Archiv Für Lebensmittelhygiene

Published by Schlütersche Verlagsgesellschaft
Observed behaviour of A. hydrophila (e) and Aerobic Plate Count (A) during refrigerated storage atj'uctuating temperature (-) of gilthead seabream. Red and blue straight lines indicate, respectively, the predicted growth of A. hydrophila
Observed behnviour of A. hydrophila (a) and  
Observed behaviour of A. hydrophila (e) and  
Observed behnviour of A. hydrophila (a) and Aerobic Plate Cotrnt (A) dtlring refrigerated storage atj7ìrctuating temperature (-) of gilthead seabream. Red and blue straigh t lines indicate, respectively, the predicted growth o f A. hydrophila (-) nnd Aerobic Plnte Cotrnt (-) using the conventional third order mode1 appronch.
The growth of Aeromonas hydrophila and aerobic natural flora (APC) on gilthead seabream surfaces was evaluated during the refrigerated storage (21 days). The related growth curves were compared with those obtained by a conventional third order predictive model obtaining a low agreement between observed and predicted data (Root Mean Squared Error = 1.77 for Aeromonas hydrophila and 0.64 for APC). The Lotka-Volterra interspecific competition model was used in order to calculate the degree of interaction between the two bacterial populations (\beta_{Ah/APC} and \beta{APC/Ah}, respectively, the interspecific competition coefficients of APC on Aeromonas hydrophila and vice-versa). Afterwards, the Lotka-Volterra equations were applied as tertiary predictive model, taking into account, simultaneously, the environmental fluctuations and the bacterial interspecific competition. This approach allowed to obtain a best fitting to the observed mean growth curves with a Root Mean Squared Error of 0.09 for Aeromonas hydrophila and 0.28 for APC. Finally, authors carry out some considerations about the necessary use of competitive models in the context of the new trends in predictive microbiology.
Changes in content of selenium and taurine, and the alteration of fatty acid profile have been studied in African catfish fillets subjected to a commercial cold- or hot smoking process. Selenium content and the fatty acid profile did not change significantly during neither of the smoking procedures. Losses of taurine were 32 and 19 % during cold-smoking and hot-smoking, respectively. Significantly more taurine was lost during cold-smoking (P < 0.05), probably due to the prolonged brining and smoking procedure. The results support conclusions from other studies, showing that low molecular water soluble components are more susceptible to losses during processing of seafood.
Peeled potatoes were cooked, completely or partly, by steaming, after which they were vacuumpacked, in portions of ca. 400 g, in pouches of polypropylene-nylon-laminate. In some of the experiments the potatoes were, after steaming and packing, prior to sealing of the pouches, inoculated with Salmonella typhimurium, Staphylococcus aureus or Clostridium botulinum, to simulate post-contamination. The other experiments were carried out without intentional addition of micro-organisms. The pouches were stored at 5°C, 14°C and 22°C, their contents were examined after different periods of storage. All experiments showed, that as to the development of micro-organisms no difference existed between completely cooked and partly cooked potatoes. In the non-inoculated portions a Bacillus flora developed consisting of either of B. cereus, or of B. polymyxa, the latter sometimes mixed with B. licheniformis. In portions, inoculated with S. typhimurium or St. aureus, these species developed, along with, however, a 'natural' flora of B. cereus. All bacterial species mentioned showed, after 36-48 h at 22°C, total counts between 10⁷ and 10⁸ per gram. Storage at 14°C yielded similar numbers for S. typhimurium after 60 h; numbers of B. cereus and St. aureus being after period about 10⁵ per gram. Storage at 5°C resulted, after 14 days, in numbers of about 10⁶ per gram for S> typhimurium and 10⁴ per gram for St. aureus. Growth of Bacillus species at 5°C was observed only after more than 3 weeks storage. In a number of cases growth of Bacillus-species was accompanied by gas formation. In some of the pouches, inoculated with spores of Cl. botulinum toxin was detected after storage at 14°C or 22°C, mostly group B, but in one case also group A. Presence of toxin, however, did not show a regular development with time. No toxin was detectable at 5°C after storage for 15 days. The conclusion is, that competely or partly cooked, vacuumpacked potatoes, in order to prevent multiplication of spoilage and pathogenic micro-organisms, should be stored in the refrigerator. Moreoever, during packing of the potatoes, care should be taken to prevent post-contamination. Even if these measures are being taken, from a microbiological point of view, storage for a period longer than 3 weeks is not possible.
Shrimps are an important food commodity in Europe. Quality control of imported shrimp is essential due to technological and hygienic problems in tropical and sub-tropical areas where the shrimps are cultivated in large scale. In this paper the processing of shrimp is described and microbial formation of indole is discussed. The effect of various process parameters on the presence of indole in shrimps is reviewed in relation to the FDA action levels for indole in shrimps of 25 μg/100 g and 50 μg/ 100 g, respectively. Various analytical procedures for the measurement of indole are evaluated. Temperature abuse is an important critical process parameter for the formation of indole. A number of bacteria has been identified as indole positive but only a few (Escherichia coli, Proteus (P.) vulgaris and P. morganii) were detected on shrimp. High indole levels in frozen shrimp can be considered an indicator of poor product quality prior to freezing and thus of hygienic practices far away from Good Hygienic Practice (GHP). High indole levels (>10 μg/100 g) are reached at the end of the shelf-life of shrimps when stored at elevated temperature levels. However, a low content of indole does not necessarily imply a good quality. Taking into account the results from the limited storage studies the FDA action level for indole is therefore at least debatable. High pressure liquid chromatography (HPLC) with fluorescence detection seems to be the most effective analytical method for the determination of indole.
