Application of emerging technologies to control Salmonella in foods: A review

Recent developments in ultrasound approach for preservation of animal origin foods

Ultrasound is a contemporary non-thermal technology that is currently being extensively evaluated for its potential to preserve highly perishable foods, while also contributing positively to the economy and environment. There has been a rise in the demand for food products that have undergone minimal processing or have been subjected to non-thermal techniques. Livestock-derived food products, such as meat, milk, eggs, and seafood, are widely recognized for their high nutritional value. These products are notably rich in proteins and quality fats, rendering them particularly vulnerable to oxidative and microbial spoilage. Ultrasound has exhibited significant antimicrobial properties, as well as the ability to deactivate enzymes and enhance mass transfer. The present review centers on the production and classification of ultrasound, as well as its recent implementation in the context of livestock-derived food products. The commercial applications, advantages, and limitations of the subject matter are also subject to scrutiny. The review indicated that ultrasound technology can be effectively utilized in food products derived from livestock, leading to favorable outcomes in terms of prolonging the shelf life of food while preserving its nutritional, functional, and sensory attributes. It is recommended that additional research be conducted to investigate the effects of ultrasound processing on nutrient bioavailability and extraction. The implementation of hurdle technology can effectively identify and mitigate the lower inactivation of certain microorganisms or vegetative cells.

Characterization of the Clostridium perfringens phage endolysin cpp-lys and its application on lettuce

Clostridium perfringens is an important foodborne pathogen that can have severe consequences, including mortality and economic losses. In this study, the gene encoding cpp-lys, an endolysin from the C. perfringens phage cpp has been cloned and overexpressed. The encoded protein was characterized, and then its efficacy in controlling C. perfringens on lettuce was evaluated. The endolysin cpp-lys presented lytic activity against seven strains of C. perfringens that produce different types of toxins. It maintained stability across a wide range of temperatures (4 °C - 50 °C), and demonstrated tolerance to varying pH levels (4-9). Storage of endolysin cpp-lys under room-temperature conditions (16 °C-25 °C) and cold-temperature conditions (4 °C, -20 °C, and -80 °C) for 30 days did not affect its lytic activity. However, the lytic activity of cpp-lys decreased by 40 % and 18 % after storage for 30 d at 42 °C and 37 °C, respectively. The endolysin cpp-lys did not display cytotoxic activity against normal eukaryotic cells. The bacterial viability on lettuce was significantly lower in the group treated with endolysin cpp-lys than in the PBS group, and >4-log of C. perfringens J1 were removed within 15 min. Cpp-lys plus Zn2+ inhibited the activity of cpp-lys. The EDTA-treated cpp-lys significantly reduced the number of bacteria by up to 0.6-log CFU compared with the endolysin cpp-lys group. The findings of this study demonstrated that endolysin cpp-lys has potential applications in controlling C. perfringens in the food industry.

Effect of the pH on the Antibacterial Potential and Cytotoxicity of Different Plasma-Activated Liquids

In this study, different plasma-activated liquids were evaluated for their antimicrobial effects against Escherichia coli, as well as for their cytotoxicity on mammalian cells. The PALs were prepared from distilled (DIS), deionized (DI), filtered (FIL), and tap (TAP) water. Additionally, 0.9% NaCl saline solution (SAL) was plasma-activated. These PALs were prepared using 5 L/min air gliding arc plasma jet for up to 60.0 min of exposure. Subsequently, the physicochemical properties, such as, the oxidation-reduction potential (ORP), the pH, the conductivity, and the total dissolved solids (TDS) were characterized by a water multiparameter. The PALs obtained showed a drastic decrease in the pH with increasing plasma exposure time, in contrast, the conductivity and TDS increased. In a general trend, the UV-vis analyses identified a higher production of the following reactive species of nitrogen and oxygen (RONS), HNO₂, H₂O₂, NO₃^-, and NO₂^-. Except for the plasma-activated filtered water (PAW-FIL), where there was a change in the position of NO₂^- and NO₃^- at some pHs, The higher production of HNO₂ and H₂O₂-reactive species was observed at a low pH. Finally, the standardized suspensions of Escherichia coli were exposed to PAL for up to 60.0 min. The plasma-activated deionized water (PAW-DI pH 2.5), plasma-activated distilled water (PAW-DIS pH 2.5 and 3), and plasma-activated tap water (PAW-TAP 3.5) showed the best antimicrobial effects at exposure times of 3.0, 10.0, and 30.0 min, respectively. The MTT analysis demonstrated low toxicity of all of the PAL samples. Our results indicate that the plasma activation of different liquids using the gliding arc system can generate specific physicochemical conditions that produce excellent antibacterial effects for E. coli with a safe application, thus bringing future contributions to creating new antimicrobial protocols.

