Production of synbiotic Doogh enriched with Plantago psyllium mucilage.

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.

Optimization of stabilized probiotic Doogh formulation by edible gums and response surface methodology: assessment of stability, viability and organoleptic attributes.

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.

Vitamin D receptor Cdx-2-dependent response of central obesity to vitamin D intake in the subjects with type 2 diabetes: a randomised clinical trial.

This study aimed to investigate the effects of daily intake of vitamin D-fortified yogurt drink (doogh) on central obesity indicators in subjects with type 2 diabetes (T2D) and the possible modulation of this effect by vitamin D receptor (VDR) Cdx-2 genotypes. A total of sixty T2D subjects were randomly allocated to two groups to receive either plain doogh (PD; n 29, containing 170 mg Ca and no vitamin D/250 ml) or vitamin D3-fortified doogh (FD; n 31, containing 170 mg Ca and 12·5 µg/250 ml) twice a day for 12 weeks. 25-hydroxyvitamin D (25(OH)D), glycaemic as well as adiposity indicators were evaluated before and after the intervention. VDR-Cdx-2 genotypes in extended number of T2D subjects in the FD group (n 60) were determined as AA, GA and GG. After 12 weeks, in FD compared with PD, serum 25(OH)D increased (+35·4 v. -4·8 nmol/l; P<0·001) and mean changes of waist circumference (WC; -1·3 v. +1·6 cm; P=0·02), body fat mass (FM; -1·9 v. +0·60 %; P=0·008), truncal fat (TF; -1·1 v. 0·13 %; P=0·003) and visceral adipose tissue (-0·80 v. +0·37 AU; P<0·001) decreased significantly. Circulating 25(OH)D was raised only in the AA group (34·8 nmo/l in AA group v. -6·4 nmol/l in AG and -1·6 nmol/l in GG groups; P<0·001), which was accompanied by a significant decrease in changes of WC (P=0·004), FM% (P=0·01) and TF% (P<0·001) in the AA genotype. Daily intake of vitamin D-FD for 12 weeks improved the central obesity indices in T2D subjects, and the improvement was more pronounced in the carriers of the AA genotype of VDR-Cdx-2.

Synbiotic potential of Doogh supplemented with free and encapsulated Lactobacillus plantarum LS5 and Helianthus tuberosus inulin.

The survival and effect of free and encapsulated probiotic Lactobacillus plantarum LS5 on acidity, exopolysaccharide production, phase separation and influence on the sensory attributes of probiotic and synbiotic Doogh (typical Iranian drink based on fermented milk) supplemented with Helianthus tuberosus inulin were studied over 22 days storage. Results showed addition of L.plantarum LS5 (free or encapsulated) increased acid development (°D) in Doogh during storage. In addition, phase separation in Doogh with encapsulated probiotic bacteria was slower compared to Doogh with free probiotic bacteria. More exopolysaccharides were observed in Doogh with encapsulated culture compared to those without encapsulated culture. The results confirmed that there was an increased survival of L.plantarum LS5 due to protection of cells by microencapsulation. Also addition of inulin improved survival of free or encapsulated cells in Doogh during storage, but effect of inulin on acidity, exoploysaccharide content and phase separation of samples containing free or encapsulated cells was not significant (P > 0.05). Moreover, sensory evaluation results indicated addition of free or encapsulated probiotic cells and inulin did not significantly affect appearance and color, acidity, flavor and after taste of the Doogh samples over the storage period. Therefore, probiotic and synbiotic Doogh (supplemented with free or encapsulated L.plantarum LS5 and Helianthus tuberosus inulin) are potentially suitable for using as functional dairy foods.

Formulation of nanoemulsion carriers containing Pennyroyal (Mentha pulegium) and Gijavash (Froriepia subpinnata) essential oils for enriching Doogh (Iranian dairy drink).

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.

Analysis of polychlorinated biphenyls (PCBs) in dairy products by modified QuEChERS/GC-QqQ-MS/MS method: A risk assessment study.

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 Æ©6-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.

Investigation of rheological, physicochemical, and sensorial properties of traditional low-fat Doogh formulated.

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.

Development of a natamycin-based non-migratory antimicrobial active packaging for extending shelf-life of yogurt drink (Doogh).

A natamycin-based non-migratory antimicrobial packaging for extending shelf-life of yogurt drink (Doogh) was developed. Firstly, the surface of low-density polyethylene film (LDPE) was modified with acrylic acid at different times of UV exposure (0-10 min) to produce carboxylic functional groups. Then, natamycin was applied to the UV-treated films to bind covalently with the pendent functional groups. The maximum grafting efficiency (81.96%) was obtained for the 6 min treated film. Moreover, surface properties of films were evaluated by Attenuated Total Reflectance/Fourier Transfer Infrared Spectroscopy (ATR-FTIR) and scanning electron microscopy (SEM). Antifungal activity of different treatments of natamycin grafted film was evaluated against two common spoilage yeasts of Doogh including Rhodotorula mucilaginosa and Candida parapsilosis. Results showed that 6 min treated film provides maximum anti-yeast activity and can be applied to control fungal growth in Doogh. Natamycin-grafted film postponed the yeast spoilage in Doogh and prolonged its shelf-life to 23 days.