Yersinia enterocolitica is the most frequent Yersinia species associated with human yersiniosis in European countries. Bioserotype 4/0:3 is the most common bioserotype isolated from human yersiniosis in many European countries, including Germany. The primary route of human infection is probably ingestion of contaminated food. However, pathogenic strains of Y. enterocolitica are difficult to isolate from food samples. The low isolation rate can be due to the low sensitivity of the culture methods available, especially when the contamination level is low and the background flora is high. In this study, the ISO 10273 method for isolation of pathogenic Y. enterocolitica in food was evaluated using spiked food samples and additionally, the ISO method was compared with a real-time PCR method based on SYBRGreen. Four different food samples (raw pork, ham, lettuce and bean sprouts) inoculated with ca. 10 2 and 104 pYV-positive Y. enterocolitica 4/O:3 bacteria per 10 g sample were studied in duplicate. ISO method was shown to be a suitable method for isolation of Y. enterocolitica 4/0:3 only in highly contaminated meat samples. This pathogen could be isolated from the meat samples by direct culturing on CIN agar plates and after selective enrichment in ITC and plating on CIN and SSDC agar plates when the contamination level was high enough (> 104). Real-time PCR method based on SYBRGreen was shown to be a valuable screening method to detect the samples contaminated with pathogenic Y. enterocolitica. Most (12/16) of the positive samples could be detected by PCR, which targets the ail gene in the chromosome of pathogenic Y. enterocolitica while only 7 out of 16 samples were positive with culturing.
A fast and simple spectrophotometric method for the determination of E 110 (Sunset yellow FCF) and E 124 (Ponceau 4R) in German salted saithe and Alaska pollock products (salmon substitute products) has been developed and validated. The method consists of the extraction of both food colours from the matrix by sodium dodecyl sulfate (SDS) solution and spectrophotometric determination at two wave lengths, 480 nm and 558 nm, respectively. Recovery rates were in the range of 95-108 % and reproducibility tests showed a variation of less than 3 %. The method yielded similar results compared with a HPLC-method. Due to its fast work up and simple performance the method seems to be suitable for the application in the quality assurance laboratories of the German salmon substitute processing companies.
Besides the detection of the pathogenic resp. toxinogenic Clostridia species (Clostridium perfringens, Clostridium botulinum) the determination of the group of sulfite-reducing Clostridia which are able to cause strong spoilage of foods or meals could be important. For practical reasons a method for detecting sulphite-reducing Clostridia instead of sulphite-reducing bacteria is necessary, because the detection of sulphite-reducing bacteria is not suitable to evaluate the hygienic quality of most of the foods examined. On the other hand, in many product groups (e. g. fresh meat, meat products, fishery products, bakery products, creame- And pudding-powder) the detection of sulfite-reducing Clostridia gives valuable information for the detection of the microbial-hygienic quality of foods. The new ISO- method 15213 ..Horizontal method for the enumeration of sulphite- reducing bacteria growing under anaerobic conditions" is in our opinion not suitable to detect sulphite-reducing Clostridia as a group, because the sodium-sulphite concentration of the proposed iron- sulphite-medium is much to high. It is necessary to reduce the sulphite content to 0.05 % for cultivating Clostridium sporogenes, most of the Clostridium bifermentans strains and some other sulphite- reducing Clostridia, which are - besides Clostridium perfringens - predominant in most foods. Furthermore, it has to be pointed out that it is not suitable to use non-selective media (e. g. iron-sulphite-agar) for the cultivation and enumeration of sulphite-reducing Clostridia from most of the foods especially of animal origin. It rather depends on the original microbial load of the substrate to be examined, whether it is useful to apply media with or without selective components for cultivation. Therefore the new horizontal ISO-method can be applied only for a limited number of product groups (e. g. cream- And pudding-powder, flavours), if sulphite-reducing Clostridia have to be detected. In this paper the reasons for the declining of the new ISO-method are documented with facts from literature including own experimental results. Moreover it will be presented basic information on cultivation of Clostridia in foods.
In 25 samples/lot of 17 different kinds of deep-frozen food the variance of aerobic plate count and Enterobacteriaceae was determined on the basis of a hierarchic design. If the content of Enterobacteriaceae went beyond the detection line, there was a homogenous distribition. Concerning the aerobic plate count the standard deviation between the units of some products reached very high values. In these cases a single sample strategy will increase the probability of false decisions.
Aquaculture of dentex commenced very recently compared to the culture of the traditional Mediterranean species such as gilthead sea bream and sea bass, which has increased in a spectacular way in recent years. Market supply in Mediterranean fish may be increased and a contribution be made to the development of aquaculture in diversifying the species being cultured, e.g. by culturing dentex. Yet, relatively few studies are available on this fish. In the current study, the proximate and fatty acid composition of the flesh of cultured and wild common dentex (Dentex dentex) were evaluated monthly during a period of 9 months. In parallel, color measurements and sensory analyses were carried out. Statistical analyses were done in order to compare wild and cultured dentex. According to the color values dentex which were cultured had a lighter and more yellow color than dentex caught in the wild. No significant differences between cultured and wild dentex were determined in the moisture content (p > 0.05). Yet, in the fat and protein content significant differences occured (p < 0.05) between cultured and wild dentex over the period of 9 months. The condition index values of cultured dentex were also in general higher than those of wild dentex. The analysis of the fatty acid composition showed that the EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) rates in the flesh of cultured common dentex were in general higher than those in the wild forms. In the sensory analysis wild dentex were perceived as having less fresh odor and fresh flavor and being less fat and less juicy. From the results obtained in the present work it can be concluded that cultured dentex can be an alternative to traditionally cultured species.
