩尔比3:1,碳酸钙与海藻酸钠质量比7:40,乳化时间15 min。此条件下薄荷香精微胶囊的包埋率为59.63±0.47%,平均粒径为290.70μm。用差示量热扫描仪(DSC)对其热稳定性能进行分析,发现微胶囊可以对香精起到部分缓释作用。

Mint essence is widely used while preparing food, however, characteristics such as volatility and environmental sensitivity reduce the duration of its aroma and shelf life. Spray drying is the most common method to prepare essence microcapsules, but the heat treatment following spray drying results in partial loss of the essence. Therefore, it is necessary to develop a preparation method that can be carried out at room-temperature. In this study, an emulsification-internal ionotropic gelation method was used to prepare mint essence microcapsules at room temperature, using calcium alginate to coat the core containing mint essence. The resultant product was spherical, with uniform particle size distribution. Fourier transform infrared spectroscopy was used to confirm that the mint essence was adequately embedded within calcium alginate. Embedding ratio and particle size distribution using single factor and orthogonal experiments were carried out to determine optimal conditions, as follows: mass ratio of the core material and sodium alginate was 1:3; mass fraction of sodium alginate was 4%; amount of added Span-80 was 2%; molar ratio of glacial acetic acid and calcium carbonate was 2:1; mass ratio of calcium carbonate and sodium alginate was 7:40; and emulsification time was 15 minutes. Under these optimized conditions, encapsulation efficiency was 59.63 ± 0.47%, and the average particle diameter was 290.70 μm. Thermal stability was measured using differential scanning calorimetry and it was found that the microcapsules contributed to sustained release of the essence.