Survival of Salmonella on refrigerated chicken carcasses and subsequent transfer to cutting board.

OBJECTIVE: To determine the effect of refrigeration time and temperature on Salmonella cell numbers on inoculated chicken carcasses and their transfer to a plastic cutting board. METHODS AND RESULTS: The survival of Salmonella on chicken skin and the transfer to a plastic cutting board when exposed to different refrigeration temperatures (2, 6 or 8 degrees C) for 9 days were the two main issues on which this work focused. Two scenarios were carried out to ascertain these effects: carcasses treated with a decontaminating acetic acid solution and untreated carcasses. All of the contaminated carcasses remained contaminated after 9 days of refrigeration. However, on untreated samples, while Salmonella numbers increased almost 1.5 log at 8 degrees C, the pathogen numbers decreased about 1 log at 2 and 6 degrees C. On acid-treated samples, cell numbers slightly decreased at all of the temperatures studied. Temperature did not affect salmonellae transfer to the cutting board, but time did. Acid decontamination increased cell numbers transferred to the cutting board compared with untreated samples. CONCLUSION: Proper refrigeration at low temperatures did not allow Salmonella numbers to rise, regardless of which carcasses had been, or had not been, acid treated. Despite the fact that the rate of transfer was not affected by temperature, the acid treatment detached Salmonella cells from the chicken skin and, therefore, the probability of greater cross-contamination should be studied further. SIGNIFICANCE AND IMPACT OF THE STUDY: The results of this study may provide better information about the refrigeration conditions for fresh chicken storage and also determine if these, along with acetic acid decontamination of broiler chicken, would affect the pathogen transfer to a cutting board.

Predictive models for reduction of Salmonella Hadar on chicken skin during single and double sequential spraying treatments with acetic acid.

AIMS: The response surface methodology was used to evaluate the effect of acetic acid concentration, spraying time and temperature on the reduction of Salmonella Hadar on poultry skin in a laboratory spraying process, and to identify the best conditions required to develop this operation. METHODS AND RESULTS: A comparative analysis was carried out to ascertain the effects of the application of single (SS) and double sequential decontamination (DSS) treatments on skin samples inoculated with Salm. Hadar. While on the SS treatment, the linear and quadratic acid concentration terms and the interaction of the temperature and time term of the model are statistically significant at P < or = 0.001, P < or = 0.01 and P < or = 0.05, respectively, the other terms do not significantly affect (P > 0.05) the reduction of Salm. Hadar. On the DSS model the acid concentration and time linear terms significantly affected (P < or = 0.001 and P < or = 0.01) the Salm. Hadar reduction within the experimental range assayed. CONCLUSION: Any of the models could be used as an approach to optimize spray washing during chicken processing. SIGNIFICANCE AND IMPACT OF THE STUDY: Neither the SS or the DSS treatment has the capability of eliminating Salm. Hadar from carcasses. However, reductions of approx. 99% initial load could be attained if DSS treatment were put into practice.

Predictive model for reduction of Escherichia coli during acetic acid decontamination of chicken skin.

AIMS: The response surface methodology was used to evaluate the effect of operating variables (acetic acid concentration, spraying time and temperature) on the reduction of Escherichia coli populations on poultry breast skin in a laboratory showering process, as well as to identify the best conditions that are required to develop this operation. METHODS AND RESULTS: Skin samples were inoculated with a 24-h E. coli culture and afterwards treated according to experimental design under selected acetic acid concentration, spraying time, and solution temperature. The E. coli reduction model was significantly affected by the acetic acid concentration and spraying time (P < or = 0.05 and < or =0.01), while temperature did not show a significant effect (P > 0.05). CONCLUSION: The predictive model obtained was validated through additional confirmatory experiments and showed to be adequate, and it could be used as an approach to optimize the acetic acid spray washes during poultry carcasses processing. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of acetic acid washes in the processing of poultry does not have the capability of eliminating E. coli populations from carcasses. However, significant reductions in the initial load could be achieved.

