Sensory satiation is probably one of the most important factors in meal termination. In this paper, the use of aromas to induce satiation via dairy products is illustrated by means of two examples: the use of organic acids, obtained by fermentation; and altering the extent of retro-nasal aroma release. In a double-blind placebo-controlled randomised cross-over preload-test meal design, it was demonstrated that a dairy beverage fermented with propionic acid bacteria was perceived as more satiating than a non-fermented equivalent dairy beverage. Satiety-inducing effects lasted up to 50 min. However, ad libitum energy intake was not reduced in the time frame tested. Another approach is to increase satiation by making use of differences in retro-nasal aroma release profiles. It is known that the physical structure of a food product is important for the extent of retro-nasal aroma release, i.e. solid foods generate a longer retro-nasal aroma release compared to liquid foods. This is possibly also related to satiation. Using olfactometry, aroma stimuli can be administered separately from other stimuli, such as different ingredients, textures and tastes. Hence, the relative importance of aroma stimuli apart from other stimuli on satiation mechanisms can be investigated. In a double-blind placebo-controlled randomised cross-over full factorial design, it was shown that perceived satiation can be increased by altering the extent of aroma release during consumption of a liquid dairy product

A survey was conducted to determine the occurrence of mycotoxins in feedstuffs of dairy cows in the Netherlands and to estimate total dietary intakes of these compounds. Twenty-four dairy farms were visited twice and samples taken of all diet ingredients. Feed intake data were collected by means of questionnaires. A total of 169 feed samples were collected and analyzed for 20 mycotoxins using a liquid chromatography tandem mass spectrometry multimethod. Silage and compound feed were the main diet ingredients, representing on average 67 and 23% of dry matter intake, respectively. Deoxynivalenol (DON), zearalenone, roquefortine C, and mycophenolic acid were the mycotoxins with the highest incidence. The incidence of DON in silage, compound feed, and feed commodity samples was 38 to 54%. The incidence of zearalenone in silage, compound feed, and feed commodity samples was 17 to 38%. The DON and zearalenone had a low incidence in forage samples and were not detected in ensiled by-product samples. Roquefortine C and mycophenolic acid were only detected in silage and ensiled by-product samples (incidence 7 to 19%). Fumonisins B(1) and B(2) were detected in 2 compound feed samples and one feed commodity sample. Aflatoxins B(1), B(2), G(1), and G(2), ochratoxin A, T-2 and HT-2 toxin, 3-acetyl-DON, 15-acetyl-DON, diacetoxyscirpenol, sterigmatocystin, fusarenon-X, ergotamine, and penicillinic acid were not detected in any of the samples. Average concentrations of DON, zearalenone, roquefortine C, and mycophenolic acid in complete diets were 273, 28, 114, and 54 microg/kg, respectively. Maximum concentrations were 969, 203, 2,211, and 1,840 microg/kg, respectively. Calculated average daily intakes of these mycotoxins were 5.0, 0.5, 2.0, and 0.9 mg/animal, respectively, and maximum daily intakes 19.3, 3.5, 38.9, and 32.3 mg/animal, respectively. Corn silage was the major source of all 4 of these mycotoxins in the diet. Extremely high concentrations of roquefortine C and mycophenolic acid (up to 45 and 25 mg/kg, respectively) were detected in visibly molded areas in surface layers of corn silage. These areas appeared to be the main source of roquefortine C and mycophenolic acid in the diet. Because carry-over of DON, zearale-none, roquefortine C, and mycophenolic acid into milk is negligible, their occurrence in feedstuffs is not considered of significant concern with respect to the safety of dairy products for consumers. Potential implications for animal health are discussed.

