High voltage atmospheric cold plasma decontamination of Salmonella enteritidis on chicken eggs

Salmonella enteritidis (SE) accounts for more than 70% of Salmonella spp. infections in humans with a primary source being chicken eggs, that can result from post-lay SE cross-contamination of the shell from contaminated equipment or the environment. The objective of this study was to apply a HVACP treatment that can achieve a minimum 5-log reduction in SE on the surface of artificially inoculated shell eggs with an initial bacterial load of 10⁸ CFU/egg, after a previous disinfection. Optimized HVACP treatment conditions were an indirect treatment with air at 60% humidity at 100 kV for one minute treatment and six hours post-treatment or alternatively, five minutes of treatment and four hours post-treatment. Egg quality parameters of Haugh unit (HU), pH, color, and vitelline membrane and shell strength were tested under the optimized conditions and showed no significant difference (p > 0.05) between treated and untreated eggs.Industrial relevance: Missing information for a possible scale up of a cold plasma system for egg surface decontamination has been addressed by an optimization of HVACP treatment focused on treatment and post-treatment time, essential parameters to have into account in the food industry. These results demonstrate that HVACP is an effective decontamination method for SE on chicken shell eggs and provides a baseline for a future scale up of the process, showing that different combinations of treatment variables can achieve the desired decontamination without affecting to key quality parameters of the egg such as Haugh Unit or vitelline membrane strength.     

Use of octanoic acid as a postlethality treatment to reduce Listeria monocytogenes on ready-to-eat meat and poultry products

The antilisterial efficacy and organoleptic impact of an octanoic acid (OA)-based treatment for ready-to-eat (RTE) meat and poultry products were investigated. Whole-muscle and comminuted RTE products were inoculated with a five-strain mixture of Listeria monocytogenes. The OA treatments were applied to the surface of RTE products by dispensing a specific volume of solution directly into the final package prior to vacuum sealing. Once sealed, the vacuum-packaged RTE products containing OA were immersed in water heated to 93.3 degrees C (200 degrees F) for 2 s to effect adequate film shrinkage. Extending the time at which the packaged, treated RTE products were exposed to water heated to 93.3 degrees C was also evaluated with a commercial cascading shrink tunnel fitted with a modified drip pan. Once treated, RTE products were examined for survivor populations of L. monocytogenes after 24 h of storage at 5 degrees C. Sensory evaluation was conducted with a 60-member trained panel on 11 uninoculated, treated RTE products. The OA treatment of RTE products reduced L. monocytogenes numbers to between 0.85 log CFU per sample (oil-browned turkey) and 2.89 log CFU per sample (cured ham) when compared with controls. The antilisterial activity of OA was improved by increasing the duration of the heat shrink exposure. Specifically, reductions of L. monocytogenes ranged from 1.46 log CFU per sample (oil-browned turkey) to 3.34 log CFU per sample (cured ham). Results from the sensory evaluation demonstrated that 10 of the 11 treated RTE products were not perceived as different (P < or = 0.05) from the untreated controls. Panelists detected reduced (P < or = 0.05) smoke flavor intensity with treated mesquite turkey, although the treated product was viewed as acceptable. Results demonstrate the effectiveness of OA as a postlethality treatment meeting U.S. Food Safety and Inspection Service regulatory guidelines for RTE meat and poultry products with minimal impact on sensory quality.     

High voltage cold atmospheric plasma: Antibacterial properties and its effect on quality of Asian sea bass slices

The effect of working gas composition (GC), treatment time (TT) and post-treatment time (PTT) of high voltage cold atmospheric pressure plasma (HVCAP) on antibacterial efficiency against spoilage microorganisms was investigated. GC had no significant effect on the antibacterial properties of HVCAP against Pseudomonas aeruginosa, Vibrio parahaemolyticus Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli (p > 0.05). On the other hand, TT and PTT significantly influenced the antibacterial properties of HVCAP (p < 0.05). When Asian sea bass slices were treated with HVCAP generated using argon and oxygen (90:10) as GC for various times (2.5–10 min), quality changes were monitored at 1 h PTT in comparison with the control. Total viable count was reduced by 1.0 log CFU/g in slices treated with HVCAP for 5–10 min. Lipid oxidation and protein degradation were higher in the slices treated with HVCAP with longer TT. Thus, HVCAP treatment for 5 min could extend shelf-life of refrigerated slices.     

