Bacteriological quality of ice cream in Tripoli—Libya

ObjectiveTo determine the bacteriological quality of ice cream sold in Tripoli city and susceptibility of the isolated bacterial agents to the commonly used antibiotics.Materials and methodsOne hundred and sixty ice cream samples were collected from six different small and two large manufactures in Tripoli. Standard bacteriological techniques were used to determine the total bacterial count (TBC) and coliforms, isolate the pathogenic organisms and determine their susceptibilities to antibiotics.ResultsTBC of samples examined ranged between 3 × 10¹ and 5 × 10⁸ cfu/ml (mean = 6.9 × 10⁷) and the MPN values of coliforms between 0.0 and 11/ml (mean = 8). Of the samples studied Escherichia coli was isolated from 10 [including 2 serogroup O157] (6%), Salmonella spp. from 8 (5%), Aeromonas spp. from 30 (19%), Staphylococcus aureus from 60 (38%) and Listeria monocytogenes from 7 (4%). Nearly 80% of the samples examined did not conform to the Libyan Standards for Ice Cream (LSIC). Resistance to one antibiotic was detected in more than 80% of the isolated bacterial pathogens and multiple-drug resistance (resistance to three antibiotics) in 25%.ConclusionAntibiotic-resistant pathogenic bacteria is not uncommon in ice cream sold in Tripoli particularly from small manufactures. Application of the HACCP system should be introduced into the ice cream industry to improve the quality of such products manufactured in Libya.     

Review of the sensitivity of different foodborne pathogens to fermentation

The characteristics of lactic acid bacterial fermentation and the principal antimicrobial factors produced by lactic acid bacteria (LAB) are reviewed and assessed. The principal anti-microbial factor identified is the ability of all LAB to produce organic acids and decrease the pH of foods in which they grow. Other factors such as the production of bacteriocins, hydrogen peroxide and ethanol may all play a contributory role in assuring the safety of fermented foods but their contribution is secondary. The efect of fermentation on non-bacterial pathogens is discussed. A tabulation is made of results from a number of published studies of the effects of fermentation on the fate of different bacterial pathogens in a vareity of food materials.     

General patterns of background microbiota and selected bacterial pathogens during production of fermented sausages in Serbia

The presence of Salmonella spp. or Escherichia coli O157 and background microbiota, pH and a_w were determined in raw fermented sausages produced from pork or beef and without lactic acid bacteria starters. The investigation was conducted at five meat processing plants, and the sampling was done at five steps of the production process at each plant. In meat trimmings, total viable count (TVC) ranged around 6 log CFU/g and around 5–6 log CFU/g in the pork and the beef sausages, respectively. Enterobacteriaceae count (EBC) ranged in the vicinity of 3–4 log CFU/g, whilst E. coli count (ECC) ranges were comparably lower (by 1–2 logs). During chopping of both the pork and the beef trimmings, the levels of TVC, EBC and ECC increased by 1–1.5 logs. After the additives and the spices were added, background microbiota tended to slightly decrease, generally more noticeably in pork sausages and with ECC. During the fermentation-drying stage, in both pork and beef sausages, initial TVC levels (6–7 log CFU/g) increased by the mid-process (by approximately 1.5–2 logs) and remained at those levels in finished products. During the same period, lactic acid bacteria (LAB) increased from initial levels of 5.5–6 log CFU/g to around 7–8 log CFU/g in pork and around 8–9 log CFU/g in beef sausages, and became the predominant microbial group. Salmonella spp. was found in the first three stages of the production process (trimmings, trimmings chopping, mixing with additives/spices), in two of three meat processing plants, but not at later stages of the production process. E. coli O157 was found only in one sample of chopped trimmings in one meat processing plant. The background microbiota patterns and levels were, generally, similar to those commonly reported for raw fermented sausages in other published studies. The initial presence of foodborne pathogens in raw fermented sausage production may be considered as a potential meat safety risk, because in the case of high initial pathogen counts, their total elimination cannot be assumed.     

Enumeration and characterization of Listeria monocytogenes in novelty ice cream samples manufactured on a specific production line linked to a listeriosis outbreak

