Microbial production of curdlan in sugar beet molasses medium: Effects on physicochemical attributes of reduced-fat frankfurter sausages

The aim of this study was to optimize the microbial production of curdlan by Paenibacillus polymyxa PTCC 1021 and assess its application in low-fat frankfurter sausage production. Optimization experiments revealed that substituting 50% of the base medium with 25 degrees Brix molasses yielded the highest bacterial growth and biomass, achieving 0.94 g/L curdlan at optimal conditions of 41 degrees C over 72h. Curdlan was then produced in a bioreactor, where a rotation speed of 400 x rpm and an aeration rate of 1vvm resulted in a peak production rate of 1.61 g/L. To confirm successful biosynthesis, FTIR and thermal analysis were conducted. In the final phase, frankfurter sausages were produced, with varying concentrations of thermo-reversible (TRC) and thermo-irreversible curdlan gel (TIRC) (2, 4, and 6 g/kg). Results indicated significant increases in pH and water-holding capacity in curdlan-containing samples compared to the control groups. Cooked loss was lower, particularly with 6 g/kg TRC gel. While curdlan increased hardness and chewiness, lower TIRC gel concentrations showed less hardness than TRC gel. Overall, adding curdlan notably altered sausage color metrics, enhancing L* and b* values while reducing redness (a* values). These findings indicate that curdlan significantly enhances the physicochemical properties of reduced-fat frankfurter sausages, highlighting its potential application in food technology.