Use of ascorbic and citric acids to increase dialyzable iron from vinal (Prosopis ruscifolia) pulp.

Vinal (Prosopis ruscifolia) is an ecologically important wild leguminous tree that grows spontaneously in Argentine deforested lands, the fruit of which is consumed by humans and animals. Because considerable iron content with low to intermediate availability has been previously reported in vinal pulps, its enhancement would be of interest. Iron availability was determined as iron dialyzability using an in vitro technique. Response surface methodology was used to evaluate iron availability increase after adding ascorbic and/or citric acids to vinal pulp at different mM acid/mM Fe ratios. Those ratios ranged from 0.05:1 to 9.95:1 and from 0.5:1 to 99.5:1 for ascorbic acid/Fe (AA:Fe) and citric acid/Fe (CA:Fe), respectively. The obtained second- and first-order polynomial equations showed that AA:Fe and CA:Fe molar ratios linear terms had a significant effect on iron dialyzability increase (P < or = 0.05). It was possible to enhance iron availability to a maximum of 4.6 times. Additional confirmatory experiments were made adding the same organic acids to different vinal pulps and to a traditional cake prepared with vinal pulp called "patay." There were no significant differences (p > 0.05) between predicted values obtained by the model and experimental results.

The role of visible faecal material as a vehicle for generic Escherichia coli, coliform, and other enterobacteria contaminating poultry carcasses during slaughtering.

AIMS: A comparison of Enterobacteriaceae, coliform and Escherichia coli counts in chicken carcasses with and without visible faecal contamination was conducted to evaluate the role of contamination as a vehicle for generic E. coli, coliform and other enterobacteria contaminating broiler chicken carcasses when processed under routine commercial operations. METHODS AND RESULTS: Samples were removed from the processing line immediately after evisceration, inside-outside shower and chilling for microbiological analysis. After evisceration, mean counts were significantly different only for E. coli (P < or = 0.05) in chicken carcasses with and without visible faecal contamination. While the spray wash practice was not efficient enough for complete removal of the visible contamination from carcasses, leading to microbiological reduction percentages lower than expected, 25 ppm chlorinated water chilling did reduce the contamination level considerably in all samples. CONCLUSIONS: Carcasses with and without visible faecal contamination harboured E. coli and other potentially hazardous enterobacteria. E. coli was the predominant strain isolated in all samples, Enterobacter cloacae being next most frequent. SIGNIFICANCE AND IMPACT OF THE STUDY: The zero tolerance of visible faecal contamination requirement alone is not sufficient to assure safety and to improve the microbial quality of carcasses.

A comparison between broiler chicken carcasses with and without visible faecal contamination during the slaughtering process on hazard identification of Salmonella spp.

AIMS: A comparison of the prevalence of Salmonella in chicken carcasses with and without visible faecal contamination during commercial slaughter practice was made. The relationship between Enterobacteriaceae, coliform and Escherichia coli counts and Salmonella status was also evaluated to establish the likelihood of using these groups as 'index' organisms to predict the presence of pathogen. METHODS AND RESULTS: Samples were removed immediately after evisceration, after the inside-outside shower and after chilling from the processing line for microbiological analysis. Of the carcasses visibly uncontaminated with faeces after the evisceration step 20% harboured salmonellas and 20.8% of the visibly contaminated carcasses were positive for the pathogen. When E. coli, coliforms and Enterobacteriaceae were used as predictor variables the error rates ranged from 33.3 to 60% for both sample types. CONCLUSIONS: There was no indication that any of the groups of organisms analysed could predict the incidence of salmonellas on the samples studied. Positive results for the pathogen were obtained at every tested step of the slaughtering process regardless of whether or not faecal contamination was present. SIGNIFICANCE AND IMPACT OF THE STUDY: The present study demonstrated that carcasses not visibly contaminated with faeces carried Salmonella as well as the visibly contaminated carcasses.

Microbiological quality and safety of ready-to-eat cooked foods from a centralized school kitchen in Argentina.

