Physicochemical properties of 3D bio-ink prepared with beef, pork, and fish gelatin

In this study, we analyzed the physical and chemical properties of bio-ink prepared using various types and ratios of animal-based gelatin. The pH analysis revealed that as the gelatin ratio increased, the pH decreased, with fish gelatin samples showing the highest pH values (p < 0.05). The color measurements indicated that the lightness (CIE L*) of the 4% gelatin sample was higher than that of the other ratios (p < 0.05), while redness (CIE a*) increased with higher gelatin ratios, and yellowness (CIE b*) was significantly higher in beef gelatin samples (p < 0.05). Viscosity measurements showed that initial viscosity increased with higher gelatin ratios, with pork gelatin exhibiting the highest viscosity. Printability results demonstrated that 4%, 12%, and 20% gelatin samples could not form structures; however, only pork gelatin formed scaffolds up to 0.5 cm in height. Structural property analysis revealed that pork gelatin samples had rough surfaces, and the 20% pork gelatin sample showed significantly higher grid size and gel strength (p < 0.05). Pearson correlation analysis indicated a strong positive correlation between gel strength and viscosity (correlation coefficient 0.88) as well as between grid size and gel strength (correlation coefficient 0.89). In conclusion, the type and ratio of gelatin significantly influence the pH, color, viscosity, printability, and structural properties of bio-ink, suggesting that using pork gelatin powder is suitable for 3D bio-ink production considering stable structure formation.