جستجوی مقالات مرتبط با کلیدواژه « شیر » در نشریات گروه « صنایع غذایی »

In the present study the effects of probiotic bacteria on textural and sensorial attributes of sour cream was considered. The cream samples were incorporated by three probiotic bacteria including Lactobacillus casei, L.helveticus and Bifidobacterium lactis as single culture. The pH values, viability of probiotics, textural and sensorial features were evaluated at the time of 1, 15 and 30 days of storage. The mentioned parameters were compared to the control cream sample. The pH values, probiotic survival, textural (firmness, consistency and adhesiveness) and sensorial (off-note, cohesiveness, creaminess, odor, sourness, metallic after taste, taste) properties of cultured cream samples differed depending on the used cultures. Totally, incorporation of probiotic bacteria into sour cream can result in manufacturing of a new healthy product in the market of dairy products.

Today, the desire to use ozone as a strong antimicrobial compound, cost-effective, and eco-friendly innovation, has increased to increase the shelf life of food products. This study was conducted in order to evaluate the chemical and microbial properties of thermally pasteurized skim milk treated with pressurized ozone injection at concentrations of zero, 1.5, 5, and 10 ppm. The chemical, microbial and sensory characteristics of the treated milk samples were evaluated on days 0, 4, 7 and 15 of storage in the refrigerator. The total viable count (TVC) in the treated samples with ozone compared to the control had a noticeable decrease in all storage days. The highest antimicrobial effect was observed on the 15th day of storage with 10 ppm ozone and the lowest effect was observed on the 4th day with 1.5 ppm ozone. However, there was no significant difference in pH (6.8-6.88) and acidity (0.16-0.18) between treated and control samples. Although the peroxide number (PV) in the treated samples and the control samples was higher than the standard, but its reduction was evident in the treated samples compared to the control samples. Also, by comparing the sensory characteristics among the samples, no significant differences were observed. In general, treatments with 5 and 10 ppm ozone had the best efficiency in increasing the shelf life of pasteurized milk. According to the results, ozone can be used as an auxiliary method to increase the effectiveness of thermal processes in pasteurization and increase the shelf life of milk.

The aim of the present study was to evaluate the viability of Lactobacillus rhamnosus IBRC-M 10754 in milk as a probiotic in cold storage and to evaluate its anti-diabetic effects. After bacterial culture in MRS medium and addition to milk, treatments containing 107, 108 and 109 cfu / ml of probiotic milk were prepared. Bacterial viability was performed for 5 days by sequential dilution and extensive culture in three replicates. Then, gavage containing probiotic-containing milk to Balb/C male rats that were infected with Streptozotocin was compared with anti-diabetic rats fed L. rhamnosus milk by measuring their blood glucose and weight. The results showed that the highest number of live bacteria in milk at 4Cº  ,belonged to the first day of storage and there was no significant difference from the second day until the end of storage period. Overall, the bacterial population in milk decreased significantly (p≤0.05) over time. Addition of 109 cfu/ml primary inoculum showed that at the end of the fifth day the bacterial population in the milk was as high as that in the probiotic milk by the end of the cold storage. Mice weighing showed that the weight of control rats increased during the storage period, but diabetic rats decreased during this time. Milk with Lactobacillus inoculated in diabetic rats at different doses of inoculation resulted in a significant (P <0.05) decrease in blood glucose during their 21-day storage period. The decline of the fourteenth day of feeding probiotics is more evident.

In recent years, cold plasma is one of the expected alternatives for post-harvest treatments and post-harvest management of products. A surface discharge plasma system was used for investigating the destruction time of Bacillus cereus, Bacillus coagulans, Bacillus stearothermophilus, and Clostridium botulinum in bottled milk. The simulation was performed by COMSOL a3.5 software for a two-dimensional geometry. The collected experimental data were simulated in COMSOL software. The k factor of microorganism deactivation data was used to validate the simulated data. Results showed that the production of reactive oxygen species during plasma treatment increases with time and extends to the entire container. The concentration of reactive oxygen species (at the output of the plasma probe) at the beginning of the production was high, and at the end when they leave the free surface of the milk, the concentration decreased. Increasing the initial temperature of milk sample, from 50 to 80℃, can cause significant changes in the amount of ozone from 125 mol/m3 to 266 mol/m3, respectively (p <0.05). However, voltage changes in these two temperatures did not show a significant effect on ozone concentration. Also, immediately upon the initiation of plasma treatment, plasma destruction begins where the concentration of active species is higher. It is shown that among the four studied bacteria, Bacillus stearothermophilus has the highest resistance against cold plasma, and after that other bacteria have shown similar resistance. Finally, it can be concluded that the deep plasma treatment in bottle can make it possible to overcome the surface limitation of cold plasma treatment.