The aim of the study presented here was to find out the effects of storage at -30 degrees C on fatty acids in fish oil, without adding antioxidants. Oils of sardines from the Sea of Marmara were extracted, analysed and stored at +4 degrees C for 4 and 8 days, and thereafter at -30 degrees C for 24 months. Fatty acid composition analyses were performed initially and after 4 and 8 days as well as after 24 months. In the case of the fatty acids C-16:0, C-20:1, C-18:3, C-22:6, C-14:0, C-16:1, and C-20:5 considerable changes with regard to their concentrations could be observed. In general, there was a decrease in minor unsaturated fatty acid (MUFA) content, and an increases in the saturated fatty acid and in some polyunsaturated fatty acid (PUFA) content.
Smoked atlantic salmon, Salmo salar, purchased in a food store contained white-greyish cysts of 2 to 5 mm length in the body musculature. After adding lactate acid the cysts released large quantities of spores of the myxosporidian species Henneguya zschokkei. The bilateral symmetric spores of this fish parasite have a length of 10 to 14 μm. They are oval in shape with a rounded apical and a conical caudal end. These spores contain two separate pear-formed polar capsules in the apex, and possess two divergent caudal appenda- ges of 20-40 μm in length. With regards to food hygiene, macroscopically visible parasites in food are disgusting and the food is ineligible for consumption. Although cases of diarrhoea have been reported in humans in connection with findings of H. zschokkei spores in stool, the importance of this parasite for humans remains still unclear.
Earlier investigations on the structure of the Lactobacillus microflora of the human intestinal tract performed in the sixties of the last century in different populations including members of the university institutes and of an industrial establishment revealed the existance of a transient (allochthonous) part of lactobacillus microflora which was picked up before by way of the daily diet unregularly and in different amounts. Besides that, a number of definite species of indigenous (autochthonous) lactobacilli could be identified in different parts of the digestive tract, from the mouth through the stomach up to the rectum. These autochthonous lactobacilli were not found in identical combinations in all individuals included in the study. Rather, an individual structure of this microflora could be found, which is maintained for a longer time period, assumably even for a full life span. This was relevant qualitatively (strains) and guantitatively (cfu/g). Bacteriological separation of the autochthonous strains could be achieved, which were later on defined as separate new species. The background of separation and the bacteriological and microbiological importance of these new species are summarized, especially in view of their application as probiotic cultures. References on the related literature are given not only for journals published in English but also for German papers. The necessity of further investigations especially for the separation of subspecies within the three species seems justified.
Research in the area of food supplied in canteens can provide useful data about types and frequency of foodborne infections and intoxications which are not explicitly notifiable according to § 3 Bundes- Seuchengesetz (§§ 6 and 7 Infektionsschutzgesetz). There are generally more individual cases of food poisoning on this area which can more readily be recorded than the cases occurring in private homes. The study presented is based on reports by the German military medical services covering 209 reliable epidemic analyses of foodborne diseases concerning 9082 individual cases between 1985 and 2000. The main cause of foodborne diseases is Bacillus cereus, which has been responsible for 30 % of the cases and for 42 % of the outbreaks. The heat resistant spores are found ubiquitious, and are encouraged to germinate when the foodstuffs are heated. They will multiply as soon as the maximum growth temperature of 55 °C is reached. If cooked food is allowed to cool, the growth of B. cereus can only be prevented if the temperature drops quickly from 55 °C to not more than 7 °C. Problems usually arise in canteens producing large quantities of foodstuffs that have to be cooled rapidly after cooking, such as puddings or potato or noodle salad. The same is true for stock produced to be reheated when needed, such as mashed potato and rice.
The transfer into practicality of the HACCP (Hazard Analysis and Critical Control Point) guidelines of the Coder Alimentarius was emphasised legally for the German dairy industry through 16 of the milk enactment (Milch-Verordnung) from 24(th) April 1995. In the county of Nordrhein-Westfalen this enactment is executed in a broad way, by the official analyses of milk and milk products according to the County-Quality-enactment (Landesgiite-Verordnung), which results in the application of additional methods, procedures and analyses for the scrutiny of the HACCP concept. Evaluation of the results of 828 samples of heat treated milk from Nordrhein-Westfalen, analysed between Ist January 1997 and 31(st) May 1999, demonstrate that 93.9% of pasteurised and 99.6% of UHT (ultra high temperature) and sterilised milk samples fulfilled the demands of the new Country-Quality-enactment of Nordrhein-Westfalen from 1996. Deviations were located predominantly in the microbiological nature. In 18 of 592 samples of pasteurised samples, coliformes were detected (in 0.1 ml of milk) and in 10 samples the bacterial numbers exceeded 200,000 colony forming units/ml. Variances in the chemical-physical (5 samples) and sensorial properties (5 samples) were extremely rare. For the additional parameters (residuals, contaminants and pathogenic agents) only one sample with a positive result in the analysis of antibiotic residues (brilliant black reduction test) was found, whilst all other results were within the limits or negative for the parameter tested. The present results demonstrate scientific evidence for the high quality standard of heat treated consumable milk in Nordrhein-Westfalen and emphasise the importance of the County-Quality-enactment of Nordrhein-Westfalen in controlling the product quality and the HACCP-concept within milk plants.
