Microbiological and sensory suitability of a novel raw material from porcine blood and collagenous rind protein as an ingredient in a fermented raw salami-type sausage.

The aim of this investigation was to develop a treatment for combined porcine blood corpuscle concentrate (BCC) and porcine collagenous connective tissue (rind) so as to make more use of these slaughter by-products as an ingredient in a high-quality product such as salami-type sausage. For this study, BCC was preserved, standardized (sBCC) (15% NaCl and 25% protein content), and then added (proportion of sBCC to rind, 15:85) to rind subjected to different treatments designated A, B, and C (A, 2 h at 90 degrees C; B, 5 min at 90 degrees C; and C, 2 h at 3 degrees C). One half of each mixture was again heated (designated A1, B1, and C1; F70, approximately 15), and the other half was only cooled (designated A2, B2, and C2). The now colored, highly proteinaceous rind mixtures (A1 to C2) were then cooled and granulated (designated GBR-A1 to GBR-C2). Three of the granulates (GBR-A1, -B1, and -B2) proved to be promising new raw materials: their aerobic plate counts were

Determination of polycyclic aromatic hydrocarbons in smoked pork by effect-directed bioassay with confirmation by chemical analysis.

Polycyclic aromatic hydrocarbons (PAHs) are generated during smoke curing and other heating treatments of food and represent a large class of chemical pollutants including a number of carcinogens. At present, PAHs are frequently detected by costly and time-consuming chemical analysis. Effect-directed in vitro cell-based bioassays of contaminants can offer a rapid, sensitive, and relatively inexpensive alternative for screening of contaminants in comparison to instrumental analysis. They enable estimation of total biological activity of all compounds acting through the same mode of binding. The aryl hydrocarbon receptor as a binding site plays an important role in PAH-induced carcinogenesis. The in vitro chemical-activated luciferase expression assay (using conditions to detect PAH) was investigated for its applicability for effect-directed analysis of PAH levels in smoked meat. There was an intra-assay variability of 0 to 15% and a mean coefficient of variation of 25% (3 to 50%) for the cleanup and bioassay analysis of the smoked pork samples. There was a correlation between the total responses of the bioassay and the individual amounts of the PAHs with a high molecular weight. The comparison of 2,3,7,8-tetrachlorodibenzo-p-dioxin and benzo[k]fluoranthene used as standard in the in vitro chemical-activated luciferase expression assay resulted in benzo[k]fluoranthene being able to be used as an alternative, nontoxic standard in the bioassay. This bioassay is an applicable effect-directed functional prescreening method for the analysis of PAHs in smoked meat and appears to have potential in being used for food control in the future.

Microbiological and color aspects of cooked sausages made from a standardized porcine blood cell concentrate.

The objective of this study was to determine the potential for blood cell concentrates (BCCs) from pigs as an ingredient in food. Sausages were made for this study according to a basic recipe for a type of blood sausage that is common in Germany. First, sausages were produced with rind and kettle broth only, and different amounts (2.5 to 31%) of standardized blood cell concentrate (s-BCC) were added (15% table salt [NaCl] and 25% protein content). Then, sausages were made with whole blood and compared with s-BCC sausages; both the BCC and blood had been pretreated either with NaCl or curing salt (nitrite). The impact of BCC and blood on the color (La*b*) of these rind sausages was determined. Finally, blood sausages were made with 12% s-BCC and either natural spices or spice extracts. These sausages were investigated microbiologically and compared to customary commercial blood sausage products (with whole blood) in terms of aerobic plate count (APC), Enterobacteriaceae, sulfite-reducing anaerobic bacteria, coagulase-positive staphylococci, and spore-forming bacilli. The desired color parameters (L, 34.5; a*, 17.8; and b*, 10.6) were obtained with the addition of about 12% s-BCC. Curing the blood or BCC beforehand had no significant (P > 0.05) influence on the color. The microbial counts of both the blood (APC, 4.4 log CFU/g) and the natural spices (APC, 6.6 log CFU/g) were relatively high. The spices were responsible for the relatively high microbial counts in the sausages, particularly the bacilli (6.4 log CFU/g). However, these counts were comparable to those found in commercial blood sausages. The bacteria introduced into the sausage by the blood had no significant impact on the bacterial counts of the end product. The bacterial loads of the sausages produced with 12% s-BCC and spice extracts were significantly lower (APC and bacilli, 2.0 log CFU/g) than those of the other blood sausages (APC, -4.4 log CFU/g; bacilli, 3.2 to 4.0 log CFU/g).

