κ-Carrageenan masking bitterness perception in surimi gels containing potassium chloride-based salt substitutes: Gel properties, oral processing, and sensory evaluation.

κ-Carrageenan (CG) was employed to mask the bitterness induced by 50% KCl in surimi gels to achieve salt reduction and gel performance improvement. The combination of KCl and CG (KCl + CG) yielded the increased textural characteristics and water-holding capacity (WHC) of surimi gels and facilitated the transition of free water to immobilized water. In addition, the KCl + CG supplement increased the turbidity and particle size of myofibrillar protein (MP) sols but decreased the surface hydrophobicity in a dose-dependent manner. The hydrophobic interactions and disulfide bonds played crucial roles in maintaining the stability of MP gels. The specific binding of potassium ions to the sulfate groups of CG limited the release and diffusion of potassium ions from the surimi gels during oral processing, effectively masking the bitterness perception and maintaining the saltiness perception. This study provides a promising strategy to reduce the utilization of sodium salt in surimi products.

Experimental Study of Fiber Pull-Outs in a Polymer Mortar Matrix.

In order to study the influence of vinyl acetate-ethylene copolymerization emulsions on the bonding performance of fiber and mortar, mortar materials with different polymer contents were prepared. The optimal mix ratio of the matrix was obtained using a pull-out test with a 0° inclination angle. On this basis, polypropylene fibers and alkali-resistant glass fibers were set at different burial depths (6 mm, 12 mm, and 18 mm) and different burial angles (0°, 30°, 45°, and 60°). The load-displacement curves of two types of fibers pulled out from the polymer mortar were obtained. The test results show that polymer contents of 3% and 5% increase the peak pull-out loads of glass fibers and polypropylene fibers by 16.28% and 30.72% and 7.41% and 27.11%, respectively. When the polymer content is 7%, the peak pull-out load decreases by 1.31% and 24.26%, especially for polypropylene fiber, which significantly weakens the bonding performance between the matrix and the fiber. The pull-out load of glass fibers and polypropylene fibers increases with the increase in the buried depth, and both show tensile failure at 18 mm. As the embedding angle increases, the pull-out load of polypropylene fibers decreases continuously, while the glass fiber shows a higher pull-out load at 30°.