258 samples of raw milk, cheese (3 types) and dried milk products (2 types), 252 of which artificially contaminated with different salmonella serovars, were examined for salmonellae using the horizontal method ISO 6579:2002 "Microbiology of Food and Animal Feeding Stuffs - Horizontal Method for the Detection of Salmonella spp." and the vertical method ISO 6785 / IDF 93:2001 "Milk and milk products - Detection of Salmonella spp." With both standards the samples are preenriched in buffered peptone water and then transferred to Rappaport-Vassiliadis medium with soya peptone (RVS). The second liquid selective enrichment medium of ISO 6579:2002 is Muller-Kauffmann tetrathionate novobiocin broth (MKTTn), that of ISO 6785/IDF 93:2001 is selenite cystine medium (SC). RVS and SC (ISO 6785/IDF 93:2001) are incubated for 24 h and additionally 24 h before plating out onto brilliant green phenol red lactose sucrose agar (BPLS), RVS and MKTTn (ISO 6579:2002) are incubated only for 24 h before plating out onto xylose lysine deoxycholate agar (XLD). With both methods the second solid selective medium is free of choice. In the study presented here mannitol lysine crystal violet brilliant green agar (MLCB) and AES Salmonella agar plate (ASAP) were used. There were no differences between both methods if raw milk was used as sample material. However, with cheese and dried milk products the sensitivity of ISO 6579:2002 (90.2% and 95.7%, resp.) was lower than that of ISO 6785/IDF 93:2001 (97.8% and 100.0%, resp.). In total RVS yielded 195, SC 185 and MKTTn 178 positive results. Depending on the type of food examined differences between the liquid selective enrichment media could be observed: In the case of raw milk SC showed the lowest recovery, in the case of cheese and dried milk products MKTTn yielded lower numbers of positive results than SC and RVS, and RVS was poorer than the other media when dried milk products were examined. In total with XLD less positive samples were found than with the other solid selective media. Plating out from MKTTn, however, the differences between XLD and BPLS were not striking.
With the EU regulation 882 on official controls a uniform juridical frame has been created within the European Community. To the member states certain transitional terms still remain to the conversion. Due to the federal principle in the Federal Republic of Germany the "Lander" are responsible for the implementation of official controls and investigations. Special efforts have to be made to achieve the defined objectives - particularly with regard to coordination and communication of the competent authorities. The results of the official controls from 2006 make clear that some efforts are necessary to reach and to conserve the specified objectives. If this is not possible, the effectivity of the German official control system has to be scrutinized critically.
According to Regulation (EC) 853/2004 all food business operators to which Annex III of this regulation applies have to be approved. From January 2006 this compulsory approval therefore also applies to butcher's shops which slaughter animals on their premises and which up to now have been registered only. In the present study, the implementation of the new European food legislation in these small-scale enterprises was to be examined. For the evaluation of the food businesses a catalogue of requirements was used. The three major areas of these requirements were: infrastructure and equipment, personnel and self-monitoring. The evaluation of the structural requirements showed that the sufficient flexibility of the new regulations enables the implementation also in smaller, non-industrial establishments. Premises which up to now were in accordance with the requirements of Annex 2 of the German Meat Hygiene Regulation can be granted conditional approval. Concerning process hygiene, which now also has to be evaluated in formerly registered, small-scale operations, major deficiencies were evident, especially in stunning (animal welfare) and in slaughtering hygiene. In this context the particularities of small-scale slaughtering have to be considered. These deficiencies can only be eliminated by an improvement of general hygiene awareness and continual training in food hygiene matters, which should at least partially be carried out by external experts. The food business operator's understanding and acceptance of these food hygiene issues are a prerequisite for optimization. The evaluation of the existing self-monitoring and documentation measures showed that the need for action is certainly given in this respect as major information deficiencies concerning the implementation of self-monitoring still exist especially in small businesses. To deal with this problem the operators should consult the official veterinarians or veterinary experts.
In recent years, there has been a continuously growing interest in the occurrence, fate and possible effects of human and veterinary drug residues in the environment. In a long-term field study conducted on a sandy soil site from the Lower Saxony Soil Monitoring Program in Northwestern Germany, we recently used liquid chromatography combined with tandem mass spectrometry to detect persistent tetracyclines and sulfamethazine in topsoil and the corresponding ground water. In the present study, these established analytical methods were successfully applied to water and sediments originating from 15 aquaculture systems raising trouts representative of northwestern Germany. As previously described, tetracyclines and sulfonamides were extracted from sediments with liquid-liquid extraction, and from water with solid-phase extraction. However, only in one of 13 sediment samples chlortetracycline and sulfadimethoxine were found in concentrations of 13.1 μg/kg and 7.7 μg/kg, respectively. Furthermore, in four of 15 water samples sulfadiazine (0.23 μg/L) or sulfadimethoxine (0.14-0.88 μg/L) were detected. The concentrations measured here do not lead to the expectation of acute toxic effects e.g. on aquatic microorganisms. At present, it cannot be conclusively determined if the antibiotic loads in German aquaculture systems at subtherapeutic concentrations may contribute to the development of antibiotic resistance. Moreover, a comparison of intensive livestock farming and aquaculture showed that the pathway aquaculture - sediment - surface water seems to be still of minor importance in northwestern Germany regarding the transfer of veterinary drugs into the environment. Future studies including other areas and other fish species should be carried out to verify these preliminary conclusions.
