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The current study was carried out with the purpose of investigating the antimicrobial properties of free and microencapsulated extract of Nepeta Binaludensis. For this purpose, the Nepeta extract was extracted by assisting pulse electric field process (6000 v and pulse number 60). Then the effect of free extract (0.2 and 0.6 %) and encapsulated extract with 4 different types of wall material (wall contain mixture of maltodextrin 7 (26.97%) with Arabic gum (29.36%) and maltodextrin 20 (43.69%), wall contain mixture of 1% sodium alginate and 1% chitosan, wall contain mixture of 1% sodium alginate and 1% Inulin and wall contain mixture of 2% sodium alginate) at two concentrates (1 and 3 %) in comparison with synthetic potassium sorbate preservative (0.1%) on sensory, total phenolic content and microbial properties of doogh during 28 days storage at refrigerator temperature was evaluated. Results demonstrated that free and microencapsulated extract was able to control the growth of mold and yeast with preservation of sensory and phenolic properties in the doogh. The lowest growth rate of mold and yeast after 28 days of refrigeration was respectively observed in the sample containing 1% sodium alginate, 1% inulin at 1 and 3% concentration and 2% sodium alginate at 3% concentration and there was no statistically significant difference with the the sample containing 0.1% potassium sorbate (P>0.0.5). The results of sensory analyze showed that doogh samples containing encapsulated extract with 4 types of wall compositions mentioned were not statistically significant in terms of sensory characteristics with doogh samples containing potassium sorbate (P>0.0.5). Also, doogh samples containing microcapsules with wall composition (1% Sodium alginate and 1% inulin) and (1% sodium alginate with 1% chitosan) and 2% sodium alginate with a concentration of 3% after 28 days of storage had more phenolic compounds. [ABSTRACT FROM AUTHOR]

IntroductionDoogh is a fermented dairy product that is produced by blending yogurt with water and some salt. This fermented beverage is widely consumed as a refreshing drink in Iran and other Middle East countries. Doogh is a source of calcium needed by the body on a daily basis and contains B vitamins that are effective in the health and strength of teeth and bones. In addition, doogh contains a low percentage of fat, which makes it a diet drink. Whey Protein Concentrate (WPC) is a product contains 25 to 89% protein and different amounts of lactose, fat and minerals. Due to the functional properties of whey protein and its nutritional value; whey protein is widely used in dairy products. The development of cross-linking bonds between protein chains by enzymes is very important today. Enzyme cross-linking of proteins can affect some of their functional properties such as solubility, water absorption, rheological and emulsifying properties. One of the most widely used enzymes in the food industry is the transglutaminase enzyme. In this study the effects of WPC in three levels (0%,1% and 2%) and the transglutaminase enzyme in two levels (0 and 1 unit per gram of milk protein) in two method of dough preparation (adding water to yogurt and fermented milk diluted with water) on rheological characteristics, and microstructure of doogh were studied. Material and MethodsRaw milk was provided by Pegah Khorasan Company, WPC from Multi Company) Mashhad (and Trans glutaminease enzyme from BDF Company of Spain. WPC was first added to milk at 45 ̊ C at three levels of zero, 1 and 2%.The milk samples were then pasteurized at 85 ̊ C for 30 min. After lowering the temperature to 45 ̊ C, the enzymatic operation was performed at two levels of zero and one unit (per gram of protein).To complete the enzyme function, the samples were incubated for 180 minutes at 45 ̊ C. Then a temperature of 90 ̊ C was applied for 1 minute to inactivate the enzyme. The samples were then cooled to 45 ̊ C. At this stage, the samples were divided into two parts. In one part of the samples; milk was diluted with water in a ratio of 6% of the total dry matter for direct production of doogh. After adding the starter, the samples were transferred to an incubator and hold at 43-42 ̊ C, until the pH reaches about 4.1.Thefermented samples were then transferred to a refrigerator. In the second part, starter was added to milk to produce yogurt; after adding starter, the mix was transferred to an incubator and hold at 43-42 ̊ C, until the pH reaches about 4.1. Doogh was produced by diluting yogurt with waterto givethe final product with 6% of total dry matter. Results and Discussion In both production methods, in samples treated only with WPC, the average particle size increased with increasing WPClevel. In both methods, the production of only enzymatically treated samples led to the formation of smaller particles with a more uniform shape and distribution. In samples of doogh produced by both production methods, WPC and transglutaminase enzyme changed the flow characteristics of doogh to non-Newtonian behavior. Samples made directly from milk had significantly higher viscosity than samples made from yogurt. In samples without enzymatic treatment, the microstructure was smooth and homogeneous with smaller particles than other samples. These particles settle very quickly. In the samples where WPC treatment was applied, the amount of large particles and non-uniformity increase with increasing WPC level. The distribution of particles in samples made directly from milk was more regular than samples made from yogurt.

Doogh is a fermented beverage made from yoghurt with water and salt. Similarly, drinks based on yoghurt are available in different countries with varying degrees of dilution, fat content, rheological properties, and taste. In this project, the use of mathematical calculations in describing rheological parameters from traditional low‐fat Doogh enriched with Caspian Sea (Huso huso) gelatin (0.4 w/v %), xanthan hydrocolloids (0.4 w/v %), and their mixture at a ratio of 0.2:0.2 w/v % studied. Also, serum isolation, pH, and sensory evaluation of samples were investigated. Also, the relationship between apparent viscosity and temperature of Doogh samples using the Arrhenius equation was studied. The sensory evaluation revealed that the overall acceptance scores of the samples containing gelatin, xanthan, mix, and control were 4.31, 4.33, 4.58, and 4.12, respectively. The study on serum separation value showed control sample (45.07) and mix sample (0.84) at the end of 30 days. On the first day, the pH of the Doogh samples decreased with the addition of hydrocolloids, and this trend was time dependent. pH reduction was higher in Doogh with gelatin than in other samples. Mathematical calculations showed that the low‐fat Doogh is a non‐Newtonian type and shear‐thinning (Pseudoplastic) fluid. The activation energy was calculated between 11.65 and 19.15 kJ/mol. According to the obtained results, it concluded that the use of two hydrocolloid compounds improved the physicochemical and sensory characteristics of the low‐fat Doogh samples. Also, the Ostwald‐de Waele mathematical model had a high correlation with the rheological behavior of the samples. [ABSTRACT FROM AUTHOR]

Abstract Today, the increasing use of chemical preservatives in foods is considered one of the main problems in food industries. This study aimed to produce the pasteurised Doogh (Iranian yogurt drink) containing a nanoemulsion of essential oil (EO) with appropriate quality. A factorial test based on a completely randomised design with two treatments in three levels, including EO type (pennyroyal, Gijavash, and their equal combination) and a control sample was applied to assess the physicochemical and sensory properties of Doogh. The highest negative zeta potential and antioxidant activity percentage were observed in the sample containing the nanoemulsion of pennyroyal and enriched with a combination of two essential oils. The microbial evaluation results indicated that the total microorganism count was minimised in the Doogh containing the nanoemulsion of Gijavash. The nanoemulsions of pennyroyal and Gijavash can be added into Doogh formulation to produce a new product with maximum sensory acceptability.