Cold atmospheric pressure plasma and low energy electron beam as alternative nonthermal decontamination technologies for dry food surfaces: A review

BackgroundDry food products are often highly contaminated, and dry stress-resistant microorganisms, such as certain types of Salmonella and bacterial spores, can be still viable and multiply if the product is incorporated into high moisture food products or rehydrated. Traditional technologies for the decontamination of these products have certain limitations and drawbacks, such as alterations of product quality, environmental impacts, carcinogenic potential and/or lower consumer acceptance. Cold atmospheric pressure plasma (CAPP) and low energy electron beam (LEEB) are two promising innovative technologies for microbial inactivation on dry food surfaces, which have shown potential to solve these certain limitations.Scope and approachThis review critically summarizes recent studies on the decontamination of dry food surfaces by CAPP and LEEB. Furthermore, proposed inactivation mechanisms, product-process interactions, current limitations and upscaling potential, as well as future trends and research needs for both emerging technologies, are discussed.Key findings and conclusionsCAPP and LEEB are nonthermal technologies with a high potential for the gentle decontamination of dry food surfaces. Both technologies have similarities in their inactivation mechanisms. Due to the limited penetration depth of both technologies, product-process interactions can be minimized by maintaining product quality. A first demonstrator with Technology Readiness Level (TRL) 7 for LEEB has already been introduced into the food industry for the decontamination of herbs and spices. Compared with LEEB, CAPP is at the advanced development stage with TRL 5, for which further work is essential to design systems that are scalable to industrial requirements.     

Optimization of decontamination conditions for Aspergillus flavus inoculated to military rations snack and physicochemical properties with atmospheric cold plasma

In this study, the effectiveness of ACP in inactivating Aspergillus flavus inoculated to military rations snack using response surface methodology (RSM) was investigated. Additionally, the effect of this treatment on the total count and yeast–mold count, as well as some quality properties of military rations snack, was examined. RSM was applied to study the voltage effects (5–15 kV), the distance between ACP emitter and sample (3–7 cm), and different treatment time (2–10 min) on the physicochemical properties of the military rations snack. Increasing voltage and time, together with reducing distance, caused a decrease in A. flavus, total count, yeast and mold count, total aflatoxin, as well as color difference. The peroxide value also increased with increasing voltage levels. The optimum conditions for treated military rations snack by ACP are as follows: a system voltage of 9 kV, a distance of 3 cm between the sample and the emitter, and a time of 6 min. Under these conditions, the responses, including the utmost reduction of 4.31 log CFU/g for the total count, 4.64 log CFU/g for yeast–mold count, and 2.98 log CFU/g for A. flavus were found from starting level of 5.2, 2, and 3.1 log CFU/g, respectively. It was found that snack samples had a 3.66% decrease in moisture content, 76.13% decrease in total aflatoxin, 3.01% increase in color difference, and 0.22 meq O₂.kg/oil increase in peroxide value as a result of ACP application. ACP has the potential to increase microbiological safety by maintaining desirable quality properties in military rations snack.     