Salmonellosis is a gastrointestinal infection caused by Salmonella enterica and commonly acquired from contaminated food. Worldwide, Salmonella causes millions of infections and thousands of deaths annually, posing a significant threat to public health. While S. serovars Typhimurium and Enteritidis are the predominant causes of nontyphoidal salmonellosis. Salmonella serovar Schwarzengrund has hitherto been an uncommon cause of human salmonellosis. However, recent reports suggest that this serovar is becoming more prevalent in Asia, Europe and the U.S. A total of 21 strains isolated from different patients from 2006 through 2010 in Switzerland were characterized by (i) assessing phenotypic antibiotic resistance profiles using the disk diffusion method and (ii) by genotyping using pulsed-field gel electrophoresis (PFGE) after macrorestriction with Xbal in order to evaluate strain relationship. The annual incidences from 2006 to 2010 of S. Schwarzengrund varied between 0.11/100'000 in 2006 (highest incidence, 8 cases) and 0.01/100'000 in 2010 (lowest incidence, lease). All of the isolates were resistant to the sulfonamide antibiotic sulfamethoxazole. Two strains were resistant to the quinolone antimicrobial nalidixic acid as well as to the ß-lactam antibiotic ampicillin and were classified multidrug-resistant. Analysis of PFGE data showed high similarity between the strains, as well as similarity to common international clones of S. Schwarzengrund. These findings highlight the need for continued surveillance of occurring genotypes and of antimicrobial resistance in Salmonella spp.
During summer 2006 at least 46 participants of a sports event in Berlin, at which confectionery (éclairs) were sold, fell ill with gastrointestinal symptoms. The results of the microbiological examination of the confectionery sold at the event and additional samples from the manufacturing pastry shop indicated that the éclairs were contaminated with Salmonella enterica subspecies enterica serovar Enteritidis phagetype 4 (PT 4). In addition, results of phenotypic and genotypic characterisations showed that the same strain was also detected in stool samples of the patients and of the confectioner and on utensils at the pastry shop. Insufficient cooling of the éclairs during transport and before sale could have enhanced bacterial growth. This paper describes the outbreak investigations and their results. Moreover, it demonstrates that for determination of the food source the public health and the food control authorities need to collaborate closely and have to react in a fast and competent manner.
The aim of this study was to monitor occurrence of Helicobacter spp. in 29 conventional broiler-chicken farms, in the Czech Republic, of which 6 were sampled repeatedly. In the period February 2013 March 2014, a total of 615 samples of caecum content of slaughtered broilers were examined. Detection was performed by optimized cultivation techniques using Brucella Agar with 5 % sheep blood and by PCR method. Identification at genus and species level was performed using PCR-RFLP (restriction fragment length polymorphism). Presence of Helicobacterspp. was confirmed in 248 broilers (40.32 %). Using PCR-RFLP method with the restriction enzyme ApaLl, these 248 positive isolates were identified as Helicobacter pullorum. Occurrence of this new potential foodborne pathogen was confirmed in 17 conventional farms, the within-farm prevalence ranged from 40-100 %. Seasonality was not statistically significant. The results show that Helicobacter pullorum is another potential foodborne pathogen in the order Campylobacterales with a high incidence in the digestive tract of broiler chickens and may present a potential risk for human consumers. In order to ensure the safety of food of animal origin, it appears to be essential to pay attention to monitoring and further characterization of this pathogen in poultry farms in Central Europe.
Two methods for enumeration of Enterobacteriaceae in foods (ISO 21528-2 and "Tempo (R)", BioMerieux) were studied with respect to a lower incubation temperature of 30 degrees C instead of the recommended temperatures of 37 and 35 degrees C, respectively. A total of 98 samples of various food categories were tested. Among the results within quantitation range, incubation at 30 degrees C yielded higher counts than incubation at 37 degrees C (ISO method; average: +0.19 log) or 35 degrees C (Tempo (R) method; +0.18 log), respectively. Among the results out of the detection range, differences > 1 log(10) for incubation at 30 degrees C compared to 37 degrees C (ISO) and 35 degrees C (Tempo (R)) were found in 5.0 and 7.1% of the samples, respectively. Results obtained by the Tempo (R) system tended to be lower than those of the ISO method (average ca. 0.2 log). As demonstrated in other studies, these two methods are practically equal. Although the average difference of bacterial counts, assessed for a variety of foods, after incubation at 30 degrees C as compared to 35/37 degrees C was quite low, it should be considered when results have to be compared to legal microbial limits (e. g. carcass surfaces; process hygiene criteria according to Reg. (EC) 2073/2005).