The occurrence of mycotoxins in 140 maize silages, 120 grass silages and 30 wheat silages produced in the Netherlands between 2002 and 2004 was determined using a liquid chromatography coupled with tandem mass spectrometry detection (LC-MS/MS) multi-method. Deoxynivalenol (DON) was detected above the limit of quantification (LOQ) of 250 mu g kg(-1) in 72% of maize and 10% of wheat silages. Average DON concentrations were 854 and 621 mu g kg(-1), respectively, and maximum concentrations 3142 and 1165 mu g kg(-1), respectively. Zearalenone was detected above the LOQ of 25 mu g kg(-1) in 49% of maize and 6% of grass silages. Average zearalenone concentrations were 174 and 93 mu g kg(-1), respectively, and maximum concentrations 943 and 308 mu g kg(-1), respectively. The incidences and average concentrations of DON and zearalenone in maize silage were highest in 2004. The incidence of other mycotoxins was low: fumonisin B1 and 15-acetyl-DON were detected in 1.4 and 5% of maize silages, respectively, and roquefortin C in 0.8% of grass silages. None of the silages contained aflatoxins, ochratoxin A, T2-toxin, HT2-toxin, sterigmatocystin, diacetoxyscirpenol, fusarenon-X, ergotamine, penicillinic acid, or mycophenolic acid. This study demonstrates that maize silage is an important source of DON and zearalenone in the diet of dairy cattle. Since the carryover of these mycotoxins into milk is negligible, their occurrence in feed is not considered to be of significant concern with respect to the safety of dairy products for consumers. Potential implications for animal health are discussed.

The shelf life of pasteurized dairy products depends partly on the concentration of Bacillus cereus spores in raw milk. Based on a translation of contamination pathways into chains of unit-operations, 2 simulation models were developed to quantitatively identify factors that have the greatest effect on the spore concentration in milk. In addition, the models can be used to determine the reduction in concentration that could be achieved via measures at the farm level. One model predicts the concentration when soil is the source of spores, most relevant during grazing of cows. The other model predicts the concentration when feed is the main source of spores, most relevant during housing of cows. It was estimated that when teats are contaminated with soil, 33% of the farm tank milk (FTM) contains more than 3 log(10) spores/L of milk. When feed is the main source, this is only 2%. Based on the predicted spore concentrations in FTM, we calculated that the average spore concentration in raw milk stored at the dairy processor during the grazing period is 3.5 log(10) spores/L of milk and during the housing period is 2.1 log(10) spores/L. It was estimated that during the grazing period a 99% reduction could be achieved if all farms minimize the soil contamination of teats and teat cleaning is optimized. During housing, reduction of the concentration by 60% should be feasible by ensuring spore concentrations in feed below 3 log(10) spores/g and a pH of the ration offered to the cows below 5. Implementation of these measures at the farm level ensures that the concentration of B. cereus spores in raw milk never exceeds 3 log(10) spores/L.

Germination and growth of spores of butyric acid bacteria (BAB) may cause severe defects in semihard cheeses. Silage is the main source of BAB spores in cheese milk. The objectives of the study were to determine the significance of grass silages and corn silages as sources of BAB spores and to investigate the relationships between high concentrations of BAB spores in corn silage and aerobic deterioration. In the first survey, samples were taken from various locations in silos containing grass and corn silages and from mixed silages in the ration offered to the cows on 21 farms. We demonstrated that the quantity of BAB spores consumed by cows was determined by a small fraction of silage with a high concentration of spores (above 5 log10 BAB/g). High concentrations were most often found in corn silage within areas with visible molds (69% of the samples). Areas with visible molds in grass silage and surface layers of corn silage contained, respectively, 21 and 19% of the cases of concentrations above 5 log10 BAB spores/g. Based on these results, we concluded that currently in the Netherlands, corn silage is a more important source of BAB than is grass silage. In a second survey, 8 corn silages were divided into 16 sections and each section was studied in detail. High concentrations of BAB spores were found in only the top 50 cm of these 8 silages. Elevated concentrations of BAB spores were associated with different signs of aerobic deterioration. In 13% of the sections in corn silage with more than 5 log10 yeasts and molds/g, more than 5 log10 BAB spores/g were found. Sections with a temperature of more than 5 degrees C above ambient temperature contained, in 21% of the cases, more than 5 log10 BAB spores/g. Concentrations above 5 log10 BAB spores/g were measured in 50% of the sections with a pH above 4.4. All sections with a pH above 4.4 also showed a temperature that was more than 5 degrees C above ambient temperature and a concentration of yeasts and molds above 5 log10 cfu/g. Based on these results, we postulated that high concentrations of BAB spores in corn silage are the result of oxygen penetration into the silage, resulting in aerobic deterioration and the formation of anaerobic niches with an increased pH just below the surface. Growth of BAB in these anaerobic niches with an increased pH caused the locally high concentrations of BAB in corn silage.