The purpose of this study was to evaluate the microbiological and sensory quality as well as the safety of ready-to-eat (RTE) cooked foods prepared in and distributed from a centralized kitchen to schools in Argentina. A total of 101 cooked food samples delivered as hot RTE cooked foods (group A) and as RTE cooked foods at room temperature (group B) and 140 surface swab environment samples were collected from February to November 1999. Petrifilm plates were used for aerobic (PAC), coliform (PCC), and Escherichia coli (PEC) counts. Standard methods were used to determine Enterobacteriaceae (EntC) and thermotolerant coliform counts (TCC). Samples were also tested for the presence of Salmonella spp., Staphylococcus aureus, Bacillus cereus, and Clostridium perfringens. Food temperatures just before samples were put into containers ranged from 80 to 98 degrees C and from 28 to 32 degrees C for group A and group B, respectively. For group A food samples, PAC ranged from 1.04 to 3.50 log CFU/g, and PCC, PEC, TCC, and EntC were not detected. For group B food samples, PAC ranged from 3.63 to 6.48 log CFU/g, PCC ranged from 1.90 to 5.36 log CFU/g, TCC ranged from 1.30 to 3.95 log CFU/g, and EntC ranged from 3.60 to 5.46 log CFU/g. Of the foodborne pathogens, only B. cereus was isolated (63.4% of samples) in both food groups (<4 log CFU/g). The microbiological and sensory quality and the safety of group A foods were satisfactory. Large numbers of PAC and EntC detected in group B foods show that better control is needed to avoid potential foodborne diseases.

Survival of Salmonella hadar after washing disinfection of minimally processed spinach.

Washing disinfection with chlorine is widely used to reduce the initial microbiological load during the preparation of minimally processed vegetables. The effects of initial concentration of chlorine, time and the liquid volume:produce weight ratio on the reduction of Salmonella counts on inoculated spinach were evaluated using response surface methodology. Initial chlorine concentration, time and the interaction between them had a significant effect on reduction of Salmonella populations. However, the liquid volume:produce weight ratio did not have significant effects. The highest Salmonella reduction was around 1.2-1.4 log at 125 ppm during 8 min regardless of the water:produce ratio. According to the results, chlorination reduced Salmonella hadar population, but the complete elimination from the produce was not achieved.

Efecto del tratamiento químico y tipo de envase sobre la calidad sensorial de espinaca mínimamente procesada / Effect of the chemical treatment and container type about the sensorial quality of spinach minimumly processed

El objetovo es analizar el efecto combinado del ácido cítrico, el ácido ascórbico y el tipo de envase, sobre la calidad sensorial, la retención de clorofila y la pérdida de peso de espinaca mínimamente procesada, durante el almacenamiento refrigerado. Se propone desarrollar modelos matemáticos que permitan analizar y predecir el efecto de las concentraciones de ácido cítrico y ácido ascórbico, y del tiempo de almacenamiento sobre el desarrollo de off-odors, apariencia general, marchitamiento, amarronamiento y color.

Combined use of acetic acid treatment and modified atmosphere packaging for extending the shelf-life of chilled chicken breast portions.

Samples of chicken breasts with skin were treated with a 1% acetic acid solution or untreated and packaged in a 70% CO2/30% N2 modified atmosphere. Two different types of films were studied to establish their usefulness within the above pre-determined conditions. After 3, 7, 14 and 21 d of storage at 4 degrees C, the samples were evaluated for spoilage microbial growth, odour and slime, as well as the gas composition in the headspace volume in the package. As a result of this, it was found that both films were adequate for using them as barriers. Samples treated with the acetic acid solution smelt slightly acidic and pleasant, while the untreated ones had 'off' odours at the end of the storage periods. However, all samples showed acceptable overall aspect by that time. Acetic acid treatment produced decreases in counts in all genera studied. Results of this study indicate that using modified atmosphere packaging (MAP) on chicken breasts previously decontaminated with acetic acid is a worthwhile technology to extend samples shelf-life.