Listeriosis is an invasive illness typically caused by the ingestion of foods contaminated with Listeria monocytogenes. In 2015, an outbreak of listeriosis was linked to ice cream products produced on a specific production line at Facility X. The United States Food and Drug Administration (FDA) obtained samples representing several lots of three products manufactured on that line from May 2014 through January 2015. Two of these products, A and B, while not linked to any reported illnesses, were analyzed to determine the frequency of contamination and the contamination level for risk assessment and dose-response analyses. These enumerations were performed utilizing a Most Probable Number (MPN) method, with a lower detection limit of 0.03 MPN/g, on 344 samples of Product A and 95 samples of Product B. Ten lots of Product A were analyzed and 77% of the samples tested were found to be positive for L. monocytogenes. Five lots of Product B were analyzed and 46% of the tested samples were found to be positive. Additionally, the level of contamination of positive Product B samples was always less than 1 MPN/g. The contamination levels of both products, overall, were low with median values of 0.1 MPN/g and 0.02 MPN/g for Products A and B, respectively. A majority of Product A samples (52%) were contaminated at levels of less than 1 MPN/g and only one sample was above 100 MPN/g. Whole genome sequencing (WGS) of L. monocytogenes isolated from ice cream samples produced in the line suggested minor strain differences related to product type, possibly due to differences in the food matrices and/or differences in the manufacturing equipment. Overall, the data showed a consistent low level of contamination in products produced from a single production line over a nine month period.     

Effect of organic acids on the photodynamic inactivation of selected foodborne pathogens using 461 nm LEDs

Light emitting diodes (LEDs) are known to inactivate foodborne pathogens. However, the effect of food acidulants on the antibacterial effect of LEDs is unknown. In this study, the influence of organic acids on the photodynamic inactivation of four foodborne pathogens (Escherichia coli O157:H7, Salmonella Typhimurium, Listeria monocytogenes and Staphylococcus aureus) by blue LEDs was investigated. Each pathogen was illuminated by 10-W 461 nm LEDs (22.1 mW/cm²) at 15 °C for 7.5 h in tryptone soya broth of pH 4.5 adjusted with citric, lactic or malic acids. The total energy dosage imparted by the LEDs over the course of the illumination was 596.7 J/cm². Our results showed that at the same pH, the nature of the acids significantly influenced the bacterial inactivation due to the LEDs, irrespective of the bacterial strain. Lactic acid was found to be the most effective in aiding the photodynamic inactivation of the pathogens, followed by citric and malic acids. The reparameterized Gompertz equation was fitted to the inactivation curves to determine the lag phase duration (λ) and the maximum inactivation rate (μ_max) under each condition. The λ values for E. coli O157:H7, S. Typhimurium, L. monocytogenes and S. aureus with lactic acid were 3.68, 3.29, 2.25 and 2.27 h, respectively. The corresponding μ_max values were 1.46, 1.31, 1.07 and 1.21 log CFU/h. The combination of organic acids and LEDs also caused significant sublethal injury to the bacterial cultures with trends similar to those of the inactivation tests. This study showed that food acidulants greatly enhanced the antibacterial effect of LEDs, suggesting the potential of LEDs in preserving acidic foods.     

Slime production,DNase activity and antibiotic resistance of Staphylococcus aureus isolated from raw milk,pasteurised milk and ice cream samples

In this study, a total of 180 samples of raw milk, pasteurised milk and ice cream were analysed for the presence of Staphylococcus aureus. There were 110 S. aureus isolated from these samples, which were investigated for DNase activity, slime production and antibiotic resistance. DNase agar that was used to investigate for DNase activity revealed DNase activity in 94.5% of 110 S. aureus. Slime production of S. aureus that was investigated by using Congo Red Agar method revealed slime production in 52.7% of S. aureus. Resistance of S. aureus to different antibiotics was determined by the Kirby–Bauer disc diffusion test. Resistance to penicillin G, methicillin and bacitracin was frequent for S. aureus strains. Few numbers of the strains were resistant to erythromycin. All strains were susceptible to vancomycin, sulbactam–ampicillin, ciprofloxacin and cefaperazone–sulbactam. Slime production positive strains were tested against penicillin G, methicillin and bacitracin. No difference was found between the antibiotic resistance of slime positive and slime negative S. aureus. There was a high rate of resistance for all S. aureus isolates against penicillin G, methicillin and bacitracin.     

Measures for controlling safety of crushed ice and tube ice in developing country

Contamination of pathogens in crushed and tube ice is a public health concern in many developing countries, calling for the development of practical preventive measures to reduce microbial and chemical contamination. By applying principles of hazard analysis and critical control points (HACCP), data on production and distribution processes in 11 ice-making plants in different provinces of Thailand were obtained. Results showed that producers of both ice forms lacked knowledge on water treatment and disinfection that could cause microbial contamination. Other sources of microbial contamination were from condensate in tube ice production and from dirty sacks used in ice transportation. A chemical hazard also was found in crushed ice due to chromium contamination in an anti-rusting agent.     