Viability of microencapsulated and non-microencapsulated Lactobacilli in a commercial beverage.

The survival rate of free and encapsulated L. acidophilus and L. rhamnosus into Doogh beverage and simulated gastrointestinal conditions during 42-day were studied. Microencapsulation considerably protected both L. acidophilus and L. rhamnosus in Doogh beverage storage and in gastrointestinal conditions. Microencapsulation provided better protection to L. acidophilus than to L. rhamnosus during Doogh storage. In beverages containing the free form of bacteria, pH and acidity changes were greater than those of microencapsulated and control groups. More activity of the free probiotic bacteria (during a 42-day period especially after 21-day) produced more acid and metabolites inside the product, thereby reducing the organoleptic properties scores, However, acidity, pH and organoleptic characteristics of Doogh containing microencapsulated bacteria did not change considerably. In conclusion, this study suggests that the encapsulation and double coating of L. acidophilus and L. rhamnosus can increase the viability of them in Doogh beverage and in simulated GI conditions.

Method development for determination of migrated phthalate acid esters from polyethylene terephthalate (PET) packaging into traditional Iranian drinking beverage (Doogh) samples: a novel approach of MSPE-GC/MS technique.

In the current study, a novel magnetic solid phase extraction (MSPE) technique combined with a gas chromatography/mass spectroscopy (GC/MS) was developed to determine the phthalate ester content of bottled Doogh samples. Doogh is a yogurt-based drinking beverage, which is frequently consumed in Middle East and Balkans. It is produced by stirring yogurt in Chern separation machine and consists of substances such as water, yogurt, and salt in addition to aqueous extracts of native herbs. The magnetic multi-walled carbon nanotubes (MWCNT-Fe3O4) were used as adsorbents of phthalate acid esters (PAEs) due to a superior adsorption capability of hydrophobic compounds. In this context, the quantity of the extractable migrated phthalate esters (dibutyl phthalate (DBP), dimethyl phthalate (DMP), butyl benzyl phthalate (BBP), diethyl phthalate (DEP), di-N-octyl phthalate (DNOP), and bis (2-ethylhexyl) phthalate (DEHP)) from polyethylene terephthalate (PET) bottles into Doogh samples was measured. The correlation between the concentration of migrated PAEs and some factors such as the type of Doogh (gaseous and without gas), difference in brand (five brands), volume (1500 and 300 mL), and the storage time also was investigated. The migration level into Doogh samples was increased by incorporating of gas as well as increasing the volume of PET bottles. Also, with elaborating of storage time, the migration of some phthalates such as DEHP (the mean from 2419.85 ng L-1 in the first week to 2716.15 ng L-1 in the second month), DEP, and total phthalate was increased. However, no significant difference in concentrations of migrated phthalate esters among different examined brands was noted. Finally, the concentration of migrated PAEs from bottle into all the examined Doogh samples was below the defined standards by EPA; 6 µg/L for DEHP in drinking water. Graphical abstract ᅟ.

Stability of Vitamin D3 in fortified yoghurt and yoghurt drink (Doogh).

BACKGROUND: Vitamin D deficiency and insufficiency are recognized as a worldwide problem with serious consequences. Fortification of foods with Vitamin D is a certain approach to improve serum Vitamin D status if the stability of vitamin in the foodstuffs was controlled. The purpose of this study was to examine the stability of Vitamin D3 added to low-fat yogurt and yogurt drink "Doogh" during the products shelf-life. MATERIALS AND METHODS: Two kinds of Vitamin D3, water- and oil-dispersible forms, suitable for food fortification, were compared to find out whether they show different stability in the products. The products were packed in opaque or translucent containers. The content of Vitamin D3 was determined by high performance liquid chromatography method. RESULTS: Vitamin D was not affected by the heat treatment (pasteurization) and other processes (homogenization and fermentation). Both water- and oil-dispersible forms were stable during the shelf-life of yogurt samples packed in opaque containers. The Vitamin D3 content of yogurt fortified with water-dispersible form and packed in translucent containers was not stable during the shelf-life and significantly reduced after 1, 2, and 3 weeks of storage compared to the day 0. The Vitamin D3 content of samples fortified with the oil-dispersible form packed in the same container was only stable after 1-week and significantly reduced after 2 and 3 weeks of storage. The Vitamin D3 content of Doogh packed in the opaque containers remained stable during the shelf-life while it was not stable in the samples packed in translucent containers. CONCLUSION: The results suggested that both forms of Vitamin D are suitable for fortification, and opaque container is a better choice for packaging of the product.

The antibacterial effect of Ziziphora clinopodioides essential oil and nisinagainst Salmonella typhimurium and Staphylococcus aureus in doogh, a yoghurt-based Iranian drink.