Salmonella contamination in pigs at slaughter and on the farm: a field study using an antibody ELISA test and a PCR technique.

An antibody ELISA test and a PCR method for identifying the risk of Salmonella contamination were compared in a field study on the same lots of animals in a slaughterhouse. The results were compared to investigations carried out on two farms with different prevalences of Salmonella antibody-positive animals. Salmonella antibody ELISA testing was carried out on all 383 meat juice samples derived from the diaphragm pillar muscle of each pig. Salmonella DNA analysis was performed by PCR technique on small intestine samples with lymph nodes from all 383 pigs, and on tonsils from the last 129 pigs. The 383 animals tested came from 32 different pig farms. Furthermore, the herd antibody blood serum status against Salmonella spp. of weaners was determined on two selected pig fattening farms, one with low and one with high seroprevalence in meat juice. A total of 7.0% (ELISA cut-off OD% > or =40) of the slaughtered pigs from 6 of 32 fattening farms were seropositive. Salmonella DNA was found in 16.4% of the jejunum/lymph nodes (383 animals) and in 15.5% of the tonsils (129 animals). Salmonella DNA was found in the jejunum/lymph nodes of 41% of the seropositive pigs. However, serotitres were also positive in only 17.5% of all pigs positive in the jejunum DNA test. Two farms were selected for further investigation: farm 13 (F13), with a high prevalence of seropositive pigs, 29.0%, Category II; and F11, with 9.4%, Category I. However, categorization according to the blood serum tests of the fattening pigs after on-farm testing was very different: F13 had 5% positive animals (Category I); and F11, 23.3% (Category II). The study led to the following results and recommendations: First, ELISA tests are useful for the detection of farms that are regularly contaminated with Salmonella, but such tests cannot give information on the infectious status of a single animal (or a group) at the point of slaughter. Second, it is crucial that management measures are taken to prevent the spread of infections by trade and transport: piglets should be supplied exclusively by a single, well-known producer, and finishers should be tested serologically on farm before going to slaughter. Third, ELISA tests and the PCR method are suitable for the detection of Salmonella and are recommended as analytical tools for all pork quality control programmes. Fourth, animals from suspicious farms should always be slaughtered at the end of the slaughter day, followed by thorough cleaning and disinfection.

Preliminary study of certain serotypes, genetic and antimicrobial resistance profiles of verotoxigenic Escherichia coli (VTEC) isolated in Bosnia and Germany from cattle or pigs and their products.

The aim of this study was to gather more information on the spread of VTEC serotypes, genetic profiles and resistance patterns from pigs or pork and from cattle or beef in different areas, and to improve detection of the source of outbreaks with a wider data pool. Of 130 Escherichia coli samples isolated from a cattle slaughter house and beef retail products in Sarajevo, Bosnia and Herzegovina (BiH), seven were identified as verotoxigenic (VTEC). In comparison, 22 VTEC of 264 E. coli isolates were isolated from bovine faeces (14) and beef products (8) from Germany. Furthermore 23 VTEC of 76 isolates were identified from pig carcasses (10), faeces (9) and pork products (4) from Germany. Gene detection and serotyping were carried out in our laboratory and in the National Reference Laboratory. Antimicrobial resistance was tested with the dilution method in microtitre plates. All porcine isolates belonged to serotypes thus far not associated with human disease. Bovine VTEC were either serotypes commonly associated with human diseases (O157:H7, O103:H2, O157:H-) or rare serotypes. One serotype (O96:H19) was found only in isolates from Sarajevo. Most German VTEC, especially those of porcine origin, had only vtx2 genes, whereas all Bosnian isolates had vtx1 and vtx2 genes. The eae gene was found only in "classical" VTEC serotypes. All 52 VTEC (100%) investigated were resistant to the three sulfonamides tested; porcine isolates were mainly resistant to oxytetracycline (43%) and chlortetracycline (37%), bovine isolates mainly to trimethoprim/sulfamethoxazole and ampicillin (10% each). If sulfonamide resistances are disregarded, more than half (53.8%) of porcine VTEC were multiresistant and one-fourth (25%) of German bovine isolates, but none of the Bosnian bovine isolates. The results show the considerable spread of resistances in VTEC. These results also point out the necessity of gathering data from different geographical areas in order to be able to identify typical local variations in serotypes or gene expression and thus to trace human infections more quickly to their source.

