Category Archives: Microbiology

Research – Effect of Peracetic Acid Solutions and Lactic Acid on Microorganisms in On-Line Reprocessing Systems for Chicken Slaughter Plants

Journal of Food Protection

ABSTRACT

During poultry slaughter and processing, microbial cross-contamination between individual chickens is possible, as well as from one slaughter animal to the next without direct contact. One option for reducing the risk of cross-contamination is to decrease the number of microorganisms on contact surfaces by using disinfectants. The aim is to decontaminate the surfaces coming into direct contact with the carcasses. In the present study, the effectiveness of different disinfectants was investigated in laboratory settings, simulating the conditions in the slaughterhouses and in a chicken slaughterhouse. For this, an artificial residue substance (consisting of yeast extract, albumin, and agar) was developed, tested, and included in the assays. Two disinfectants were tested under laboratory conditions: lactic acid (5 and 6.67%) and peracetic acid (0.33 and 0.5%). At the slaughterhouse, peracetic acid (0.021%) was used. In the laboratory tests, it was found that the peracetic acid solution had the highest disinfection potential with respect to an Escherichia coli strain (reduction >4 log CFU mL−1) at 0.5% without an artificial residue substance. The tested lactic acid solutions also showed the highest disinfection potential against a Pseudomonas aeruginosa strain, without an artificial residue substance. When applying the artificial residue substance, the reduction potential of lactic acid and peracetic acid was decreased to less than 1.4 log CFU mL−1. Application of peracetic acid in the slaughterhouse reduced the number of total aerobic bacteria by more than 4 log CFU mL−1 and the number of Enterobacteriaceae by more than 3 log CFU mL−1, depending on the place of sampling.

HIGHLIGHTS
  • Peracetic acid and lactic acid decreases E. coli and P. aeruginosa numbers in vitro.
  • Sanitation in place reduces the number of bacteria in a chicken slaughterhouse.
  • The number of total aerobic bacteria and Enterobacteriaceae was significantly reduced.

USA – Possible Hepatitis A at LaRoma’s Pizzeria in Rome, New York

Food Poisoning Bulletin

An employee tested positive for hepatitis A at LaRoma’s Pizzeria in Rome, New York, according to a press release issued by the Oneida County Health Department. The employee “worked while infectious and may have exposed people who were patrons of the shop,” according to the press release. The Health Department is also alerting people who ordered take-out food from that venue.

Scotland – HPS publishes annual surveillance reports for Hepatitis A, Hepatitis E, Listeria, Norovirus, Shigella and Yersinia in Scotland for 2019

HPS

12 May 2020

Article: 54/1901

On 12 May 2020, Health Protection Scotland (HPS) published the following annual surveillance reports:

Research – Phage Biocontrol Improves Food Safety by Significantly Reducing the Level and Prevalence of Escherichia coli O157:H7 in Various Foods

Journal of Food Protection

ABSTRACT

Management of Shiga toxin–producing Escherichia coli (STEC), including E. coli O157:H7, in food products is a major challenge for the food industry. Several interventions, such as irradiation, chemical disinfection, and pasteurization, have had variable success controlling STEC contamination. However, these interventions also indiscriminately kill beneficial bacteria in foods, may impact organoleptic properties of foods, and are not always environmentally friendly. Biocontrol using bacteriophage-based products to reduce or eliminate specific foodborne pathogens in food products has been gaining attention due to the specificity, safety, and environmentally friendly properties of lytic bacteriophages. We developed EcoShield PX, a cocktail of lytic bacteriophages, that specifically targets STEC. This study was conducted to examine the efficacy of this bacteriophage cocktail for reducing the levels of E. coli O157:H7 in eight food products: beef chuck roast, ground beef, chicken breast, cooked chicken, salmon, cheese, cantaloupe, and romaine lettuce. The food products were challenged with E. coli O157:H7 at ca. 3.0 log CFU/g and treated with the bacteriophage preparation at ca. 1 × 106, 5 × 106, or 1 × 107 PFU/g. Application of 5 × 106 and 1 × 107 PFU/g resulted in significant reductions (P < 0.05) in E. coli O157:H7 levels of up to 97% in all foods. When bacteriophages (ca. 1 × 106 PFU/g) were used to treat lower levels of E. coli O157:H7 (ca. 1 to 10 CFU/10 g) on beef chuck roast samples, mimicking the levels of STEC found under real-life conditions in food processing plants, the prevalence of STEC in the samples was significantly reduced (P < 0.05) by ≥80%. Our results suggest that this STEC-targeting bacteriophage preparation can result in significant reduction of both the levels and prevalence of STEC in various foods and, therefore, may help improve the safety and reduce the risk of recalls of foods at high risk for STEC contamination.

