Cream cheese made with exopolysaccharide-producing Lactococcus lactis Impact of strain and curd homogenization pressure on texture and syneresis

Abstract:

This study examined texture, syneresis and microstructure of cream cheese manufactured at curd homogenization pressures of 0.05, 15 or 30 MPa and with three Lactococcus lactis strains differing largely in type and molecular characteristics of their exopolysaccharides (EPS). Cream cheese with non-ropy EPS showed higher firmness and serum retention after curd homogenization at higher pressure, but also larger particles. The presence of ropy EPS, however, resulted in higher yield stress and creaminess, and capsular EPS presumably to higher serum retention of cheese after curd homogenization at 0.05 and 15 MPa. Applying 30 MPa had an opposed effect probably due to lower shear resistance of the ropy and capsular EPS. The cluster analysis revealed two groups of EPS-pressure combinations (0.05/15 MPa for ropy and capsular EPS; 15/30 MPa for non-ropy EPS) which resulted in cream cheese with high firmness and serum retention, and are therefore suggested for application at industrial level.

Conclusion:

This study examined the role of EPS type and curd homogenization pressure in tailoring cream cheese texture, forced syneresis, and microstructure as EPS functionality may be impaired by the shearing step during manufacture. After homogenization at 0 or 15 MPa, ropy EPS of LL-1+ and LL-2A+ contributed to higher yield stress, a more creamy perception and homogeneous microstructure of cream cheese compared to non-ropy EPS of LL-2. Both strains produce also cell-bound EPS which contributed to a high serum retention because of their high water-binding capacity compared to ropy EPS (Mende et al., 2014). The larger hydrodynamic radii determined in molecular and structural analysis of isolated LL-1+ and LL-2A+ EPS were mainly responsible for the improved cream cheese texture, forced syneresis, and microstructure. However, excessive curd homogenization at 30 MPa had an opposed effect which might be explained by the low shear resistance of ropy EPS. Likewise, it is possible that ropy EPS aggregate due to shear-induced separation from proteins (Hassan et al., 2002; Zhang et al., 2016), and therefore they are still able to reduce protein interactions. Non-ropy EPS of LL-2 did not affect protein interactions at 30 MPa and thus the cream cheese had a high firmness and serum retention, but particle growth was induced. Based on cheese stiffness, yield stress, and released serum cluster analysis suggested the following combinations for application at industrial level: curd homogenization pressures of 0 or 15 MPa for ropy and cEPS producing strains, and 15 or 30 MPa for non-ropy EPS producing strains.

References:

Mende, S., Rohm, H., Jaros, D., 2016. Influence of exopolysaccharides on the structure, texture, stability and sensory properties of yoghurt and related products. Int. Dairy J. 52, 57–71.

Hassan, A.N.N., Frank, J.F., Qvist, K.B., 2002. Direct observation of bacterial exopolysaccharides in dairy products using confocal scanning laser microscopy. J. Dairy Sci. 85, 1705–1708.

Zhang, L., Folkenberg, D.M., Amigo, J.M., Ipsen, R., 2016. Effect of exopolysaccharide- producing starter cultures and post-fermentation mechanical treatment on textural properties and microstructure of low fat yoghurt. Int. Dairy J. 53, 10–19.

[140] Surber, G.; Spiegel, T.; Wolfschoon-Pombo, A. F.; Rohm, H.; Jaros, D. Cream cheese made with exopolysaccharide-producing Lactococcus lactis: Impact of strain and curd homogenization pressure on texture and syneresis. Journal of Food Engineering, 308, 110664, 2021.