Novel soft food gels using beta-lactoglobulin via enzymatic crosslinking as agar gel alternatives

Soft food gels are of high interest for food innovation that can cater to the specific needs of various populations. This study explores the innovative development of soft beta-lactoglobulin (β-LG) gels through a green process that combines heat treatment and transglutaminase (TGase)-catalyzed crosslinking at a moderate pH. The optimal procedure involves heating β-LG solutions, pH 7.5 at 80 °C for 30 min to facilitate protein unfolding and aggregation, followed by TGase catalysis at 50 U TGase/g β-LG. This process produced soft and moist β-LG gels at a low concentration of 5% (w/v). The softness of β-LG gels was characterized through rheological measurements, suggesting a low storage modulus and high frequency dependence. Morphological observations of β-LG gels using TEM showed a loosely arranged network. SDS-PAGE and FTIR analyses indicated the formation of covalent disulfide bonds and isopeptide bonds in β-LG gels through the heat and TGase treatments. The potential of the novel β-LG gels as traditional agar gel substitutes was comparatively analyzed on their textural properties. Both gels showed distinctive jelly-like characteristics, whereas β-LG gels exhibited superior softness and reduced brittleness, positioning them as viable protein-based alternatives to agar gels for various applications in both food and nonfood sectors.