Mycobacterium avium subsp. paratuberculosis (MAP) is the etiologic agent of paratuberculosis, a disease with considerable economic impact, principally on dairy cattle herds. Animals with paratuberculosis shed viable MAP especially in their milk, faeces and semen. MAP may have a role in the development of Crohn's disease in humans via the consumption of contaminated milk and milk products. The current methods of milk pasteurization are not sufficient to kill all MAP cells present in milk and MAP has been cultured from raw or pasteurized milk and isolated from cheese. The purpose of the present study was to review the different methods used for detection of MAP in milk and milk products. We analyze the current methods for direct or non direct identification of MAP and culture and molecular biology methods that can be applied to milk and milk products.

Jan‰tová B., J. Luká‰ová: Heat Resistance of Bacillus spp. Spores Isolated from Cow's Milk and Farm Environment. Acta Vet. Brno 2001, 70: 179-184.The aim of this study was to compare heat resistance of the spores of mesophile Bacillus spp. from raw milk (bulk tank milk and milk from individual cows) and farm environment (faeces, silage, litter, swabs from skin and udder) as related to their survival in heat-treated dairy products. Fifty-eight strains of 9 species of Bacillus were tested for termoresistance within the temperature range of 95 -135 °C and various exposure times. The highest termoresistance was found in B. licheniformis spores, which survived the temperature of 135 °C. Except for the spores B. coagulans and B. pumilus all remaining spores were able to germinate after heat treatment of up to 120 °C. The greatest reduction of the spore numbers was found in B. cereus. The results indicate that some Bacillus spores may survive in milk even after heat treatment. Bacillus spp., raw milk, faeces, silage, litter, swabs from skin and udder, spores, termoresistanceAerobic and facultative anaerobic spore-forming bacteria of the genus Bacillus present a serious problem in milk industry. Because of the heat resistance of spores and ability of vegetative cells to produce extra-cellular enzymes they may cause milk and milk product deterioration. Bacillus spp. are quite common in the agricultural environment and may contaminate milk from various sources both during the production, storage and processing. Raw milk is most frequently contaminated under conditions of inadequate udder hygiene, from soil, feed, dust and faeces (C h ristiansson et al. 1999). Species such as B. licheniformis, B. subtilis and B. cereus (Crielly et al.1994; Páãová et al. 1996) are most commonly isolated from raw milk. B. licheniformis together with B. subtilis and B. pumilus belong to mesophiles, whereas B. cereus is rather a psychrophile able to grow in milk and milk products at cold-storage temperatures and even cause alimentary diseases (Christiansson 1992). It is known that the spores of bacilli survive pasteurisation and have suitable conditions for germination created in the pasteurised milk. B. cereus is a predominating micro-organism influencing the maintenance of pasteurised milk. It causes sweet curdling of milk and changes to milk odour and taste due to the production of the enzymes proteinase, lipase and phospholipase (Meer et al. 1991). Sterilisation and UHT milk treatment are the most effective means of spore destruction showing 99.99% success (Cox 1974).Heat resistance is an important character of Bacillus spp. spores. Appropriate temperature selection and duration of heating are crucial for the required microbial quality of the milk product, as with a linear temperature increase the time needed to achieve nearly complete abiosis becomes shorter exponentially. When determining the heat resistance and thus the sufficient duration of thermic treatment, it is useful to define the D value (decimal reduction time), i.e.,...

Cholesterol concentrations in goat milk, goat milk cheeses, ewe’s milk, ewes milk cheeses, dairy bioproducts, and concentrations of cholesterol, stigmasterol and sitosterol in butter, butter with added vegetable fats and margarines were evaluated by RP HPLC method. Parallel analyses by capillary GC were performed. Prior to the final chromatographic analyses the saponification step was used, followed by the extraction of the unsaponificable residue into <I>n</I>-hexane. Parameters of RP HPLC method were compared with parameters of GC determination. The detection limits (LOD) determinated on the bases of blank samples analysis were 5.2 mg/kg for cholesterol, 4.8 mg/kg for stigmasterol and 14.7 mg/kg for sitosterol. Recovery ranged between 80–92%, repeatibility expressed as RSD of 12 parallel samples measurements was 4.2–6.8%. Accuracy tested on the SRM 1845 Whole Egg Powder (NIST) was 95.7%.