A review of food additives to control the proliferation and transmission of pathogenic microorganisms with emphasis on applications to raw meat-based diets for companion animals

Raw meat-based diets (RMBDs) or sometimes described as biologically appropriate raw food (BARFs) are gaining in popularity amongst dog and cat owners. These pet guardians prefer their animals to eat minimally processed and more “natural” foods instead of highly heat-processed diets manufactured with synthetic preservatives. The market for RMBDs for dogs and cats is estimated at $33 million in the United States. This figure is likely underestimated because some pet owners feed their animals raw diets prepared at home. Despite their increasing demand, RMBDs have been plagued with numerous recalls because of contamination from foodborne pathogens like Salmonella, E. coli, or Campylobacter. Existing literature regarding mitigation strategies in RMBD's for dogs/cats are very limited. Thus, a comprehensive search for published research was conducted regarding technologies used in meat and poultry processing and raw materials tangential to this trade (e.g., meats and poultry). In this review paper, we explored multiple non-thermal processes and GRAS approved food additives that can be used as potential antimicrobials alone or in combinations to assert multiple stressors that impede microbial growth, ultimately leading to pathogen inactivation through hurdle technology. This review focuses on use of high-pressure pasteurization, organic acidulants, essential oils, and bacteriophages as possible approaches to commercially pasteurize RMBDs effectively at a relatively low cost. A summary of the different ways these technologies have been used in the past to control foodborne pathogens in meat and poultry related products and how they can be applied successfully to impede growth of enteric pathogens in commercially produced raw diets for companion animals is provided.

The Physicochemical, Microbiological, and Structural Changes in Beef Are Dependent on the Ultrasound System, Time, and One-Side Exposition

The effect of high-intensity ultrasound (HIU) system (bath, 37 kHz and 90 W/cm2; or probe, 24 kHz and 400 W) and application time (25 or 50 min, one-side exposition) on the properties of bovine Longissimus lumborum after 7 d of storage at 4 °C was studied. The bath system significantly increased the lightness of the muscle, while other color parameters (a*, b*, hue, and chroma) were not different from the control. The water holding capacity and shear force decreased significantly (3.1-5% and 0.59-0.72 kgf, respectively) in sonicated meat independently of the system, favoring the tenderization of the muscle after storage. Microstructural changes observed in the HIU-exposed surface provided evidence of a higher area of interfibrillar spaces (1813 vs. 705 µm2 in the control), producing tenderization of the muscle, compared with the control. HIU significantly increased counts of total aerobic and coliform bacteria, especially after 50 min of ultrasonication. HIU also increased lactic acid bacterial counts in the bath system. Single-sided muscle exposition to ultrasound may produce sufficient significant changes in muscle properties, which could decrease long treatment times that would be needed for the exposition of both sides. HIU in bath systems increases tenderness by modifying meat ultrastructure, with no significant changes in physicochemical parameters. Nevertheless, microbiological quality may need to be considered during the process due to a slight increase in bacterial counts.

