State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
State Key Laboratory of Food Science and Technology, Jiangnan University, Wuxi 214122, China.
Int J Biol Macromol. 2022 Sep 30;217:1012-1026. doi: 10.1016/j.ijbiomac.2022.07.222. Epub 2022 Aug 1.
In this study, chitosan (CS) with different molecular weights was functionalized with protocatechuic acid (PA) by free-radical grafting reaction, and used for the inhibition of lipid oxidation and the enhancement of stability of β-carotene in Pickering emulsions. The order of grafting ratio of PA in CS-PA conjugates was CS400 (400 kDa CS) > CS200 (200 kDa CS) > CS100 (100 kDa CS). UV-vis, FT-IR and H NMR spectra proved that PA was covalently bonded to CS through amino and ester linkages. Compared with native CS, three CS-PA conjugates exhibited reduced crystallinity and thermal stability and improved antioxidant activity, with a molecular weight-dependent relationship. Besides, CS-PA-conjugate particles formed by ionic gelling procedure were spherically shaped and homogeneously dispersed, which substantially improved the stability of β-carotene in Pickering emulsions than CS particles under ultraviolet irradiation, natural light exposure and heat treatment, and the retention rates of β-carotene were in the following order: CS200-PA- > CS400-PA- > CS100-PA-conjugate particles. Furthermore, the oxidation stability of Pickering emulsions fabricated by CS-PA-conjugate particles was also higher than that of CS particles. These results will provide valuable information for the application of CS-PA conjugates to protect bioactive components and inhibit lipid oxidation in emulsion systems.
在这项研究中，通过自由基接枝反应，将不同分子量的壳聚糖（CS）与原儿茶酸（PA）进行功能化，用于抑制脂质氧化和增强 Pickering 乳液中β-胡萝卜素的稳定性。PA 在 CS-PA 缀合物中的接枝率顺序为 CS400（400 kDa CS）> CS200（200 kDa CS）> CS100（100 kDa CS）。UV-vis、FT-IR 和 H NMR 光谱证明 PA 通过氨基和酯键共价键合到 CS 上。与天然 CS 相比，三种 CS-PA 缀合物的结晶度和热稳定性降低，抗氧化活性提高，具有分子量依赖性。此外，通过离子凝胶过程形成的 CS-PA 缀合物颗粒呈球形且均匀分散，在紫外线照射、自然光暴露和热处理下，显著提高了 Pickering 乳液中β-胡萝卜素的稳定性，β-胡萝卜素的保留率顺序为：CS200-PA->CS400-PA->CS100-PA 缀合物颗粒。此外，由 CS-PA 缀合物颗粒制备的 Pickering 乳液的氧化稳定性也高于 CS 颗粒。这些结果将为 CS-PA 缀合物在乳液系统中保护生物活性成分和抑制脂质氧化的应用提供有价值的信息。
