Storage stability of poultry fat and diesel fuel mixtures: Part II - Chemical properties

This publication continues previously published work from the authors which evaluates the storage potential of poultry fat for its use as an unmodified biofuel in heat and steam generating systems [1]. The previous work examined the physical properties of these fats while this study is concerned with chemical properties. In this study poultry fat (biofuel) and its 20%, 40%, 60% and 80% mixtures with #2 pump diesel fuel were stored for 1 year at bench scale (1L) under controlled laboratory conditions at 4, 38, 54.4 °C and at 22 °C. One hundred percent of poultry fat was studied under these same conditions with and without an antioxidant additive. Twenty and eighty percent of poultry fat mixtures were also stored at pilot scale (250 gallons) under outdoor, ambient conditions. Chemical properties relevant to the use of these mixtures as a biofuel for industrial boilers were studied and tracked. These properties include Energy Values (BTU), Ultimate Analysis (carbon, hydrogen, oxygen, ash, nitrogen, and sulfur), moisture, impurities, unsaponafiables (MIU), and Free Fatty Acid Content. Energy content of the biofuel samples dropped over the course of the study with untreated biofuel losing 18.9% of its BTU value over the course of a year. Ultimate analyses showed an overall increase in carbon composition and a decrease in oxygen content. Hydrogen levels increased in most treatments as did overall ash and sulfur percent composition. MIU values increased, this overall increase was attributable to variable increases in insolubles and unsaponifiables. Free fatty acid levels increased in all treatments. Most of the chemical changes observed in this study were reduced by the addition of antioxidant to 100% biofuel.     

Escherichia coli and Enterobacteriaceae counts on poultry carcasses along the slaughterline: A systematic review and meta-analysis

BackgroundThe slaughtering process consists of a highly coordinated system of different operations and is of critical importance for meat hygiene. The evaluation of the impact of different stages on bacterial counts is useful to monitor carcass contamination and to improve the hygiene of different stages. Escherichia coli and Enterobacteriaceae are considered an interesting target for microbiological analysis.ObjectivesThe aim of this review was to summarize literature data about the influence of slaughter stage on E. coli and Enterobacteriaceae counts along the poultry slaughterline.ResultsSystematic review of the available literature and the meta-analysis of the data collected revealed that scalding resulted in a significant reduction of E. coli counts. Washing and chilling were able to decrease E. coli counts in a statistically significant way; however, the observed reductions were of no practical importance. Enterobacteriaceae were reduced only by defeathering and washing but no practical significance was observed. None of the other stages of the slaughterline resulted in significant changes of indicator bacteria counts.Conclusions and implicationsInformation provided would be useful to suggest suitable ways for the implementation of processes hygiene in poultry slaughterhouses in particular GMP (Good Manufacturing Practices) and HACCP through the identification of suitable CCPs.     

Isolation of salmonellae using two forms of Rappaport-Vassiliadis medium and brilliant green agar

The relative efficiencies of Rappaport-Vassiliadis medium containing tryptone (RV medium) or soya peptone (RV-soya) were compared for the isolation of salmonellae from 518 naturally contaminated chicken livers. RV-soya (299 of 518) gave slightly better recoveries than the standard RV medium (295 of 518) although the difference was not statistically significant (P> 0.05). 60% of the samples which were found to be positive after 24 h enrichment in RV-soya were also positive after just 6 h incubation. It was shown that the use of 14 cm plates of brilliant green agar gave better Salmonella recoveries than did 9 cm plates of the same medium. However, when sulphamandelate supplement was incorporated into the medium, recoveries were further increased. We conclude that RV-soya is an effective alternative to the standard RV medium for the isolation of salmonellae from poultry and would recommend a protocol of pre-enrichment in buffered peptone water, enrichment in RV-soya for 24 h at 43°C and plating on brilliant green agar containing sulphamandelate supplement.     

Biohydrogen production from dual digestion pretreatment of poultry slaughterhouse sludge by anaerobic self-fermentation

Poultry slaughterhouse sludge from chicken processing wastewater treatment plant was tested for their suitability as a substrate and inoculum source for fermentation hydrogen production. Dual digestion of poultry slaughterhouse sludge was employed to produce hydrogen by batch anaerobic self-fermentation without any extra-seeds. The sludge (5% TS) was dual digested by aerobic thermophilic digestion at 55 °C with the varying retention time before using as substrate in anaerobic self-fermentation. The best digestion time for enriching hydrogen-producing seeds was 48 h as it completely repressed methanogenic activity and gave the maximum hydrogen yield of 136.9 mL H₂/g TS with a hydrogen production rate of 2.56 mL H₂/L/h. The hydrogen production of treated sludge at 48 h (136.9 mL H₂/g TS) was 15 times higher than that of the raw sludge (8.83 mL H₂/g TS). With this fermentation process, tCOD value in the activated sludge could be reduced up to 30%.     

