Introduction: Lactic acid bacteria (LAB), as the main dairy starters, play an essential role in the production of volatile compounds such as proteolytic and lipolytic enzymes involved in cheese processing, suppression of pathogenic microorganisms, formation of curdling tissue, and creation of a fresh acidic flavor.Materials and Methods: In this study, the LABs were isolated from fourteen samples of traditional cheeses in different part of Iran. The isolates with the highest cheese production capacities were selected and subsequently various factors including pH and temperature were evaluated on their activity. Besides, the viability of strains, which were used to produce traditional cheeses, under microencapsulation and gastric simulation conditions was also investigated. Finally, the best LAB strains (BCC7 and BCC10), with desirable characteristics for cheese production, were molecularly identified by using the 16srDNA test.Results: This study showed that the survival rate of BCC7 and BCC10 isolates microencapsulated with sodium alginate/chitosan were higher than free cells in the storage condition of -80 °C after six weeks by 23.50% and 20.78%, respectively. Moreover, the quantification of the activity of BCC7 and BCC10 strains at a temperature of 4 °C yielded 11 107 CFU/ml and 9 107 CFU/ml, respectively; exhibiting a greater activity than that observed at a temperature of 28 °C. Furthermore, the preservation of their morphological and biochemical properties was observed.Discussion and Conclusion: The present study determined the sequences of the most efficient lactic acid strains, and subsequent analyses indicated that the BCC7 and BCC10 strains isolated from native cheese samples, were corresponded to Enterococcus faecium strains SKL-4 and 276-18, respectively. Therefore, these two strains are good candidate to introduce to the market as high-quality starters for dairy industries.

The influence of the type of lactic starter inoculation on the physicochemical and sensory properties of Iranian white cheese was investigated. Five treatments of starters were examined as follows: A) Lactobacillus casei 01+ aromatic mesophile CH-N-01 (1:1): B) Aromatic mesophile CH-N01 + thermophile CH-1 (1:1): C) Thermophile CH-1; D) Thermophile CH-1 + mesophile 54 (1:1); E) Mesophile 54. The cheeses were analyzed for sensory characteristics moisture, pH, total protein, soluble nitrogen, acid degree value and hardness. Cheese samples treatments were taken in a completely randomized design. The results indicated that the type of starter bacteria and storage time had a significant effect on composition and hardness. The pH value in all treatments dropped drastically in such a way that curds made in intreatments B, C, and D reached their lowest pH during manufacturing whereas those made in treatments A and E reached their lowest pH during storage and ripening (P<0.01). The soluble nitrogen in treatment A was greater than all other treatments due to higher proteolytic activity. Results from acid degree value revealed that the contribution of lipolysis in such type of cheese was less than proteolysis but mesophilic starters particularly treatment A, gave higher value of lipolysis. The hardness of all cheeses decreased during storage and ripening. Sensory evaluation scores were the highest for starters A and B cheese (P<0.01). Thus, a combination of combination of combination of commercially available mesophilic starters and Lactobacillus casei subsp. casei might be considered appropriate for Iranian white cheese production.

The effect of a selected autochthonous starter culture made up by Streptococcus thermophilus, Lactobacillus delbrueckii subsp. lactis and Lactobacillus helveticus on the microbiological and physicochemical properties of Pecorino Romano cheese during ripening was investigated. The suitability of the experimental starter culture was tested at industrial scales in cheese-making trials of Pecorino Romano. Pecorino Romano cheese manufactured by use of scotta-fermento served as control. The lactic microflora increased significantly in experimental cheeses as compared to the control and this was also accompanied by a substantial decrease of spoilage microorganisms in experimental cheeses. Free amino acids (FAAs) were more abundant in experimental cheeses, arginine+Y-aminobutyric acid and leucine in particular. These differences could be likely due to a different enzymatic activity of the selected starter culture as compared to the scotta-fermento used in the control trials. Oleic (C18: 1), palmitic (C16: 0), butyric (C4), stearic (C18: 0) and myristic (C14: 0) acids were the most abundant Free Fatty Acids (FFAs) detected in both brand of cheeses at the end of ripening. Overall, the level of FFAs in experimental and control cheeses did not show significant differences, even if the average values in experimental cheeses were always slightly higher than those recorded for the control. Moreover, the average content of FFAs of Pecorino Romano was found the lowest when compared with the other Sardinian PDO cheeses; most likely the high content of sodium chloride and the low aW of Pecorino Romano influenced all the lipase activities, even those present in the rennet paste. Despite this, the employment of the selected starter culture revealed useful to improve the physico-chemical features of Pecorino Romano while preserving its tipicity.