Effect of ultrasound and chlorine dioxide on Salmonella Typhimurium and Escherichia coli inactivation in poultry chiller tank water

This study evaluated the application of ultrasound alone or combined with chlorine dioxide (ClO₂) for Salmonella Typhimurium and Escherichia coli inactivation in poultry processing chiller tank water. A Full Factorial Design (FFD) 2² was conducted for each microorganism to evaluate the effect of ultrasound exposure time (x₁: 1 to 9 min; fixed: 37 kHz; 330 W; 25 °C) using a bath, and ClO₂ concentration (x₂: 1 to 17 mg L^-1) on microorganism count expressed in log CFU mL^-1 in distilled water. Variable x₂ had a negative effect on Salmonella Typhimurium (-5.09) and Escherichia coli (-2.00) count, improving the inactivation; while a x₁ increase present no inactivation improvement, explaining the use of x₁ lower level (1 min) and x₂ higher level (17 mg L^-1). The best condition for microorganism inactivation based on FFD was evaluated in chiller tank water (with organic matter) at 25, 16, and 4 °C; x₁ was kept (1 min), however x₂ was adjusted to obtain the same residual free chlorine (2.38 mg L^-1) considering the ClO₂ consumption by organic matter, achieving the value of 30 mg L^-1. An inactivation of 49% and 31% were observed for Salmonella Typhimurium and Escherichia coli. When ultrasound was replaced by a simple agitation in the presence of ClO₂, there was no inactivation for both microorganisms. Moreover, at poultry carcass pre-chilling (16 °C) and chilling (4 °C) conditions, the synergism of ultrasound combined with ClO₂ was more pronounced, with microorganisms' reductions up to 100%.

Endolysin LysSTG2: Characterization and application to control Salmonella Typhimurium biofilm alone and in combination with slightly acidic hypochlorous water

The gene encoding LysSTG2, an endolysin from Salmonella-lytic bacteriophage STG2, was cloned, overexpressed, and characterized. LysSTG2 consists of a single domain belonging to the Peptidase_M15 superfamily. LysSTG2 showed strong lytic activity against chloroform-treated S. Typhimurium cells after incubation at 4-50 °C for 30 min, at pH ranging from 7.0 to 11.0, and in the presence of NaCl from 0 to 300 mmol/L. It also showed lytic activity against all the 14 tested Gram-negative strains treated with chloroform, including Salmonella, E. coli, and Pseudomonas aeruginosa, but not against the Gram-positive bacteria tested. In addition, LysSTG2 (100 μg/mL) reduced the viability of S. Typhimurium NBRC 12529 planktonic cells by 1.2 log and that of the biofilm cells after 1-h treatment. Sequential treatment of slightly acidic hypochlorous water (SAHW) containing 40 mg/L available chlorine and LysSTG2 (100 μg/mL) was effective on S. Typhimurium NBRC 12529 biofilm cells, removing more than 99% of biofilm cells. These results demonstrate that LysSTG2 alone can effectively kill S. Typhimurium cells after permeabilization treatment and successfully control S. Typhimurium in biofilms in combination with SAHW, suggesting that the combined use of LysSTG2 and SAHW might be a novel and promising method for combating S. Typhimurium in food industries.

Physical Methods for the Decontamination of Meat Surfaces

Purpose of Review

The market for minimally processed products is constantly growing due to consumer demand. Besides food safety and increased shelf life, nutritional value and sensory appearance also play a major role and have to be considered by the food processors. Therefore, the purpose of the review was to summarize recent knowledge about important alternative non-thermal physical technologies, including both those which are actually applied (e.g. high-pressure processing and irradiation) and those demonstrating a high potential for future application in raw meat decontamination (e.g. pulsed light UV-C and cold plasma treatment). The evaluation of the methods is carried out with respect to efficiency, preservation of food quality and consumer acceptance.

Recent Findings

It was evident that significantly higher bacterial reductions are achieved with gamma-ray, electron beam irradiation and high pressure, followed by pulsed light, UV-C and cold plasma, with ultrasound alone proving the least effective. As a limitation, it must be noted that sensory deviations may occur and that legal approvals may have to be applied for.