Porcine blood cell concentrates for food products: hygiene, composition, and preservation.

The objective of this study was to determine whether porcine blood cell concentrates (BCC) can be produced and stored using hygienic measures independent of the temperature acting upon the substrate. A number of additives widely accepted by the consumer (NaCl, sugars, food-grade acids) were used to form so-called hurdles (water activity [a(w)], pH) to spoilage, and their impact was tested on microbiological and sensory parameters of the BCC. BCC, whole blood, plasma, and the anticoagulant were collected on 23 days in a slaughterhouse. The BCC with the additives were stored for 27 days at + 3 degrees C and at +20 degrees C. Microbiological and chemical tests were carried out on the raw materials, and a(w) and the pH values of the stored BCC combinations were determined; the combinations were also submitted to sensory testing. The amounts of protein (33.4%) and hemoglobin (29.5 g/dl) in the BCC were significantly higher than in whole blood (19.4%; 13.8 g/dl). The mean total aerobic plate count was similar in all three substrates. However, the highest count (4.83 log CFU/g) was found in BCC; the count was lower in whole blood (4.62 log CFU/g) and lowest in plasma (4.22 log CFU/g). Storability (defined as a count of <5 log CFU/g) for 27 days at +20 degrees C was achieved only with two additive types: 15% NaCl and 10% NaCl plus 10% glucose plus 1% of a food-grade acid. Spoilage of the BCC was inhibited by an a(w) of 0.824 (with 15% NaCl) and by the combination of a(w) 0.87 and a pH of 5 (with 10% NaCl, 10% sugar, 1% acid). Both substrates retained their red color and fresh odor over the entire storage time.

Validation of a method for the detection of virulent Yersinia enterocolitica and their distribution in slaughter pigs from conventional and alternative housing systems.

Various methods have been described in the literature for the detection of virulent Yersinia enterocolitica in pigs. The risk factors for pig herd contamination have yet to be determined. The objective of this study was to validate a sensitive method for the detection of Y. enterocolitica and to describe the distribution of the bacteria in pigs at slaughter from conventional and alternative ("organic") housing systems. First, samples were collected from tonsils, caecum with caecal contents, and the caecal lymph nodes of 60 slaughter pigs. These samples were used to compare the sensitivity of six different laboratory culture methods either in common use or described in the literature with that of a polymerase chain reaction with two primer pairs (multiplex PCR). Then, only PCR was used to examine tonsils, caecum and caecal lymph nodes from two groups of slaughter pigs: 210 from six conventional fattening farms and 200 from three with alternative housing. The results of the multiplex PCR were positive in 28 cases. All culture methods proved inferior to PCR in sensitivity. In the second part of the study, PCR detected 36 (18%) positive pigs from alternative housing and 60 (29%) from conventional housing (p<0.05). The highest rate of Y. enterocolitica contamination was found in tonsils (11% alternative, 22% conventional; p<0.05), followed by caecum (5%, 11%) and lymph nodes (2%, 7%). The housing system appears to be one important factor in the prevalence of this common pathogen in pig herds, as we found important differences between the two systems studied here. In the conventional system, the main risk factors appeared to be sourcing pigs from different pig suppliers, use of commercial feed and transportation to slaughter.