Polychlorinated biphenyls (PCBs) are harmful chemicals that are persistent in the environment and can accumulate in the food chain. The purpose of the present research was to assess non‐dioxin‐like polychlorinated biphenyls (NDL‐PCBs) in some dairy products (yogurt, doogh, and kashk) using modified QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) technique and gas chromatography–triple‐quadrupole mass spectrometry (GC‐QqQ‐MS/MS) method and risk assessment study. The LOQs (limit of quantifications), LODs (limit of detections), recovery, and RSD for the PCB analytes were 0.180–0.360, 0.06–0.12 ng/g fat, 97.45–102.63%, and 6.33–8.86%, respectively. The results revealed that the mean concentrations of Ʃ6‐NDL‐PCBs in samples were 15.17 ± 3.44 ng/g fat, which was lower than the standard level established by European Union (EU, 40 ng/g fat). The maximum mean level was PCB 180 (9.98 ± 2.04 ng/g fat) and the minimum mean level of PCBs in samples was PCB 28 (0.09 ± 0.06 ng/g fat). Also, results showed that kashk samples had a maximum mean level of 6‐NDL‐PCBs (18.66 ± 2.42 ng/g fat) and doogh samples had a minimum mean level of 6‐NDL‐PCBs (12.21 ± 2.22 ng/g fat). The mean level of 6‐NDL‐PCBs in yogurt samples was 14.65 ± 2.02 ng/g fat. The heat map results showed the correlation between the spectral indices of 6‐NDL‐PCBs in different dairy products. According to the Monte Carlo method, risk assessment was done using calculating the Estimated Daily Intake (EDI) and Incremental Life Cancer Risk (ILCR). The EDI values of 6 NDL‐PCBs based on the 95th percentile in yogurt, doogh, and kashk were 14.3, 1.49, and 0.5 ng/kg.day, respectively. Considering that the contaminant level in the samples is lower than the EU limit, it can be concluded that dietary exposure to 6 NDL‐PCBs may not pose a risk to the health of consumers. [ABSTRACT FROM AUTHOR]

Today, the increasing use of chemical preservatives in foods is considered one of the main problems in food industries. This study aimed to produce the pasteurised Doogh (Iranian yogurt drink) containing a nanoemulsion of essential oil (EO) with appropriate quality. A factorial test based on a completely randomised design with two treatments in three levels, including EO type (pennyroyal, Gijavash, and their equal combination) and a control sample was applied to assess the physicochemical and sensory properties of Doogh. The highest negative zeta potential and antioxidant activity percentage were observed in the sample containing the nanoemulsion of pennyroyal and enriched with a combination of two essential oils. The microbial evaluation results indicated that the total microorganism count was minimised in the Doogh containing the nanoemulsion of Gijavash. The nanoemulsions of pennyroyal and Gijavash can be added into Doogh formulation to produce a new product with maximum sensory acceptability. [ABSTRACT FROM AUTHOR]

Introduction: Yogurt contains valuable compounds, some of which enter yogurt whey and if discarded, remains unused. Yogurt whey has a high nutritional value due to its high quality biological proteins which can be a good source of bioactive peptides. Bioactive peptides are food-derived peptides that are small in size and usually consist of 3- 20 amino acids. These peptides are considered as functional ingredients. Bioactive peptides have antioxidants and antimicrobial properties. The aim of this study was to investigate the effect of adding bioactive peptide derived from enzymatic hydrolysis of yogurt whey on physicochemical, sensory and microbial properties of doogh during storage. Materials and Methods: In this study, peptide derived from tryptic hydrolysis of yogurt whey protein fractionated by RP- HPLC was used. Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) of this peptide were determined against Staphylococcus aureus and Escherichia coli. This peptide was incorporated to heated doogh at concentrations of 12, 20, 24, 40, 48, and 80 mg/mL. Moreover, doogh samples were inoculated with 106 CFU/mL Staphylococcus aureus and Escherichia coli. Doogh samples were stored for two months. During 60 days storage, bacterial count, pH, acidity, ABTS radical cation inhibitory activity and sensory properties (taste, odor, texture, color and overall acceptance) of doogh samples were studied. Results and Discussion: The MIC of yogurt whey peptide against Staphylococcus aureus and Escherichia coli was 12.2 and 24.4 mg/mL, respectively. Moreover, the MBC of yogurt whey peptide against Staphylococcus aureus and Escherichia coli was 12.2 and 48.8 mg/mL, respectively. Addition of this peptide to doogh showed that during storage period, the Staphylococcus aureus and Escherichia coli counts, pH and ABTS cation radical inhibitory activity of the samples were significantly decreased, but acidity was increased (p

[Display omitted] • Simultaneous extraction and derivatization of biogenic amines was performed by dansyl chloride. • In-situ deep eutectic solvent- based liquid phase extraction was used for biogenic amines. • Biogenic amines were determined in doogh samples by HPLC-DAD. • ChCl: p-anisidine was formed in solution as the extraction solvent. A simple and efficient microwave-assisted extraction method using deep eutectic solvent was developed for the simultaneous analysis of four biogenic amines (putrescine, tyramine, cadaverine and histamine) in Doogh (yogurt-based beverage) samples. Important parameters like precipitating agent volume, vortexing time, microwave power, and exposure time were optimized. Zinc sulfate was utilized for proteins precipitation prior to extraction of analytes with the deep eutectic solvent choline chloride/ p -anisidine. The analytes were derivatized with dansyl chloride and analyzed by HPLC-DAD. The method showed good linearity (r2 ≥ 0.994) over wide ranges with low limits of detection (0.52–0.78 ng mL−1) and quantification (1.7–2.5 ng mL−1). Extraction recoveries ranged from 68–72 % and relative standard ≤8.1 %. Negligible matrix effects were observed. When the method was applied to real Doogh samples and several biogenic amines were detected. The developed method provided reliable results in terms of sensitivity and selectivity. [ABSTRACT FROM AUTHOR]

Physical instability and loss of viability of probiotic bacteria are the most important problems in production of synbiotic Doogh. Some plant hydrocolloids have been recognised as effective components to prevent these problems. In this study the effect of Plantago psyllium mucilage (PPM) (0, 0.15%, 0.30%, 0.75% (w/w) on the physicochemical, microbial, and sensory properties of Doogh samples was evaluated by measuring phase separation, viscosity, flow behaviour, probiotic viability and sensory parameters. The results revealed that the stability of samples containing PPM were higher than samples without this hydrocolloid. By increasing the amounts of PPM, the viscosity of treated samples were increased compared to control sample. Herschel-Bulkley rheological model was an appropriate model for describing the flow behavior of Doogh formulated with PPM and the power-law rheological model was suitable model for describing the flow behavior of control samples. PPM had non-digestible food ingredients and improved the viability of Lactobacillus casei; therefore, this herbal mucilage may have prebiotic potential. Finally, the samples treated with 0.30% PPM on the 15th day were chosen as the best formulation for the production. [ABSTRACT FROM AUTHOR]

