南开大学医学院王硕教授课题组在Food Chemistry发表题目为“Effects of saccharide type and extended heating on the Maillard reaction and physicochemical properties of high-solid gelatin gels”研究论文（糖类种类及加热时间对高固形明胶美拉德反应及理化性质的影响）。摘要： 本研究深入研究了高固体明胶-糖混合物中的美拉德反应 (MR)，该混合物由 8% 和 72% 的阿洛酮糖、果糖或低聚果糖组成，在凝胶化之前经过不同时间（0-60 分钟）的热处理。研究了凝胶的物理化学性质，包括颜色、化学成分、蛋白质交联、机械强度、体外消化率和抗氧化活性。在 pH ∼5.5 和中等水活度（0.6–0.7）下，通过糖降解和糖胺相互作用观察到快速褐变，长时间加热会加剧褐变。糖的 MR 反应性顺序为：AL > FRU > FOS。鉴定出特征产物（MRP，例如 a-二羰基、5-羟甲基糠醛和高级糖基化终产物），单糖和寡糖的 MRP 光谱差异很大。MR 诱导的蛋白质糖基化和交联对凝胶强度和体外蛋白质消化率表现出一定的负面影响。此外，所有明胶-糖混合物均表现出增强的抗氧化性能，其中明胶-AL 混合物表现出最高的自由基清除率。研究结果：3.1 明胶-糖混合凝胶的显色Fig. 1. Appearances (A) of gels prepared with 8% gelatin and various levels of allulose, fructose, and fructooligosaccharides (FOS) and the browning index of high-solid gels with different duration of thermal treatments (B).3.2. 底物的消耗和MRP的形成3.2.1. 还原糖和游离胺的消耗Fig. 2. Consumption (%) of reducing sugars (A) and free amine (B) in high-solid gelatin-saccharide mixtures with 8% gelatin and 72% saccharides as a function of hold time in a 95 °C incubator, and the molar ratios* between the loss of reducing sugars and that of free amines (B-inset). UV-visual absorbances of diluted gelatinsaccharide mixtures prepared from the high-solid gelatin-saccharide mixed gels at 294 nm (C, 20-fold dilution) and 420 nm (D, 10-fold dilution).3.2.2. 明胶-糖混合凝胶中 MRP 的定量Fig. 3. Concentrations of selected Maillard reaction products in high-solid gelatin-saccharide gels3.3 蛋白质糖化对凝胶特性的影响3.3.1. MR引起的分子量分布变化Fig. 4. Molecular weight distribution of proteins in gelatin-saccharide mixed gels processed with different hold time in 95 °C incubator by reducing SDS-PAGE (A) and corresponding densitometry results (B-G, taking those of gelatin-allulose mixtures as examples).3.3.2 糖化对明胶-糖混合物粘度和凝胶性质的影响Fig. 5. Complex viscosity of gelatin high-solid gelatin-saccharide mixtures at 60 °C (A), storage modulus (G') after 30-min at 22°C (B) and gel hardness after 24 h of setting at 22 °C (C), as a function of high-temperature incubation time.3.4. 体外蛋白质消化和水解物的抗氧化特性3.4.1. 肽的水解度和分子量Fig. 6. Degree of protein (100 mg) hydrolysis in gelatin-saccharide mixed gels after in-vitro gastrointestinal digestion.Fig. 7. Molecular weight (MW) distribution of the hydrolysates from in-vitro gastrointestinal digestion characterized by Tricine-SDS-PAGE (A) and GPC (Bsingle bondD), and the weight percentages of different MW fractions based on the GPC results (E-G).3.4.2. 抗氧化特性Fig. 8. Antioxidant activities of the saccharides (A, 25.7 mg/mL in water) and the hydrolysates from gelatinsaccharide mixed gels (B).原文链接：https://doi.org/10.1016/j.foodchem.2024.140249