Anaerobic co-digestion of sewage sludge,wine vinasse and poultry manure for bio-hydrogen production

The influence of the addition of poultry manure on the thermophilic acid co-fermentation of sewage sludge and wine vinasse was studied. For this, discontinuous tests were carried out to determine the potential for hydrogen production (BHP tests) of 50:50 mixtures of sludge and wine vinasse with different amounts of poultry manure (10  g/L, 20  g/L and 30  g/L). The hydrogen production performance was determined under the tested conditions. The experimental results revealed performance values of TCOD and SCOD, TS and VS, similar in all tests, with removal efficiencies lower than 25%. Likewise, an increase in the production of volatile fatty acids was observed. Regarding the yield, the best results were obtained for the mixture with 10 g/L of poultry manure (with a C/N ratio: 27). Thus, the H₂ production and the yield expressed as mL H₂/gVS_added was 18.20% and 27.57% higher in the test with 10  g/L of poultry manure compared to the test with 20  g/L. Furthermore, from 20 g/L of poultry manure, the mixtures showed poorer purification behavior and performance.     

Simultaneous determination of melamine and cyanuric acid in dairy products by mixed-mode solid phase extraction and GC–MS

This report described a method for simultaneous determination of cyanuric acid (CYA) and melamine (MEL) in dairy products. The samples were extracted by a mixture of acetonitrile/water and cleaned by graphite carbon/strong cation exchange (CARB/SCX) mixed-mode solid phase extraction column. The CYA and MEL were derivatized with bis(trimethylsily1)trifluoroacetamide (BSTFA) containing 1% Trimethylchlorosilane (TMCS), and quantified with the internal standards of ¹⁵N₃-cyanuric acid and ¹³C₃-melamine by GC–MS. The results indicated that CARB/SCX mixed solid phase extraction column could be used for sample pretreatment. The fortification recoveries were 80.8–101.5%, and the relative standard deviations (RSDs) were 3.6–7.9%. The detection limits of CYA and MEL were 0.025 mg kg⁻¹ and 0.01 mg kg⁻¹ respectively.     

Differences in pressure tolerance of Listeria monocytogenes strains are not correlated with other stress tolerances and are not based on differences in CtsR

Thirty strains of Listeria monocytogenes were screened for their pressure tolerance phenotype at 400 MPa for 2 min at 21 °C. The strains exhibited reductions ranging from 1.9 to 7.1log₁₀ CFU/ml in tryptic soy broth with 6% yeast extract (TSBYE). The 3 most and the 3 least pressure-tolerant strains were further tested for their thermal resistance (based on their ability to survive at 55 °C), acid tolerance (based on their ability to survive in acidified TSBYE; pH 2.0) and for their nisin sensitivity. No correlation between pressure tolerance and heat, acid or nisin resistances was found. Nucleotide sequence analysis of the ctsR region in these 6 strains demonstrated that this gene codes for a CtsR protein with identical predicted amino acid sequences. The sequences of the 200-bp region located immediately upstream of the ctsR start codon of the different strains were virtually identical and it is therefore likely that differences in pressure tolerance are based on factors other than the stress gene regulator CtsR. The pressure sensitivity of a cocktail of the 2 most pressure-resistant strains and a cocktail of the 2 most-sensitive strains was investigated when the cocktails were inoculated into a real food system consisting of ground chicken meat. We demonstrated that the nature of the suspending substrate or the temperature did not change the expected pressure tolerance of the cocktails.     

Procedures for the isolation of Campylobacter jejuni and Campylobacter coli from poultry

The effect of different techniques for the isolation of Campylobacter from 198 samples of chicken giblets was studied. Four enrichment broths and two plating media were compared. A protocol of enrichment in Preston or Doyle and Roman's broth followed by plating on Preston agar is recommended for routine use. The duration of incubation of enrichment media was shown to have a significant effect on the number of Campylobacter isolates obtained, 48 h being statistically superior to either 24h or 72h for media incubated at 42°C. Of the 198 samples examined, 177 were found to contain Campylobacter by at least one of the procedures used.     

Textural analysis of hyperspectral images for improving contaminant detection accuracy

Previous studies demonstrated a hyperspectral imaging system has a potential for poultry fecal contaminant detection by measuring reflectance intensity. The simple image ratio at 565 and 517 nm images with optimal thresholding was able to detect fecal contaminants on broiler carcasses with high accuracy. However, differentiating false positives from real contaminants, especially cecal feces were challenging. Further image processing such as textural analysis in the spatial domain was able to reduce false positive errors. In this study, textural analysis of hyperspectral images was conducted to improve detection accuracy by reducing false positives. Specifically, textural analysis with co-occurrence matrix of hyperspectral images performed well to identify “true” contamination. In addition, co-occurrence matrix textural features including average, variance, entropy, contrast, correlation, moment of poultry hyperspectral images were investigated for selecting optimal features to represent contamination. Image pre-processing with co-occurrence textural analysis, specifically mean of co-occurrence textural feature from the matrix (0° angle and distance equals to one) followed by image ratio was able to improve fecal detection accuracy without additional optical filters that increase cost for system hardware of multispectral imaging system for on-line application. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.