College of Ocean Food and Biological Engineering, Jimei University, Xiamen 361021, China; National R&D Center for Red Alga Processing Technology, Xiamen, Fujian Province 361021, China; Fujian Provincial Engineering Technology Research Center of Marine Functional Food, Xiamen, Fujian Province 361021, China; Xiamen Key Laboratory of Marine Functional Food, Xiamen 361021, China.
Sanming Inspection & Testing Center for Product Quality, Sanming 365000, China.
Int J Biol Macromol. 2023 Jun 1;239:124254. doi: 10.1016/j.ijbiomac.2023.124254. Epub 2023 Mar 31.
Agar benzoate (AB) with different degrees of substitution (DS) was synthesized by the esterification of agar and benzoic anhydride in aqueous solution. The DS could be regulated by adjusting composition ratio, pH, and temperature. Its chemical structure was determined by Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance spectroscopy (NMR). C NMR spectrum of the AB suggested the main substitution occurred at the C-6 in the d-galactopyranose. Cryo-scanning electron microscopy (Cryo-SEM) showed that the aperture of AB was larger than that of agar. The thermal performance of AB decreased slightly, but this did not affect its performance. AB showed the highest relative antibacterial activity against Escherichia coli, S. aureus and Alternaria alternata, reaching 100 % (AB 20 g/L), 100 % (AB 40 g/L) and 19.35 % (7 d incubation), respectively. Moreover, the obtained AB possessed good emulsion stability. These antibacterial AB have broad application prospects in the field of fruit and vegetable preservation.
苯甲酸钠（AB）的不同取代度（DS）是通过琼脂和苯甲酸酐在水溶液中的酯化反应合成的。DS 可以通过调整组成比、pH 值和温度来调节。其化学结构通过傅里叶变换红外光谱（FTIR）和核磁共振光谱（NMR）确定。AB 的 13C NMR 谱表明，取代主要发生在 d-半乳糖吡喃糖的 C-6 位。冷冻扫描电子显微镜（Cryo-SEM）显示 AB 的孔径大于琼脂。AB 的热性能略有下降，但这并不影响其性能。AB 对大肠杆菌、金黄色葡萄球菌和交链孢霉的相对抑菌活性最高，分别达到 100%（AB20g/L）、100%（AB40g/L）和 19.35%（7d 培养）。此外，所得到的 AB 具有良好的乳液稳定性。这些具有抗菌活性的 AB 在果蔬保鲜领域具有广阔的应用前景。
