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

After testing and verification of resistance to gastrointestinal conditions confirming the strain selected to prepare probiotic fermented goat milk, 0.5 g of Lactobacillus plantarum (PTCC 1058( and Lactobacillus casei (PTCC 1608( were inoculated into 200 mL of goat milk sample. Then, 2, 4, and 6% of barley malt extract were added to the treatments to evaluate the effects of malt extract on the survival and activity of probiotic bacteria. Sample tests (including physicochemical, colorimetric indices, viscosity, antioxidant activity, and general acceptance) were evaluated on production days 7, 14, 21, and 28. The results showed that increasing the concentration of malt extract increased the content of soluble proteins, antioxidant activity, acidity, and decreased pH in all treatments increased (P<0.05). Also, adding malt extract and increasing its concentration increased the viscosity and brix on the day of production, but during 28 days, these parameters decreased (P<0.05). The color indices showed L* sample decreased and a* and b* increased with increasing the concentration of malt extract during storage (P<0.05). Evaluation of general acceptance of samples showed by increasing the malt extract concentration, treatment desirability declined. As well as, evaluation growth probiotic bacteria showed during the 7th day, due to the presence of sufficient nutrients, they significantly increased. Then the population of probiotic bacteria decreased (P<0.05). Generally, according to the results and sensory evaluation, probiotic goat milk containing 4% malt extract is the best sample, and recommend that consumed during the 7th day as the best time.

Ice cream, as a frozen dairy product, has high nutrition values which is consumed extensively throughout the world. In this study, the physicochemical and sensory properties of two types of ice cream (produced from goat and cow milk) containing cinnamon and cardamom essences were investigated. The results showed that the cardamom essence reduces pH and overrun and increases total solid more than cinnamon essence, whereas the effect of cinnamon essence on the fat content was more so that the maximum fat content was due to goat milk ice cream containing this essence. On the other hand, Hardness and viscosity of goat milk ice cream was significantly higher than cow milk ice cream and adding essences insignificantly also increased these factors. Also, the sensory evaluation results show that adding cinnamon essence leads to production of ice cream with better sensory properties. In final, it can be stated that the use of goat milk and also plant essences in ice cream production could increase the desirable properties of this product.

Nisin is a biological bacteriocin with many functions against food pathogenic bacteria. The disadvantages of chemical preservatives in foods have attracted attention to natural preservatives such as nisin. This study evaluated the antimicrobial properties of nisin extracted from Lactococcus lactis isolated from goat milk. Ten goat milk samples were collected from around Kerman city under sterile conditions, and Lactococcus lactis were isolated in the selected environment of Eliker-trimethoprim. Biochemical tests were used to Strain identification and nisin gene confirm by polymerase chain reaction with specific primers was used. HPLC method was used to confirm the presence of nisin using bacterially extracted proteins. The antibacterial properties of nisin were performed by disk diffusion agar method against Staphylococcus aureus, Bacillus cereus, Acinetobacter baumannii, and Pseudomonas aeruginosa. The minimum inhibitory concentration of bacteriocin was performed by Provide serial dilution in a microtiter plate. One of the four strains of Lactococcus lactis was identified and selected with the best growth conditions for further investigation. The presence of the nisin gene in Lactococcus lactis was confirmed by a specific primer and polymerase chain reaction method. The amount of nisin produced protein was 41.5 mg/kg. The diameter of inhibitory zone for Staphylococcus aureus, Bacillus cereus, Acinetobacter baumannii, and Pseudomonas aeruginosa were 13, 17, 14, and 0, respectively, and minimum inhibitory concentrations for extracted nisin were in dilutions of 10-5, 10-6, 10-5 and 10-1, respectively. Therefore, nisin extracted from Lactococcus lactis in goat milk can be a suitable substitute for chemical preservatives.

Nowadays, due to some problems, such as allergic reactions and high fat content, the partial replacement of cow's milk with milk of other animals, such as goat's milk, is so crucial by proper techniques to improve the quality with the aim of yogurt production. The aim of this study was to evaluate the effect of Zataria multifliora and Mentha longifolia L extract on the qualitative characteristics of probiotic yogurt produced from the cow-goat milk in proportions 10: 90, 30: 70, 50: 50 and 0: 100. Sensory evaluation was performed on produced samples one day after production to selecting the best samples and then, the experiments were carried out on selected samples during 28 days. The results showed that, over time, acidity and syneresis values increased and pH value, viscosity and probiotic count decreased. The highest viscosity was related to the equal ratio of cow - goat milk and 0.05% of Zataria multifliora extract. The antioxidant activity (AA) trend was irregular but descending and extracts had a significant effect on AA. The treatment of cow-goat milk (10 : 90%) and 0.03% of Zataria multifliora extract had the highest probiotic count. The treatment of cow's milk (100%) containing the equal concentrations of two extract (0.02%), showed the highest color, taste, consistency and overall acceptance scores by panelist. As a conclusion, it can be concluded that in order to achieve the best quality of probiotic yogurt, various concentrations of extracts and optimal ratios of cow-goat milk should be used. .

In this study the antimicrobial potential of Lactobacillus plantarum strains isolated from goat,s milk was evaluated. Sixty seven goat,s milk samples were collected from Tehran and Karaj and screened for the presence of lactic acid bacteria (LAB). Among the isolated LAB, 18 strains were identified as Lactobacillus plantarum by their carbohydrate fermentation pattern and 16S rRNA sequencing. Antimicrobial activity of the isolatedLactobacillus plantarum strains against a number of pathogens including Staphylococcus aureus, Pseudomonas aeruginosa, Salmonella typhi, Listeria monocytogenes and Escherichia coli was evaluated by agar spot and well diffusion method. Results indicated 10 of theLactobasillusplantarum strains to possess inhibitory activity towards the tested pathogens, while 6 of these strains were shown to have wide spectrum of inhibitory activity and were able to inhibit the growth of the entire tested gram positive and gram negative pathogens. The antibacterial activity demonstrated by these 6 strains was further analyzed by subjecting their supernatant fluid to various physico-chemical treatments. The supernatant fluid of these strains retained their antagonistic action even after neutralization, while only 2 strains (LP4 and LP14) retained their antimicrobial activity after treatment with 1 mg/ml catalase. The supernatant fluids of the respected isolates LP4 was resistant to enzyme Lysozyme and lipase, while proteolytic enzymes like pepsin, trypsin and proteinase K completely destroyed its antibacterial potential. The isolates were resistant to their own antagonistic action. The bacteriocin like substance produced by LP4 was pH and heat resistant as it resisted wide pH range of 3-8 and autoclave temperatures of 121ºC for 15 min. This substance after 4 weeks storage at -20 0C still retained its antimicrobial activity and after treating by concentration of 7 percent NaCl, it was still active.