In the first step of this study, Anethum graveolens and Nasturtium officinale essential oils prepared with Clevenger apparatus and then, essential oils ingredients evaluated by GC-Mass. Minimum Inhibitory (MIC) and Minimum Bactericidal Concentration (MBC) and antioxidant activity of essential oils were evaluated at concentrations of 350, 400, 500, 600 and 650 mg/L during 60 days. Then, encapsulated essential oils of A. graveolens and N. officinale in the mentioned concentrations by maltodextrin and coacervation methods to evaluate morphology and particle size distribution. Finally, to achieve the optimal concentration of essential oils in order to further preserve the probiotic population of Bifidobacterium lactis, the viability of this bacterium in doogh was evaluated for 21 days. In the second step of the study, the effect of adding essential oils on optimal concentration to the product investigated according to dry matter content, pH, acidity, serum separation rate, rheology and sensory evaluation. The results showed the essential oils have high terpene and phenolic content, which caused proper antioxidant and antimicrobial activity. The viscosity, consistency and acidity of the final product increased on the other hand, pH and serum separation rate decreased significantly. Considering the results of sensory evaluation and lack of any negative effects at optilam concentrations of 400 mg/L and 500 mg/L for A. graveolens and N. officinale essential oils, respectively, the possibility of its industrial application can be examined. [ABSTRACT FROM AUTHOR]

Background: Encapsulation of probiotics in a carrier material is a useful tool to improve the viability, release, delivery of probiotic cells and extend food shelf by holding extra multiplying of probiotic cells to prevent changing the sensory characteristic of supplemented food. This study aimed to determine the effects of microencapsulation on the viability of Lactobacillus acidophilus and Saccharomycess boulardii probiotics in Doogh samples stored at different temperatures and their combined effect on pH, stability, and sensory attributes of Doogh samples. Methods: Micro-encapsulation of probiotics was done using the emulsion method under sterile conditions. Enumeration of probiotics and physical analysis (pH, stability, and organoleptic characteristics) of 120 heated Doogh samples containing free and encapsulated Lacidophilus and S.boulardii probiotics were conducted for 28 days at 7day intervals (0, 7,14, 21, 28 days) at three temperatures (4, 20, 35 °C). Results: The survival of probiotics decreased continuously at all temperatures during storage time except for the encapsulated forms of Lacidophilus at 4 and 20 °C and the free forms of S.boulardii at 4 °C remained constant significantly (P <0.05). The treatments containing free S.boulardii had the least significant decrease in pH on the last day of storage at 20 and 35 QC temperatures. The sensory evaluation shows acceptable scores in all treatments stored at 4 °C. Conclusion: Our results show synergistic effects of encapsulated probiotics on extending the shelf life of Doogh. [ABSTRACT FROM AUTHOR]

Introduction: Diseases caused by the consumption of bacteria-contaminated foods have been of great importance in public health. Therefore, control of dairy product contamination with coliforms is a concern for the durability of dairy producers. Control of the contamination by natural products may have dual action; nutritive value and natural antibiotics. In this study, the antimicrobial activity of thyme essential oil against Escherichia coli O157: H7 in doogh (Iranian fermented dairy drink) was examined and the MIC and MBC were determined. Methods: Antimicrobial activity of thyme essential oil was examined using different concentrations (0, 30, 60, 90, and 120 µl/ml) against bacteria with a density of 105CFU/ml during the 60-day at 4 °C. Moreover, the effect of different concentrations of essential oils on the taste of doogh was also studied. Taste evaluation was performed based on 5 points hedonic test to evaluate the effect of Thyme oil on the sense of taste. Duncan software was used to determine the difference between test and control groups at a confidence level of 5%. The SPSS software was also used for statistical analysis.. Results: All concentrations of thyme essential oil could stop the growth of bacteria (P<0.05). The inhibitory effect of oil increased with increasing concentration and time. Based on the results of sensory (taste) evaluation, treatment 2 (containing 60 µl/ml of essential oil of thyme) was selected as the best treatment.. Conclusion: Thyme essential oil can be used as a natural preservative with a positive impact on taste and nutritive value. [ABSTRACT FROM AUTHOR]

The aim of this study was to produce nanoparticles of plant extract such as peppermint in,β-Cyclodextrin by ultrasonication. This study was meant to investigate method of extract, size of the Nano particles, physical properties of Nanoparticles, microbial analysis such as the effect of Nano extract on Ecoli O157:H7 in doogh and sensory test. A randomized complete design (RCD) was used to characterize the factors, Factor T (variable storage temperature) in 3 levels (4,19 and 35 ° C) and a variable storage time (Z) in 3 levels (time and days of the 22,45 and zero maintenance) was investigated. The results represent the means of three replicates. The results showed that with increasing temperature the growth of E. coli will be increase(P ≤ 0.05).All interaction between bilateral interactionson the number of E. coli were significant on Dough(p<0.01).E. coli bacteria decreased with increasing storage time, Escherichia coli yeast growth during the storage in Nano samples was significantly lower than control samples (P ≤ 0.05). Nano extracts with gradual release of phenolic compounds over time have inhibitory for micro-organisms. Temperature and storage were significant (p<0.01).As well as the interaction between bilateralreleases of phenolic compounds were significant(p<0.01).And the result of sensory test showed that the Nano extract sample got the highest score. [ABSTRACT FROM AUTHOR]

In this present study, essential oils (EOs) were extracted from Chaerophyllum macropodum, Oliveria decumbents, and Zataria multiflora Boiss. The chemical composition and antimicrobial activity of the EOs were tested against Staphylococcus aureus (G+), Escherichia coli O157: H7 (G−), and three species of fungi (Rhodotorula glutinis, Kluyveromyces marxianus and Penicillium digitatum). The outcomes were evaluated in vitro and in a food model system for 28 days of storage. Carvacrol comprised 10.83, 22.51 and 73.66% of the EOs being extracted from Chaerophyllum, Oliveria and Zataria, respectively, while thymol comprised 9.57, 36.49 and 17.17%. By evaluating antibacterial properties in vitro, the bacteria were greatly inhibited by all of the three EOs with more sensitivity of S. aureus. Oliveria and Zataria EOs were more effective than Chaerophyllum EO in preventing the growth of the three fungi. Doogh samples were inoculated before receiving the EOs (1%) and stored at 4°C for 28 days. Chaerophyllum EO caused the highest value of pH in doogh. Viscosity was significantly higher (p

In this study, the amount of dill essential oil and wheat fiber was optimized in synbiotic doogh using Box Behnken design and Response Surface Methodology (RSM). Independent variables benig dill essential oil in the range of 0-80 μl/l, wheat fiber in the range of 0-2% and storage time in the range of 10-50 days. The survival of Bifidobacterium lactis and physicochemical and sensory properties of synbiotic doogh were eveluated during storage. The results of statistical analysis of data showed that the survival of Bifidobacterium lactis increased with increasing the dill essential oil concentration up to 30 μl/l, but decreased with more increasing its concentration (P<0.05). However, the number of probiotics significantly decreased during storage (P <0.05). Increasing the amount of wheat fiber, the acidity and dry matter increased and pH decreased. Doogh stability increased with increasing fiber at levels up 0.6% but decreased during storage time (P <0.05). The results of sensory evaluation of the samples showed that increasing the amount of wheat fiber, caused decrease in the color and flavor score of the samples and increase in the texture score. However, increasing the amount of essential oil to 40 μl/l, caused an increase in the flavor score, and then decreased significantly (P<0.05). Accordingly, the optimal conditions for the production of synbiotic doogh containing Bifidobacterium lactis, the amount of wheat fiber and dill essential oil of 1.6% and 40 μl / l, respectively, and storage time was evaluated being 30 days. [ABSTRACT FROM AUTHOR]

