Effect of Using Probiotic Bacteria as Adjunct Culture in Domiati Cheese Making

Abstract

The composition and quality of probiotic Domiati cheese were studied during 90 days of ripening in brine. Six cheese treatments were made using different types of cultures, which are: C (Control): Lactococcus lactis subsp. lactis and Lactococcus lactis subsp. cremoris, T1: as control + Lactobacillus casei, T2: as control +Lactobacillus acidophilus, T3: as control + Lactococcus lactis biovar diacetylactis, T4:Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus and T5:Lactobacillus acidophilus, Bifidobacterium bifidum and Streptococcus thermophilus. A gradual decrease in moisture content was observed as pickling proceeded. Titratable acidity, salt and fat content continuously increased as storage proceeded in all treatments. The soluble nitrogen and amino nitrogen were higher in the probiotic cheese, compared with the control. Enumeration of lactic acid bacteria (LAB) increased up to 45 days of storage and started to decrease with prolonging the storage period. The highest numbers of total bacteria and LAB were detected in T1 and T4, respectively, at the end of the storage, while the lowest was found in T5and T3, respectively. All fresh cheese treatments were found completely free of yeasts and moulds, while it started to appear after 15 days of storage. Absence of coliform bacteria was detected in all treatments. Higher overall scores were achieved in all treatments with added probiotic bacteria compared with control at the end of the storage period. Using probiotic bacteria as adjuncts enhanced the quality and improved the organoleptic properties of the resultant cheese.