Department of Food Science and Technology, School of Agriculture, Aristotle University, GR-541 24, P.O. Box 235, Thessaloniki, Greece.
Food Funct. 2013 Jan;4(1):121-9. doi: 10.1039/c2fo30129f. Epub 2012 Oct 15.
Chitin nanocrystals (ChN) have been shown to form stable Pickering emulsions. These oil-in-water emulsions were compared with conventional milk (whey protein isolate, WPI, and sodium caseinate, SCn) protein-stabilized emulsions in terms of their lipid digestion kinetics using an in vitro enzymatic protocol. The kinetics of fatty acid release were evaluated as well as the change in oil droplet size of the respective emulsions during lipid digestion. The interfacial pressure was measured by addition of the duodenal components using drop tensiometry and the electrical charge of the oil droplets was also assessed, in an attempt to relate the interfacial properties with the stability of the emulsions towards lipolysis. Lipid hydrolysis in the ChN-stabilized emulsion was appreciably slower and the plateau values of the total concentration of fatty acids released were much lower, compared to the WPI- and SCn-stabilized emulsions. Moreover, the ChN-stabilized emulsions were relatively stable to coalescence during lipid digestion, whereas the WPI- and SCn-stabilized emulsions exhibited a significant increase in their droplet size. On the other hand, no major differences were shown among the different emulsion samples in terms of their interfacial properties. The increased stability of the ChN-stabilized emulsions towards lipolysis could be attributed to several underlying mechanisms: (i) strong and irreversible adsorption of the chitin nanocrystals at the interface that might inhibit an extensive displacement of the solid particles by bile salts and lipase, (ii) network formation by the nanocrystals in the bulk (continuous) phase that may reduce lipid digestion kinetics, and (iii) the ability of chitin, and consequently of ChNs, to impair pancreatic lipase activity. The finding that ChNs can be used to impede lipid digestion may have important implications for the design and fabrication of structured emulsions with controlled lipid digestibility that could provide the basis for the development of novel products that may promote satiety, reduce caloric intake and combat obesity.
壳聚糖纳米晶体 (ChN) 已被证明可以形成稳定的 Pickering 乳液。这些油包水乳液与传统的牛奶（乳清蛋白分离物 (WPI) 和酪蛋白酸钠 (SCn)）蛋白稳定的乳液相比，在使用体外酶促方案进行脂质消化动力学方面进行了比较。评估了脂肪酸释放的动力学以及在脂质消化过程中各乳液的油滴粒径的变化。通过添加十二指肠成分使用滴点滴度法测量界面压力，并评估油滴的电荷量，试图将界面特性与乳液对脂肪分解的稳定性相关联。与 WPI 和 SCn 稳定的乳液相比，ChN 稳定的乳液中的脂质水解明显较慢，并且释放的脂肪酸总浓度的平台值要低得多。此外，ChN 稳定的乳液在脂质消化过程中相对稳定，不易聚结，而 WPI 和 SCn 稳定的乳液则表现出其粒径明显增加。另一方面，不同乳液样品在界面特性方面没有显示出主要差异。ChN 稳定的乳液对脂肪分解的稳定性增加可能归因于几种潜在机制：(i) 壳聚糖纳米晶体在界面上的强且不可逆吸附，这可能抑制胆盐和脂肪酶对固体颗粒的广泛置换，(ii) 纳米晶体在体相（连续相）中的网络形成，这可能会降低脂质消化动力学，以及 (iii) 壳聚糖的能力，进而壳聚糖纳米晶体的能力，可能会损害胰脂肪酶的活性。壳聚糖纳米晶体可用于阻碍脂质消化的发现可能对具有控制脂质消化性的结构化乳液的设计和制造具有重要意义，这可能为开发新型产品提供基础，这些产品可能会促进饱腹感、减少热量摄入和对抗肥胖。