HIGHLIGHTS
  • Shiga toxin–producing E. coli is a major food safety challenge for the food industry.
  • EcoShield PX bacteriophage cocktail reduced E. coli O157:H7 levels in foods by up to 97%.
  • The bacteriophage cocktail reduced the prevalence of E. coli O157:H7 in foods by ≥80%.

Research – Evaluation of eight essential oils for postharvest control of Aspergillus carbonarius in grapes

Journal of Food Protection

A wide range of fungal species is associated with post-harvest spoilage of grapes. However, Aspergillus carbonarius is the primary fungus responsible for the contamination of grapes with ochratoxin A, a mycotoxin causing several confirmed health effects to humans and animals. Aiming to find a method, safe for the consumers, to prevent post-harvest decay and ochratoxin A contamination of grapes, the potential use of essential oils as preservatives was investigated. Essential oils of Origanum dictamnus (dittany) , Origanum onites (oregano) , Origanum microphyllum (marjoram) , Thymbra capitata (thyme) , Satureja thymbra (savory) , Rosmarinus officinalis (rosemary) , Laurus nobilis (laurel) and Salvia officinalis (sage) were tested. The essential oil components were identified by GC/MS analysis. A first evaluation of the effectiveness of essential oils was performed in vitro , at a range of concentrations up to 300 μL L -1 . Based on the results of the in vitro tests, the four most effective essential oils ( O. dictamnus , O. onites , T. capitata and S. thymbra ) were tested on Sultana grapes, during post-harvest storage. The four essential oils tested, having the carvacrol and/or thymol as a common component, at a high concentration, significantly reduced, or even completely inhibited the growth of the fungus, in all treatments. As revealed from the results, the essential oils of O. dictamnus , O. onites and S. thymbra were the most effective, causing total inhibition on the growth of the fungus with a minimum concentration of 100 μL L -1 , followed by the essential oil of T. capitata , total effective with a minimum concentration of 200 μL L -1 . Essential oils of O. microphyllum , L. nobilis , S. officinalis and R. officinalis , although they had a significant effect on the growth of A. carbonarius , failed to inhibit its growth completely at any of the concentrations tested.

Research – Comparison of stomaching versus rinsing, for recovering bacterial communities from rainbow trout (Oncorhynchus mykiss) fillets.

Journal of Food Protection

The use of high-throughput methods allows a better characterization of food-related bacterial communities. However, such methods require large amounts of high quality bacterial DNA, which may be a challenge when dealing with a complex matrix that has a low concentration of bacteria like fresh fish fillets. Therefore, the choice of method used to recover bacteria from a food matrix in a cost-effective way is critical, yet little information is available on the performance of commonly used methods. We assessed the recovery capacity of two such methods: stomaching and mechanical rinsing. The efficiency of the methods was evaluated through the quantitative recovery and compatibility with end-point qPCR. Fresh rainbow trout ( Oncorhynchus mykiss ) fillets were inoculated with a bacterial marker, Brochothrix thermosphacta , at different concentrations (7.52 to 1.52 log CFU/g). The fillets were processed by one of the two methods and the recovery of the marker in the suspensions was assessed by plate counting and qPCR targeting B. thermosphacta – rpoC . The same analyses were performed on 6 non-inoculated fresh fillets. Stomaching and mechanical rinsing allowed an efficient and repeatable recovery of the bacterial communities from the 42 inoculated fillets. No significant differences of Recovery Ratios were observed between the marker enumerated in the inoculation suspensions and in the corresponding recovery suspensions after rinsing and stomaching. However, the stomaching method allowed too many particles to pass through the filters bag, making necessary a limiting supplementary filtration step. As a consequence, only the rinsing recovery method allowed a proper PCR quantification of the inoculated B. thermosphacta. The mean recovered bacterial level of the fillets was around 3 log CFU/g. It seems more relevant and cost-effective to recover the endogenous bacterial microbiota of a fish fillet structure using the rinsing method rather than the stomaching method.

