Effect of Potassium Sorbate And/or Probiotic Bacteria on Spoilage Bacteria During Cold Storage of Soft Cheese

In this study, the effect of potassium sorbate and /or probiotic bacteria on spoilage organisms during manufacturing and cold storage of soft cheese in attempt to improve the hygienic quality of soft cheese have been assessed. Ten batches of white soft cheese were prepared from cowʹs milk containing 5% Sodium Chloride and inoculated with pseudomonas fluorescens, the first batch was a control (containing no probiotic bacteria or potassium sorbate),the following four batches (2 - 5) containing different concentrations of potassium sorbate (0.02, 0.05, 0.1 and 0.2 %). The sixth batch contains Bifidobacterium longum, the rest four batches (7-10) containing both potassium Sorbate at concentrations of 0.02, 0.05, 0.1 and 0.2 and Xongum. The cheese batches were examined physically and bacteriologically at zero time, after 3, 9, 12, 18, 21, 27 and 30 days, The reduction percent of Pseudomonas fluorescens count at the end of storage period (30 days) were 93.6, 94.6, 97.78 and 99.5 for cheese containing potassium sorbate at concentrations of 0.02, 0.05, 0.1 and 0.2%, respectively. While the reduction percent in case of cheese containing B. longum only was 96.25%. But in case of combined addition of both Potassium Sorbate andS. longum the reduction percent were 96.39, 97.6, 99.40 and 99.47% for 0.02, 0.05, 0.1 and 0.2% added Potassium Sorbate andS. longum, respectively. In the same time, in the control batch, the reduction percent of Pseudomonas fluorescens count at the end of storage period (30 days) was 87.50%. A significant (p < 0.05) inhibition of growth of Pseudomonas fluorescens in batches (9,10) containing both potassium sorbate 0.1 %, 0.2% and B. longum was observed all over the experiment. Sorbate above 0.1% although highly effective, cause unobjectionable sweet flavor, a condition that can acts as an effective check against excessive use of the preservatives. In conclusion the combined addition of potassium sorbate at concentration of 0.1% and B. longum had a great inhibitoiy effect up on existing microorganism and also improved the organoleptic quality of cheese.