Spoilage of dairy products can be caused by a variety of microorganisms, including bacteria, yeasts and molds. due to production of mycotoxins by some molds in dairy products, it is important to identification of exact causes mold in order to adopt an appropriate method to prevent such contamination; Therefore, in the present study, 30 samples of contaminated Doogh with signs of spoilage such as swelling, bad smell and bitter taste were collected from a dairy factory during one year. According to the results, molds were observed in only two samples. After purification, 4 isolates were identified based on macroscopic observations, microscopic characteristics and PCR technique. Three isolates were Aspergillus flavus, and one isolate was identified as Penicillium chrysogenum. Due to the ability of the identified species to produce toxins, monitoring the critical points of the Doogh production line in order to process control and prevent secondary contamination in order to achieve a healthy product will be very important. [ABSTRACT FROM AUTHOR]

Background: A lot of people consume traditional foods throughout the world, however there are concerns for their safety. The purpose of the current study is to evaluate the safety of traditional doogh (a traditional fermented dairy beverage) with respect to microbiological, chemical, and toxicological aspects. Methods: 89 samples of traditional doogh from Khuzestan province, Iran, were analysed according to microbiological ( Staphylococcus aureus, Echerichia coli, coliforms, mold and yeast), chemical (pH, total solid, fat, and salt content), and toxicological (aflatoxin M1, potassium sorbate, sodium benzoate, and natamycin) aspects. Results: Results showed that 89.88% of samples would be rejected according to the guidelines specified by the Institute of Standards and Industrial Research of Iran (ISIRI). 78 sample had higher mold and yeast than standard. The salt content of five out of 89 samples were higher than the established Iranian standard. Conclusion: The most challenging problem was mold and yeast contamination, indicating poor hygienic manufacturing conditions. However, the unfavorable conditions for microbial growth such as low pH may prevent the toxic metabolites formation, and therefore, consuming it presents no major concerns to public health. Nonetheless, the authors suggest that efforts should be made to improve hygienic conditions in traditional doogh manufacturing environments. [ABSTRACT FROM AUTHOR]

The consumption of locally produced organic foods has become a popular trend in those seeking better health through diet. Despite their proposed health benefits, there are concerns regarding the safety of these foods, as they may contain pathogens due to poor hygienic conditions during production. This study aimed to explore the microbial inhibitory effects of ewe milk, yogurt, and doogh prepared by nomads from Ghasr-e-Shirin region in Iran, and to identify the bacterial community of these products using next-generation sequencing of 16S rRNA gene. The antimicrobial activity of cell-free supernatants (CFSs) of samples were evaluated against 3 fungi and 5 bacteria by agar disc diffusion and broth microdilution assays. The findings of this research showed that there is great diversity of bacteria in milk collected by nomads. The most dominant bacteria were Enterobacteriaceae (49.16%) in milk. However, non-lactic acid bacteria were overtaken by Lactobacillus delbrueckii (99.9%) in doogh and yogurt. The CFSs of yogurt and doogh showed growth inhibitory activity against the microorganisms used in this study. [ABSTRACT FROM AUTHOR]

Introduction: Due to development of dairy industries, consumption of Doogh in Iran as a functional fermented beverage is increasing. On the other hand in case of using the preservatives to reduce the microbial contamination in Doogh may rising the risk of chronic diseases during long time. In this study, the protective effect of natamycin as preservative on microbial population in Iranian Doogh at different storing temperatures extensively investigated. Methods: Microbial analyses included total count of microorganisms, population of fungi (mold and yeast), coliforms, Escherichia coli, coagulase positive staphylococci, and lactic acid bacteria on Doogh samples were extensively evaluated. Results: Microbial population in Doogh samples stored at 4 °C in both treatments )with and without natamycin( was less when compare to samples stored at 25 °C and 35 °C during the shelf life period. At 25 °C, natamycin was able to significantly (P Conclusion: According to the findings, it can be concluded that paying attention to the microbial quality of raw milk, heat treatment and cooling system during transportation, environmental hygienic conditions, as well as the storage condition of the final product at refrigerated temperatures by food retailers and consumers can effectively reduce the microbial population of Doogh and preventing the spoilage.

Background: Plant extracts and essential oils are commonly used in traditional and industrial doogh products to inhibit bacterial activities. Objective: In this study, the antibacterial effects of the essential oils of Olivera decumbens and Nepeta binaludensis against Staphylococcus aureus and Escherichia coli in doogh were investigated. Methods: Essential oils of Olivera decumbens and Nepeta binaludensis were collected from Binalud and Pol-Dokhtar respectively and the essential oil of these species were extracted by the hydro-distillation method. Then, different concentrations of essential oils (12.5, 50, 100 and 200 μl mL-1) were added to doogh containing 104 Staphylococcus aureus and Escherichia coli bacteria. Finally, the bacteria were counted during 5 days of storage. Results: The results showed that, at the maximum duration of 5 days storage, the difference between the inhibitory activity of Oliveria decumbens and Nepeta binaludensis essential oils at concentrations of 50 and 100 μl mL-1 respectively against Escherichia coli and Staphylococcus aureus in comparison with control sample was significant (P < 0.05). Moreover, it was observed that the antibacterial effect of Oliveria decumbens was higher than Nepeta binaludensis due to its more phenolic compounds. Conclusion: The results of the present study have shown that essential oils of Oliveria decumbens and Nepeta binaludensis have good inhibitory effects against Staphylococcus aureus and Escherichia coli in doogh. So they can be used as preservatives in traditional and industrial doogh products.

The seed husk of psyllium (Plantago ovate Forsk) has a long history of use as a dietary fiber supplement and in traditional herbal medicine, it has been used for treating various disorders. It has an important role in lowering blood cholesterol and has potential to stimulate bacterial growth in digestive system. Therefore, in the present study psyllium husk powder (PHP) at amount of 0, 0.25, 0.5 and 0.75% was added to Doogh samples and its influence on viability of probiotic bacteria Lactobacillus casei was investigated. In addition, the amount of serum separation, pH and sensory properties of this product were studied. Results showed that in the presence of husk powder the growth of Lactobacillus casei has been increased insignificantly. The pH values of the all Doogh samples reduced during 14 days of storage but psyllium husk did not affect the pH even at 0.75% concentration. The addition of PHP increased the consistency, resulted in a reduction in the rate of phase separation. Sensory evaluation revealed that the sample containing 0.25% psyllium powder had more acceptability than others. According to the results, addition of PHP at amount of 0.25% in the presence of probiotic bacteria Lactobacillus casei for production functional Doogh product is recommended.

