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This study aimed to assess the effect of Persian gum (PG) and microbial transglutaminase enzyme (MTGase) on some physicochemical and microstructural characteristics of low‐fat ultrafiltrated Iranian white cheese during 60 days of cold storage. To manufacture the low‐fat cheese samples, PG (0%, 0.25%, and 0.5%) and MTGase (0, 0.5 and 1 U/g of protein) were used and cheeses (low‐ and full‐fat) without PG and MTGase were considered as controls. The obtained results revealed that the treated samples with PG had a higher titratable acidity, moisture content, and moisture‐to‐protein ratio (M:P), but a lower protein content as compared to the low‐fat control (p ≤ 0.05). Furthermore, the cheese samples treated with the higher level of MTGase (i.e., 1 U/g of protein) had a higher protein and fat content (p ≤ 0.05). Methyl palmitate (C16:0) and methyl oleate (C18:1) were found to be the most abundant fatty acids in the tested cheeses. Additionally, scanning electron micrographs revealed that addition of PG and MTGase improved the microstructure of the samples, so that the sample containing 0.5 U enzyme and 0.5% gum was more similar to its full‐fat counterpart and obtained the highest overall acceptance score among the cheeses. Therefore, our findings revealed that with incorporation of PG and MTGase, a low‐fat ultrafiltrated white cheese could be produced with an appropriate functional, physicochemical, and microstructural characteristics comparable to the full‐fat product. [ABSTRACT FROM AUTHOR]

In this study, the effects of gelatin‐starch (GS) composite coating containing cucumber peel extract (CPE) and cumin essential oil (CEO) were evaluated on the shelf life enhancement of ultrafiltered (UF) cheese during 56 days of storage under refrigerated conditions. The obtained hydroethanolic CPE by the microwave method showed the best results in terms of the total phenolic content, reducing power, 2,2′‐diphenyl‐1‐picrylhydrazyl (DPPH) activity, and 2,2‐azino‐bis‐3‐ethylbenzothiazoline‐6‐sulfonic acid (ABTS) radical scavenging activity compared to the immersion and ultrasound methods. The studied treatments were as follows: Control (C), GS, CPE, CEO, GS‐CPE, GS‐CEO, and GS‐CPE‐CEO. Scanning electron microscopic surface morphology of treated cheese samples showed the formation of a firm, integrated, flawless, and homogenous layer on the cheese slices of the GS‐CPE‐CEO treatment. All treatments significantly (p ≤.05) decreased the total viable count, psychotropic bacteria, and yeast–mold population compared to the control group. Adding CEO and/or CPE to GS significantly (p ≤.05) controlled undesirable changes in physical characteristics, such as weight, color, and hardness of the cheese slices. Throughout storage time, the coated cheese slices showed more stable chemical features in comparison to the uncoated cheese samples in terms of moisture, lipid oxidation, pH, and titratable acidity (TA). Sensory evaluation of the preparations showed that the GS coating containing CPE and CEO significantly (p ≤.05) had pleasant effects on the sensory features (taste, odor, texture, and overall acceptability) of the cheese samples during storage time. It was concluded that composite coating of GS containing CPE and CEO could improve the microbial, physical, chemical, and sensory features of ultrafiltration (UF) cheese during refrigerated storage. [ABSTRACT FROM AUTHOR]

Cheese is one of the valuable dairy products that has a significant role in feeding most people in society. During or after the production process, cheeses may become contaminated with moulds, which can endanger the health of the product and reduce its marketability. Cheese is one of the foods that has the suitable conditions for the growth of fungi. The purpose of this study was to isolate and identify the contaminants of ultrafiltration (UF) cheeses offered in Fasa city. For this purpose, 110 samples of cheese cans from different factories were randomly collected from the market and kept both open and closed. After growth, moulds were identified morphologically and molecularly. The results showed that the highest contamination of open cheeses was related to Penicillium, followed by Aspergillus, Paecilomyces and Trichoderma. In closed cheeses, Byssochlamys spectabilis was the most contaminated mould. During this study, for the first time in Iran, this type of fungus was isolated and identified. [ABSTRACT FROM AUTHOR]

In this study the rheological and textural properties of Iranian white cheese produced by ultrafiltration technique containing gum tragacanth and xanthan each in the range of 0-0.1%, and basil seed and linseed mucilage each in the range of 0-0.2% were evaluated. According to the results obtained, values of Elastic (G/) and viscous (G//) moduli increased with increasing frequency sweep in all the cheese samples. G/ was always greater than G//. The values of G/ and G// in the sample containing 0.05% of gum tragacanth, 0.05% of xanthan gum and 0.1% of basil seed mucilage and the sample containing 0.05% of xanthan gum, 0.1% basil seed and 0.1% linseed mucilage were maximum. Also, in samples containing 0.1% of xanthan gum and 0.2% of linseed mucilage and containing 0.1% of gum tragacanth were minimum. With increasing basil seeds mucilage in the samples, hardness, cohesiveness, gumminess and chewiness increased in comparison with the control sample (p < 0.01). According to the results obtained, for preparation of white cheese produced by ultrafiltration technique, application of 0.05% of gum tragacanth, 0.05 % of xanthan gum and 0.1 % of linseed mucilage, is recommended.