Summary

In summary, it can be concluded that physical methods have the potential to be used for decontamination of meat surfaces in addition to common hygiene measures. However, the aim of future research should be more focused on the combined use of different technologies to further increase the inactivation effects by keeping meat quality at the same time.

Effective pretreatment technologies for fresh foods aimed for use in central kitchen processing

The central kitchen concept is a new trend in the food industry, where centralized preparation and processing of fresh foods and the distribution of finished or semi-finished products to catering chains or related units take place. Fresh foods processed by a central kitchen mainly include fruit and vegetables, meat, aquatic products, and edible fungi; these foods have high water activities and thermal sensitivities and must be processed with care. Appropriate pretreatments are generally required for these food materials; typical pretreatment processes include cleaning, enzyme inactivation, and disinfection, as well as packaging and coating. To improve the working efficiency of a central kitchen, novel efficient pretreatment technologies are needed. This article systematically reviews various high-efficiency pretreatment technologies for fresh foods. These include ultrasonic cleaning technologies, physical-field enzyme inactivation technologies, non-thermal disinfection technologies, and modified-atmosphere packagings and coatings. Mechanisms, applications, influencing factors, and advantages and disadvantages of these technologies, which can be used in a central kitchen, are outlined and discussed. Possible solutions to problems related to central-kitchen food processing are addressed, including low cleaning efficiency and automation feasibility, high nutrition loss, high energy consumption, and short shelf life of products. These should lead us to the next step of fresh food processing for a highly demanding modern society. © 2020 Society of Chemical Industry.

Detection of Exiguobacterium spp. and E. acetylicum on fresh-cut leafy vegetables by a multiplex PCR assay

AIMS

To identify the main spoilage bacterium on fresh-cut leafy vegetables and establish a multiplex PCR assay.

METHODS AND RESULTS

Based on physiological-biochemical, molecular identification, and artificial contamination tests, the main bacterium to spoil fresh-cut leafy vegetables was identified as Exiguobacterium spp. and Exiguobacterium acetylicum. Comparative genomics showed that P401_RS0117025 and oxi_50,582,462 genes are specific to Exiguobacterium spp. and E. acetylicum. Based on this, three pairs of primer sets to EaG-291, EaS-2B, and Ea16S-12 genes were designed and used to develop a multiplex PCR assay, which exhibited 100% specificity among 16 Exiguobacterium and 10 non-Exiguobacterium strains. Finally, 84 fresh-cut leafy vegetable samples were analyzed by multiplex PCR assay and standard physiological-biochemical experiments, the results showed multiplex PCR assay reached a detection rate of 96%.

CONCLUSIONS

The main spoilage bacterium was identified as Exiguobacterium spp. and E. acetylicum on fresh-cut leafy vegetables based on the novel specific genes explored in this study.

SIGNIFICANCE AND IMPACT OF STUDY

A rapid, specific, and sensitive PCR assay was developed for the detection of Exiguobacterium spp. and E. acetylicum.

Microbiological properties of poultry breast meat treated with high-intensity ultrasound

Lactic acid, psychrophilic, and mesophilic bacteria, Escherichia coli, Salmonella spp. and Staphylococcus aureus were enumerated on chicken breasts after treatment with different high intensity ultrasound (frequency 40 kHz, intensity 9.6 W/cm^-2) application times (0, 30, and 50 min) and packaging atmospheres (aerobic and vacuum) after a 7-day storage. The experiment was performed in commercial 7-week-old chicken breasts. Counts were performed prior to and immediately after ultrasonication, and on the 7th day of chill-storage. After sonication and storage, mesophiles, psychrophiles, LAB and S. aureus increased statistically. Psychrophiles decreased significantly under anaerobic packaging. There were no differences among ultrasonication times in terms of mesophiles, psychrophiles, LAB, E. coli and Salmonella spp. S. aureus numbers had a significant reduction after 50 min sonication. Under these experimental conditions, high-intensity ultrasound for 50 min is a control method of S. aureus and the anaerobic packaging reduces numbers of psychrophiles in chicken breast. The effect of ultrasound is only significant after the storage time.