The present study was targeted toward the investigation of the survival of probiotic strains, namely Lactobacillus acidophilus (LAFTI-L10) and Bifidobacterium lactis (LAFTI-B94), in both microencapsulated and free forms and their effects on physicochemical and sensory properties, stability, and microstructures of Doogh during storage for 45 days in a cold room at a temperature of 5±1°C. The statistical analysis of the results showed that the number of L. acidophilus and B. lactis in free forms decreased about 1.1 and 2.2 log cycles, respectively. However, the number of the microencapsulated forms remained relatively constant during the storage period. Both free and microencapsulated forms were successful in keeping the counts of L. acidophilus and B. lactis in Doogh high enough for the therapeutic minimum (106-107 cfu/g) after 45 days. Nonetheless, the number of microencapsulated probiotics was higher than that of the free cells (P

Doogh is a fermented dairy beverage which its shelf-life can be reduced by the activity of microorganisms and chemical and sensory changes of product. This study aimed at producing a heat treated doogh using combination of dill (0.05, 0.075, and 0.1%) and garlic (0.04, 0.06, and 0.08%) extracts as biopreservatives. Microbial, chemical, and sensory properties of samples were evaluated during six weeks of storage at 8°C. The results showed that microbial count were dependent on the amounts of extracts used in doogh samples formulation. On the other hand, by increasing concentration of extracts, total bacterial counts, mold and yeast counts decreased significantly (p

Doogh is a fermented dairy drink that produced with mixing of pasteurized yogurt, water, essential oils and salt. Due to low pH, doogh is susceptible to spoilage with mold and yeast that is the main challenge for its shelf life. At the same time, the consistency is very important in quality and marketability of doogh. Nowadays, the interesting of consumers to natural antimicrobial substances rather than chemical preservatives has been progressively increased. Chitosan is a derivative of chitin, unlike synthetic polymer compounds, is non-toxic and biodegradable in nature. The aim of this study was investigation on the effect of chitosan on the qualitative features and shelf life of doogh. In this research, chitosan was added to the doogh in four levels (0.05, 0.1, 0.2, 0.3%) and qualitative characteristics of them were investigated by physico-chemical, microbiological and sensory analysis during 60 days. The results showed that, use of chitosan resulted decreasing of phase separation rate, acidity, mold and yeast, Streptococcus salivarius subspecies thermophilus and Lactobacillus delbrueckii subspecies bulgaricus counts and increasing of viscosity and pH. So that, samples containing 0.3% chitosan had 97% decrease in phase separation rate, 24% decrease in acidity, 6% decrease in mold and yeast count, 19% decrease in Streptococcus salivarius count, 11% decrease in Lactobacillus delbrueckii count, 122% increase in viscosity and 15% increase in pH compared with control samples, at the last day of storage. In the case of sensory features, chitosan did not have any effect on the color and appearance of doogh, but had effect on the flavor and also consistency was improved. [ABSTRACT FROM AUTHOR]

In the present study, stinging nettle extract (SNE)-loaded nano-emulsion was produced utilizing tween 20 and cress seed gum as the wall materials. The developed nanoparticles were evaluated based on their particle size, zeta potential and encapsulation efficiency. Then, fabricated extract-loaded nano-emulsion was added to Doogh as a functionalizing agent (at 5 and 10% w/w concentrations) and consequently the properties of the samples including total phenolic content (TPC), DPPH radical scavenging activity, reducing power (FRAP), pH, acidity, phase stability and sensorial characteristics were assessed during 21 days of storage. The untreated Doogh as well as fortified Doogh with free extract (at 5 and 10% w/w concentrations) were used as the control samples. The average droplet size of the fabricated nano-emulsion was 404.6 nm, the overall formulation possessed a negative charge and the encapsulation efficiency was 58.04%. After 3 weeks of analysis, Doogh sample enriched with 10% SNE-bearing nano-emulsion displayed the highest TPC (30.3 mg GAE/100 mL), DPPH (50%), FRAP (0.76), pH (3.45), and phase stability (64%) as well as the lowest acidity (2.1%) (p < 0.05). SNE possesses astringent and bitter flavors which could limit its application in food products. However, compared to the free extract-enriched Doogh, fortified samples with nano-emulsion had closer sensory characteristics scores to untreated Doogh which clarified the minimization of these undesired flavors following encapsulation. In conclusion, SNE can be successfully entrapped within tween 20 and cress seed gum nano-emulsions with an excellent encapsulation efficiency and be utilized in the functionalization of dairy fermented beverages. [ABSTRACT FROM AUTHOR]

Doogh is an Iranian drink produced from yoghurt. Swelling is an undesirable change of Doogh, usually caused by Kluyveromyces marxianus. The aim of this study was the investigation of the effect of the thermosonication process on Kluyveromyces marxianus survival as well as the determination of the impact of this process on other quality parameters (viscosity and serum separation). For this reason, Kluyveromyces marxianus (about 105 cells per milliliter) inoculated into Doogh samples, thereafter samples being exposed to various thermosonication process conditions. Results showed that the thermosonication operation resulted in the reduction of the yeast population of Doogh samples (p <0.05). The lowest yeast population was observed in the sample subjected to acoustic density=1w/ml, T= 60°C and t=30min (1.7±0.01CFU/ml). Other operation conditions also had impact on yeast survival (p <0.05). Thermosonication also had significant effects on the viscosity of the Doogh samples. Serum separation of samples was also measured and observation implied changing serum separation magnitude between different samples in comparison with the control sample (p <0.05). [ABSTRACT FROM AUTHOR]

In this study the effect of gelan, xanthan and quince seed gum (QSG) on stability, probiotic viability and qualitative properties of Doogh using response surface methodology was determined. Three gums were used at three levels of 0, 0.25 and 0.5%. The results showed that the effect of QSG on viscosity and serum separation was significant (P < 0.05). The effect of QSG on viability of B. bifidum was significant (P < 0.05). Sensory evaluation showed that effect of using of QSG was significant and the score of taste, odor and overall acceptance increased by increasing of concentration of QSG. At the optimum point, the stability, viscosity pH, probiotic load and overall acceptance were 92.24%, 11.852 mPa s, 3.87, 8.37 log cfu/mL and 4.42, respectively. Using of combination of gums at the optimal concentration prevented phase separation and maintained the probiotic viability of Doogh. Therefore, the optimization of formulation can be used for production of stabilized probiotic Doogh in dairy industry. [ABSTRACT FROM AUTHOR]

