The Evaluation of the Effects of Dietary Vitamin E or Selenium on Lipid Oxidation in Rabbit Hamburgers: Comparing TBARS and Hexanal SPME-GC Analyses

The effects and specificity of dietary supplementation of EconomasETM (EcoE), mainly consisting of organic selenium (0.15 or 0.30 mg/kg feed; Se) or of vitamin E (100 or 200 mg/kg feed; VE), on lipid oxidation were evaluated in rabbit hamburgers during refrigerated storage. Oxidation data obtained by thiobarbituric acid-reactive substances (TBARS) spectrophotometric analysis and solid-phase microextraction (SPME) coupled with gas chromatography (GC) to determine hexanal content were compared. The relationships between oxidation levels, colour and pH and the discriminability of EcoE- or VE-treatment compared with control were also examined. TBARS content decreased in both VE and EcoE groups, while hexanal showed lower values only in the VE100 dietary group. The colour parameters were compatible with acceptable product quality and seemed to parallel the TBARS values up to the second day storage. Both VE and EcoE improved oxidative stability without affecting the sensory properties, but the VE effect appeared to more specifically hamper lipid oxidation, as evidenced by the determination and quantification of hexanal, a specific product of fatty acid peroxidation

In vivo and in vitro effects of selected antioxidants on rabbit meat microbiota

The purpose of this study was to investigate the effect of dietary vitamin E or EconomasE™ supplementation on the growth of several background/pathogenic bacteria on rabbit carcasses and hamburgers during refrigerated storage. For 51days, 270 New Zealand rabbits received either a basal diet, or experimental diets enriched with 100 or 200mg/kg of vitamin E or EconomasE™. The bacteria studied were Salmonella, Listeria monocytogenes, Pseudomonas, Enterobacteriaceae, Escherichia coli, coagulase-positive staphylococci, plus both mesophilic and psychrotrophic aerobes. The growth of Listeria monocytogenes on contaminated patties was evaluated through a challenge test. The potential protective or antimicrobial effect of vitamin E or EconomasE™ on Listeria monocytogenes or Pseudomonas aeruginosa was assessed in vitro. Diet did not influence the concentrations of bacteria found on rabbit carcasses and developing on hamburgers. Vitamin E (in vivo and in vitro) and EconomasE™ in vivo had a protective antioxidant role, while EconomasE™ in vitro had strong antibacterial activity against Listeria monocytogenes, but not against Pseudomonas aeruginosa

Fecal carriage of Escherichia coli O157:H7 and carcass contamination in cattle at slaughter in northern Italy

Feedlot cattle slaughtered at a large abattoir in northern Italy during 2002 were examined for intestinal carriage and carcass contamination with Escherichia coli O157:H7. Carcass samples were taken following the excision method described in the Decision 471/2001/EC, and fecal material was taken from the colon of the calves after evisceration. Bacteria were isolated and identified according to the MFLP-80 and MFLP-90 procedures (Food Directorate’s Health Canada’s). Eighty-eight non-sorbitol-fermenting E. coli O157:H7 isolates were obtained from 12 of the 45 calves examined. In particular, E. coli O157:H7 isolates were found in 11 (24%) fecal and five (11%) carcass samples. PCR analysis showed that all 11 fecal samples and five carcass samples carried eae-γ1-positive E. coli O157:H7 isolates. In addition, genes encoding Shigatoxins were detected in O157:H7 isolates from nine and two of those 11 fecal and five carcasses, respectively. A representative group of 32 E. coli O157:H7 isolates was analyzed by phage typing and DNA macrorestriction fragment analysis (PFGE). Five phage types (PT8, PT32v, PT32, PT54, and PT not typable) and seven (I–VII) distinct restriction patterns of similarity > 85% were detected. Up to three different O157:H7 strains in an individual fecal sample and up to four from the same animal could be isolated. These findings provide evidence of the epidemiological importance of subtyping more than one isolate from the same sample. Phage typing together with PFGE proved to be very useful tools to detect cross-contamination among carcasses and should therefore be included in HACCP programs at abattoirs. The results showed that the same PFGE-phage type E. coli O157:H7 profile was detected in the fecal and carcass samples from an animal, and also in two more carcasses corresponding to two animals slaughtered the same day. [Int Microbiol 2007; 10(2):109-116

