Microencapsulation of oxidation sensitive oils aims to separate lipids from the environmental oxygen by embedding oil droplets in a solid matrix, which builds a physical barrier. Some oil droplets are not fully incorporated and are in contact with the powder surface generating surface oil. It is proposed that the probability of oil droplets being in contact with the particle surface increases with the oil droplet size. The aim of the study is to investigate the impact of the oil droplet size on the encapsulation efficiency (EE). Two sets of feed emulsions differing in the applied homogenization pressure and in the protein to oil ratio were spray dried using a pilot plant spray dryer. The oil droplet size of the emulsion was determined by static light scattering (SLS). In addition, nuclear magnetic resonance (NMR) was used to measure the d_3,2 of oil droplets in the emulsion and in the powder before and after surface oil removal. Encapsulates were analyzed regarding a_w, moisture content, particle size, oil load and EE. The oil droplet size in the emulsion decreased with increasing protein to oil ratio as well as with the homogenization pressure. Large oil droplets and in particular droplet clusters resulted in more non-encapsulated oil. The experimentally determined EE was in accordance with the theoretical one, calculated based on the droplet and particle diameter. For emulsions with a diameter > 1 µm, the d_3,2 decreased in the powder and further by removing the surface oil, which was related to the deformation of oil droplets contributing to the non-encapsulated oil.

中文翻译：

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决定包封的脂质颗粒的表面油浓度的因素：乳液油滴大小的影响

氧化敏感油的微囊化旨在通过将油滴嵌入固体基质中，从而将脂质与环境氧气分离，从而建立物理屏障。一些油滴未完全掺入并与产生粉末表面的表面油接触。提出油滴与颗粒表面接触的可能性随着油滴尺寸的增加而增加。该研究的目的是研究油滴大小对封装效率（EE）的影响。使用中试喷雾干燥器将干燥的两组饲料乳化剂的均质压力和蛋白油比例不同。乳液的油滴大小通过静态光散射（SLS）确定。此外，核磁共振（NMR）用于测量d在表面除油之前和之后，乳液和粉末中的油滴_3,2。分析包囊的_w，水分含量，粒度，油负荷和EE。乳化液中的油滴尺寸随着蛋白质/油比的增加以及均质化压力的降低而减小。大的油滴，尤其是油滴团簇会导致更多的非胶囊油。实验确定的EE符合理论值，是基于液滴和粒径计算的。对于直径> 1 µm的乳液，粉末中的d _3,2减少，并且进一步通过除去表面油而降低，这与油滴变形有关，而油滴的变形会导致未包封的油。