THIS STUDY EVALUATED THE INFLUENCE OF STARCH-PROTEIN INTERACTIONS ON THE CHEMICAL PROPERTIES AND DIGESTIBILITY OF A 3D-PRINTED GEL BASED ON SALMON BY-PRODUCT PROTEIN. CHANGES IN THE STARCH-PROTEIN INTERACTIONS OF THE STABLE CORNSTARCH (CS, 15%) AND SALMON PROTEIN ISOLATE (SPI, 4%?12%) PRINTABLE GELS DURING THE IN VITRO GASTROINTESTINAL DIGESTION PROCESS WERE STUDIED BY PRINCIPAL COMPONENT ANALYSIS. PROTEIN-RICH PRINTED GELS INCREASED RESISTANT STARCH CONTENT BY 18.05%. CHANGES IN CHEMICAL PROPERTIES AND THE STARCH-PROTEIN CONCENTRATION OF THE GELS DURING THE DIGESTION PROCESS WERE HIGHLY CORRELATED. THE CS-SPI GELS IN THE GASTRIC AND INTESTINAL PHASES EXHIBITED LOWER ?-HELIX/?-SHEET RATIO AND FLUORESCENCE INTENSITY VALUES, WHEREAS SURFACE HYDROPHOBICITY INCREASED. THIS RESULTED IN MORE ORDERED STRUCTURES WITH A HIGH LEVEL OF MOLECULAR INTERACTION THAT INHIBITED ENZYMATIC HYDROLYSIS. THIS STUDY PROVIDES CRUCIAL INFORMATION ABOUT THE TRANSFORMATIONS OF STARCH-PROTEIN INTERACTIONS DURING THE DI- GESTIBILITY OF 3D-PRINTED FOOD MATRICES AS AN ALTERNATIVE SOURCE OF NUTRIENTS WITH A HIGH NUTRITIONAL QUALITY.

THIS STUDY AIMED TO OPTIMIZE THE 3D PRINTING PARAMETERS OF SALMON GELATIN GELS (SGG) USING ARTIFICIAL NEURAL NETWORKS WITH THE GENETIC ALGORITHM (ANN-GA) AND RESPONSE SURFACE METHODOLOGY (RSM). IN ADDITION, THE INFLUENCE OF THE OPTIMAL PARAMETERS OBTAINED USING THE TWO DIFFERENT METHODOLOGIES WAS EVALUATED FOR THE PHYSICOCHEMICAL AND DIGESTIBILITY PROPERTIES OF THE PRINTED SGG (PSGG). THE ANN-GA HAD A BETTER FIT (R2 = 99.98%) WITH THE EXPERIMENTAL CONDITIONS OF THE 3D PRINTING PROCESS THAN THE RSM (R2 = 93.99%). THE EXTRUSION SPEED WAS THE MOST INFLUENTIAL PARAMETER ACCORDING TO BOTH METHODOLOGIES. THE OPTIMAL VALUES OF THE PRINTING PARAMETERS FOR THE SGG WERE 0.70 MM FOR THE NOZZLE DIAMETER, 0.5 MM FOR THE NOZZLE HEIGHT, AND 24 MM/S FOR THE EXTRUSION SPEED. GEL THERMAL PROPERTIES SHOWED THAT THE OPTIMAL 3D PRINTING CONDITIONS AFFECTED DENATURATION TEMPER- ATURE AND ENTHALPY, IMPROVING DIGESTIBILITY FROM 46.93% (SGG) TO 51.52% (PSGG). THE SECONDARY GEL STRUCTURES SHOWED THAT THE ?-TURN STRUCTURE WAS THE MOST RESISTANT TO ENZYMATIC HYDROLYSIS, WHILE THE INTERMOLECULAR ?-SHEET WAS THE MOST LABILE. THIS STUDY VALIDATED TWO OPTIMIZATION METHODOLOGIES TO ACHIEVE OPTIMAL 3D PRINTING PARAMETERS OF SALMON GELATIN GELS, WITH IMPROVED PHYSICOCHEMICAL AND DIGESTIBILITY PROPERTIES FOR USE AS TRANSPORTERS TO INCORPORATE HIGH VALUE NUTRIENTS TO THE BODY.