Antimicrobial capacity of ultrasound and ozone for enhancing bacterial safety on inoculated shredded green cabbage (Brassica oleracea var. capitata)

The high frequency and incidence of foodborne outbreaks related to fresh vegetables consumption is a major public health concern and an economic burden worldwide. This study evaluated the effect of individual and combined application of ultrasound (40 kHz, 100 W) and ozone on the inactivation of foodborne Escherichia coli and Salmonella, as well as their impact on cabbage color and vitamin C content. Plate count, scanning electron microscopy (SEM), and flow cytometry (FCM) following single or double staining with carboxyfluorescein diacetate and (or) propidium iodide were used to determine bacterial inactivation parameters, such as cell culturability, membrane integrity, intracellular enzyme activity, and injured and dead cells. The results of FCM and SEM showed that ultrasound treatment affected bacteria mainly by acting on the cell membrane and inactivating intracellular esterase, which resulted in bacterial death. Furthermore, when combined with ozone at 1.5 mg/L, the maximum reduction of bacterial populations was observed at 8 min with no damage on the surface of treated leaves. Therefore, fresh products sanitization using a combination of ultrasound and ozone has the potential to be an alternative for maintaining the color and vitamin C content of green cabbage.

Effects of Ultrahigh Temperature Pasteurization on the Liquid Components and Functional Properties of Stored Liquid Whole Eggs

Ultrahigh temperature (UHT) pasteurization is often used to sterilize liquid whole eggs in egg processing enterprises in China. Although this treatment generates satisfactory sterilization effect, there are few studies on the processing characteristics and physical and chemical properties of the liquid whole eggs treated by UHT pasteurization. We compared the physical and chemical properties (i.e., foaming ability and stability, emulsification ability and stability, viscosity, thiol content, gel strength, and color) of unsterilized eggs and liquid whole eggs pasteurized with UHT over five weeks of storage. The emulsifying properties of sterilized liquid whole eggs were initially low and decreased further with the storage time. The emulsification stability index of UHT-pasteurized liquid whole eggs was higher than that of unsterilized eggs and increased by 21.9%, from 7.850 to 9.567. The foaming ability of UHT-pasteurized and unsterilized liquid whole eggs increased by 33.38% and 15.48%, respectively. The viscosity, gel strength, and soluble protein content were higher in UHT-pasteurized liquid whole eggs than those in unsterilized liquid whole eggs and increased further with storage time. Our results demonstrate that UHT pasteurization preserves and improves the processing characteristics and shelf life of liquid whole eggs.

Effects of combination treatments of lysozyme and high power ultrasound on the Salmonella typhimurium inactivation and quality of liquid whole egg

An investigation was conducted into the utilization of treatments combining ultrasound and lysozyme (US + Lys) to deactivate Salmonella typhimurium (S. typhimurium) in the liquid whole egg (LWE). Furthermore, US + Lys and heat treatment (HT) with a similar microbial inactivation effect were comparatively evaluated by examining their impact on the quality attributes of LWE. The LWE was treated with US at 35-45 °C and 605-968 W/cm² for 5-35 min, and with HT at 58-64 °C for 3-4 min. Lysozyme (Lys) alone achieved a minimal degree of inactivation in S. typhimurium, while it was enhanced with the application of US alone when the treatment temperature, time, and energy were increased. Furthermore, US and US + Lys caused a reduction of 3.31 and 4.26 log₁₀ cycles in S. typhimurium, respectively at 968 W/cm² and 35 °C for 20 min, indicating a synergistic relationship between US and Lys for the effective inactivation of S. typhimurium. Similarly, HT and HT + Lys achieved a reduction of 4.10 and 4.75 log₁₀ cycles at 64 °C/3 min, respectively. The L* and b* values of the LWE following US and US + Lys application were significantly higher than untreated and heat-treated LWE, indicating that US treated LWE had a brighter and yellower appearance. The protein solubility (PS) slightly decreased after all treatments, while the pH increased. Furthermore, the foaming capacity (FC) and foam stability (FS) were decreased, revealing that LWE had a lower FC and unstable foam after all treatments. Therefore, US and US + Lys could increase the viscosity and gelation temperature (Tg) of LWE, indicating that LWE exhibited higher heat resistance after US treatment. These results indicated that US + Lys might be a promising pasteurization technology in the processing of LWE.