With the increasing awareness of consumers regarding the health effects of calcium, the enrichment of dairy products with calcium has increased. However, adding calcium salts to sterile milk can cause milk instability and increase sedimentation. In this research, the effect of adding hydrocolloids of carbox ymethyl cellulose (0.01%), kappa carrageenan (0.02%) and a mixture of carboxy methyl cellulose and kappa carrageenan on the physicochemical and sensory properties of calcium-enriched sterile milk was investigated. The results indicated that the addition of carboxy methyl cellulose and kappa carrageenan had no significant effect on the pH, acidity, and electrical conductivity of milk samples (p˃0.05), but during the storage period, the pH of the samples decreased, and their acidity and electrical conductivity increased significantly (p<0.05). The maximum thermal stability was observed in the first treatment (0.01% carboxymethyl cellulose and 0.15% calcium citrate) and the third (0.01% carboxymethyl cellulose, 0.02% capacarrageenan and 0.15% calcium citrate), while Control samples and the second treatment (0.02% capacarrageenan and 0.15% calcium citrate) had less thermal stability.The results showed that in all the samples, the percentage of precipitation increased significantly with increasing storage time (p<0.05), but in the treatment samples and in the presence of carboxy methyl cellulose hydrocolloids and kappa carrageenan, the percentage of calcium precipitation decreased and viscosity increased significantly (p<0.05). It seems that the sediment consists of accumulations of proteins or protein particles of different sizes that are precipitated together with calcium and phosphate under the influence of gravity. Evaluation of overall acceptance determined that the control sample and the first treatment were the most acceptable among the tested treatments. It seems that the reduction of sediment in the first treatment and its lower viscosity compared to other treatments have been effective in increasing the overall acceptance score of the first treatment in terms of evaluators.

Microbial quality of raw milk is very important in two respects. First, milk consumption itself plays a very significant role in people's food tables and its high microbial load endangers consumer health. Second, if the microbial quality of milk is not suitable, from a technology point of view, milk-derived products will not have a good quality. In this project, which has been carried out in collaboration with Pegah Golestan Company, the separation process (with separators) and double bactofugation was used to reduce microbial load with the aim of reducing milk heating (in order to reduce the nutritional value as a result of heat). Milk samples used for lactic cheese production in Golestan province were examined in 2020 and 2021. After the process, total microbial counting, aerobic and anaerobic spores were counted. The results showed that by using this method, the total microbial load, aerobic and anaerobic spores of the collected milks were reduced to an acceptable level throughout the year without decreasing the microbial quality of the produced cheese during the storage period. On the other hand, the process of separation and bactofugation produces dairy sludge. Normally, dairy sludge is removed every 20 minutes, which was performed in separator and bactofuge1 to 21 minutes to reduce dairy sludge.

Cinnamon has proven health and healing effects due to its numerous phenolic compounds. On the other hand, the use of nanoliposome to overcome incompatibility between bioactive compounds and food matrices targeting fortification has been widely acknowledged. Therefore, in order to produce a functional product and increase the desire to consume milk, in the present study, high-fat milk enriched with cinnamon was prepared by a nanoliposomal system with zein hydrolysate. Encapsulation efficiency, loading capacity, particle size, and particle size distribution of the prepared liposomes were evaluated and then the amount of total phenolic compounds, antioxidant activity, color index, viscosity, and sensory properties of enriched milk were evaluated on the first and seventh days. The results were compared with milk containing cinnamon extract and control milk. The particle size and distribution of the liposomal system were in the range of 376-403 nm and 0.63-0.54, respectively, and the encapsulation efficiency and loading capacity were higher than 85% and 53%, respectively. The results showed that the addition of cinnamon using the liposomal system had no significant effect on the properties of fortified milk and was evaluated similarly to the control sample. The amount of phenolic compounds and antioxidant activity of cinnamon-enriched milk by the liposomal system on the seventh day was higher than the control sample and also the sample enriched with cinnamon extract. In terms of color, the addition of cinnamon as extract decreased the L*, increased a* and b* of milk, while it was evaluated similarly to the control sample as the liposomal system was used as a carrier. Sensually, enriched samples using the liposomal system due to lack of negative effect on sensory properties had a high similarity to the control sample and no significant difference was observed between the two samples