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BACKGROUND: Cheese is a dairy product that is popular in the world. Prebiotics and probiotics are increasingly being used to produce potentially symbiotic foods, particularly through dairy products as vehicle. It is well known that both ingredients may offer benefits to improve host health. OBJECTIVES: In this study prebiotic effect of Olive leaf extract or survival of Lactobacillus casei in UF cheese production during 10 weeks storage in cold condition was researched. METHODS: After provision of aqueous extract of olive leaf, probiotic bacteria and starter culture were prepared for inoculation. This extract was added to UF cheese in the presence of the bacteria then, counting of L.Casei on MRSbile agar with pour plate was done during 10 weeks of storage and sensory evaluation was performed after 10 weeks of cheese storage at 4 °C. RESULTS: The number of L. Casei was affected significantly by the addition of OLE (P<0.05). The bacterial growth had a significant relationship with the increase in OLE concentrations (P< 0.05). After 10 weeks, in all probiotic cheese, the concentration of L. Casei was at the level of 106 - 108 cfu/g. Also, sensory quality was positively affected by the presence of OLE in cheese samples. Cheese sample produced with the addition of 0.5% of OLE was the most desirable. CONCLUSIONS: The number of Lactobacillus casei was significantly increased during the storage weeks due to the addition of different concentrations of olive leaf extract. The number of probiotic was increased with increasing concentrations of the extract (P<0.05). Also, positive effects on the sensory properties of cheese samples affected by olive leaf extract were observed and the most common cheese sample was 0.5% of this extract. [ABSTRACT FROM AUTHOR]

The effect of oxidation-reduction (redox) potential (ORP) on the composition, viability of starter, and proteolysis of ultrafiltered (UF) white cheese was determined during 90 days of ripening. For the modification of the redox potential of cheese, Na 2 S 2 O 4 (0.01%, w/w) and KIO 3 (0.05%, w/w) were added as reducing or oxidizing agents, respectively, to UF retentate. A single strain of either Lactococcus lactis subsp. lactis CM41 or L. lactis subsp. cremoris UD459 was used as a starter culture. Three different types of cheese were produced for each culture, including control, reduced, and oxidized. The redox environment significantly affected the viability of starter lactococci, the chemical composition, and the proteolysis of cheese samples. During ripening, the redox potentials of the cheeses made with the reducing agent were slightly different than the control cheese (approximately −20 mV lower), while the cheeses made with the oxidizing agent exhibited positive redox potential (ORP +120 mV to +210 mV) during ripening. The starter lactococci in the oxidized cheeses lost their viability after the 60th day of ripening. Reducing conditions (ORP −315 mV to −350 mV) stimulated secondary proteolysis, and this was strain-dependent. These findings support the importance of redox environment on starter activity and accordingly cheese characteristics. • Redox potential affected viability and activity of the starter lactococci. • Altering redox environment can significantly affect the biochemical reactions in cheese. • Redox potential affected the proteolysis in UF cheese. • Redox potential exhibits starter strain-dependent effect. • Starter selection depending on its redox activity can be important for the quality of cheese. [ABSTRACT FROM AUTHOR]

Nowadays, consumers are interested in cheese produced without chemical additives or high-temperature treatments, among which, protective lactic acid bacteria (LAB) cultures could play a major role. In this study, the aims were to isolate, identify and characterize antilisterial LAB from traditionally produced cheese, and utilize suitable LAB in cheese production. Among 200 isolated LAB colonies, isolate PFMI565, with the strongest antilisterial activity, was identified as Enterococcus durans. E. durans PFMI565 was sensitive to clinically important antibiotics (erytromicin, tetracycline, kanamycin, penicillin, vancomycin) and had low acidifying activity in milk. E. durans PFMI565 and the previously isolated bacteriocin producer, Lactococcus lactis subsp. lactis BGBU1–4, were tested for their capability to control Listeria monocytogenes in experimentally contaminated ultrafiltered (UF) cheeses during 35 days of storage at 4 °C. The greatest reductions of L. monocytogenes numbers were achieved in UF cheese made with L. lactis subsp. lactis BGBU1–4 or with the combination of L. lactis subsp. lactis BGBU1–4 and E. durans PFMI565. This study underlines the potential application of E. durans PFMI565 and L. lactis subsp. lactis BGBU1–4 in bio-control of L. monocytogenes in UF cheese.

