Selection of microencapsulation method to improve antimicrobial agents production by some lactobacillus species and propionibacterium thoenii in dairy products

The aim of this research is to select the agreeable encapsulation method to improve antimicrobial production from Lactobacillus acidophilus, Lactobacillus reuteri, Lactobacillus rhamnosus and Propionibacterium thoenii. The effect of different organic acid concentrations [1 and 2 w/v], different pH values [3, 4, 5, 6. 7 and 8], different temperature degrees [0, 7, 25, 37 and 45°C] and storage temperature on viability of encapsulated bacteria were investigated. Also, the efficiency of microencapsulated methods [alginate + NaCI, alginate + oil and K-carrageenan] on enhancement of antimicrobial production were studied. Microencapsulation with alginate + NaCI offered greater production in extreme conditions [low pH, low temperature and in the presence of organic acids]. In addition, this method was more effective against pathogenic bacteria by enhancement of antimicrobial production, thus it may be effectively used to increase the safety and the shelf- life of dairy products

use of nigella sativa oil as a natural preservative agent in processed cheese spread

Nigella sativa oil as a natural preservative agent was added at concentrations ratio of 0.1, 0.2 and 0.3% to processed cheese spread. Microbial count, chemical composition, and organoleptic properties of the processed cheese were investigated. The oil used had acid number of 29.5%, saponification value of 176.8% and iodine value of 129.5. Physical properties of the oil were 0.9251 specific gravity, refractive index of 1.472 at 25 degrees, and 0.55 polenske number. The fatty acid composition of the oil were 48.54% linoleic, 38.35% oleic, 13.2% palmitic, 3.25% stearic, 1.9% linolenic and 0.18% myristic acids. Nigella sativa oil had no effect on the chemical properties of processed spread. The treatment of processed cheese spread with sodium bisulfite or Nigella sativa oil at different concentrations led to reduce the microbial groups investigated, the reduction depended upon the concentration of preservative used and the resistance nature of the microbial groups