Milk is one of the most widely consumed dairy products in the world that has a high nutritional value. Due to the presence of several bioactive compounds, this food has different biological properties such as antimicrobial activity. In recent years, the tendency to consume milk from domestic animals other than cattle such as donkey, horse and camel milk has increased. This study aimed to evaluate and compare the natural antimicrobial properties of raw milk of horse, donkey and camel againstBacillus cereus (as an important foodborne pathogen). Also, the effect of storage temperature on the antimicrobial properties of milk samples of these animals was studied. After a random collection of samples, the B. cereus was inoculated into the samples and they were incubated at 5, 10 and 20 °C for 96 h. To evaluate the inhibitory activity of milk samples against the behavior of this bacterium, samples were cultured on the selective medium every 24 h. At temperatures of 5 and 10 °C, the milk of these animals showed a better antimicrobial activity compared to 20 °C. The antimicrobial effect of horse and camel milk at 5 and 10 °C was higher than donkey milk after 96 h of storage, while the effect of donkey and horse milk at 20 °C was stronger than camel milk particularly during 72 h of storage. According to the findings of this study, it can be concluded that the level of natural antimicrobial activity of milk varies depending on the animal species and storage temperature.

Excessive use of antibiotics in the production of livestock has led to the accumulation of antibiotic residues in various livestock products such as meat and milk. Consumption of foods containing antibiotics leads to problems such as increased antibiotic resistance, while their accumulation in the body can lead to mutagenesis and cancers, liver damage and abortion. For this reason, monitoring residual antibiotics, especially in high-consumption and beneficial food products such as milk and dairy products, is of particular importance. In this research, a dispersive solid-phase micro-extraction method for the extraction of tetracycline, oxytetracycline, chlortetracycline and doxycycline antibiotics from 50 milk samples and their quantitative measurement by HPLC was developed. For this purpose, the effect of various parameters affecting the extraction efficiency such as the volume of the precipitating agent, the type and amount of solid adsorbent, ionic strength, aeration time and flow rate, type and amount of surfactant and type and volume of elution solvent were optimized. The results showed that all milk samples contained tetracycline residue and its concentration varied in the range of 146 to 319 ng / ml. No other antibiotics were found in the samples. The advantages of the proposed extraction method include high separation power and the possibility of analyzing a mixture of highly sensitive analytes, so that under optimal conditions, recoveries of the proposed method ranging from 80 to 91%, the LOD were in the range of 0.17-0.33 ng / ml and the linear range was in the range of 0.63-2000 ng / ml.

Aflatoxins are acute toxigenic and stable in heating process. Therefore determination of its concentration in milk is critical. The aim of this study was to evaluate aflatoxin M1 concentration in packaged milk produced in Mashhad and Gonabad. Aflatoxin concentration in milk samples was detected by ELISA (Enzyme Linked Immunosorbent Assay) technique and compared by limit of EU regulation and ISIRI. Totally 80 samples were analyzed for AFM1. The lower layer after separation fat by centrifuge was tested by ELIZA at 450 nm. The average concentration and standard deviation of aflatoxin M1 in the packaged milks produced in Mashhad were 0.040±0.015, 0.021±0.007, 0.022±0.003, 0.05±0.008 and in the packaged milks produced in Gonabad were 0.024±0.019, 0.027±0.021 & 0.031±0.029 ppb respectively. In overall, 13% of the milk samples had the aflatoxin M1 concentration higher than the 0.05 ppb (Iranian standard) and only one sample had aflatoxin M1 greater than 0.08 ppb. According to the results in this study, the average aflatoxin M1 levels of all factories was below European community and Codex Alimentary and ISIRI. The data showed that the differences of between two cities were not statistically significant.

