Characterization of bacteriologically acidified feta cheese using soy protein isolate in different substitution percentages: rheological, microbiological and sensory properties

Soy proteins are used in foods as non-dairy alternatives and they play significant role in human health. The use of different concentrations of soy protein isolate (SPI) (0-6% w/v dry basis) in the development of bacteriologically acidified feta type (BAF) cheeses applied with milk protein concentrate (MPC) was investigated during 45 days of storage. The results showed that substitution of MPC by SPI increased acidity and the time of coagulation. With an increase in the SPI concentration, the viscoelastic behavior of all samples demonstrated the higher GMODIFIER LETTER PRIME compared to G", showing a solid-like behavior of the manufactured samples. The addition of SPI led to the reduction of GMODIFIER LETTER PRIME, G" and texture parameters (hardness, cohesiveness, gumminess and springiness). The images of microstructure indicated a more open protein network and weaker structure in BAF cheeses fortified with high levels of SPI. Microbiological results showed that the use of MPC and SPI was able to obtain a matrix that could provide a protection to the starter bacteria. In conclusion, MPC can be substituted by SPI to the rate of 3% without adversely effecting on the sensory properties of BAF cheese.