The effect of rennet paste on soft cheese making and quality was investigated. Two different calf rennet pastes (CRP1 and CRP2) were used. The rennet clotting time (RCT) increased as the fat content of the salted milk increased. Skim milk samples containing 12 % NaCl with CRP2 decreased, compared with the CRP1. The cheeses made by using the different rennets did not differ in their moisture, protein and fat content or in the total nitrogen, which resulted from proteolysis. The cheese produced with rennet CRP2 had the highest lipolysis than the cheese made with CRP1. The FFAs in the soft cheese made with CRP2 rennet paste was higher than the cheese made with CRP1. The value of TVFA increased during cheese ripening. The higher concentration of TVFA might be attributed to higher degree of fat hydrolysis being occurred by residual activity of enzyme and microflora. Fresh cheese showed the lowest thiobarbitutic acid (TBA) value compared to ripened cheese. Cheese produced by CRP2 showed higher TBA values than that of CRP1 cheese sample. There was a remarkable inhibition in the growth of spore forming bacteria and yeasts & moulds. The α1-Icasein band was found in all cheese samples. Sensory quality attributes of cheese were improved with the prolongation of the ripening period. Ripening of cheese resulted in better flavor as well as body and texture.
Raw milk Domiati cheese is the main soft white pickled cheese produced in Egypt. The objective of this study was to assess the microbiological hazards, physiochemical quality and safety of some raw Domiati cheese subtypes including Double Cream, Tallaga, Baramely and Istanbully. The cheese samples were randomly collected from different cheese retailers in Cairo. The results indicated that the protein content and fat content were high in Double cream cheese. The pH value was low in Baramely cheese. Total solid, ash, and EC were high in Istanbully cheese because it is high salt level. Also, results indicated high microbiological hazards. the cheese samples were highly contaminated, having microbial load exceeding the acceptable limits such as: Total bacterial count, Total coliform, Fecal E. coli and yeast & molds. Pathogenic bacteria (Staphylococcus aureus, E. coli O157:H7, Salmonella sp., Shigella sp., Listeria monocytogenes, Bacillus cereus and Campylobacter jejuni) were detected in three cheese samples. Except Istanbully cheese sample were found free of most pathogenic bacteria. A high microbial load of the cheese samples present a public health hazard to the consumers and emphasize the need for improving hygienic standard. Microbiological hazards must be limited to the stander limit of food safety. Raw milk soft white cheese must be manufactured according to hygienic standard.
Nonstarter lactic acid bacteria (NSLAB) have an important role in quality and safety of traditional Baramily cheese (Domiati cheese related type). Therefore, the objective of this study was to isolate and identify NSLAB with potential technological features from traditional Baramily cheese. Thirty-three samples of Baramily cheese randomly collected from retails in Cairo metropolitan area. The samples were characterized by physiochemical, textural profile and microbiological analysis. Ninety presumptive NSLAB (30 Lactobacillus spp. and 35 Enterococcus spp.) strains were isolated on MRS and Kenner-Faecal (KF) Streptococci media; and were characterized for growth temperature, salt tolerance and milk coagulation. All presumptive NSLAB isolates were tolerant to 6.5 % NaCl. Of them, 40 isolates were tolerant to 10.0 % NaCl including 16 presumptive Lactobacillus spp., and 24 presumptive Enterococcus spp. isolates. based on the results, 11 representative isolates with potential technological features were selected for genetic identification using 16S rRNA technique, then were confirmed for growth and acidity development in skim milk within 48 h, and were tested for antimicrobial activity against some food spoilage and pathogenic microorganisms. The eleven isolates were identified as Ent. durans (1), Ent. faecalis (5), Lb. paraplantarum (1), Lb. plantarum (3), and Lb. rhamnosus (1). All isolated strains were confirmed active in skim milk, and some exhibited antimicrobial activity against tested food spoilage and pathogenic microorganisms. Both Lb. rhamnosus and Lb. plantarum were confirmed as the isolates with high activity in milk. Ent. durans and Ent. faecalis exhibited antimicrobial activity against Enterobacer aerogenes and E. coli. However, Lb. plantarum exhibited antimicrobial activity against both Enterobacer aerogenes, E. coli and Ps. aeruginosa. Listeria. monocytogenes, S. typhimurium, and Campylobacter. jejuni showed significant resistance to all tested NSLAB isolates. They can be concluded that the identified NSLAB isolated can be used to standardized and improve the quality and safety of Baramily cheese and other types related to Domiati cheese.
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