Effect of Spirulina platensis on the structure and aggregation of gluten proteins to improve texture and physiochemical properties of wheat noodles

Spirulina is a well-known nutritional food additive and texturizing agent of wheat-flour products. However, the effect of different concentrations of Spirulina powder on the gluten aggregation behavior and its associated mechanism had not been elucidated. To understand this mechanism, physiochemical and structural changes of wheat noodles in response to Spirulina addition was investigated in this study. Results showed improved gluten aggregation and strengthening of its fine structure due to Spirulina addition. It significantly increases the hardness, elasticity, and chewiness of noodles (p < 0.05). Noodles with 2% Spirulina (S2) had most acceptable textural profile, represented by 5963.13 gf chewability and 6937.14 gf hardness. S2 noodles also got higher scores for taste, viscoelasticity, and palatability as compared to control, S3, and S4 noodles. Structural changes indicated 39.30% and 13.55% decrease in a/(3- and y-gliadin contents respectively along with 40.31% and 13.79% increase in HMS and B/C-LMS proteins subunits of S2 noodles. Disulfide bond formation and increase in the proportion of high molecular weight components of aggregates in wheat gluten found to prompt crosslinking aggregation of protein macromolecules. Regulation of -SH/-SS exchange reaction and -SH oxidation reaction along with increase in non-covalent interactions (e.g., hydrogen bonding, hydrophobic interactions) stabilized and enhanced the structure of gluten protein network. Furthermore, increase in (3-sheet structure by the reduction of (3-turns and random coils structure of gluten proteins positively changed the spatial conformation of gluten protein to provide much needed elasticity and chewability. This study provides a comprehensive molecular basis for texturizing role of Spirulina.