Sesame is a valuable oilseed. The type of black sesame seeds is a source of unsaturated fatty acids. Due to the consumption of high-fat dairy products containing high amounts of saturated fatty acids and cholesterol, it is harmful to the health of people, especially cardiovascular patients; many efforts have been made to reduce the amount of these compounds in these products. In this research, milk enrichment with flour from sesame seeds and wheat in amounts of 10, 20, 30 and 40% was added to milk and its effect on sensory and physicochemical properties during storage was investigated. Samples were stored in a refrigerator at 5 ° C and chemical tests (acid number, peroxide value and fatty acid analysis), visceral viscosity determination and sensory evaluation were performed. The results showed that increasing the percentage of sesame flour due to increased fat, acid number and peroxide value increased significantly (p

One of the ways to avoid dairy products being discontinued by people who are lactose intolerant is to make new products that are easily available. The aim of ths study was production types of low-lactose banana powder and low-lactose cocoa powder with the use of β-galactosidase enzyme using spray dryer and investigation the chemical and mcroal properties of them. The amount of moisture, protein, fat and lactose, particle size, solubility index and scorched particles of low lactose banana milk powder and low lactose cocoa milk powder were studied.Microbiological tests including aerobic mesophilic bacteria, Coliform, Escherichia coli and Staphylococcus aureus coagulase positive were also performed. About chemical characteristics moisuire content, fat and ptotein were n standard range. The results showed that 68% of powders size were between 180 to 500 µm, 30% larger than 500 µm and 2% smaller than 125 µm. Sensory evaluation was performed after the treatments were reconstituted with water.Studies have shown that low-lactose milk due to its sweet taste and banana milk and cacao milk were not desirable due to lack of sweetness (no added sugar), but low lactose banana milk had a desirable acceptance.Low lactose cocoamilk had lower scores due to taste and had significant difference with low lactose banana milk (p

Cinnamon primarily contains several phenolic compounds and its health and therapeutic effects has been proved. To produce functional product and renewed interest in milk consumption, honey milk formulations containing cinnamon (0.1, 0.4 and 0.7%), guar and kappa-carrageenan (0, 0.05 and 0.1%) have been studied in current research. Statistical analyze has been performed through Design Expert software and surface response methodology with Box-Behnken design. Physico-chemical properties such as pH, acidity, viscosity and sedimentation rate moreover nutritional value through radical scavenging activity (DPPH) have been evaluated. Antibacterial effect of cinnamon has been surveyed through total bacterial count and sensory properties analyzed using 5-point hedonic scale. The results showed that adding cinnamon to formula, improved the anti-oxidative properties without any side-effect on pH and acidity but at higher concentrations, sensory attributes associated with sandiness. Furthermore, with increasing amount of cinnamon in the samples, the bacterial population was reduced significantly. The use of guar and kappa-carrageenan gums significantly reduced sedimentation rate and increased sensory acceptability. The results of optimization showed that using cinnamon at 0.43%, guar gum 0.09% and kappa-carrageenan 0.08%, functional product formulation with high stability, extended shelf life and overall acceptability, is feasible.

Many models are proposed to predict flux decline in membrane ultrafiltration, but since these models have limiting assumptions, they are not applicable to all solutions. The present study modeled fouling in skim milk concentration process using proposed equations for the main mechanisms of fouling, including complete blocking mechanism, intermediate blocking mechanism, standard blocking mechanism and cake filtration mechanism. These models then were compared with experimental data at 50, 100, 150, 200 and 250 kPa trans-membrane pressures to investigate the effect of trans-membrane pressure on flux decline. Based on the results obtained here, it was found that predictions of cake filtration model were in good agreement with experimental data, while those of standard blocking model were in poor agreement. Complete blocking mechanism was not capable of predicting flux data using CurveExpert Professional. With decreasing trans-membrane pressure, the differences between experimental data and models decreased. The results also showed that the second mechanism responsible for flux decline was intermediate blocking model. In fact, cake filtration mechanism and intermediate blocking mechanism are the two main mechanisms responsible for fouling in skim milk concentration process. Moreover, the results obtained from modeling of resistance showed that the cake layer resistance was the main resistance to flow, which was in accordance with what we had expected from accumulation of protein and fat molecules on the surface of the membrane. All in all, the cake filtration mechanism is the main mechanism for predicting flux decline, and it is expected that this model in combination with intermediate blocking model, would result in the best prediction of fouling phenomena in milk concentration process.

