Exopolysaccharides and Texture of Yogurts

Project entitled:

Use of Exopolysaccharides in Acidic Dairy Products

Summary

In Canada, several yogourts are produced containing commercial polysaccharides (PSs) as stabilizers. Bacteria that produce exopolysaccharides (EPSs) are also increasingly used in yogourt production due to their ability to improve its texture, viscosity and water retention. Until now, studies on the role of EPSs pertained to systems that didn’t contain commercial PSs. The proposed approach was to 1) determine the types of interactions that occur between EPSs and PSs in model dairy systems and in yogourt, 2) verify the biocompatibility of strains and compare yogourts with and without EPSs, and 3) evaluate the impact of the composition of the milk mixture and the production parameters on the rheological properties of yogourts. Our work confirmed that there is no direct correlation between the amount of EPSs and the resulting improvements. The structure of EPSs (charge, stringy nature) and their interactions with molecules in the environment influence their ability to modulate the sensory properties of yogourts. A model dairy system was developed and makes it possible to study the effect of proteins and EPSs on the structural organization of yogourt. Certain EPSs, although they significantly modify the structure of yogourt (marked phase separation), yield more firm yogourts without syneresis, proving the importance of the structural characteristics of each EPS. Strain pairs that produce biocompatible EPSs act in synergy to improve the properties of yogourts. This project therefore offers considerable opportunities for improving the quality of fermented dairy products and developing new products.