Pathogens and spoilage microorganisms can be transmitted to milk via dirt (e.g., feces, bedding material, soil, or a combination of these) attached to the exterior of the cows' teats. To determine the relevance of this pathway and to perform quantitative microbial risk analysis of the microbial contamination of farm tank milk (FTM), it is important to know the amount of dirt transmitted to milk via the exterior of teats. In this study at 11 randomly selected Dutch farms the amount of dirt transmitted to milk via the exterior of teats is determined using spores of mesophilic aerobic bacteria as a marker for transmitted dirt. The amount of transmitted dirt to milk varied among farms from approximately 3 to 300 mg/L, with an average of 59 mg/L. The usefulness of the data for microbial risk analyses is briefly illustrated using the contamination of FTM with spores of butyric acid bacteria as a case study. In a similar way the data can be used to identify measures to control the contamination of FTM with other microorganisms or chemical residues.

In a year-long survey on 24 Dutch farms, Bacillus cereus spore concentrations were measured in farm tank milk (FTM), feces, bedding material, mixed grass and corn silage, and soil from the pasture. The aim of this study was to determine, in practice, factors affecting the concentration of B. cereus spores in FTM throughout the year. In addition, the results of the survey were used in combination with a previously published modeling study to determine requirements for a strategy to control B. cereus spore concentrations in FTM below the MSL of 3 log10 spores/L. The B. cereus spore concentration in FTM was 1.2±0.05 log10 spores/L and in none of samples was the concentration above the MSL. The spore concentration in soil (4.9±0.04 log10 spores/g) was more than 100-fold higher than the concentration in feces (2.2±0.05 log10 spores/g), bedding material (2.8±0.07 log10 spores/g), and mixed silage (2.4±0.07 log10 spores/g). The spore concentration in FTM increased between July and September compared with the rest of the year (0.5±0.02 log10 spores/L difference). In this period, comparable increases of the concentrations in feces (0.4±0.03 log10 spores/g), bedding material (0.5±0.05 log10 spores/g), and mixed silage (0.4±0.05 log10 spores/g) were found. The increased B. cereus spore concentration in FTM was not related to the grazing of cows. Significant correlations were found between the spore concentrations in FTM and feces (r=0.51) and in feces and mixed silage (r=0.43) when the cows grazed. The increased concentrations during summer could be explained by an increased growth of B. cereus due to the higher temperatures. We concluded that year-round B. cereus spores were predominantly transmitted from feeds, via feces, to FTM. Farmers should take measures that minimize the transmission of spores via this route by ensuring low initial contamination levels in the feeds (<3 log10 spores/g) and by preventing growth of B. cereus in the farm environment. In addition, because of the extremely high B. cereus spore concentrations in soil, the contamination of teats with soil needs to be prevented.

A year-long survey of 24 dairy farms was conducted to determine the effects of farm management on the concentrations of butyric acid bacteria (BAB) spores in farm tank milk (FTM). The results were used to validate a control strategy derived from model simulations. The BAB spore concentrations were measured in samples of FTM, feces, bedding material, mixed corn and grass silage fed to cows in the barn, and soil. In addition, a questionnaire was used to gather farm management information such as bedding material used and teat cleaning method applied. The average BAB spore concentration in FTM was 2.7 log10 spores/L, and 33% of the FTM samples exceeded a concentration of 3 log10 spores/L. Control of the average spore concentration in mixed silage fed was the only aspect of farm management that was significantly related to the concentration of BAB spores in FTM. Farms that fed mixed silage with the lowest average BAB spore concentrations (3.4 log10 spores/g) produced FTM with the lowest average concentration (2.1 log10 spores/L). The efficiency of farm management in controlling the BAB spore concentration in FTM depended to a large extent on the ability of farmers to prevent incidents with elevated BAB spore concentrations in mixed silage (>5 log10 spores/g) and not on the average BAB spore concentration in mixed silage across the year. The survey showed that farmers should aim for a concentration in mixed silage of less than 3 log10 spores/g and should prevent the concentration from exceeding 5 log10 spores/g to ensure a concentration in FTM of less than 3 log10 spores/L. These results correspond with the previously reported model simulations.

