Effect of different immobilization media on breakdown of whey proteins by Streptococcus thermophilus

Abstract

Objective: In this study, we aimed to compare the efficiency of different immobilization media to facilitate breakdown of whey proteins by Streptococcus thermophilus (S. thermophilus). Materials and Methods: S. thermophilus was isolated from yoghurt. High-protein whey powder was present in fermentation media and two-phase dispersion technique was used for immobilization of S. thermophilus in agar, agarose and κ-carrageenan. Total protein after fermentation of whey proteins with S. thermophilus in different media was measured. We have also performed sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) analysis to observe changes in individual whey proteins after fermentation in different media. Results:Total protein concentration showed a significant decrease at the end of 24 hours of fermentation in all media. SDS-PAGE results showed that the amount of both α-lactalbumin and β-lactoglobulin were reduced in all immobilization media compared to control. The effect of κ-carrageenan was considerably higher compared to other media. Conclusion:Our results showed that immobilization in κ-carrageenan increased the breakdown of whey proteins by S. thermophilus and can be used to increase fermentation efficiency