The effect of exopolysaccharid - producing starters on the proteolysis and lipolysis of the ultrafiltered white cheese

The effect of exopolysaccharide producing (EPS+) starter culture on the proteolysis and lipolysis of the ultrafiltered white cheese was investigated. Four treatment of UF white cheese were produced: C1، with EPS-producing starter culture Y 8. 86 F، C2، with EPS-producing starter culture L904، C3، with EPS-producing starter cultures (L904 and Y 8. 86 F) and control samples with commercial starter culture DELVO-TEC. Cheese samples were ripened at 8-12°C for 60 days. Assessment of proteolysis in cheese samples was investigated by determination of soluble nitrogen (SN) at pH= 4. 6، tricholoracetic acid soluble nitrogen (TCA-SN) and urea-polyacrylamide gel electrophoresis and assessment of lipolysis were investigated by determining acidity index. The results showed that amount of SN، TCA-SN and acidity index in all cheeses increased progressively during ripening. The amounts of SN and TCA-SN in EPS+ cheeses were higher than control. The urea-PAGE electrophoresis showed that EPS producing starter culture was effective in the s1-casein break down in UF white cheese. The amount of acidity index content in cheese samples containing EPS-producing starter cultures and control cheese were not significantly different (P>0. 05).