From 2003 to 2005 the feasibility as well as the didactics of the practical in meat inspection and in hygiene control according to the TAppO (German regulation for the curriculum in veterinary medicine) were studied in the Munich slaughterhouse. All in all, it was shown that it is possible to increase the knowledge as well as the interest of the students within the practicals' duration of three weeks each. In the course of the meat hygiene practical the students' knowledge was doubled, while during the hygiene control practical a fivefold increase was achieved. As far as the meat inspection practical is concerned, the highest interest was in cattle and pig slaughtering (49.2 and 44.9%, respectively), whereas for the hygiene control practical meat processing plants were preferred (66.7%). Less interest was shown for ante-mortem inspections (27.1% ante-mortem inspection pigs) and cutting plants (41.7%). The reason most frequently mentioned for choosing the place of the practical was proximity to the place of residence. The main problems from the part of the students are limited previous knowledge and interest. From the part of the official veterinarians the major disadvantage is the necessity to squeeze in the time for the students' education into their actual and regular duties. Carrying out separate meat inspection and food control practical in a slaughterhouse does not seem to be useful. If somebody later works in this field the knowledge and skills obtained in both of these practical will be needed. Therefore, a separation of these two areas, which are so closely interlinked, is rather misleading. In addition, if students carry out the hygiene control practical after the 6 th semester they did not have the opportunity to gain any practical experience in the university and their theoretical education is also not yet completed. If both practicals are carried out after the 8 th semester they normally follow one another rather closely and in consequence there are many repetitions which are considered boring. It would at least be an improvement not to carry out the hygiene practicals in slaughterhouses anymore, but only in veterinary offices.
In this study, a private abattoir was visited 7 times between January 2000 and August 2000. During visits, a random sampling method was used and one of two (1/2) cattle was sampled. First of all, selected cattle were examined clinically and sex, ages and breed were recorded. 22 female and 53 male cattle were sampled. These were between 1-5 years old and 68 of them were Holstein breed. The samples taken for bacteriological culturing were divided into 4 groups consisting of fecal swabs, carcasses, water and environmental (knifes, saws, hooks, hands, clothes, benches, surfaces) samples. The samples were taken using the sterile cotton swabs (surface swabbing). The fecal and carcass swabs were immediately placed into 10 ml modified Escherichia coli broths (mEC broth). The environmental swabs were placed into 10 mi GN Broth. For water, 2 liter of water was taken into a sterile bottle and mTSB was used for isolation. The immunomagnetic separation was used for the isolation of E. coli from the enrichment broth. The isolates were then checked for MUG, indol, rhamnose, urease activity and motility. The slide agglutination test was used for serogrouping by using specific rabbit anti-E. coli O157:H7 (NCTC-12900). In total, 3 isolates, one from feces, one from knife and one from clothes of a butcher were identified as E. coli O157:H7. No E. coli O157:H7 was isolated from water, carcasses and other samples.
The anatomical-pathological findings, recorded as routine meat inspections at the abattoir, are a valuable information source, enabling conclusions in relation to the herd's health status. However, farmers often question the exactness and repeatability of such findings. To examine the repeatability of the meat inspection, the findings of 20 selected carcasses and 20 organs with 11 veterinarians and meat inspectors have been analysed in order to proof the repeatability of anatomicalpathological findings. The accordance of the results has been calculated by making use of Kendalls Konkordanzkoeffizient W and feature-related percentage for agreement. The results for kidneys (82 % agreement) and pericarditis (82 %) were corresponding to a high degree among the meat inspectors. In contrast, the assessments of lesions of lungs (25 %), liver (30 %), skin (31 %) and pleuritis, (38 %) differed notably. In order to improve the validity of the data and their acceptance as a tool for quality assurance it is recommended to continuously analyse the differences between meat inspectors with regard to their individual diagnostic patterns. The implementation of a feed back mechanism is expected to reduce variation between meat inspectors and to improve the training effects in the use of the findings categories.
At sequential steps of slaughter, 200 pig carcasses from two abattoirs were examined for total viable counts (TVC), Enterobacteriaceae and coagulase positive Staphylococcus (CPS) by the wet-dry double swab technique at the neck, belly, back, and ham. At abattoir A, mean TVCs (log CFU cm-2) and the proportion of Enterobacteriaceae positive carcasses were reduced after scalding (1.9,12 %), singeing (1.9,66 %) and blast chilling (2.3,17 %), and increased after dehairing (3.4,100 %) and polishing (2.9) (p < 0.05). At abattoir B, mean TVCs (log CFU cm-2) and the proportion of Enterobacteriaceae positive carcasses were reduced after scalding (2.4, 29 %), polishing (3.7) and chilling (2.6; 55 %), and increased after the combined dehairing/singeing (4.7; 97 %) (p < 0.05).The effects of certain process stages were abattoir- and site-specific: (i) at abattoir B, higher results than at abattoir A were obtained after dehairing/singeing and the following process stages, (ii) at abattoir A, the dehairing and polishing processes were important contamination sources, and (iii) for the neck, evisceration and carcass splitting were identified as hygienic weak points. Moreover, scalding, singeing and chilling may be integrated in a risk-based system for pig slaughter, when process parameters are standardized. CPS were found at abattoir A only in few samples after scalding, singeing, and the following process stages. At abattoir B,CPS detection rates increased significantly after dehairing/singeing and remained at a high level. Further investigations and phenotypic and genotypic characterization data are required to evaluate, if a CPS population may have established on the surfaces of the equipment.
The possible migration of nematodes from the intestines into the muscle of ungutted saithe, haddock and ocean perch was studied. Fishes were examined immediately after catch and after ice storage for 6 days or longer. The results have shown that Anisakis larvae are present in the flesh of all three fish species already at capture, but no post-mortem migration into the flesh was observed during ice storage. Abundance and prevalence varied between the three fish species. Studies on the occurrence of nematodes in pike-perch revealed that fishes from the Greifswalder Bodden were infected by nematodes, both in muscle and intestines. The infection rate increased with fish size and was related to the fishing month.
