Sulfatase-induced in situ gelation of κ-carrageenan provides an enzyme-based texturizing solution for plant-based milk systems

Carrageenans are essential texturizers in various dairy products, where they form elastic gel networks through specific interactions with casein micelles, enabling effective structure formation even at low concentrations. Plant-based milk alternatives on the other side, such as almond- or oat-based products, recently experience a rising consumer demand, but are devoid of these protein–polysaccharide interactions, which poses major challenges for their efficient texturization. Consequently, new mild, adaptable, and label-friendly gelation strategies are required to achieve desirable texture and stability in such systems. Here, we present an enzymatic approach to trigger gel formation in non-dairy matrices using the carrageenan sulfatase CaCgS1 from Cellulophaga algicola DSM 14237. The enzyme catalyzes the desulfation of κ-carrageenan to a κ/β-hybrid carrageenan under mild conditions, which triggers the gelation of the reaction product in-situ and yields a homogenous hydrogel with enhanced gel strength and thermal stability by an increased helical aggregation activity of the modified polymer chains. The increased gel strength relies exclusively on the cleavage of sulfate groups without the need to alter the ionic composition or increase the polymer concentration. Applied to plant-based milk formulations, this process enables the generation of homogeneous, stable textures at low polymer concentrations. The concept provides a novel method for structuring plant-based foods and expands the application scope of enzyme-induced gelation in modern food design, and beyond. • The enzymatic desulfation of κ-carrageenan to β-carrageenan by a sulfatase is a new concept to trigger in-situ gelation. • The enzymatic desulfation presents the exclusive driver for gelation. • The resulting κ/β-hybrid carrageenan forms homogeneous, thermo-reversible gels with increased strength and thermal stability at low polymer concentrations without the addition of cations. • The concept of sulfatase-induced gelation of κ-carrageenan was successfully applied for the carrageenan-based in-situ generation of almond- and oat-milk gels.