In this present study, essential oils (EOs) were extracted from Chaerophyllum macropodum, Oliveria decumbents, and Zataria multiflora Boiss. The chemical composition and antimicrobial activity of the EOs were tested against Staphylococcus aureus (G+), Escherichia coli O157: H7 (G-), and three species of fungi (Rhodotorula glutinis, Kluyveromyces marxianus and Penicillium digitatum). The outcomes were evaluated in vitro and in a food model system for 28 days of storage. Carvacrol comprised 10.83, 22.51 and 73.66% of the EOs being extracted from Chaerophyllum, Oliveria and Zataria, respectively, while thymol comprised 9.57, 36.49 and 17.17%. By evaluating antibacterial properties in vitro, the bacteria were greatly inhibited by all of the three EOs with more sensitivity of S. aureus. Oliveria and Zataria EOs were more effective than Chaerophyllum EO in preventing the growth of the three fungi. Doogh samples were inoculated before receiving the EOs (1%) and stored at 4°C for 28 days. Chaerophyllum EO caused the highest value of pH in doogh. Viscosity was significantly higher (p < .05) in the treated samples than in the control. All three EOs inhibited the bacterial populations more effectively (p < .05) than fungal populations. Regarding sensory attributes, all fortified doogh samples received comparably higher scores than the doogh containing microorganisms. In summary, the present study revealed that Chaerophyllum, Oliveria and Zataria EOs can serve as natural antimicrobial agents in doogh. [ABSTRACT FROM AUTHOR]

Background and purpose: Today, due to improvement and progress of human knowledge in food industry, plastic coatings such as PET (polyethylene terephthalate) that has unique characteristics are widely used for food and beverage packaging such as water and doogh. Phthalate esters are used in order to improve flexibility, efficiency and sustainability of materials. Chronic exposure with such materials play a role in incidence of many diseases and cancer in human. The aim of this study was to investigate the presence and concentration of phthalates in different brands of doogh. Materials and methods: In this study, we synthesized multi-walled magnetic carbon nanotubes using iron oxide. Then, the synthesized magnetic nanotubes were used for absorption and extraction of phthalate esters from doogh matrix. After sample preparation, the concentration of each phthalate esters was measured by GC-MS. Results: Concentration of phthalate esters in all samples were found to be lower than the standard levels but DEHP had the highest concentration. Statistical analysis showed no significant differences between the concentration of phthalate esters in different brands and storage time of doogh. Conclusion: According to these findings and low concentration of each phthalate ester compared with standard levels in different types of doogh, it has no health effect on consumers.

Background and purpose: Polycyclic aromatic hydrocarbons (PAHs) are one of the most common environmental pollutants that are proven to be carcinogenic and mutagenic. Doogh, is a widely consumed fermented yoghurt drink in Iran. The aim of this study was to determine the presence and concentration of PAHs in different brands of Doogh in Tehran, Iran. Materials and methods: In this study, we synthesized multi-walled magnetic carbon nanotubes using iron oxide. Then synthesized magnetic nanotubes were used for absorption and extraction of PAHs from Doogh matrix. After sample preparation, concentrations of all PAHs were measured by GC-MS. Materials and methods: In this study, we synthesized multi-walled magnetic carbon nanotubes using iron oxide. Then synthesized magnetic nanotubes were used for absorption and extraction of PAHs from 24 samples of Doogh matrix (3 high-consumption brands randomly selected in all four seasons and two dates) and one sample as a control. After sample preparation, concentrations of all 16 PAHs were measured by GC-MS. Conclusion: In this study, the concentrations of PAHs in different brands of Doogh were lower than standard levels, so it would create no harmful effect to the consumers. [ABSTRACT FROM AUTHOR]

Doogh is widely used as a healthy dairy product in Iran which is a suitable alternative to soft drinks in the society. Ginkgo biloba is an ancient plant species on earth which is also known as the living fossil. The leaves of these tree have several nutritional and therapeutic properties and therefore the Ginkgo-enriched doogh has a high nutritional value. In this study, the impact of the addition ofGinkgoextract at the levels of 0, 1, 2, 3 and 4 percent on some attributes plus the survival rate of probiotic bacteria containing 0.2 g/l shallot extract during 21 days of storage at the temperature of 4°C was explored. According to the results, by enhancing the concentration of Ginkgoextract, acidity, population of Lactobacillus acidophilus LA-5 and Bifidobacterium lactis Bb-12 plus the antioxidant activity and total phenol level were significantly enhanced (p<0.05). Also, with the increase in the level ofGinkgoextract, the sensorial score of the samples were reduced considerably (p<0.05). Storage of the samples during 21 days resulted in the reduction of Lactobacillus acidophilus LA-5 and Bifidobacterium lactis Bb-12 population as well as antioxidant activity, total phenol content and sensory acceptability considering odor, taste and color (p<0.05). Overall, the sample containing 2 g/lGinkgoextract was selected as the best sample and can be prepared as a healthy product in the dairy industry. [ABSTRACT FROM AUTHOR]

The aims of this study were evaluating the effect of Mellis herb (Melissa officinalis) powder and extract addition on the microbiological, chemical, rheological and sensorial attributes of pasteurized Doogh. In this study, 72 different Doogh samples were produced with Mellis extract and powder. On days 1, 10, 20, and 30, the physicochemical, microbial, rheological and sensory properties of Doogh samples were measured with three replications. pH, acidity, dry matter and SNF of Doogh samples containing Mellis powder and extract were significantly different (p<0.05). In the case of all of parameters the mean value of powder was greater than extract and there were no significant differences in syneresis and viscosity of Doogh samples. The rheological pattern of Doogh samples were as pseudoplastic fluid. In the case of sensorial properties, the flavor of mellis containing Doogh samples with powder and extract were not significantly different, but the about the texture, appearance and general acceptability, the extract and powder were significantly different and the scores of taste, texture, appearance and general acceptability of extract was higher than powder. Mellis addition inhibited the overall growth of moulds and yeasts until the 20th day. In the case of syneresis, at the first days, extract containing samples had lower syneresis but it increases with acidity development during the shelflife. As a result, using Mellis in Doogh production have beneficial effect on chemical, microbiological and sensorial properties of the product. [ABSTRACT FROM AUTHOR]

The effects of locust bean, carboxymethyl cellulose, a mixture of locust bean and carboxymethyl cellulose and Persian gum on different properties of nonfat doogh were studied over a period of 28 days. The results showed that samples containing a mixture of locust bean and carboxymethyl cellulose had the highest stability. Furthermore, the rheological behaviour of the doogh changed from Newtonian to pseudoplastic. Better sensory acceptability was shown for the treatments containing a mixture of locust bean gum and carboxymethyl cellulose. In general, it was shown that a mixture of locust bean and carboxymethyl cellulose could be of practical use in the industrial production of nonfat doogh. [ABSTRACT FROM AUTHOR]

The combined effects of lipase/cream reaction, temperature/time and pH of fermentation on levels of free fatty acids (FFAs), biochemical changes, oxidative stability and flavour development of the dough during 21 days of cold storage were investigated. Levels of short‐chain FFAs increased in doogh samples, while long‐chain FFAs decreased. Under the severe conditions of the lipase/cream reaction, the lowest pH drop, acidity increase and the highest intensity of lipid oxidation were observed. Treatment with a shorter reaction time and a lower temperature of the lipase/cream mixture and a lower final pH of fermentation (4.0‐20‐30) achieved the highest sensory acceptability, which could be used to improve industrial doogh. [ABSTRACT FROM AUTHOR]

