ISOLATED NON-STARTER LACTIC ACID BACTERIA USED TO IMPROVE KAREISH CHEESE QUALITY

Document Type : Original Article

Abstract

Lactobacillus caseiand Streptococcus thermophilus werehighly proteolytic activity that collected from Egypt.Streptococcusthermophilusis produced metallo-proteases while Lactobacillus casei
is produced metallo-, serine- and cysteine-proteases. The proteases ofthese isolates are classified as PIII type, which proteolyses S1-, - andg-caseins with optimal pH and temperature of 6.5-7.2 and 37 - 42°,
respectively. Unsalted Kareish cheese is manufactured by traditionalstarter [Lactococcus lactis subsp. lactis and Lactococcus lactis subsp.cremoris(Treatment A) as a control and with goodtechnologicalcharacteristics strains [Lactobacillus casei (Treatment B) andStreptococcus thermophilus(Treatment C)] that mixed with traditionalstarter.After 21 days of cold storage (5±2°C), treatment B had thehighest acidity (2.49 %) and total solids (36.34 %). The protein contentgradually decreased during storage while there was a gradual increasein cheese soluble nitrogen content in all cheese treatments.Treatments B and C suppressed bacterial and fungal growth in cheeseduring all storage period as compared to control (Treatment A). The
sensory evaluation of cheeses showed the best acceptability oftreatment (C) as compared to other cheese treatments (B and A) at theend of storage period with total score of 92.0.

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