Development and Characterization of Protein-Enriched Gluten-Free 3D- Printed Snacks: Implications for Nutritional and Functional Properties

Abstract

Three-dimensional (3D) printing technology, as a form of additive manufacturing, offers an innovative way to design personalized gluten-free foods tailored to specific nutritional and sensory needs. This study focused on creating a gluten-free 3D-printed snack with enhanced nutritional and functional properties by incorporating plant- and microbial-derived proteins into a millet-based matrix. A dough formulation consisting of proso millet flour, almond protein, and yeast protein was prepared and processed using extrusion-based 3D food printing. The rheological properties of the gluten-free dough were analysed to ensure proper flow during extrusion and shape stability after printing. Thermal processing followed to produce ready-to-eat snacks suitable for further evaluation. The enriched gluten-free dough demonstrated favourable rheological behaviour, supporting smooth printing and stable shape retention. The snack contained a high protein content (28.16 g/100 g dry basis of sample) meeting the criteria for the “high protein” nutrition claim in accordance with Regulation (EC) No. 1924/2006. Amino acid analysis revealed a significant increase in essential amino acids (EAAs)—lysine, leucine, isoleucine, tryptophan, arginine, threonine, valine, phenylalanine, tyrosine, and methionine— compared to the control. The total EAA content was 11.78 g/100 g, while non-essential amino acids amounted to 16.93 g/100 g of dry sample. Polyphenolic analysis revealed diverse phenolic acids and flavonoids in various binding forms, with the proportion of free polyphenols being up to ten times higher than esterified and bound forms. The textural properties of the final gluten- free snack remained acceptable, and sensory evaluation indicated improvements in flavour, aroma, and overall acceptability. This research shows that integrating almond and yeast proteins into a millet-based gluten-free formulation successfully enhances both nutritional quality and functional performance of 3D-printed snacks. The findings highlight the potential of combining sustainable protein sources with advanced food fabrication technologies to create clean-label, nutrient-dense, gluten-free, and consumer-appealing functional foods.