Doogh is the most popular and commonly consumed yoghurt-based Iranian drink. The aim of this study was to investigate the antibacterial effects of Ziziphora clinopodioides essential oil (ZEO) at 0.10 and 0.20% concentrations, nisin at 250 and 500 IU mL-1, and their combination against Salmonella typhimurium and Staphylococcusaureus in doogh during storage at 4 ˚C for  9 days. Nine batches were studied as follows: control: no ZEO or nisin added, A: 0.10% ZEO, B: 0.20% ZEO, C: 250 IU mL-1 nisin, D: 500 IU mL-1 nisin, E: 0.10% ZEO + 250 IU mL-1 nisin, F: 0.10% ZEO + 500 IU mL-1 nisin, G: 0.20% ZEO + 250 IU mL-1 nisin and H: 0.20% ZEO + 500 IU mL-1 nisin. Based on gas-chromatography and mass spectrometry, carvacrol (65.22%), thymol (19.51%), p-cymene (4.86%) and É£-terpinene (4.63%) were the major components of ZEO. The populations of S. typhimurium and S.aureus in samples treated with all concentrations of the ZEO and nisin were kept below 1 log CFU mL-1 on day 5 of storage, while the count of S. typhimurium and S.aureus was found as 2.72 ± 0.02 and 2.21 ± 0.00 log CFU mL-1 on day 5 for untreated samples, respectively. The ZEO separately and in combination with nisin, was very effective against these two common food-borne pathogens. The ZEO alone and in combination with nisin could be considered as a potential strong antimicrobial agent that can be used for the growth inhibition of aforementioned bacteria in food products especially doogh.

Sodium benzoate and potassium sorbate preservatives in Iranian doogh.

Sodium benzoate and potassium sorbate are two common preservatives used in Iran, yet use of these preservatives in doogh (Iranian dairy-based drink) is forbidden according to national standards. The aim of this study was to consider the presence of these preservatives in doogh by high-performance liquid chromatography with UV detection (HPLC-UV). The method was performed using a C18 column and detection at 225 nm. The mobile phase contained ammonium acetate buffer (pH = 4.2) and acetonitrile (80:20 v/v). The survey included 130 samples of doogh for identification and quantification of the named preservatives. All samples contained sodium benzoate, but potassium sorbate was detected in only 13% of them. The means of benzoate and sorbate were 21.3 ± 2.7 and 13.3 ± 39.6 mg kg(-1), respectively. The limits of detection were 2 and 40 ng g(-1) for benzoate and sorbate, respectively. Results indicate that sodium benzoate may occur in doogh naturally.

The impact of inoculation rate and order on physicochemical, microstructural and sensory attributes of probiotic doogh.

Effects of inoculation level (4 or 8-fold compared to standard inoculation) and order (standard inoculation before fermentation and 3-fold inoculation at the end of fermentation = 1+3, Two-fold inoculation before fermentation and the same at the end of fermentation = 2+2, 2+6, 4-fold before fermentation = 4, 4+4, and 8) of culture inoculums containing probiotics on viscosity, phase separation, particle size analysis, microstructure and sensory attributes of probiotic Doogh were studied. The probiotic microorganisms were Lactobacillus acidophilus LA-5 and Bifidobacterium lactis BB-12. Treatments with 2- and 4-fold inoculation before fermentation had the highest instrumental viscosity and surface tension at the end of fermentation. The size diameter of particles in the structure of treatment 8I was significantly (p < 0.05) smaller than I after stirring with a Lab stirrer (1500 rpm), and even after homogenization with a homogenizer (150 bar). 8I was an un-uniform, disintegrated and clumped structure with limited junctions in its network that resulted in a weak structure with bigger particles after agitation and smaller particles after stirring and homogenization compared to other treatments. This treatment also had the lowest record in ranking sensory test among treatments with a mixed culture-like and vinegary-like taint. Overall, treatments with 2- and 4-fold inoculation were realized as the best from the sum of physiochemical and sensory properties point of view.

Combined effects of inoculation level and sequence on biochemical and microbiological characteristics of probiotic doogh.

The combined effects of inoculation level (4 or 8-fold compared to standard inoculation) and sequence (standard inoculation before fermentation and 3-fold inoculation at the end of fermentation=1+3, Two-fold inoculation before fermentation and the same at the end of fermentation=2+2, 2+6, 4-fold before fermentation=4, 4+4, and 8) of culture inoculum containing probiotics on biochemical and microbiological characteristics of probiotic Doogh during fermentation and over 21 days of refrigerated storage (4˚C) were investigated. The probiotic microorganisms were L. acidophilus LA-5 and Bifidobacterium lactis BB-12. Overall, the treatments 8, 4 and 4+4 resulted in the highest viability at the end of fermentation as well as at early days of refrigerated storage. During the second half of cold storage period, the greatest viability of probiotics was related to the treatment 2+6. The treatment '8' showed the shortest incubation time as well as the highest pH drop rate and acidity increase rate during fermentation and over the storage period.