Application of ultrasoundpower and its beneficial effects on food process and improved quality compared with conventional methods already have been demonstrated. In the currentstudy, the effects of ultrasound power intensity (200, 300, 400 and 500watts) at 15 and 30 minutes withdifferent storage temperature (28°C and 4°C) on Doogh pH, turbidity, fat percentage and stability was assessed. The results showed that increasingultrasound intensity and duration, caused pH reduction compared to the control,while in 400 watts sonication intensity and 4°C treatment,,samplesturbidityhad the lowest value. In comparison to control samples, there were no significant differencesin fat contentofall sonicated treatments. Also results illustrated thatall sonicated treatments had the higher stability and increasing ultrasound intensity and duration, increasedDooghstability. According to the finding, the optimal treatment during 30 minutessonication at 400 W,28°C and 4°C had the most consistency on treated Doogh samples. [ABSTRACT FROM AUTHOR]

The transglutaminase enzyme has a positive effect on serum storage capacity and gel strength in food products by creating a crosslinking effect on proteins and enhancing the protein-based structure. Inulin is fructose polymers with 2 to 60 degree of polymerization that linked by β (2-1) fructosyl bonds. Prebiotic and bifidogenic features of this matter have caused it uses as a functio nal ingredient in food products. The purpose of this study was to study the effect of the addition of MTGase and long-chain inulin on the physicochemical and sensory properties of doogh. In this study, the effect of using MTGase (0-0.3%) and long-chain inulin (0-1.5%) in 5 samples of doogh was examined on physicochemical (pH, titratable acidity, density, SNF, viscosity and phase separation) and organoleptic properties (consistency, flavor, color and overall acceptability). Evaluations were performed at 24 hours and 30 days of storage. The results revealed that with increase of transglutaminase and inulin no significant difference in pH, acidity and flavor between the control sample and other treatments containing inulin and MTGase after 24 hours and 30 days was observed (P>0.05). The viscosity, SNF, density, serum phase separation and overall acceptability of samples R3 (1.5% inulin and 0.3% MTGase) and R4 (1.5% inulin and 0.1% MTGase) shown superior physicochemical and sensory properties. [ABSTRACT FROM AUTHOR]

The possibility of a Bio‐Doogh production with active and live probiotic bacteria was investigated. In this study, the effect of zinc and vitamin B12 as micronutrients together with thyme and Aloe vera extracts at days 1, 11 and 21 of production on the development and viability of Lactobacillus acidophilusLA‐5® at 4 °C was studied. The addition of vitamin B12 (1.9 μg/L) and zinc (17.6 mg/L) increased the bacterial count of the probiotic strain; the effect of zinc was greater than that of vitamin B12. In addition, the data obtained indicated that the logarithmic bacterial count of the probiotic strain increased with addition of the thyme and Aloe vera extracts (10 mg/L). The simultaneous use of zinc and Aloe vera extract resulted in the highest probiotic bacterial count. Statistical analysis indicated that there were significant differences in the acidity and pH between the samples. The syneresis and odour of the test samples were different from the untreated samples. [ABSTRACT FROM AUTHOR]

Background: Doogh is a traditional dairy product, which is widely used as a popular drink in the Middle East, in general, and in Iran, in particular. There has been no research study regarding its effects on vigilance and mental-cognitive performance so far; the present study aimed at investigating this effect. Objectives: The current study aimed at objectively evaluating the effect of Doogh (Yogurt drink) on attention, reaction time and vigilance-sleepiness of healthy young adults. Methods: In this repeated measurement study, participants included 17 healthy adults between 20 and 40 years old, with adequate night sleep and without any symptoms of daytime sleepiness that entered the clinical trial one at a time via public invitations. The intervention included drinking 250 cc of doogh or water in the morning or in the afternoon. Therefore, there were 4 interventions for each participant with random sequences, lasting 3 to 5 days. Right before and 1.5 to 2 hours after drinking each of the drinks, the participants were assessed using test of variables of attention (TOVA) and sleepiness test via the visual analogue scale (VAS). The data were analyzed by paired t test and Generalized Estimating Equation (GEE) model at the final stage. Results: Ten female and 7 male participants took part in the study. Doogh caused a significant increase in reaction time and commission error and reduced vigilance. These changes occurring after drinking doogh were significant in the afternoons, while they were insignificant in the mornings despite the fact that they lasted longer. There was no change regarding TOVA variables caused by water in any of the case. Although reduced level of vigilance was observed after drinking water, the differences weremoresignificant with regards to doogh and its post intervention comparison with water was meaningful. Conclusions: Dooghcaused sleepiness in the afternoon time along with a significant increase in reaction time and commission and omission errors. Regarding the cognitive effects of doogh, the timing and activity type of the drinker should be taken into account. Positive effects of drinking doogh on sleepiness and the risk of accidents caused by drinking it should be studied in other research projects. [ABSTRACT FROM AUTHOR]

Serum separation of Doogh, an Iranian yoghurt drink, is a major problem. In this study, the effects of whey protein concentrate (WPC) addition, pH of the product and dissolved salt (sodium chloride) in milk on the colloidal stability of Doogh were investigated. By increasing the amount of WPC (from 0.5 to 3%) and salt in milk (from 0 to 1.6%), the serum separation decreased. Increasing pH values of sample (from 3.5 to 4.5), WPC (from 0.5 to 4%) and salt concentration in milk (from 0 to 2%) also increased the samples’ viscosity. All samples showed Newtonian behaviour except samples at pH 4.5, containing 4% WPC and 2% dissolved salt in milk. [ABSTRACT FROM AUTHOR]

This study aimed to nanoencapsulate the essential oil of the Nepeta crispa and its application in yogurt drink (doogh) to investigate the product's physicochemical, microbial, and sensory properties. N. crispa essential oil was nanoencapsulated with the different ratios of pectin:whey protein concentrate (25:75, 50:50, 75:25 w/w) using spray drying. The highest nanoencapsulation efficiency and the lowest nanoencapsulated phenolic compounds release were obtained in the 75:25 pectin: whey protein concentrate ratio. The nanoparticles had a semi-spherical structure and a size of about 400 nm. FT-IR confirmed the presence of hydroxyl bonds related to phenolic compounds in the essential oil. Different concentrations (0.075, 0.15, and 0.20 mg/mL) of free and encapsulated essential oil were added to the doogh. With the increase in essential oil concentration, acidity had an upward trend. The sample containing 0.20 mg/mL of encapsulated essential oil showed the highest percentage of DPPH radical inhibition and the lowest IC 50. The addition of nanoencapsulated essential oil positively affected on the doogh sensory quality. Doogh containing 0.20 mg/mL of nanoencapsulated essential oil had a greater inhibitory effect on Escherichia coli and Staphylococcus aureus. Since this sample had an acceptable sensory quality, it was chosen as the best sample. [Display omitted] • Nepeta crispa essential oil was nanoencapsulated with pectin and WPC. • The highest encapsulation efficiency was obtained in the ratio of 75:25 pectin:WPC. • The lowest phenolic compounds release was obtained in the ratio of 75:25 pectin:WPC. • Doogh with 0.20 mg/mL of NEO showed the highest antioxidant activity. • Doogh with 0.20 mg/mL of NEO had the greatest inhibitory effect on pathogenic bacteria. [ABSTRACT FROM AUTHOR]