Investigation of a large gap cold plasma reactor for continuous in-package decontamination of fresh strawberries and spinach

The aim of this work was to investigate the efficacy of a large gap atmospheric cold plasma (ACP) generated with an open-air high-voltage dielectric barrier discharge (DBD) pilot-scale reactor, operated in either static (batch) or continuous mode for produce decontamination and quality retention. Significant reductions in the bacterial populations inoculated on the strawberries and spinach were obtained after the static mode of ACP treatment with 2.0 and 2.2 log₁₀ CFU/ml reductions for E. coli and 1.3 and 1.7 log₁₀ CFU/ml reductions for L. innocua, respectively. Continuous treatment was effective against L. innocua inoculated on strawberries, with 3.8 log₁₀ CFU/ml reductions achieved. No significant differences in colour, firmness, pH or total soluble solids (TSS) was observed between control and ACP-treated samples with the effects of treatment retained during the shelf-life period. The pilot-scale atmospheric air plasma reactor retained the strawberry quality characteristics in tandem with useful antimicrobial efficacy.Industrial relevanceThis in-package plasma technology approach is a low-power, water-free, non-thermal, post-package treatment. Generating cold plasma discharges inside food packages achieved useful antimicrobial effects on fresh produce. Depending on the bacterial type, produce and mode of ACP treatment significant reductions in the populations of pathogenic microorganisms attached to the fresh produce was achieved within 2.5 min of treatment. The principal technical advantages include contaminant control, quality retention, mitigation of re-contamination and crucially the retention of bactericidal reactive gas molecules in the food package volume, which then revert back to the original gas.     

冷链即食食品生产加工环境中李斯特氏菌属检测方法的建立与应用

目的 开发一种建立可用于冷链即食食品生产加工环境中李斯特氏菌属的分离与检测方法,应用于对生产企业中的环境进行监控。方法 本研究结合GB4789. 30-2016国标方法和美国美国食品药品监督管理局细菌学分析手册Food and Drug Administration Bacteriological Analytical Manual（FDA BAM ）FDA BAM 单增李斯特氏菌检测方法,通过制备冻干定量菌球模拟增菌实验,对增菌液中萘啶酮酸和吖啶黄素的添加时间、头孢曲松钠的添加浓度进行了研究,确定最佳增菌方式和头孢曲松钠浓度,并将其应用到实际冷链即食食品生产企业环境中李斯特菌属的分离检测中。,确认该方法的可行性。结果 3种李斯特氏菌属和背景菌的冻干菌球的浓度分别为102 CFU/球及103 CFU/球。通过模拟增菌实验,延后4小时 h使用添加剂,可使李斯特氏菌属及单增李斯特氏菌的检出率均提高10%,在此基础上头孢曲松钠添加量在6 μg/mL至~8 μg/mL时,李斯特氏菌属及单增李斯特氏菌的检出率均为100%。结论 以上该方法应用在生产企业实际环境监测中,可提高李斯特氏菌属的检出率。该方法可应用于为冷链即食食品生产企业中李斯特氏菌属的环境监控,为生产企业的环境监控提供了技术保障。     

Pulsed UV light as a postprocessing intervention for decontamination of hard‐cooked peeled eggs

The efficiency of pulsed UV light (PL) for inactivation of E. coli K12 on hard‐cooked eggs was investigated. Temperature, colour and texture were recorded to determine adverse effects on quality. Distance from the quartz window (5.5, 9.5 cm) and time (1–30 s) was set as the experimental variables. Results indicated that E. coli K12 viability decreased at closer distances and increased time (P < 0.05). Bacterial populations were reduced to 3.54 log CFU per egg and 3.23 log CFU per egg after 15 and 20 s at 5.5 cm and 9.5 cm, respectively. Scanning electron micrographs revealed the existence of photophysical mechanisms, bacterial overlapping and internalisation interfering inactivation. Treated samples experienced slight thermal increases (6–9 °C) contributing to the preservation of colour and texture, not significantly different from untreated samples (P > 0.05). Our findings support the use of PL to enhance the safety of hard‐cooked eggs although bacterial shadowing may have significant implications on treatment efficiency.     