In this study probiotic microcapsules with three different shell compositions were produced through enzymatic gelation of skim milk powder by rennet, skim milk powder by transglutaminase and sodium caseinate by transglutaminase. Fabricated microcapsules and free Lactobacillus paracasei cells were incorporated into Iranian UF Feta cheese with different salt levels. Viability of L. paracasei (LAFTI L26), antioxidative capacity, ripening index, titrable acidity, salt content and texture profile analysis (TPA test) parameters including hardness, cohesiveness and stringiness were monitored during 45 days of storage time. Rennet based encapsulation was the most efficient method and could keep L. paracasei viable in all cheese samples (> 7 log10 CFU/g) at the end of storage time. Proteolysis pattern and acidification rate were strongly influenced by shell composition, salt level and storage time. Hardness and stringiness of probiotic cheese samples were influenced by shell composition of microcapsules and storage time but cohesiveness was only dependent on storage time. Therefore, storage time was the only effective factor on free radical scavenging activity of cheese samples. [ABSTRACT FROM AUTHOR]

A new antimicrobial bilayer film was developed using chitosan, cellulose, and nisin. Chitosan solution containing nisin (500 and 1000 μg/mL) was prepared by sol-gel method and then the solution was coated on cellulose paper by dip coating method. A chitosan-cellulose film without antimicrobial had no inhibitory effect on Listeria monocytogenes , whereas, the incorporation of nisin made a significant increase ( P < 0.05) in antimicrobial characteristics of the films. Moreover, no significant differences were shown on antimicrobial activity of developed films during the storage at 4 °C for one month. However, the addition of nisin showed a significant increase in the swelling index and solubility of bilayer film. Scanning electron microscope images revealed a uniform coating of chitosan solution on cellulose paper. The FTIR analysis also confırmed successful introducing and binding of the nisin in double layer film. Films with 1000 μg/mL of nisin completely inactivated the initial (∼5 log 10 CFU/g) counts of L. monocytogenes on the surface of Ultra-filter white cheese after storage at 4 °C for 14 days. We concluded that nanocomposite film of chitosan-cellulose containing nisin has novel antibacterial activity and can be used for packaging in cheese. [ABSTRACT FROM AUTHOR]

Nowadays, due to the antioxidant and antimicrobial properties of essential oil and the trend towards the substitution of chemical materials by natural ones, the use of this natural product is prevalent. The essential oil of Pistacia atlantica subsp. kurdica is among essential oils which demonstrate antimicrobial activity against some microorganisms. In Iran, the growth of mould on UF-cheese has been a constant problem resulted in the increased number of returns. The most common type of cheese contamination among fungi is Penicillium, especially P. citrinum. This study investigates the effect of P. atlantica subsp. kurdicaʼs essential oil on the growth of P. citrinum in culture media and UF-cheese. According to the results, the essential oil with concentration of 2500 µL/L reduced the growth of P. citrinum in culture medium and its minimum inhibitory concentration was estimated at 3000 µL/L. The effective inhibitory concentration of the essential oil on the growth of fungus on cheese was 24000 µL/L. From the organoleptic point of view, the use of this essential oil in cheese is partly acceptable.

Background and Objectives: Antimicrobial active packaging with metallic nanoparticles is used as antimicrobial agent in the packaging of food. This study considers the coliform retarding ability of antimicrobial packaging in ultra-filtrated (UF) cheese. Materials and Methods: Plastic films based on low-density polyethylene containing organoclay (cloisite 30B) and different percentages of Ag and CuO nanoparticles produced by extrusion method. Coliform bacteria growth in UF cheese was investigated. The release of nanoparticles from nanocomposite into a food simulant was also assessed. Results: An amount of 3.17-log cfu/g and 0.75-log cfu/g reduction for coliform bacteria obtained for nanocomposite and control films, respectively after four weeks of storage at 4 °C. Nanocomposite film with 1.3% Ag and 2.7% CuO in LDPE matrix introduced as optimum point by Design Expert 7.1.5 software. Microbial model for decreasing growth of coliform bacteria in this product was also determined. Validation of optimum point was carried out using a one-way ANOVA. It was shown that ther is a non-significant (p>0.05) difference with its repeat and a significant (p<0.05) difference with the pure film. Conclusions: Plastic nanocomposite films containing nanoparticle of organoclay and metal can decrease the severity of food processing and application of chemical preservatives in the food industries. [ABSTRACT FROM AUTHOR]

