[Identification and evaluation of the probiotic effect of isolated lactic acid bacteria in traditional goat cheese]

In order to identify lactic acid bacteria [LAB] associated with traditional goat cheeses and to assess their probiotic effect, chemical and microbiological analysis were carried out on seven products collected from different Lebanese regions: Laban [L], Labneh Ambarise[LA], Labneh Serdalli [LS], Jebneh Darfieh [JD], Keshek [K], Shanklish [Sh] and Labneh Darfiyeh [LD]. These samples were analysed for their pH and acidity. The isolation of lactic acid bacteria was achieved using two selective media, namely MRS and M17 agar. Isolated strains were identified according to morphology, Gram staining, catalase and oxydase, ammonia production from arginine, carbon dioxide production from glucose, growth in MRS broth at 10degree C and 45degree C, salt tolerance [2, 4 and 6.5% of NaCl], sugar fermentation with API [Analytical Profile Index] system methods [50CHL and 20Strep]. The probiotic potential of isolates to inhibit pathogenic bacteria [Salmonella, Staphylococcus aureus and E. coli], their survival at different pH [1, 2, 3 and 7.2], the time needed to reach acidification end point in full and skimmed milk were assessed. Labneh Ambarise and Labneh Darfiyeh had an average pH of 4+/-0.5 and a titratable acidity of 2%+/-0.1 [w/w], while the average pH and titrable acidity of Darfiyeh cheese were 5.22 and 0.62 respectively. The presence of LAB in one year old samples preserved in olive oil could not be detected. Twenty five strains were isolated and identified from different samples, where nine of them belong to Lactobacillus plantarum [L2, Sh2, K2, K3, K4, K5, LS1, LS3 and LS4], three are Lactobacillus paracasei spp. paracasei [Sh3, LS2 and LS5] and five are Leuconostoc mesenteroides spp. dextranicum 2 [JD1, JD2, JD3, JD4 and JD5]; four colonies are suspected to be Lactobacillus casei [L1, Sh4, K1 and K6] and four others are probably yeasts [L3, L4, L5 and L6]. Identified strains showed a capacity to produce antimicrobial substances with maximum inhibition diameters of 20 mm against Salmonella [K1, Sh4, LS1 and JD1], 21 mm and 19 mm for L2 against Escherichia coli and Staphylococcus aureus, respectively. The microorganisms survival rate in simulated gastric juice [SGJ] varied between 50% and 93% at pH 3 [Sh3, K2, LS2, LS5, JD1 and JD3]. Their growth was inhibited at pH 1 [0.05% to 0.08%]; only JD1 and JD3 showed more then 50% of viability at pH 2. The time needed for milk acidification had an average of more than 10 h exceeding the time required by yogurt starter cultures [5 h]. The Jebneh Darfieh sample, rich in Leuconostoc mesenteroides, showed the most interesting characteristics of cell viability at pH 2 [50% for JD1 and JD2] and a maximum of 20 mm of inhibition against Salmonella. It could be used as a natural source of probiotic. The isolates of the samples Laban, Shanklish, Keshek and Labneh Serdalli [L. plantarum and L. paracasei mainly] were more sensitive to high acidity [pH=2], but showed good antimicrobial activity against pathogens. Microencapsulation is probably required to protect them from harsh conditions. Further tests are needed to determine the exact identity of some strains and the nature of secreted substances responsible of the probiotic effects

[Optimisation des conditions de production du hallou demi-ecreme]

The aim of the study was to develop the optimal conditions for the manufacturing of low-fat halloum cheese without significant alterations of the organoleptic attributes. Twenty one experiments were carried out on a factorial design basis to study the effect of various factors on the quality of finished halloum. These include the level of fat [0.05-1.4% in the milk], lecithin [0.04-0.1%], CaCl[2] [0.01-0.02%], temperature [30 +/- 2[degree sign]C], time of coagulation [45-60 min], and pH [6.61-6.78]. For each experiment, samples of milk and resultant cheese were subjected to analysis of moisture, fat-in-dry matter, pH and acidity. The texture of cheese was determined using a penetrometer. Sensory properties of the finished halloum were carried out to evaluate saltiness, bitterness, insipidness, aftertaste, chewiness, sourness and overall acceptance using the profiling method. Physicochemical characteristics and sensory properties demonstrated significant correlations between attributes. The texture is influenced by dry matter of milk [R=0.73, P<0.01] and duration of cooking [R=0.56, P<0.05]. Overall acceptance was significantly correlated to fat [R=0.54, P<0.05], white color [R=0.64, P<0.01], hardness [R=0.61, P<0.01] and chewiness [R=0.48, P<0.05]; and negatively correlated to bitterness [R=-0.67, P<0.01] and aftertaste [R=-0.72, P<0.01]. The optimal conditions to have a low fat halloum was to use a low fat milk [<0.85%], a low coagulation temperature [28 [degree sign] C], a prolonged time of coagulation [60 min] and reduced time of cooking [5-8 min]

[Chemical and microbiological characteristics of Lebanese cheeses of local industeries]

In order to characterize, protect dairy products and develop new probiotics, a survey was conducted amongst 37 dairy factories. Chemical [pH, acidity, DM, protein, fat, soluble nitrogen and free fatty acid] and microbiological [total aerobic bacteria, Coliforms, E. coli, Salmonella, Listeria, and Staphylococcus aureus] analysis were carried out on samples collected from factories [7 Baladi, 22 Akkawi, 18 Double creme and 22 Halloum] of different regions. These cheeses are made by 73% of visited factories. Chemical analysis showed low acidity [0.18 to 0.26%], variable levels of moisture [54 to 70%] protein [19 to 24%] and fat [12 to 18%] except Double crŠme [3.26 +/- 1.78%]. Except 8%, Good Hygienic and Manufacturing Practices [GHP/GMP] are not applied in visited factories. This is confirmed with the high levels of Coliforms, detectable in most varieties at an alarming level [72 a 86%]. Besides, 23-71% of samples were contaminated with E. coli. However, all samples were found free of staphylococcus aureus; Halloum cheese was the only one free of Listeria and Salmonella. The highest off standard for these bacteria was noticed in Baladi cheese where 29% were contaminated with Listeria and Salmonella. Listeria was also found in 10% of Akkawi and 17% of Double crŠme. These results show a violation of the Good Hygienic and Manufacturing Practices [GHP/GMP] by most factories in all visited regions

Safety of fresh produce: bacterial risk assessment of irrigation water and soil

Irrigating fresh produce with contaminated water may increase the bacterial load and subsequently introduce hazards of food poisoning. Bacterial risk assessment through possible pathogenic cross-contamination of soil and river water used for the irrigation of fresh produce was investigated. Various sites on Berdawny and Ghzayel Rivers in Beka'a Valley were selected to determine the quality of their water [based on microbial contamination] for irrigation and then bacterial load and type. Berdawny river sites were heavily contaminated with faecal coliforms and E. coli [average of 4.7 and 2.5 Log 10 cfu/g respectively]. Ghzayel sites [Chamsine and Darzanun] were found to be clear of any contamination indicators. Rawda and Hawsh El Harimeh sites, however, were contaminated with bacteria of faecal origin. The microbial analysis of soil samples taken from nearby farms which were irrigated with water from these rivers indicated that the growing fields were contaminated with the same microbial organisms found in the irrigation water. The contamination level of soil obtained from Rawda and El Hawsh sites [average 4 Log 10 cfu/g] were lower than that of Berdawny sites [average 8 Log 10 cfu/g]. The overall findings suggest that the growing crops in these areas are likely to be contaminated and thereby evaluating the health risk of these crops is needed