Printability of bigel inks as fat analogs: Impact of gelators on structure

Bigels are biphasic systems that mimic the structural and functional properties of animal fat, making them promising adipose tissue analogs for plant-based meat alternatives. This study investigates the impact of gelator selection on the structure and three-dimensional (3D) printing performance of bigels. Formulations included a lipid-based low molecular weight gelator, glycerin monostearate (GMS), or a non-lipidic polymeric gelator, ethylcellulose (EC), in combination with thermally reversible hydrocolloids, sodium alginate (SA) or low acyl gellan gum (GG). The textural, rheological, thermal, and microstructural properties of bigels were evaluated to determine their suitability as 3D-printed adipose tissue analogs. Results demonstrated that GMS bigels formed a bicontinuous structure with higher viscosity, yield stress, and mechanical strength, whereas EC-based bigels exhibited a W/O structure with lower rigidity. GMS bigels effectively replicate the thermal softening of adipose tissue, closely mimicking its behavior under varying temperature conditions. Additionally, GMS bigels with smaller particle sizes demonstrated enhanced long-term structural stability. SA exhibited better printing performance than GG by enhancing self-supporting ability and shape retention after extrusion. GMS-SA resulted in the most structurally stable and printable bigels, characterized by smooth surfaces, strong appearance, and excellent extrusion fidelity. In contrast, EC-based bigels, while printable, demonstrated inferior mechanical properties and weaker structural integrity. These findings highlight the critical role of gelator selection in defining the functional properties of bigels, particularly in optimizing their performance as 3D-printable adipose tissue analogs. This study provides new insights into the formulation of plant-based fat analogs, contributing to the advancement of sustainable meat alternatives.