Beijing Laboratory for Food Quality and Safety, College of Food Science and Nutritional Engineering, China Agricultural University, Beijing, China.
Department of Food Science, Nutrition and Health Promotion, Mississippi State University, Starkville, Mississippi, USA.
J Food Sci. 2024 Jul;89(7):4389-4402. doi: 10.1111/1750-3841.17107. Epub 2024 Jun 21.
Previously, we showed that water extract (soymilk, except pH was increased to 8 from 6.5) of whole soybean could be used directly as a raw material for producing edible soy films by deposition of the film-forming solution (soy extract with enhancers). However, the strength of such soy films needed improvement because they were weak. The purpose of this study was to investigate how transglutaminase (TG) cross-linking reactions and film enhancers, including pectin (low- and high-methoxyl pectin), whey protein isolate (WPI), and soy protein isolate (SPI), improve the physical properties of soy films. Soy films prepared with TG had tensile strength (TS) of 3.01 MPa and puncture strength (PS) of 0.78 MPa, which were higher by as much as 51% and 30% than that of soy films without TG treatment, respectively. Pectin showed significant effects on the mechanical properties of TG-added soy films in terms of TS, PS, and % elongation. On the other hand, only TS and PS were increased by the addition of WPI or SPI. Heat curing had a significant effect on soy film's physical properties. TG treatment significantly reduced film solubility when soaked in water and various levels of acid (vinegar) and base (baking soda) solutions. Under the experimental conditions of 35 unit TG and 28 min of reaction, the degrees of cross-linking were evidenced by the disappearance of individual protein subunits, except the basic subunit of glycinin, and the reduction of 21% of lysine residues of the proteins. HIGHLIGHTS: Edible soy films were made with transglutaminase and about 21% lysine cross-linked. The mechanical strength of soy films was increased by incorporating film enhancers. Transglutaminase enhanced the mechanical properties of soy films.
先前，我们表明，全豆的水提取物（豆浆，除了 pH 值从 6.5 增加到 8 之外）可直接用作生产可食用大豆薄膜的原料，通过成膜溶液（含增强剂的大豆提取物）的沉积。然而，由于这些大豆薄膜较弱，因此需要提高其强度。本研究的目的是研究转谷氨酰胺酶 (TG) 交联反应和薄膜增强剂（包括果胶（低甲氧基果胶和高甲氧基果胶）、乳清蛋白分离物 (WPI) 和大豆蛋白分离物 (SPI)）如何改善大豆薄膜的物理性质。用 TG 制备的大豆薄膜的拉伸强度 (TS) 为 3.01 MPa，穿刺强度 (PS) 为 0.78 MPa，分别比未用 TG 处理的大豆薄膜提高了 51%和 30%。果胶在添加 TG 的大豆薄膜的机械性能方面，如 TS、PS 和伸长率，均有显著效果。另一方面，仅添加 WPI 或 SPI 可提高 TS 和 PS。热固化对大豆薄膜的物理性能有显著影响。TG 处理显著降低了薄膜在水中和不同水平的酸（醋）和碱（小苏打）溶液中的溶解度。在 35 个单位 TG 和 28 分钟反应的实验条件下，除了伴大豆球蛋白的碱性亚基外，个别蛋白质亚基的消失和蛋白质中赖氨酸残基减少 21%，表明交联程度。要点：用转谷氨酰胺酶和大约 21%的赖氨酸交联制成可食用的大豆薄膜。通过加入薄膜增强剂，提高了大豆薄膜的机械强度。转谷氨酰胺酶增强了大豆薄膜的机械性能。