Implementation of traceability and food safety systems (HACCP) under the ISO 22000:2005 standard in North Africa: The case study of an ice cream company in Algeria

Our study aims at establishing and implementing the HACCP and traceability system, in an integrated approach, of ice cream processing in order to control food borne safety hazards, to minimize the production and distribution of unsafe or poor quality products, thereby the potential food safety risks and associated food recalls. Internal information capture points were identified in ice cream process and the corresponding traceability information to be recorded were determined. Biological, physical, chemical and allergens hazards that could emerge at each stage of the production were identified. After hazards identification, the critical control points (CCPs) and operational prerequisites programs (oPRPs) were selected using a decision tree. Results showed that cleaning-in-place, filtration, pasteurization, cooling storage and transport stages were the critical control points identified. Critical limits, monitoring methods and frequency, responsibilities and corrective actions of the processes are also presented. Finally, the impact of implementation of food safety system (HACCP) on aerobic plate count (APC) and coliforms in vanilla, strawberry and chocolate flavoured ice cream was investigated. The results of HACCP adoption showed the reduction of APC in all flavours of the ice cream samples tested, being higher for the strawberry from 4.18 ± 3.03 till 3.80 ± 2.71 log CFU/g. Besides, a significant decrease of coliforms from 2.39 ± 1.76 till 2.11 ± 1.42 and 2.54 ± 1.62 till 2.02 ± 1.15 log CFU/g was observed in ice cream samples with a chocolate and strawberry flavour, respectively. In conclusion, the implementation of traceability and HACCP system, under the ISO 22000 standard has allowed tracking and tracing of ice cream products improving the microbiological quality of the ice creams.     

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The youth isthe future of our motherland, They are expected to realize China＇s dream for the country＇s prosperity, the national powerfulness and people＇s happiness. China National Committee of World Petroleum Council has always attached great importance to development of young experts. It hosted the First Session of the Youth Forum of World Petroleum Council in 2004 to promote mutual exchange among young people of the member nations.     

The incidence of significant foodborne pathogens in domestic refrigerators

The interior surfaces of household refrigerators are at risk of becoming contaminated with foodborne pathogens, increasing the risks of cross-contamination to other food items, including higher risk ready-to-eat foods. This study determined the incidence of a number of significant foodborne pathogens, and the general hygienic status (as estimated by total viable counts (TVCs), and total coliform counts (TCCs)) on the interior surfaces of domestic refrigerators (n = 342). Campylobacter spp., Salmonella spp. and Escherichia coli O157:H7 were not recovered from any refrigerators, but Staphylococcus aureus was recovered from 6.4%, Listeria monocytogenes and E. coli from 1.2% and Yersinia enterocolitica from 0.6% of examined refrigerators. As the recovered species can survive and grow under refrigeration or conditions of mild temperature abuse, such pathogens may transfer to (and develop to clinically significant numbers in) food in domestic fridges. Such risks are of particular concern in relation to “ready-to-eat” foods, which will not receive further bactericidal treatments (cooking) before consumption. The study estimated TVCs ranging from 2.91 log₁₀ cfu/cm² to 8.78 log₁₀ cfu/cm² and TTCs ranging from 0.045 log₁₀ cfu/cm² to 5.96 log₁₀ cfu/cm² indicating very poor standards of consumer refrigerator management and hygiene, and posing risks to consumer health. The study findings highlight the importance of adequate temperature control and thorough, regular cleaning of domestic refrigerators to ensure food safety, and of effective cooking as the last link in the domestic food service chain.     

俄罗斯可燃冰开发现状及未来发展

可燃冰（天然气水合物）是一种清洁高效能源。随着社会对天然气需求的增加,世界各国对可燃冰开发越来越重视。俄罗斯具有丰富的可燃冰资源,其可燃冰开发水平影响中俄天然气供求关系。从跟踪及借鉴的角度出发,介绍了俄罗斯可燃冰研发历程、储量及分布、研发机构,阐述了俄罗斯可燃冰目前技术进展、下步开采方案、近期发展规划,分析了中国可燃冰试采成功对俄罗斯的影响及俄罗斯应对措施。在此基础上,建议中国在可燃冰领域与俄罗斯开展合作,加快可燃冰开发进程,改善我国天然气短缺局面。     

干冰清洗技术在注汽锅炉的应用

注汽锅炉在长时间运行后,其对流段翅片管表面积累了大量的灰垢,大大降低了对流段的换热能力,造成了排烟温度升高、热效率降低等问题.与常规的水洗、风吹扫等除垢方法相比,运用压缩空气携带干冰颗粒对结垢炉管的清洗技术,可达到清垢彻底、简便、经济、安全的目的.辽河油田公司特种油开发公司在注汽锅炉上采用该方法,对对流段翅片管进行清洗后.排烟温度由315.6℃下降至241℃,锅炉热效率提高3.6%,节油率提高3.8%,具有重要的节能意义.