The aim of this study was to evaluate the effects of temperature and storage time on the formation of biogenic amines (BAs) in the traditional Czech curd cheese (Olomoucké tvarůžky). Samples were stored for 7 weeks at 5 °C and 20 °C. BAs were studied as dansyl derivatives by the RP-HPLC method with fluorescence detection, histamine was determined using a photodiode array detector. Physical and chemical properties were analyzed as specified by the Czech National Standard, as were the sensory characteristics (colour, odour, texture and flavour). The major amines found were cadaverine (124-2 413 mg·kg -1 ) and tyramine (117-1 058 mg·kg -1), followed by putrescine (75-767 mg·kg -1) and histamine (74-411 mg·kg -1 ). Low concentrations of tryptamine, spermine and spermidine were present. Total concentrations of BAs significantly increased with storage time (P  0.01), depending significantly on temperature (P  0.01). Total BAs in cheese stored at 20 °C compared to 5 °C were more than three times higher, reaching 4 600 mg·kg −1 at the end of storage. The toxicologically critical value of 900 mg·kg −1 for the sum of histamine + tyramine + putrescine + cadaverine was reached 17 days later in the cheese stored at 5 °C compared to 20 °C. When stored at 5 °C, the samples retained adequate sensory characteristics for the entire safe storage time. The effects of storage conditions on BAs formation are relevant to reducing the risk associated with consumption of cheese high in BAs.

The aim of this study was to assess the quality of raw cow's milk from an automatic milking system. Samples of milk (48) were analyzed chemically and microbiologically and the somatic cell count, freezing point and inhibitor residues were determined. For comparison purposes, milk analysis data from two farms using conventional machine milking and 2008 milk analysis report data for the Czech Republic were used. All physical and chemical characteristics of the study samples were within the established limits

ABSTRACT:The freezing point (FP) was established in 48 bulk tank samples of raw and 48 samples of pasteurized goat milk that were collected in the course of lactation. Alongside, non-fat solids (NFS) content was monitored. Milk freezing point measurements were carried out using the thermistor cryoscope method in compliance with the standard CTS 570538 (1998). The mean freezing point of raw milk was found to be in an interval of -0.5513 ± 0.0046°C, variation ranged from -0.5466°C to -0.5567°C, with higher values in the spring months and a drop at the end of lactation. FP corresponded to the NFS content. The average freezing point of goat milk heat-treated on the farm to the temperature of 72°C over a period of 20 s was -0.5488 ± 0.0046°C, pasteurisation brought an average increase in FP by 0.0025°C.

Janštová B., Dračková M., Cupáková Š., Přidalová H., Pospíšilová M., Karpíšková R., Vorlová L. (2010): Safety and quality of farm fresh goat's cheese in the Czech Republic. Czech J. Food Sci., 28: 1-8.The composition and selected physical and chemical parameters of 44 samples of fresh goat cheeses produced on a farm in the Czech Republic were determined. The following average values were obtained for the parameters analysed: pH 4.87 ± 0.14, titratable acidity (SH) 98.09 ± 4.93, dry matter 46.83 ± 1.57%, fat in dry matter 52.74 ± 5.24%, sodium chloride (NaCl) 2.08 ± 0.54%, and a w 0.979 ± 0.007. All samples showed excellent sensory characteristics and their compositions corresponded to those declared by the producer. Microbiological tests were used for the detection of Enterobacteriaceae spp., lactic acid bacteria, Escherichia coli, Enterococcus spp., Staphylococcus aureus, Bacillus cereus, Salmonella spp. and listeria monocytogenes. Under the applicable regulations, the analysed fresh goat's cheeses were microbiologically safe and had the appropriate physical and chemical characteristics.

Navrátilová P., Borkovcová I., Dračková M., Janštová B., Vorlová L. (2009): Occurrence of tetracycline, chlortetracycline, and oxytetracycline residues in raw cow's milk. Czech J. Food, Sci., 27: 379-385.The objective of this study was the detection of tetracycline, chlortetracycline and oxytetracycline residues in raw cow's milk. When analysing bulk milk (n = 57) and tanker trailer'a (n = 113) samples, two methods were used simultaneously: a specific rapid test Milk Tetrasensor Kit and high performance liquid chromatography (HPLC) with ultraviolet detection and isocratic elution. For HPLC analysis, Breeze (Waters, USA), a liquid chromatographic system, was used. The samples underwent solid phase extraction before the HPLC analysis. The Nova Pack C8 column (3.9 × 150 mm, 4 μm, Waters) and mobile phase (0.8 ml/min) consisting of acetonitrile, methanol, and 0.05 mol/l of oxalic acid in a 13:13:74 ratio were used. None of the samples analysed with the use of the specific rapid test displayed the presence of tetracycline antibiotics. In all of the samples analysed by means of HPLC, low concentrations of tetracycline antibiotics residues were detected. None of the samples displayed the presence of chlortetracycline. All of the analysed samples displayed residues of tetracycline. Oxytetracycline residues were detected only in 50.6% of analysed samples.