Characterisation of lactic acid bacteria isolated from artisanal Egyptian Ras cheese

Abstract

-Wild LAB (188 strains) isolated from artisanal Egyptian Ras cheese including Lactococcus (15), Lactobacillus (95), Enterococcus (77) and Pediococcus (1) were characterised for biochemical and production characteristics related to their technological performance. All Lactococcus (subsp. lactis and cremoris) were able to grow at 40 °C and in the presence of 4% NaCl. Six L. lactis subsp. lactis, one strain of subsp. cremoris and 95% of Lactobacillus strains were salt-tolerant, as they were able to grow in 6.5% NaCl. Twenty percent of lactococci, 21% of lactobacilli and 43% of enterococci showed a medium acidification rate, one strain of Lb. delbrueckii subsp. lactis and E. faecium exhibited a fast acidifying ability. Most lactobacilli revealed higher aminopeptidase and autolytic activity when compared with other strains. Twenty-seven percent of tested strains appeared to have antimicrobial activity and the highest inhibitory activity was observed among enterococci (13% of 188 strains). Exopolysaccharides (capsule) were detected in 4.3% of the lactobacilli. Most strains were able to produce a high yield of biomass after growth, showed a good biomass separation and were not affected by lyophilisation treatment. Strains which showed outstanding characteristics were screened for their flavour-forming abilities in milk cultures. Ninety-one strains, 7 Lactococcus, 52 Lactobacillus and 32 Enterococcus, were selected for an application in Ras cheese according to their production and technological criteria: salt tolerance, ability to grow at 40-45°C, acid production, proteolytic activity, flavour and bacteriocin production. These strains are currently being tested in pilot-scale cheese trials to improve Egyptian Ras cheese.

Technological characterization of the natural lactic acid bacteria of artisanal Turkish White Pickled cheese

“…cremoris had relatively low acidifying activity, with values of pH after 6 and 24 h of 6.28 and 5.01, respectively. These results were in agreement with Ayad et al . (2006), who indicated that wild lactococci had the low acidifying activity.…”

“…parabuchneri. Heterofermentative lactobacilli in high numbers have been described by some authors in artisanal cheeses (Estepar et al Vol 61, No 2 May 2008El-Soda et al 2003, Sengül andCakmakci 2003;Sengül 2006;Ayad et al 2006). Haddadin (2005) stated that Lb.…”

CHARACTERIZATION OF Streptococcus thermophilus ASSOCIATED WITH EGYPTIAN DAIRY PRODUCTS

“…The above results show that traditional Egyptian dairy products examined in this study could contain both LAB cocci and lactobacilli. This is consistent with previous findings reported by Ayad et al (2004Ayad et al ( & 2006, who isolated several LAB genera including Lactococcus, Lactobacillus, Enterococcus, Streptococcus and Pediococcus from Domiatti cheese, Ras cheese, Mish, Zabady and Laban Rayeb. The occurrence of S. thermophilus in traditional Egyptian dairy products including Zabady and Mish was also reported by El-Baradei et al (2004.…”

Isolation of Exopolysaccharide – Producing Lactic Acid Bacteria From Traditional Egyptian Dairy Products

“…The above results show that diverse LAB isolates belonging to different species could exist in traditional Egyptian dairy products, which was also reported in previous studies. For instance, Ayad et al (2004Ayad et al ( & 2006 isolated LAB strains of the genera Lactococcus, Lactobacillus, Enterococcus, Streptococcus and Pediococcus from Domiatti cheese, Ras cheese, Mish, Zabady and Laban Rayeb. However, the present results show that Enterococcus isolates were the most frequently isolated LAB from traditional Egyptian dairy products.…”