Combined effect of cold atmospheric plasma,intrinsic and extrinsic factors on the microbial behavior in/on (food) model systems during storage

Microbial decontamination by means of cold atmospheric plasma (CAP) offers great potential for treatment of heat-sensitive food products, extending their storage life. CAP is created by applying a high voltage to a gas stream, resulting in microbial inactivation according to different mechanisms. This paper thoroughly assesses the influence of CAP on the storage life of food model systems inoculated with Salmonella Typhimurium. (Food) model systems, with varying intrinsic factors (pH, salt concentration, and food (micro)structure), are treated for 5 min using a dielectric barrier discharge reactor generating a helium‑oxygen plasma. Following treatment, the impact of extrinsic factors is evaluated by storage at 8 °C or 20 °C. During storage, cell densities are determined. Data are fitted with predictive (growth or inactivation) models. As additional experiments indicate that the CAP treatment itself has a limited or even negligible effect on the properties of the model system (pH, a_w, (micro)structure), the microbial behavior of CAP treated samples during storage can be attributed to the treatment. CAP treatment can result in microbial reductions up to 2.7 log₁₀ and prolongs storage, however its rate of success is dependent on both extrinsic and intrinsic factors. An important factor is the storage temperature, as recovery of CAP treated cells proves more difficult when stored at 8 °C. At 20 °C, cell growth is merely slowed down. Additionally, at pH 5.5, 6% (w/v) NaCl, osmotic stress is induced on the microorganisms, which results in low cell recovery or further inactivation. The influence of the food (model) structure on the storage behavior is insignificant.Industrial relevanceAlthough being a very promising technology, most studies regarding the use of cold atmospheric plasma (CAP) for food decontamination focus on the inactivation of a target microorganism, in relation to a specific food product. Fundamental knowledge on this non-thermal technology, including its impact on the storage life, is lacking. This study investigates the effect of CAP on the microbial behavior during storage. By performing tests on model systems, for a variation of intrinsic and extrinsic factors, this work renders information on the suitability of this novel technology regarding treatment of a broad spectrum of food products. Moreover, this study demonstrates the limited impact of CAP on the food (model) properties, enhancing the suitability of the technology to be implemented in the food industry.     

北京“十三五”时期食品安全智慧监管科技 保障体系

食品安全已成为一个国家、乃至整个世界面临的一个根本性的公共卫生问题,食品安全监管是各级政府的重要责任。"十三五"期间,针对北京市食品监管现状,建议北京市政府开展食品安全智慧监管科技保障工程,研发食品安全快速检测装备、便携技术、在线检测技术。利用信息化技术和数据采集设备,建设京津冀一体化、互联互通的信息平台,实现信息共享,提高监督抽检的针对性,实现对问题样品全过程的信息溯源。     

Pulsed UV light as an intervention strategy against Listeria monocytogenes and Escherichia coli O157:H7 on the surface of a meat slicing knife

The main objective of this work was to explore the applicability of the Intense Light Pulses (ILP) for decontamination of a stainless steel meat contact surface, exemplified by a slicing knife, as a function of time between contamination and decontamination, number of light pulses applied, and the prior contact with different meat matrices. Listeria monocytogenes and Escherichia coli O157:H7 were chosen as the challenge microorganisms. The ILP system was a laboratory-scale four-lamp batch system generating 3 J/cm² with an input voltage of 3000 V. The results obtained demonstrate successful application of ILP treatment for reduction of L. monocytogenes and E. coli O157:H7 on a surface of stainless steel slicing knife. The inactivation effectiveness depended on the type of meat product that was in the contact with the treated surface and on the time between the contamination and the ILP treatment. Statistical analysis showed the significant interaction between the time and type of meat product on the effectiveness of ILP treatment. The highest effectiveness of the ILP (the complete inactivation of 6.5 log CFU/side of knife) was obtained when the knife surface was in contact with the products containing lower fat and protein content and when it was treated with pulsed light as fast as possible after the contamination (within 60 s). The decontamination efficacy of ILP treatment could not be improved by multiple light pulses if lost due to the extended time between the moment of contamination and ILP treatment. Results showed that the suggested approach can be very effective as an intervention strategy along meat processing lines preventing cross-contamination between the equipment and the final product.     