Limiti di carica microbica ed accettabilità delle carni avicole fresche

The minimum number of bacteria, which correlate to end of shelf-life, should be defined by producers in order to establish microbiological standards at the end of productive process or at specifie defect action points, taking into account the possible temperature conditions the various products will probably meet. This would allow the quality assurance of all lots of products until the end of declared shelf life. Entire chicken, sliced chicken breast, skewers of chicken with pepper, ripened chicken leg and cordon bleu samples were stored at temperature condition from -0.2° to 5.9°C for 9-11 days. Then they were analysed for microbiological traits and, on the basis of sensorial characteristics, were classified as acceptable, marginally acceptable or not acceptable. It was defined the maximum number of Pseudomonas spp., total coliforms or total plate count at which unacceptable products were not found and significance of these discriminatory limits was evaluated. Per stabilire la durata commerciale delle diverse preparazioni di carni avicole i produttori dovrebbero conoscere quali sono le concentrazioni minime di batteri alteranti correlabili alla comparsa di alterazioni e quali sono, quindi, gli standard microbiologici in fase di produzione od in specifici punti critici di controllo (defect action point) che permettano di assicurare, in condizioni programmate di temperatura, la qualità di un lotto di produzione fine al termine indicato in etichetta. Campioni di diversi lotti di busti di pollo, petti di pollo a fette, spiedini con peperone, fusotti ripieni e cordon bleu sono stati sottoposti a regimi di temperatura tra -0,2° e 5,9°C per 9-11 giorni. Al termine di questo periodo sono stati fatti controlli microbiologici e sulla base delle caratteristiche organolettiche sono stati classificati accettabili, marginali o inaccettabili. È stato quindi individuato il limite più alto di Pseudomonas spp., coliformi totali o carica mesofila totale al di sotto del quale non fossero riscontrabili unità inaccettabili ed è stata valutata la significatività di questo limite discriminante

Quantitative risk assessment of human salmonellosis and listeriosis related to the consumption of raw milk in Italy.

Two quantitative risk assessment (RA) models were developed to describe the risk of salmonellosis and listeriosis linked to consumption of raw milk sold in vending machines in Italy. Exposure assessment considered the official microbiological records monitoring raw milk samples from vending machines performed by the regional veterinary authorities from 2008 to 2011, microbial growth during storage, destruction experiments, consumption frequency of raw milk, serving size, and consumption preference. Two separate RA models were developed: one for the consumption of boiled milk and the other for the consumption of raw milk. The RA models predicted no human listeriosis cases per year either in the best or worst storage conditions and with or without boiling raw milk, whereas the annual estimated cases of salmonellosis depend on the dose-response relationships used in the model, the milk storage conditions, and consumer behavior in relation to boiling raw milk or not. For example, the estimated salmonellosis cases ranged from no expected cases, assuming that the entire population boiled milk before consumption, to a maximum of 980,128 cases, assuming that the entire population drank raw milk without boiling, in the worst milk storage conditions, and with the lowest dose-response model. The findings of this study clearly show how consumer behavior could affect the probability and number of salmonellosis cases and in general, the risk of illness. Hence, the proposed RA models emphasize yet again that boiling milk before drinking is a simple yet effective tool to protect consumers against the risk of illness inherent in the consumption of raw milk. The models may also offer risk managers a useful tool to identify or implement appropriate measures to control the risk of acquiring foodborne pathogens. Quantification of the risks associated with raw milk consumption is necessary from a public health perspective