Effect of ropy and capsular exopolysaccharides producing strain of Lactobacillus plantarum 162RM on characteristics and functionality of fermented milk and soft Kareish type cheese

Abstract

The contribution of selected ropy and capsular Lactobacillus plantarum 162RM on texture of fermented 
milk as well as on the functionality of kareish cheese was established in this study. The cell suspension 
of this strain was used in combination with commercial starter cultures MY900 (Lactobacillus 
delbrueckii ssp. bulgaricus and Streptococcus thermophilus) and MM100 (Lactococcus lactis ssp. 
lactis, Lactococcus lactis ssp. cremoris and Lactococcus lactis ssp. diacetyllactis) obtained from 
Rhodia Food to manufacture fermented milk and Kareish cheese respectively. The final pH of fermented 
milks manufactured with the combination of starter MY900 and different concentration of strain L. 
plantarum 162RM were not significantly different. Fermented milk hardness, consistency, and 
adhesiveness increased significantly when 8 % (V/V) of strain Lactobacillus plantarum 162RM was 
used. This strain produces exopolysaccharides (EPS), which by attaching to the casein matrix 
increases and improves the texture characteristics of fermented milk. The Experimental Kareish Cheese 
(EKC), made by pairing commercial starter MM100 with 8% (v/v) of L. plantarum 162RM were also 
compared to Control Kareich Cheese (CKC) in terms of their moisture content and textural properties. 
The EKC showed the greatest moisture retention and the use of ropy and capsular strain of L. 
plantarum 162RM affects significantly some textural properties of EKC cheese, relative to the control. 
The CKC samples were gummier and more chewy than the EKC fresh samples. It is therefore evident 
that, used in appropriate amount, this strain can increase moisture content in low fat Kareish cheese 
leading to improvement of textural properties.