In spite of the availability of a sizeable bibliography on Food Microbiology and on processing-for-safety experience in the area of Assurance of the Microbiological Integrity, i.e. safety and quality, of the incidence of food-borne diseases with a microbiological aetiology foods in privileged regions of the world is not consistently decreasing. Faecally transmitted viroses have been identified as a substantial component of this - in essence completely preventable disease burden. Introduction and adoption of HACCP-based, longitudinally integrated intervention strategies, relying on Codes of Good Manufacturing and Distribution Practices, issued by the Codex Alimentarius Commission, have, to some extent, improved the situation, without, however, rectifying it, as is within reach, when at least all raw materials, entering the food manufacture and catering, were henceforth to be delivered in pathogen "free" condition, like pasteurized milk. This lack of adequate consumer protection points to the pressing need for increasing and upgrading structured postgraduate education and training in Public Health Microbiology of Foods with emphasis on intervention along the processing lines. Introduction of such an educational track in current University programmes would entail a marked and therefore unwelcome delay. Consequently, a European web-site distance learning programme, leading to the degree MSc Public Health Science: Food und Drinking Water, is offered, from the Academic Year 2003/2004, by the Faculty of Health and Human Sciences, University of Hertfordshire. Collaboration with the Scottish Center for Infection and Environmental Health, the University of Strathclyde (Glasgow), the Eijkman Foundation at Utrecht University and the University of Lynköping is assured. Other European Academic Institutions may consider participation.
In order to check the microbiological contamination during the production of the pasteurised sugar containing end product CVE (concentrated whole egg) from liquid whole egg the hygienic status of the egg products was determined at 4 points of the processing line. Besides 512 samples of egg products the room air, the pasteurisation system and the condensated water collected from the final containers were bacteriologically analysed. Simultaneously impedance and culture methods were performed to get aerobic mesophilic counts for the raw material (n = 190) and to detect conforms qualitatively in 184 intermediate products and quantitatively in 95 CVE samples. More than 50 % of the total bacterial counts of the untreated whole liquid egg lay above the acceptable limit of 10 6 cfu/g. This, together with a constant prevalence of enterobacteriaceae, indicates a lack of hygienic management at the supplying step. Under existing law, three out of the ten checked CVE-batches were not permitted for sale. Within the three rejected lots a total of 4 containers were found to exceed the legal limit M fixed at 100 enterobacteriaceae/g. The step by step controls verified the product to be safe after pasteurisation (74°C/10 min). However, subsequent recontamination was possible resulting from egg material scorched to the evaporator and containing conforms. The results of drop plating technique showed a strong correlation to impedimetric detection times in case of determining mesophilic aerobic counts as well as the coliform counts. That is why impedance technique permits the egg processing industry permanent monitoring, better quality management and enhancing the safety of egg products. Minimum need of personnel, material and time (not more than 9 hours for total aerobic count and 15 hours for coliforms count) combined with a maximum of examination capacity proved rapid impedance measurements superior to conventional culture methods even with regard to economical aspects.
Estrogens and androgens are efficient growth promoters in animal production. The improvement of protein anabolism and N-retention provide economic and ecologic advantages. Nevertheless there are scientific arguments to maintain the EU import ban of meat from animals treated with the approved compounds foreign to the body trenbolone acetate, zeranol and melengestrol acetate. There is demand for an updated and more strict risk assessment as performed at the first approvals by the Food and Drug Administration in the USA. The harmless and complete removal of pellet-rests from animal's body is not secured just by the instructions; the milligram order of magnitude of those residues represents the quantitatively most important risk potential. As a matter of fact there are missing controls and reliability tests of the application routine in practice. The risk resulting from improper manipulations and from possible introduction of residues of the implantation site into the route of food processing has not been defined. Further research is still demanded concerning the positive results of mutagenicity tests of trenbolone, concerning the potential of formation of long chain and long acting esters of trenbolone and zeranol stored in fatty tissue, and concerning the importance of the recently discovered additional receptors for related compounds. The covalent bound residues of trenbolone to DNA and proteins has to be reconsidered. Those properties hardly fulfill the consumers' expectations for genuine food. Residues in meat detectable even after proper applications diminish the chance of control of illegal and hence risky application practices of those compounds; this could increase the risk potential. Recently a scientific publication from an American export country informed about the increase of illegal treatments with trenbolone.
An automated clean-up procedure for the determination of acetylgestagen residues in animal fat is presented, where acetylgestagens are separated from fat by gel permeation chromatography and analyzed directly by EIA without any additional clean-up. The method shows good recoveries for the acetylgestagens tested.
