جستجوی مقالات مرتبط با کلیدواژه « fermented milk » در نشریات گروه « پزشکی »

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.

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 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.

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.

Antibacterial activities of kefir beverage are attributed to kefiran polysaccharide. The aim of this study was to investigate the effect of type of milk, fermentation time, temperature and stirring conditions on antibacterial activity of extracted kefiran from kefir grains. Kefir grains were added to full-fat and non-fat milk. Fermentation was carried out at 25°C and 37°C under stirred and non-stirred conditions. After 24, 48, 72 and 120 hours, the grains were separated from kefir extract and kefiran was extracted. The antibacterial activity of extracted kefiran was carried out by well method. Fermentation time had a significant effect on the inhibition zone of all tested bacteria. Milk type had significant effect on antibacterial activity of kefiran samples against tested bacteria except S. dysenteriae. Fermentation temperature had a significant effect on the inhibition zone of E. coli and B. cereus, but stirring conditions only had significant effect on inhibition zone of B. cereus. Considering all factors and their interactions, in order to extraction of kefiran with higher antibacterial activity is recommended, fermentation in full-fat milk. Also, to achieve higher antibacterial activity against B. cereus, E. coli, S. dysenteriae, and S. aureus, is recommended fermentation time for 24, 48, 48 and 120 hours, respectively. Fermentation at 37°C compared to 25°C and under stirred compared to non-stirred conditions did not create noticeable differences in the antibacterial activity of extracted kefiran from kefir grains. Fermentation conditions had significant effect on antibacterial activity of extracted kefiran from kefir grains.

Folate, also known as vitamin B9, is essential in cell metabolism and very important especially for pregnant women and lactating mothers. Natural folate is available in food but it is very unstable. Synthetic folate is generally used as an alternative to meet daily needs due to its stability, even though it has a negative effect causing a variety of metabolic disorders. Some lactic acid bacteria have been reported as being able to synthesize natural folate during the fermentation process. Lactic acid bacteria are the main microorganisms for lactic fermentation such as fermented milk, fruits, and vegetables. Milk is the most nutritious food and contains folate-binding protein, hence it is considered the ideal fermentation medium to increase folate stability during storage. Fermentation of milk with folate-producing lactic acid bacteria can be used as a technique to produce natural folate-rich fermented foods as an attempt to prevent folate deficiency without side effects to the consumers.

Nowadays, milk tablets are considered favorable due to several advantages, including good taste and chewing properties, ease of transport, increased bioavailability, ease of storage, stability of active ingredients and improved functional properties.This study seeks to investigate the characteristics of fermented milk tablets in relation to its use as a beverage producing tablet. The effects of effervescent agent contents (0, 20, 40, 50, 60 %) (citric acid, tartaric acid and sodium bicarbonate) on physical and sensory properties of fermented milk tablets were evaluated. Physical properties, including weight and diameter of the tablet containing different percentages of effervescent agent (i.e. 0-60 %) did not differ significantly (P≤0.05). Increasing the level of the effervescent agent (i.e. 0-60%) led to hardness reduction, as well as the friability value and dissolution time of this tablet in water. Regarding the sensory properties of the fermented milky drink produced by tablets, the appearance, mouth feel and flavor acceptability of fermented milk tablets containing 40 % effervescent agent had the highest significant score (P≤0.05).

Lactic acid bacteria, including lactobacilli, enterococci, leuconostoc and weissella species isolated from Iranian traditional fermented camel milk (Chal) were assessed for the incidence of virulence determinants (gelE, efaAfm, efaAfs, ace, espfs, cylM, cylA and cylB), sensitivity to various antibiotics and virulence phenotypes. The incidence of virulence genes was determined by polymerase chain reaction and antibiotic susceptibility was tested by disk diffusion method. The results of this study indicated that all of the strains harbor at least two or more of the virulence genes. The most frequent virulence genes detected among tested strains were cylB, gelE and efaAfs. All strains showed no β-hemolysis while tyrosine decarboxylase activity and gelatinase production were observed in enterococcus and leuconostoc strains. Majority of strains were resistant to Polymyxin B and kanamycin. Lactobacillus strains including L. paraplantarum, L. kefiri, L. paracasei, L. plantarum and Weissella cibaria were resistant to both vancomycin and kanamycin. The possibility of transferring the antibiotic resistance and virulence genes to other starter and commensal strains makes the usage of these strains in food and dairy products controversial without required safety assessments.

The aim of this study was to investigate the effects of starters and storage temperature 4 ºC, 25 ºC) on microbiological and physicochemical properties, volatile compounds and sensory evaluation of kefir. Kefirs produced by KFA and Chr. Hansen starters were stored at 4 ºC and 25 ºC for 40 days. pH and acidity at 4 ºC did not change (p ≥ 0.05), while at 25 ºC pH and total solid decreased as well as acidity. Concentrations of acetaldehyde and ethanol increased (p