The effect of addition of a commercial enzyme derived from Bacillus Polymyxa type IX on Iranian UF-Feta cheese during a 60- day ripening period on chemical composition, pH and proteolysis of cheese samples was investigated. No Significant differences were observed in the chemical composition between experimental and control cheeses. ​​In experimental cheese, pH values were significantly (P< 0.05) higher throughout whole ripening period and at 60d it was 4.6 and 4.77 in control and experimental cheeses, respectively. Soluble nitrogen in pH=4.6 was significantly (P< 0.05) higher in experimental cheese at 45 and 60d. At 60d, this index was 6.38 and 7.73% in the control and experimental treatments, respectively. Significant difference in the level of trichloroacetic acid (TCA) 12% was also observed at 45 and 60d. Urea- polyacrylamide gel electrophoresis of the pH 4.6-insoluble fractions showed that αs1-casein was hydrolysed faster than the β-casein. Intact αs1-casein values from 100 % on the first day reached to 82.93 % and 71.24 % and in β- casein reached to 90.28 and 90.56% at 60d in control and experimental cheeses, respectively. The concentration of total free amino acids in whole ripening period was significantly (P< 0.05) higher in experimental cheese and at the end of the ripening period was 0.68 versus 0.54 in control cheese (mg Glycine/g cheese). Levels of individual free amino acids were also different between treatments. [ABSTRACT FROM AUTHOR]

Milk is a complicated liquid that contains necessary components for the growth of mammalian neonate. Milk can get polluted by heavy metals such as lead and cadmium. In this study, the concentrations of lead and cadmium were measured in 12 yoghurt and 12 UF cheese samples produced in each of the Isfahan and Golpayegan-Pegah Dairy Processing Establishments. The samples were analyzed using atomic absorption spectrometry by furnace according to AOAC instruction. According to the results, lead concentrations (Mean ± SD) in yoghurt and UF cheese samples produced in Isfahan and Golpayegan-Pegah were estimated at 54.96 ± 35.21, 61.65 ± 19.62, 105.38 ± 59.09, 141.94 ± 63.44 μg/Kg, respectively. In the case of cadmium, the concentrations were determined as 19.03 ± 1.23, 16.84 ± 8.08, 53.79 ± 19.29, 37.67 ± 22.58 μg/Kg, respectively. Results revealed a significant difference (P≥0.05) in lead and cadmium concentrations among the cheese samples of the two Dairy Processing Establishments. However, lead and cadmium concentrations in all samples were within the international approved limit (200 ppb).

Polymer/clay nanocomposites are a group of hybrid materials made from layered silicates of clay dispersed in the polymer matrix with a layer thickness in nanometre. The ability of organoclay nanoparticle including cloisite 15A, cloisite 20A and cloisite 30B incorporated into a low-density polyethylene (LDPE) polymeric matrix was investigated in order to inhibit the growth of coliform bacteria in ultra-filtrated cheese. The number of surviving cells of coliforms was decreased by 2.21 log cfu/g after 4 weeks storage at 4 ± 0.5°C, while pure LDPE showed a reduction of only 0.759 log cfu/g. LDPE film composed of 3% cloisite 15A, 3% cloisite 20A, with no cloisite 30B nano-filler was found as optimum point by combined design approach in design-expert analysis. The resulting film showed coliform load decreased by 2.05 log cfu/g in the optimum point, which was in line with Japanese industrial standard (JIS Z 2801: 2000) about antibacterial effect on coliform bacteria. A suitable microbial model for bacteria growth reduction was also suggested. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Various blends of milk coagulants Rhizomucor miehei protease and camel chymosin were mixed at levels of 100:0, 75:25, 50:50, 25:75 and 0:100, respectively and used in the manufacture of Iranian ultrafiltered (UF) White cheese. Effect of different blends of these coagulants on microstructure and rheological properties of Iranian UF White cheese were studied during 90 days of ripening. The results showed that both microstructure and rheology of the cheeses were influenced by type and concentration of these coagulant blends due to their different proteolytic activities. Use of high concentrations of camel chymosin resulted in a more compact protein network and firmer structure in the cheeses. Increasing levels of camel chymosin in the coagulant blends increased the storage ( G′ ) and loss ( G″ ) moduli and decreased loss tangent (δ) in the cheeses. In conclusion, increasing levels of camel chymosin provided less protein breakdown and more solid-like viscoelastic structure in UF cheeses. [ABSTRACT FROM AUTHOR]