Element signature analysis: its validation as a tool for geographic authentication of the origin of dried beef and poultry meat

Element concentrations of 56 poultry meat and 53 dried beef samples were determined and statistically analyzed using analysis of variance and linear discriminant analysis (LDA) to identify the single or combination of elements with the highest potential to determine the geographic origin. In order to validate the applicability of this technique, the results were additionally combined with data from an earlier assessment including 25 poultry meat and 23 dried beef samples. Validation was performed by estimating the origin of the first samples based on the data of the second, larger, dataset. Elements significantly discriminating among countries were As, Na, Rb, Se, Sr, and Tl for poultry meat and As, B, Ba, Ca, Cd, Cu, Dy, Er, Fe, Li, Mn, Pd, Rb, Se, Sr, Te, Tl, U, and V for dried beef out of about 50 elements each. The LDA gave mean correct classification rates of 77 and 79% for poultry meat and dried beef, respectively. Validation allowed identifying some, but not all, origins. For a higher discriminative power, this method should be combined with other ways of authentication.     

Evidence for the safety of gum karaya (Sterculia spp.) as a food additive

Gum karaya (GK), accepted as Generally Recognised as Safe (GRAS) in the USA since 1961, was accepted temporarily (Annex II) as a food additive by the EEC in 1974. Since then no adverse incident involving human health has been attributed to the ingestion of GK, which is used in extremely small amounts in foods. This report collates the evidence of safety now available and presents the data on Need, production tonnages and dietary intake levels.     

Comparison of a cold enrichment and the FDA method for isolating Listeria monocytogenes and other Listeria spp. from ready-to-eat food on retail sale in the U.K

A cold enrichment and the modified FDA selective enrichment method were compared for their ability to detect Listeria monocytogenes and other Listeria species from various ready-to-eat foods on sale in the UK. Of 57 food samples examined using cold enrichment, five yielded L. monocytogenes, and two L. innocua. The FDA enrichment method yielded three samples positive for L. monocytogenes only. Foods examined included soft cheeses, fermented meat sausages, pates and salads.     

Development of a novel microbial sensor with baker's yeast cells for monitoring temperature control during cold food chain

A novel microbial sensor containing a commercial baker's yeast with a high freeze tolerance was developed for visibly detecting inappropriate temperature control of food. When the yeast cells fermented glucose, the resulting gas production triggered the microbial sensor. The biosensor was a simple, small bag containing a solution of yeast cells, yeast extract, glucose, and glycerol sealed up with multilayer transparent film with barriers against oxygen and humidity. Fine adjustment of gas productivity in the biosensor at low temperatures was achieved by changing either or both concentrations of glucose and yeast cells. Moreover, the amount of time that food was exposed to inappropriate temperatures could be deduced by the amount of gas produced in the biosensor. The biosensor was stable without any functional loss for up to 1 week in frozen storage. The biosensor could offer a useful tool for securing food safety by maintaining low-temperature control in every stage from farm to fork, including during transportation, in the store, and at home.     

Swab-based enzyme immunoassay system for detection of meat residues on food contact surfaces as a hygiene monitoring tool.

An enzyme immunoassay system based on the use of a macroporous swab as a solid phase for the capture and subsequent immunoenzymatic detection of immunoglobulin G (IgG) from meat residues on food contact surfaces was developed as a hygiene-monitoring tool. Moistened polyester swabs coated with anti-bovine or anti-chicken IgG were rubbed on the test surface, and the captured IgG was subsequently detected directly on the swabs by brief sequential reactions with anti-bovine or anti-chicken IgG-peroxidase conjugate and chromogenic peroxidase substrate.     