Research – Enhanced elimination of Salmonella Typhimurium and Campylobacter jejuni on chicken skin by sequential exposure to ultrasound and peroxyacetic acid

Wiley Online

The present study investigated the effects of combined ultrasound (37 kHz, 380 W for 5 min) and peroxyacetic acid (PAA; 50–200 ppm) treatment on the reduction of Salmonella Typhimurium and Campylobacter jejuni on chicken skin. Ultrasound was not sufficient to inactivate S. Typhimurium (0.48 log CFU/g reduction) or C. jejuni (0.25 log CFU/g reduction), whereas PAA significantly (p < .05) reduced S. Typhimurium (0.93–1.59 log CFU/g reduction) and C. jejuni (0.77–1.52 log CFU/g reduction). However, maximum reductions of 2.21 and 2.08 log CFU/g were observed for S. Typhimurium and C. jejuni, respectively, for combined treatment with 5 min of ultrasound and 200 ppm PAA. Our results indicate that a combination of ultrasound treatment for 5 min and 200 ppm PAA was more effective in reducing S. Typhimurium and C. jejuni compared to the individual treatments, without significantly affecting the color or texture of the chicken skin, thus, demonstrating its potential to increase the microbial safety during poultry processing.

Research -The impacts of tomato residuum extract with Arabic gum and dill essential oil on the shelf life improvement of trout fillets stored at chilly condition

Wiley Online

The objective of this study was to evaluate the effects of tomato residuum extract (TRE) dipping and Arabic gum (AG) coating enriched with dill essential oil (DEO) on the shelf life extension of refrigerated trout fillets. Gas chromatography/mass spectrometry analysis revealed that the main constituents of DEO were alpha‐phellandrene (30.17%), limonene (28.31%), and carvone (21.31%). Antioxidant activities of acetone, ethanol, methanol, cold, and hot water extracts of tomato residuum were examined using reducing power and 2,2‐azinobis‐3‐ethylbenzothiazoline‐6‐sulphonic acid assays in maceration, ultrasound, and combined ultrasound and maceration extraction methods. The strongest antioxidant activities were found in the ultrasound‐assisted extraction with ethanol 50%. Thiobarbituric acid, total volatile basic nitrogen, and peroxide values indicated that TRE 3%–AG–DEO 2% and TRE 6%–AG–DEO 2% treatments could significantly (p ≤ .05) extend the shelf life of the fillets. Also, sensory evaluation showed that TRE along with DEO had significant (p ≤ .05) pleasant effects on the sensory characteristics of the fillets. It was concluded that TRE dipping along with AG coating containing DEO could be a suitable alternative for the synthetic preservative in the refrigerated trout fillets.

Research – Protective shield: How pathogens withstand acidic environments in the body

Science Daily

Certain bacteria, including the dangerous nosocomial pathogen MRSA, can protect themselves from acidic conditions in our body and thus ensure their survival. Researchers at the Biozentrum of the University of Basel have now elucidated an important mechanism in this process. A transport protein involved in cell wall biosynthesis plays a key role, they report in the journal Nature Structural & Molecular Biology.

Each year, thousands of patients in Swiss hospitals become infected with dangerous pathogens that can hardly be controlled with antibiotics. The methicillin-resistant bacterium Staphylococcus aureus, MRSA for short, is particularly feared among the multi-resistant nosocomial germs. It can cause severe wound, respiratory and urinary tract infections and life-threatening sepsis. This is aggravated by the fact that MRSA causes chronic infections.

RASFF Alert – Animal Feed – Salmonella – Soybean Cakes

RASFF-Logo

RASFF – Salmonella (presence /25g) in soybean cakes from Ukraine in Poland