جستجوی مقالات مرتبط با کلیدواژه « lactic cheese » در نشریات گروه « دامپزشکی »

Cheese is one of the most important dairy products which contains almost all essential amino acids. Cheese ingredients and environmental conditions often cause excessive growth of fungi and bacteria on the its surface. Therefore, coating and packaging can be considered as a basic step to increase preservation and shelf life. In this study, effect of coating lactic cheese by aloe vera gel, gum arabic and liquid smoke essence on the chemical changes during 21 days of storage in the refrigerator was investigated. Based on the limits determined by Design Expert software, 18 solutions containing 0, 10, and 20% v/v of aloe vera gel, 0, 5, and 10% w/v of gum arabic, and 0, 0.5, and 1% v/v of liquid smoke essential oil was prepared and cheese pieces were coated by immersion method. According to the obtained results, a trend of increasing pH and decreasing acidity was observed in the samples which were coated by maximum amounts of biopolymers and essential oil (20% v/v of aloe vera gel, 10% w/v of gum arabic and 1% v/v of liquid smoke essence). In case of moisture content and weight loss, the best coating solution contained the highest amounts of aloe vera gel and gum arabic, (20% v/v and 10% w/v), respectively. Finally, by optimizing the process by software, the best coating mixture could be produced by 1% v/v of liquid smoke essential oil, 18/507% v/v aloe vera gel and 10% w/v of gum arabic.

The detrimental effects of chemical preservatives and the tendency of consumers to use foods without preservatives or with natural preservatives have increased the use of natural antimicrobial compounds, including plant essential oils and extracts in food industries. Considering the numerous antimicrobial properties of Caraway (Bunium persicum Boiss) and the assumption that its use in lactic cheese increases the shelf life of a product with an acceptable aroma and flavor, in this study the effects of essential oil and alcoholic extract of Caraway on the growth of Staphylococcus aureus, Listeria monocytogenes, E. coli O157, Aspergillus flavus, and Aspergillus niger as well as total counts of mold and yeast were evaluated. Also, its effect on total counts of LABs and sensory properties of cheese was studied. Results showed that this plant was able to delay microbial growth. Caraway showed a more inhibitory effect on the studied microbes in lactic cheese and the antimicrobial activity of the essential oil was higher than the extract so that at the end of storage samples containing 1% essential oil had the lowest count of the target microbes. Comparison of the effect of essential oil and extract on the growth of the studied microbes showed that the Caraway had more effect on the growth control of Aspergillus flavus and Escherichia coli O157in lactic cheese. In the case of lactic acid bacteria, as the shelf life increased, the number of bacteria decreased in the cheese, and decreasing was greater in the control samples.

Some probiotic microorganisms can prevent the growth of pathogenic microorganisms in addition to improve the intestinal microbial balance. In this study, the qualitative characteristics and viability of two foodborne pathogens (Staphylococcus aureus and Escherichia coli) lactic cheese were investigated. For this purpose, in the first stage, four types of lactic cheese (60 samples) were produced as probiotics (containing Lactobacillus casei and Lactobacillus acidophilus) and non-probiotic with 3 and 4.5% fat milk in three replicates, and the quality parameters were evaluated at days 0, 14, 28, 42 and 56. Then, 12 types of lactic cheeses [(probiotic/non-probiotic) fat percentage (3 and 4.5%) and pathogenic microorganisms (absence, presence of Staphylococcus aureus or Escherichia coli)] (180 samples) were prepared and the viability of pathogenic microorganisms in the presence of probiotic was evaluated on days 0, 7, 14, 28 and 35. The addition of probiotics to lactic cheese significantly reduced fatty acid oxidation and increased acidity and volatile nitrogen compounds (P < 0.05). The addition of probiotics to high-fat cheeses increased non-protein nitrogen compounds but decreased in low-fat cheeses. The addition of probiotic to lactic cheese significantly reduced the growth of S. aureus and E. coli (P < 0.05). Increasing fat percent did not show a significant effect on bacterial growth inhibition by probiotics (P < 0.05). Due to the effects of adding probiotics on decreasing the pathogenic bacterial growth and not significantly altering the sensory properties of lactic cheese, it is recommended to use these probiotics in the production of low-fat lactic cheese.

Nowadays, coating by natural materials is one of the novel food preservation methods with extensive applications. Cheese is a popular food, however, its high daily intake due to its high salt content may threaten the health of consumers. In this study, instead of stored in brine, the novel method for cheese coating was used with the combination of 2% sodium alginate and 3% carboxymethyl cellulose with wild garlic extract at three concentrations of 0.5, 1 and 1.5%. Two uncoated cheese specimens (stored in or out of brine) were considered as the control groups. Physicochemical (pH, acidity and weight loss), microbial (thermophile, psychrophile, mold and yeast count), and sensory properties of the samples were investigated for 21 days at 4 °C. The results showed that during storage, pH decreased significantly (p< 0.05) while acidity, weight loss and microbial load increased. Coating with various ratios affected all of the sensory properties of the cheese samples. So that the highest score of total acceptance was related to the coating with 1.5% wild garlic extract. According to the results, edible coating based on sodium alginate and carboxymethyl cellulose, containing the wild garlic extract, can be used to increase the shelf life of cheese.