Aim and Background: The development of molecular methods such as RAPD-PCR and 16Sr-RNA sequencing has facilitated the identification and evaluation of microbial diversity of complex microbial environment like fermented food. The aim of this study is identifying and genotyping of different lactic acid bacteria genius and species involved in maturation of traditional Taleshi Cheese.Methods: About 54 wild isolates on MRS and M17 mediums were selected and analyzed by culture dependent RAPD-PCR technique. Gel patterns derived by randomly designed M13 and D8635 primers clustered based on Pearson product moment correlation coefficient and UPGMA via MVSP software.16SrRNA sequencing has been used for species identification.Results: The results revealed dominate non-starter lactic acid bacteria among isolates belonged to Lactobacillus genus including paraplantarum, curvatus, Sakei, paracase species following by Streptococcus gallolyticusand Enterococcus faecalis / Enterococcus faecium.Conclusion: The results showed that RAPD-PCR and 16SrRNA sequencing were useful and rapid tools for grouping, strain discrimination and identification of lactic acid bacteria. Also, obtained 26 different genotypes represented a wide genetic diversity in this type of traditional cheese.

Tragacanth gum and EPSs have properties that they can be fat replacers in cheese. The effect of tragacanth gum and EPS producing starter on physicochemical, textural and microstructure properties of low-fat cheddar cheese was investigated during ripening. Cheddar cheese was produced in 5 treatments, including: low fat and full fat control, containing 0.06 % tragacanth gum, containing EPS producing starter and containing combination of 0.06 % tragacanth gum and EPS producing starter. Samples were vacuum packed and stored for 6 months in 6 ± 1oC. The results of ANOVA showed that with addition of tragacanth gum, dry matter and fat in dry matter of cheeses decreased and salt and cheese production yield increased in comparison to full- fat control sample (P<0.05). But addition of EPS producing starter had no significant effect on these properties. Regarding the texture analysis results, EPS producing starter increased hardness and cohesiveness considerably in comparison to full- fat control cheese (P<0.05). But the effect of tragacanth gum on TPA parameters was not significant (P>0.05). In images of samples containing tragacanth gum obtained by scanning electron microscopy, a protein matrix with many holes was observed while the samples containing EPS producing starter, had more homogeneous structure and samples containing both fat replacers, were between two conditions. The results of sensory evaluation also showed that adding of tragacanth gum and EPS producing starter had no significant effect on sensory factors (P>0.05). The results of this research showed that tragacanth gum and EPS producing starter can be used as fat replacers with desirable textural properties in cheddar cheese production.

The main objective of this study was to determine the effect of attenuated adjunct culture of lactobacillus plantarumon the lipolysis of UF-white cheese as measured by acid degree value, the fatty acids profile, physicochemical, microbial and sensory characteristics during ripening. The results showed that, treated UF cheeses exhibited no significant (p>0.05) differences in chemical composition (dry matter, fat, salt and pH) in comparison with the control UF cheeses throughout 60 days of ripening. Total bacterial count and mesophilic lactobacillus count in the UF cheeses using attenuated adjunct starter were significantly (p<0.01) higher than the control cheeses after 45 days of ripening. The results of fatty acid profiles revealed that due to increasing of the lipolysis in the first 30 days of ripening, the samples containing attenuated adjunct lactobacillus plantarum had significantly (p<0.01) lower percentages of fatty acids with medium and short chains (C4:0 -C14:0) in comparison with the control cheeses while the percentage of fatty acids with long chains (C16:0 -C18:3) increased. Acid degree value, as indicated by total free fatty acids was significantly (p<0.01) higher in cheeses using attenuated adjunct lactobacillus plantarum. In organoleptic evaluation, UF cheeses received significantly (p<0.01) higher total scores than the control samples on day 45. Finally, it could be concluded that cheeses produced by attenuated adjunct lactobacillus plantarum have more nutritional quality than the control UF cheeses.

This study aimed to assess the behavior of various strains of Yersinia enterocolitica in ultra-filtered (UF) cheese and to evaluate the inhibitory effect of lactic starter bacteria on survival of Y. enterocolitica. To this end, pasteurized ultra-filtered milk was inoculated with 3 log cfu/g of two standard strains (DSM 11502 and DSM 9499) and one native strain of Y. enterocolitica. UF cheese samples were produced with and without starter culture. Enumeration of Y. enterocolitica was performed at the time of inoculation, after incubation time and during the 2-months storage period on CIN agar. The enumerated colonies were confirmed by PCR. Results revealed that after incubation, the populations of Y. enterocolitica in both groups increased by 4.14 log cfu/g (P < 0.01). However, during the storage period the number of Y. enterocolitica decreased only in the samples made with starter cultures. pH values revealed a significant difference (P < 0.01) between the samples made with and without starter culture; therefore, it seems that acidic pH is the major factor inhibiting the survival of Y. enterocolitica in UF cheese. Besides, a significantly (P < 0.01) different behavior was observed among native and standard strains. Considering the inhibitory effect of starter bacteria, it seems that creation of proper conditions in terms of temperature and the time necessary for proliferation and activity of starter bacteria or application of cultures capable of producing antagonistic products can be effective in controlling possible microbial contaminations along with the development of desirable aroma and texture in UF cheese.