Department of Food Science and Technology, School of Agriculture, Shiraz University, Shiraz, Iran.
J Texture Stud. 2023 Oct;54(5):720-735. doi: 10.1111/jtxs.12761. Epub 2023 Apr 27.
Effects of different pH values (4-7) and whey protein isolate (WPI) concentrations (0.5-1.5%) were evaluated on physical, mechanical, and rheological properties of cold-set alginate-based soybean oil hybrid emulgels. The pH value changes were more effective than WPI concentration changes on emulgel properties. According to syneresis and texture profile analysis results, 1% WPI was selected as the optimum concentration. The XRD analysis showed that calcium alginate (CA) emulgel at pH 6 had a different peak at 2θ of 14.8°, likely indicating the highest amount of ion-bridging and maximum number of junction zones. The homogeneity of CA and CA + WPI emulgels (determined by image entropy analysis) decreased by pH reduction from 7 to 4, which can be related to acid-induced intermolecular interactions between alginate chains. The rheological properties of CA and CA + WPI emulgels revealed predominant elastic character (G' > G'') at different pH values. Creep test results showed that the relative recovery of emulgel prepared at pH 7 and 5 was 18.10 and 63.83%, respectively, suggesting pH reduction contributed to increase in the elastic component of material. The findings of this study can be applied for developing structured cold-set emulgels as solid fat replacers in meat and dairy products.
不同 pH 值（4-7）和乳清蛋白分离物（WPI）浓度（0.5-1.5%）对冷凝胶化海藻酸钠-大豆油混合乳剂的物理、机械和流变性能的影响。pH 值变化比 WPI 浓度变化对乳剂性能的影响更大。根据离水收缩和质地分析结果，选择 1%的 WPI 为最佳浓度。XRD 分析表明，pH 值为 6 的藻酸钙（CA）乳凝胶在 2θ 处有一个不同的峰，可能表明离子桥接的数量最多，连接区的数量最多。CA 和 CA+WPI 乳凝胶的均匀性（通过图像熵分析确定）随着 pH 值从 7 降低到 4 而降低，这可能与酸诱导的藻酸盐链之间的分子间相互作用有关。不同 pH 值下 CA 和 CA+WPI 乳凝胶的流变性能均表现出明显的弹性特征（G'>G''）。蠕变试验结果表明，在 pH 值为 7 和 5 下制备的乳凝胶的相对恢复率分别为 18.10%和 63.83%，这表明 pH 值降低有助于增加材料的弹性成分。本研究的结果可应用于开发作为肉类和乳制品中固体脂肪替代品的结构化冷凝胶化乳剂。