Functional properties of bovine blood plasma intended for use as a functional ingredient in human food

With the aim of using bovine blood as functional ingredient in food processing, as an emulsifier or fat replacer, a study of some functional properties of blood plasma was made. The effect of pH (3.0–8.0), tryptic hydrolysis and NaCl addition (0.034 mol/L) on the solubility, hydrophobicity and emulsifying properties of bovine blood plasma were studied. The results showed that the hydrophobicity and emulsifying activity index (EAI) of bovine blood plasma reached a maximum at pH 3.0 and 7.0, respectively, while the other parameters stayed nearly constant with pH change. Tryptic hydrolysis improved hydrophobicity at certain hydrolysis times, reduced solubility and emulsifying capacity (EC) and showed no effect on EAI and emulsion stability (ES). The influence of NaCl tested at pH 5.0 and 6.0 was only positive for plasma EAI at pH 5.0 and significantly reduced solubility, hydrophobicity and EC at pH 5.0 and 6.0. For ES, NaCl addition did not produce any modification.     

Cold plasma as a tool for the elimination of food contaminants: Recent advances and future trends

Abstract

Food contaminants are challenging the food industry due to the inefficiency of conventional decontamination techniques. Cold plasma as an emerging technique for the degradation of food contaminants attracted notable attention. The current study overviews the plasma-induced degradation of food contaminants, discusses the mechanisms involved, points its benefits and drawbacks out, highlights the research needed in this area, and explores future trends. According to the literature, cold plasma efficiently degraded many common pesticides (e.g. parathion, paraoxon, omethoate, dichlorvos, malathion, azoxystrobin, cyprodinil, fludioxonil, cypermethrin, and chlorpyrifos) and food allergens (e.g. tropomyosin, b-conglycinin, glycinin, trypsin inhibitor, and Kunitztype trypsin inhibitor). These degradations occurred primarily due to the presence of reactive oxygen species (ROS) and reactive nitrogen species (RNS) in the plasma that attack the chemical bonds of food contaminants. The type of pesticide degrades are highly dependent on the concentrations of plasma-generated ROS and RNS. Research showed that several parameters, such as plasma generation device, plasma exposure time, plasma power, and the carrier gas composition, influence the type and concentration of reactive species (e.g. ROS and RNS) and the overall efficiency of cold plasma degradation for a specific pesticide or allergen.

• Highlights

• Cold plasma can be used for degradation of many types of pesticides and allergens.

• Plasma-generated reactive species and UV can interact with pesticides and allergens.

• The scaled up removal of pesticides and allergens by plasma can be challenging.

     

Complete validation of a unique digestion assay to detect Trichinella larvae in horse meat demonstrates the reliability of this assay for meeting food safety and trade requirements

A tissue digestion assay using a double separatory funnel procedure for the detection of Trichinella larvae in horse meat was validated for application in food safety programs and trade. The assay consisted of a pepsin-HCl digestion step to release larvae from muscle tissue and two sequential sedimentation steps in separatory funnels to recover and concentrate larvae for detection with a stereomicroscope. With defined critical control points, the assay was conducted within a quality assurance system compliant with International Organization for Standardization-International Electrotechnical Commission (ISO/IEC) 17025 guidelines. Samples used in the validation were obtained from horses experimentally infected with Trichinella spiralis to obtain a range of muscle larvae densities. One-, 5-, and 10-g samples of infected tissue were combined with 99, 95, and 90 g, respectively, of known negative horse tissue to create a 100-g sample for testing. Samples of 5 and 10 g were more likely to be positive than were 1-g samples when larval densities were less than three larvae per gram (lpg). This difference is important because ingested meat with 1 lpg is considered the threshold for clinical disease in humans. Using a 5-g sample size, all samples containing 1.3 to 2 lpg were detected, and 60 to 100% of samples with infected horse meat containing 0.1 to 0.7 lpg were detected. In this study, the double separatory funnel digestion assay was efficient and reliable for its intended use in food safety and trade. This procedure is the only digestion assay for Trichinella in horse meat that has been validated as consistent and effective at critical levels of sensitivity.