Background and Objectives: Doogh is considered as one of the traditional drink in Iran and other nations like Eastern Europe, Middle East and Asia. In the past the “doogh” was applied to a product which remained after dilution of full fat yoghurt with water and fat separation using the musk. Nowadays Doogh has have physical, chemical, physico-chemical, microbial and sensory characteristics and standards. In this study the microbial quality of four famous brands produced in Iran was assessed. Materials and Methods: This is a cross-sectional study. Totally, 126 samples were selected from the foodstuff suppliers using random sampling .In order to determine Staphylococcus aureus, Baird Parker Agar (recognition test) and coagulase test (confirmation test) were used. Results: The results were analyzed using SPSS, and T-Test and one way ANOVA were performed. The results showed that in view of contamination there is Significant differences between the months, the brands and the types of doogh (p

Liquid gel technology is a method that applies in stabilizing of suspension and dispersion of solid particles in beverages. Doogh which is an Iranian traditional and functional drink has allocated a unique position among consumers. Precipitation of hydrocolloids in Doogh has been always one of the most important challenge in producing this drink. Base of this fact, this study deals with using liquid gel technology (Guar gum and Hydrocolloids of Psyllium Husk ) .Different hydrocolloids concentration (0.01, 0.03, 0.05 %w/w) in Doogh heated to be hydrated at 80 ˚C resulting in producing Gel. Their flow behavior, particle distribution and microstructure analyzed, phase separation also evaluated by measuring volume of separated phases .Guar remarkably effected on Doogh flow behavior and caused to a high apparent viscosity in low shear rates, changing microstructure therefore changing particles size as well. It also subtracted the volume of separated phase .Xanthan and Psyllium increased stability of Doogh by increasing more repulsive force between particles, however larger particles precipitated. Samples containing Guar Gum indicated more yield stress.

Doogh is a fermented dairy product that derived from a combinationof water and yoghurt and some flavoring additives.In this study, the effect of adding of whey powder in range of 0.2 to 0.4%, commercial stabilizer in range of 0.2 to 0.4% and milk powder in range of 0.3 to 0.5%, on phase separation of dooghby response surface methodology and also the rheological andorganoleptic properties by 5-point hedonic method were investigated. The results showed that with increasing stabilizer phase separation decreasedas well as increased whey powder to 0.3%(P<0.05).The results of optimization showed that the phase separation of dooghwas 57% by using of 0.4% commercial stabilizer, 0.35% whey powder and 0.4% milk powder.Also, increasing of these compounds changeddoogh rheologicalbehavior from newtonian to shear thinning.The optimized formulation gained the highest score of sensory evaluation. [ABSTRACT FROM AUTHOR]

In this paper, a dispersive liquid-liquid microextraction method has been developed for the extraction and preconcentration of natamycin from cheese and doogh samples and its determination by indirect flame atomic absorption spectrometry. For this purpose, an appropriate mixture of a disperser solvent (ethanol) and an extraction solvent (1,1,2-trichloroethane) is rapidly injected into the samples and Zn cation was added. During this process, natamycin-Zn complex is extracted into fine droplets of the extraction solvent. After centrifugation, the fine droplets of the extractant containing the complex are sedimented at the bottom of a tube with conical bottom. The sedimented phase is injected into the determination system via a home-made sample introduction system. Under the optimal conditions, the linear range was between 5 and 1000 ng mL. The limit of detection of the target analyte was obtained 1.8 ng mL. The relative recoveries obtained for the spiked cheese and doogh samples were between 86 and 98%. Moreover, the precision of the method was acceptable (<3.9%) in all spiked concentrations. Finally, the method was successfully applied to determine natamycin in cheese and doogh samples. [ABSTRACT FROM AUTHOR]

Background and purpose: Today, due to improvement and progress of human knowledge in food industry, plastic coatings such as PET (polyethylene terephthalate) that has unique characteristics are widely used for food and beverage packaging such as water and doogh. Phthalate esters are used in order to improve flexibility, efficiency and sustainability of materials. Chronic exposure with such materials play a role in incidence of many diseases and cancer in human. The aim of this study was to investigate the presence and concentration of phthalates in different brands of doogh. Materials and methods: In this study, we synthesized multi-walled magnetic carbon nanotubes using iron oxide. Then, the synthesized magnetic nanotubes were used for absorption and extraction of phthalate esters from doogh matrix. After sample preparation, the concentration of each phthalate esters was measured by GC-MS. Results: Concentration of phthalate esters in all samples were found to be lower than the standard levels but DEHP had the highest concentration. Statistical analysis showed no significant differences between the concentration of phthalate esters in different brands and storage time of doogh. Conclusion: According to these findings and low concentration of each phthalate ester compared with standard levels in different types of doogh, it has no health effect on consumers. [ABSTRACT FROM AUTHOR]

Doogh is a fermented beverage that is prepared by mixing yoghurt with water and some salt. There are resembling beverage basis of yogurt in neighboring countries around Iran. For example, dilution ratio, fat content, rheological characteristics and taste like doogh, however, they all contain aggregated casein Serum separation is one of the main problems of this product during storage period. In this study, the effect of the additional of guar gums (0.3%), and xanthan (0.3%) and a mixture of two gums (0.15%0.15%) on the rheological properties and serum separation of low fat doogh was examined. Rheological behavior of doogh samples was fitted with Ostwald-de Waele model. Mathematical calculations of data based Ostwald-de Waele model, showed that the low-fat doogh is non-Newtonian and shear thinning (Pseudo plastic) fluid type. Also, using the Arrhenius equation dependence of the apparent viscosity to temperature is determined and the activation energy between 11.09 to 19.07 kJ/mol is calculated. [ABSTRACT FROM AUTHOR]

Aflatoxin M 1 is an important mycotoxin mostly found in milk and dairy products. The main objective of this work was to study the effects of probiotic strains, a probiotic inoculated population, the physiology of probiotic bacteria and final fermentation pH at four consecutive stages on the reduction of 0.500 ppb of free aflatoxin M 1 (AFM 1 ) in Doogh (a traditional Iranian fermented milk drink). Samples’ biochemical, microbial and AFM 1 binding characteristics were monitored during fermentation and storage (5 °C for 28 days). An immunoaffinity column was used to extract AFM 1 and a high-performance liquid chromatograph with a fluorescence detector was used to measure it. Results showed that Lactobacillus acidophilus was probiotic strain that most reduced free AFM 1 . Inoculation of L. acidophilus at 9 log cfu/mL, despite the higher cost, revealed significantly higher free AFM 1 binding capacity than 7 log cfu/mL. Heat-killed (dead) L. acidophilus bacteria reduced less free AFM 1 at the end of storage than viable. Samples with a final fermentation pH of 4.5 bound more free AFM 1 during fermentation and storage than those with a pH of 4.2. It is concluded that inoculation of 7 log cfu/mL L. acidophilus viable cells in Doogh with a final fermentation pH of 4.5 supplied a safety- and health-promoting and cost-effective drink. [ABSTRACT FROM AUTHOR]