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The effect of breed and stage of lactation on the microbiological status of raw milk
37-45Views:296The microbiological quality of the milk is important not only for food safety, but it can also influence the quality of dairy products. The microbiological status of raw cow milk can be influenced by many factors. Our aim was to determine whether there was a difference between the microbiological quality of milk of two different cow breeds (Holstein Friesian and Jersey) kept and milked in the same conditions, and how the microbiological quality of the raw cow milk changed during lactation (beginning, mid, and end). Samples were taken and analysed in July, August and September in 2018 from two dairy farms in Hajdú-Bihar county. During the conducted studies, the total plate count (TPC), the coliform count, the Staphylococcus aureus count and the coagulase-negative Staphylococcus (CNS) count of raw milk samples were determined.
There was no significant difference (P>0.05) between the milk of the Holstein Friesian and Jersey breeds in the case of TPC. However, the mean coliform count of milk samples taken from Holstein Friesian cows was significantly lower (P<0.05) than the mean coliform count of milk samples taken from Jersey cows. S. aureus was detected in one of the twelve milk samples taken from Holstein Friesian cows, and in two of the eleven milk samples taken from Jersey cows. CNS was found in larger amount in milk samples taken from Holstein Friesian cows, and the difference was significant (P<0.05). Both TPC and CNS count were significantly higher (P<0.05) in individual milk samples taken at the end stage of lactation, than in samples taken in the earlier stages of lactation from Farm “A”. However, in the case of Farm “B”, there was no significant difference (P>0.05) in colony counts at different stages of lactation. S. aureus was only present in milk samples that collected from cows, which were at the beginning and middle stages of lactation. Testimg the hemolysin production ability of S. aureus strains isolated from the raw milk samples, only weak hemolysis was observed on blood agar. In case of antibiotic resistance testing, it was found that all strains were susceptible to cefoxitin, chloramphenicol, clindamycin, erythromycin, gentamicin, penicillin G, tetracycline and trimethoprim/sulphamethoxazole.
Based on the results of our studies, staphylococci were detected in a higher amount in the milk of Holstein Friesian cows, and coliform bacteria were detected in a higher number in the milk of Jersey cows. Summing up the results of the milk samples taken from the different stages of lactation in one of the farms, it can be concluded that higher TPC and CNS count could be detected at the end stage of lactation than in the samples taken from the earlier stages of lactation. The fact that at the end of lactation the microorganisms could be detected in a higher colony count may be related to the fact that teats could be damaged during lactation by the milking machine, which increased the chance of imvading the microorganisms into the udder.
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The effect of season on the microbiological status of raw milk
95-99Views:117Many factors can influence the microbiological quality of raw cow’s milk. In this study, our aim was to determine whether there was any difference between the microbiological statuses of milk produced in different seasons. Samples were collected and analysed from five dairy farms in Hajdú-Bihar County, from February to November in 2019. During our studies, total plate count (TPC), coliform count and Staphylococcus aureus count of raw cow’s milk samples were determined.
There was no significant difference (P>0.05) between the mean TPC values detected in the milk collected in winter and autumn, but that values were significantly (P<0.05) lower than in the milk samples collected in spring and summer. Similarly to the TPC, in the case of coliform bacteria the lowest mean colony count was detected in the samples collected in winter. The difference was significant (P<0.05), compared to the values observed in the samples collected in summer. S. aureus was detected in bulk milk of only two farms in excess of 1.0 log10 cfu/ml. Also in case of S. aureus, there was a significant difference (P<0.05) between the values observed in the samples collected in winter and in summer. Samples from spring and summer contained the highest amount of S. aureus.
Based on the results of our studies, in the case of almost all farms the mean TPC, coliform and S. aureus counts were lower in the samples collected in winter, than in the samples collected in summer. The fact that the samples collected in winter contained the lowest amount of colonies could be attributed to the inhibition of growth of mesophilic microorganisms below 8 °C. Furthermore, the fact that we observed the highest colony counts in samples collected in summer, can be related to the heat stress of cows during the summer due to unfavorable weather conditions (high temperature and humidity).
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Determining the antioxidant compounds of beer
5-10Views:298The increasing consumption of beer indicates the necessity of the thorough analysis of its composition. In this study, the total phenolic content, flavonoid content and colour intensity of 24 beer samples have been determined. The samples contained pale barley, dark barley, pale wheat and dark wheat beers. The aim of the study was to determine the amount of the antioxidant compounds in beer, as well as to find correlation between different beer types and the above mentioned parameters.
Dark barley samples contained phenolic compounds in the highest concentrations, and it can also be concluded that dark beers contain phenolic compounds and flavonoids in higher concentrations than pale beers in the case of barley and wheat samples.
According to the performed statistical analysis, these beer types cannot be differentiated based on the analysed parameters. The highest percentage of correctly classified samples could be observed in case of dark barley samples, but this value has only been 75%, and the total result of correctly classified cases was only 41.7%. The analysis of more samples and parameters is required to carry out a successful differentiation.
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Development of the antioxidant indexes (FRAP, TFC, TPC) of scabbing resistant apple varieties in storage
89-94Views:132One of the most important groups of bioactive substances in apples are antioxidants, which have a health-preserving effect. The amount of these compounds varies not only during the ripening of the apple fruit, but also continuously during post-harvest storage. A growing group of health-conscious consumers are looking for apple varieties with a nutritional value that satisfies their needs.
In the scope of our research, we examined 5 apple varieties originating from the Derecske horticultural site of KITE cPlc. in 2016. The plantation was planted to be suitable for intensive apple production. Samples were collected at the time of maturity (August-October) of the given variety. The 5 examined apple varieties (Gaia, Isaaq, Modí, Smeralda and Fujion) are all resistant to apple scab (fungal disease caused by Venturia inaequalis). The 2-month storage experiment was conducted at 16–17 °C, which had an aggressive effect on our stored apples. Total polyphenol (TPC) and flavonoid (TFC) content as well as FRAP values of the apples were measured. Measurements were taken immediately after harvest and after 1 and 2 months of storage. Our results were evaluated by using the IBM SPSS Statistics 20 software. Our aim was to compare the antioxidant results of 5 scab-resistant apple varieties, which change continuously during storage.
The antioxidant content of our apple varieties increased during 2 months storage. The best result was achieved by the Modí apple variety (FRAP: 467.32 mg/100g; TFC: 317.76 mg/100g; TPC: 1771.97 mg/100g). Consumers may want to consume apples stored for a longer period of time if they are to absorb large amounts of antioxidants.