Control of contamination of farm tank milk (FTM) with the spore-forming butyric acid bacteria (BAB) is important to prevent the late-blowing defect in semi-hard cheeses. The risk of late blowing can be decreased via control of the contamination level of FTM with BAB. A modeling approach was applied to identify an effective control strategy at the farm level. The simulation model developed was based on a translation of the contamination pathway into a chain of unit operations. Using various simulations, the effects of factors related to feed quality, feed management, cattlehouse hygiene, and milking practices on the contamination level of FTM were evaluated. Contamination level of silage was found to be the most important factor. When silage contains on average less than 3 log10 BAB/g, a basic pretreatment of udder teats before milking (∼75% removal of attached spores) is sufficient to assure an FTM contamination level below 1 BAB/mL. When silage contains more than 5 log10 BAB/g, it should not be fed, because it then becomes almost impossible to assure an FTM contamination level below 1 BAB/mL. Measures aimed at improving cattlehouse hygiene, the contamination via soil, and the contamination level of other feeds contribute only marginally to the control of the contamination of FTM with BAB. Application of the modeling methodology could be beneficial for the control of the contamination of FTM with other microorganisms such as Bacillus cereus.

The application of Terminal Restriction Fragment Length Polymorphism (T-RFLP) analysis of the small subunit ribosomal gene to examine the bacterial dynamics of relatively fast dairy fermentation processes is illustrated. All individual starter strains yielded characteristic terminal restriction fragments (TRFs). Growth independent T-RFLP analysis was used to identify and follow the dynamics of streptococci, lactobacilli, lactococci and propionibacteria in yoghurt and hard cheese production while samples had been stored frozen until analysis. Starter cultures could be differentiated and followed during production and ripening of hard cheese (Gouda type and Maasdam) as well as production of yoghurt. T-RFLP analysis enabled the characterization of bacterial population structure and dynamics between short time spans, i.e., within hours. Eight samples taken at different times within 5.5h yoghurt fermentation revealed shifting relative signal intensities in TRF peaks between streptococci and lactobacilli, indicating a (semi) quantitative relation of the TRFLP signal with the actual numbers of bacteria.

One of the important micro-organisms causing environmental mastitis is E. coli This paper describes a case study to illustrate the use of the microbial process risk modeling methodology (MPRM) to estimate the exposure udder teats to an infectious microorganism, the occurrence of mastitis in a specific situation and to quantitatively identify effective control measures.

Disinfection is the treatment of surfaces/equipment using physical or chemical means such that the amount of microorganisms present is reduced to an acceptable level. Disinfection reduces the amount of remaining microorganisms. This means that, in general, a disinfected surface/piece of equipment is not sterile and means that disinfection is not equal to sterilization where viable microorganisms can no longer be detected. Resistance development as a result of cleaning and disinfection is not a matter of major concern for the food industry. However, the food industry and the pharmaceutical industry have to realize that the current processes of cleaning and disinfecting need to be carried out properly in order to avoid development of resistance. Application of the right type of agent is important to achieve the desired chemical effect. As microorganisms evolve and adapt to disinfecting strategies, the development of more effective cleaning and disinfecting strategies and new tools to monitor the efficiency of these strategies would continue.

Modelling is a useful tool to assist farmers in taking efficient control measures to reduce the contamination of raw milk with bacterial spores. One of the measures that can be applied is cleaning of the udder, and particularly the teats prior to milking. In practice various cleaning strategies can be applied. To evaluate different cleaning strategies a mathematical model was developed describing teat cleaning and milking practices. The model divides a herd in three groups of cows with different contamination levels of the udder teats and facilitates the application of different cleaning methods to each group of cows. In total, 19 cleaning strategies were evaluated using Monte Carlo simulations. The model simulations showed that it is most effective to apply time consuming methods only to cows with visible dirt attached to the udder teats. But it is not essential to clean the teats of cows with no visible contamination when the only objective is to reduce to the contamination of raw milk with bacterial spores.

With the introduction of automatic milking (AM) systems, increased levels of free fatty acids (FFA) in milk were observed, which might result in off-flavours in milk and dairy products. The aim of this study was to investigate the factors contributing to elevated FFA levels: influence of the milking frequency, technical parameters of the milking system, and finally, farm management aspects. Milking frequency was studied in a Latin square design with milking intervals of 4, 8 and 12 hours and showed increased FFA -levels for the shorter intervals. Technical factors were studied in a laboratory study using milking machine components of AM-systems and of conventional systems. With susceptible milk, differences in increase in FFA levels were found, but results were difficult to interpret. Tests will be repeated. Some FFA problems remained after solving technical and milking frequency problems. Indications were found that feed composition and feeding regime might influence susceptibility of milk for FFA-formation. These farm management aspects are subject of ongoing research.