The purpose of this study was to investigate antibacterial potential of low-density polyethylene (LDPE) packaging films incorporating silver (Ag), copper oxide (CuO) and zinc oxide (ZnO) nanoparticles in measuring of coliform amounts of ultra-filtrated (UF) cheese. The initial LDPE/nanoparticle composites were produced by melting extrusion followed by extruding the obtained composites through a die to achieve a film thickness of 45 ± 5 μm. The number of surviving coliform bacteria was decreased by 4.21 log cfu/g after 4 weeks of storage at 4 ± 0.5 °C, whilst pure LDPE films showed a reduction of only 1.04 log cfu/g. A composition of 0% Ag, 1% CuO, 0% ZnO gave an optimum point in combined design using Design Expert analysis. A suitable microbial model was suggested for retarding coliform bacteria growth in UF cheese. The difference between the optimum point of nanocomposite film and its repeat was not significant (p < 0.05) by one-way ANOVA analysis using SPSS software, while the difference was significant for pure film. Migration of metallic nanoparticles into a food stimulant was within the accepted safe level. [ABSTRACT FROM AUTHOR]

Few data are available on the thermophysical properties of cheese in the ripening process. The main objective of this work was to investigate the effects of brining and temperature on the thermophysical properties, i.e., thermal conductivity, specific heat, density and water activity of UF cheese and finally we measure surface heat transfer coefficient. Then we develop models for thermophysical properties based on physical and multiple regression concept. [ABSTRACT FROM AUTHOR]

Abstract: The objective of this work was to study the autolytic behaviour of strains of mesophilic (Lactococcus lactis subsp. lactis and L. lactis subsp. cremoris) and thermophilic lactic acid bacteria (Lactobacillus helveticus, Lb. delbrueckii subsp. lactis and Streptococcus thermophilus) in UF cheese. Cheeses were made from a UF-retentate (milk concentrated by a factor of 6) of microfiltered milk (0.8μm pore size membrane) using the following starter systems: (1) single inocula of autolytic strains of L. lactis (US3, AM2 or AM1), non-autolytic strains of L. lactis (AM2-C or CNRZ-144), (2) a co-inocula of strains of Lb. helveticus (ITG-LH1, CNRZ-32 or CNRZ-303), Lb. delbrueckii subsp. lactis (ITG-LL14 or ITG-LL51) with the same strain of S. thermophilus CNRZ-1358. Cell viability was monitored over a 28 day ripening period by enumeration on selective media. Degree of lysis was determined by the measurement of the intracellular marker lactate dehydrogenase (LDH) activity, and also by immunodetection of intracellular proteins with species specific antibodies. In UF cheeses, lysis of autolytic strains of L. lactis was significantly delayed, showing release of intracellular components after 21 days of ripening. No lysis was observed for non-autolytic L. lactis strains or for S. thermophilus. Lysis of thermophilic lactobacilli (Lb. helveticus, Lb. delbrueckii), was observed from the start of ripening, but the onset and the level of lysis observed was strain and species dependent. [Copyright &y& Elsevier]

The purpose of this study was to determine the impact of extracellular oxidation-reduction (redox) potential (E h) on organic acids and residual lactose, volatile compounds, and sensorial properties of experimental ultrafiltered (UF) cheese during ripening. In addition, the changes in E h and pH of UF cheese were simultaneously determined during the simulated UF cheesemaking. Sodium hydrosulfite (reducing agent) and potassium iodate (oxidizing agent) were added to UF retentate to modify E h of cheeses. After addition of the redox agents, E h7 values of UF retentates (pH 6.5 ± 0.1) used in the production of control, reduced and oxidized cheeses were +330, −157 and + 340 mV, while experimental UF cheeses had E h7 values of −230, −247 and + 241 mV at 25 °C, respectively, 3 days after cheese manufacture. E h was significantly effective on the sugar metabolism of starter cultures thereby on organic acid contents. Lactose fermentation was limited in the oxidized cheeses. The most important differences between volatile compounds of the cheeses resulted from ethanol, benzaldehyde, 4-methyl benzaldehyde, and sulfurous compounds such as methanethiol, dimethyl disulfide and dimethyl trisulfide. The results indicate that redox potential is a crucial parameter that influences organic acids and volatile compounds and consequently of sensorial characteristics of cheese. • E h affected lactose metabolism of starter lactococci. • E h influenced organic acid and volatile compound profiles of UF white cheese. • Low E h was favored by starters to achieve suitable pH for UF white cheese. • Negative E h was required to get desirable sensorial attributes for UF white cheese. [ABSTRACT FROM AUTHOR]