Yeasts and molds are considered as major causes of spoilage of acidic foods. Various studies have shown that green tea (Camellia sinensis) has antimicrobial properties. the study aimed to investigate the antiyeast activity of green tea extract in the plate and sterilized milk. Total phenol and flavonoid content were determined by colorimetric method. Anti-yeast activity of green tea against Saccharomyces cerevisiae, Kluyveromyces marxianus and Rhodotorula glutinis was measured using well diffusion and disk diffusion agar. The minimum inhibitory concentration (MIC) and the minimum fungicidal concentration (MFC) of green tea were examined by micro dilution in plate and by macro-dilution in sterilized milk in tubes. MIC of green tea extract was in range of 12.5 to 25 mg/ml in microdilution method and 6.5 to 25 mg/ml in macro dilution method. Kluyveromyces marxianus was the most resistant yeast against green tea extract. Consequently, because of the positive effect of green tea extract against the studied yeasts, it could be utilized as an anti-yeast compound in food and drug technology.

Studies have shown that camel milk and its fermented products have therapeutic properties and high nutritional value. Lactic acid bacteria play important role in Fermented dairy products. The aim of this study is to determine the lactobacillus community of camel milk. A total of 9 Lactobacillus were isolated from camel milk of Golestan province in Iran. The log10 CFU of Lactobacillus per ml on MRS medium under anaerobic condition at 20, 37 and 450C included 8.792± 0.14, 8.301±0.07 and 7.301±0.03 respectively. Isolates were identified on the basis of Biochemical and Phenotypic Characteristics as Lactobacillus paraplantarum, Lactobacillus ferintoshensis, Lactobacillus brevis, Lactobacillus pantheris, Lactobacillus johnsonii, Lactobacillus mali. Presence of Lactic acid bacteria was confirmed by band formation of PCR product in 1500 bp (amplification 16S rRNA gene using B27F-U1492Runiversal bacterial primer). Evaluation of their technological properties of isolates showed that isolated Lactobacillus fromcamelmilkhave lipoliticy, Proteolytic activity and high acidifying activity (except for Lb. mali and Lb. johnsonii). Also, allisolates, except Lb. Johnsonii, have autolytic activity in fair level. Based on technological properties ofisolates, Lb. paraplantarum, Lb. Brevis and Lb. pantheris are suggested as good candidates for camels milk processing or other fermentation process.

Milk as a strategic commodity was directly related to public health and food security of the country. The annual per capita consumption of milk in Iran in 1388 from 61. 7 kg decreased to 38. 73 in 1391. The main objective of this study was investigation of effect of consumer characteristics on consumer preferences for milk in Tabriz. The research population is Tabriz households. The data were collected through questionnaires completed by 158 heads of households in Tabriz. To achieve the objective of research multinomial logit model is used. The calculated results of marginal effect of each variables show that، age of household head، household size، monthly household income، child less than 6 years of age in household، health of the unpacked milk and indirect use of milk variables have positive effect and importance of shelf-life of milk variable has negative effect on the probability of choosing of unpacked milk. Age of household head، importance of shelf-life of milk and indirect use of milk variables have positive effect and household size، monthly household income، child less than 6 years of age in household، health of the unpacked milk variables have negative effect on the probability of choosing of pasteurized milk. Also، household size، monthly household income، health of the unpacked milk and importance of shelf-life of milk variables have positive effect and age of household head، child less than 6 years of age in household and indirect use of milk variables have negative effect on the probability of choosing of sterilized milk.

In current investigation a quality control ultrasonic system has been presented for detecting microbial contamination of UHT milk packages. This system is able to detect microbial contamination of milk packages without opening them. Microorganisms’ growth causes some changes in physical and chemical properties of milk resulting in changes of ultrasonic properties of milk. In this study amplitude and time of flight of ultrasonic waves were measured. The center frequency of piezoelectric discs was 1.02 MHz and all of experiments were done in temperature 35°C. Ultrasonic tests were conducted for microorganisms Escherichia coli, Staphylococcus aurous and Bacillus cereus. The results showed that different bacteria’s metabolisms affected chemical properties of milk and detecting process of microbial contamination. Ultrasonic system was able to detect microbial contamination after 7.25 to 12.5 h. from microbe injection. Also, the results showed that ultrasonic system can detect microbial contamination in various values of acidity and pH of milk packages.