Entomophagy is rather uncommon in Germany since most Europeans ban it as disgusting. This contrasts sharply with the fact that many insect species constitute a valuable foodstuff that is used by many non-European peoples. So, who seeks to consume insects in Germany often has to rely on pet shops specializing in herpetofauna and selling insects as food animals. Three Ensifera and Caelifera species were evaluated via proximal chemical analysis. It was seen that Acheta domestica contained 29.4% dry matter, 6.6% lipids, 20.4% protein, 1.1% crude fibre together with carbohydrates, as well as 1.3% ashes. Corresponding values amounted to 21.6%, 3.5%, 13.1%, 4.3% and 0.7% in Schistocerca gregaria, and 31.4%, 3.6%, 22.65%, 4.3% and 0.9% in Phymateus saxosus. The first two species were purchased as live animals, Phymateus saxosus as a canned product. Another sample comprised Schistocerca gregaria kept under laboratory conditions that were prepared in the Mexican style, i. e. without wings and tibiae of the 3rd pair of legs. Thus, the content of crude fibre and carbohydrates was reduced by approx. 10% in dry matter. Acheta domestica and Schistocerca gregaria proved to be a valuable foodstuff that may be consumed readily by humans after a corresponding preparation of the animals took place. Since free-ranging Phymateus saxosus are considered toxic, more research is necessary.
Free fatty acids (FFA) reduce the quality of milk and dairy products by generating a rancid and soapy taste. They are produced by the spontaneous or induced enzymatic hydrolysis of milk fat. Induced lipolysis has its origin in the mechanical stresses produced in milk by pumping the milk, and by the milking process itself. In this study, the effect of the milking system, specifically MultiLactor®, on the resulting concentration of FFA was examined. The MultiLactor® is an individual quarter-milking system with periodic air intake and sequential pulsation, designed to be used in conventional milking parlours. The experimental design included testing 40 milk samples at two different flow rates. It was found that milking with the MultiLactor® caused an increase in the concentration of FFA in fresh milk. The FFA increase was higher for a flow rate of 1 l/min compared with a flow rate of 3 l/min. Based on the data obtained, the MultiLactor® generates no higher increase in FFA than that found when using other milking systems.
Restriction site analysis of polymerase chain reaction (PCR) pro-ducts from a conserved region of the alpha-actin gene has been used for the specific identification of wreck fish (Poly-prion americanus) and Nile perch (Lates niloticus)fillets. PCR amplification was carried out using a set of primers designed from the DNA nucleotide sequences reported for alpha-actins from humans and various animals. Restriction endonuclease analysis based on sequence data of the PCR products of each fish species revealed the presence of species-specific polymorphic sites for Rsal and Hinfl endonucleases. Electrophoretic analysis of the amplicons digested with these endonucleases produced species-specific profiles that allowed the genetic identification of wreck fish and Nile perch.
The influence of acid adaptation on the subsequent sensitivity of S. Typhimurium to osmotic and oxidative stresses was assessed using cells grown in buffered BHI (pH 7.0) and BHI acidified up to pH 4.5 with acetic, citric, lactic and hydrochloric acids and treated in (i) BHI-2.5 M NaCI and (ii) BHI-30 mM H 2O 2.The growth of S. Typhimurium in the presence of organic acids resulted in an increased vulnerability to the toxicity of salt and hydrogen peroxide, especially when acetic acid was used to obtain acid adapted cells. Non-acid adapted cells showed D-values of 493.45 and 31.85 min in BHI-2.5 M NaCI and BHI-30 mM H 2O 2, respectively, which turned out to be about 1.5-2 and 1.5-2.5 times higher than those observed for acid adapted cells. These findings may show an impact on food preservation regimes, as the synergistic effect of the combination of acid and osmotic and oxidative stresses could help in controlling pathogen contamination or survival in several food products, such as cheese and other fermented foods.
Für Säuglingsanfangsnahrung in Pulverform (PIF) ist der Parameter Enterobacteriaceae als Prozesshygienekriterium (nicht nachweisbar in 100 g) definiert. Dennoch können aber gelegentlich Enterobacteriaceae in solchen Produkten nachgewiesen werden. Eine kürzlich publizierte Studie konzentrierte sich auf das Vorkommen von Cronobacter spp., einen pathogenen Vertreter aus der Familie der Enterobacteriaceae, um mögliche Kontaminationswege zu untersuchen. Das Ziel der aktuellen Studie war es, andere häufig gefundene Spezies aus der Familie der Enterobacteriaceae aus Rohstoffen, dem Produktionsumfeld und von Endprodukten eines PIF Verarbeitungsbetriebes mittels PFGE zu genotypisieren, um mögliche Kontaminationswege aufzuzeigen und die Eignung dieser Spezies für betriebsepidemiologische Studien zu evaluieren. Insgesamt wurden 216 Isolate von drei verschiedenen Spezies (Enterobacter (E.) cloacae, Klebsiella (K.) pneumoniae und Leclercia (L.) adecarboxylata) in die Untersuchung miteinbezogen. Der Restriktionsverdau mittes XbaI ergab für alle drei Spezies aussagekräftige PFGE Muster. Endproduktkontaminationen konnten zum einen auf hitzeempfindliche Zusatzstoffe, aber vor allem auch auf das Produktionsumfeld zurückgeführt werden. Dabei hat sich vor allem die Spezies E. cloacae, die in den gleichen Nischen wie Cronobacter spp. gefunden werden kann, als ein guter Parameter für betriebsepidemiologische Untersuchungen erwiesen. Bestimmte Genotypen von E. cloacae scheinen fähig, im Produktionsumfeld zu persistieren, was möglicherweise auf besondere Eigenschaften, wie z. B. verstärkte Austrocknungstoleranz zurückzuführen ist.
Top-cited authors
Roger Stephan
  • University of Zurich
Horst Karl
Hannu Korkeala
  • University of Helsinki
Lidija Kozacinski
  • University of Zagreb
Mirza Hadžiosmanović
  • University of Zagreb