Two Nonthermal Technologies for Food Safety and Quality-Ultrasound and High Pressure Homogenization: Effects on Microorganisms, Advances, and Possibilities: A Review

Some nonthermal technologies have gained special interest as alternative approaches to thermal treatments. High pressure homogenization (HPH) and ultrasound (US) are two of the most promising approaches. They rely upon two different modes of action, although they share some mechanisms or ways of actions (mechanic burden against cells, cavitation and micronization, primary targets being the cell wall and the membrane, temperature and pressure playing important roles for their antimicrobial potential, and their effect on cells can be either positive or negative). HPH is generally used in milk and dairy products to break lipid micelles, whereas US is used for mixing and/or to obtain active compounds of food. HPH and US have been tested on pathogens and spoilers with different effects; thus, the main goal of this article is to describe how US and HPH act on biological systems, with a focus on antimicrobial activity, mode of action, positive effects, and equipment. The article is composed of three main parts: (i) an overview of US and HPH, with a focus on some results covered by other reviews (mode of action toward microorganisms and effect on enzymes) and some new data (positive effect and modulation of metabolism); (ii) a tentative approach for a comparative resistance of microorganisms; and (iii) future perspectives.

Understanding Antimicrobial Resistance (AMR) Profiles of Salmonella Biofilm and Planktonic Bacteria Challenged with Disinfectants Commonly Used During Poultry Processing

Foodborne pathogens such as Salmonella that survive cleaning and disinfection during poultry processing are a public health concern because pathogens that survive disinfectants have greater potential to exhibit resistance to antibiotics and disinfectants after their initial disinfectant challenge. While the mechanisms conferring antimicrobial resistance (AMR) after exposure to disinfectants is complex, understanding the effects of disinfectants on Salmonella in both their planktonic and biofilm states is becoming increasingly important, as AMR and disinfectant tolerant bacteria are becoming more prevalent in the food chain. This review examines the modes of action of various types of disinfectants commonly used during poultry processing (quaternary ammonium, organic acids, chlorine, alkaline detergents) and the mechanisms that may confer tolerance to disinfectants and cross-protection to antibiotics. The goal of this review article is to characterize the AMR profiles of Salmonella in both their planktonic and biofilm state that have been challenged with hexadecylpyridinium chloride (HDP), peracetic acid (PAA), sodium hypochlorite (SHY) and trisodium phosphate (TSP) in order to understand the risk of these disinfectants inducing AMR in surviving bacteria that may enter the food chain.

Ultrasound and meat quality: A review

High intensity ultrasound (HIU) offers an alternative to traditional methods of food preservation, and is regarded as a green and promising emerging technology. Ultrasound generates acoustic cavitation in a liquid medium, developing physical forces that are considered the main mechanism responsible for changes in exposed materials. In meat, ultrasound has been successfully used to improve processes such as mass transfer and marination, tenderization of meat and inactivation of microorganisms. It is also an alternative to traditional meat ageing methods for improving the quality properties of meat. Moreover, the combination of ultrasonic energy with a sanitizing agent can improve the effect of microbial reduction in foods. This review describes recent potential applications of ultrasound in meat systems, as well as physical and chemical effects of ultrasound treatment on the conservation and modification of processed meat foods. Finally, the ultrasound application parameters must be deep explored and established before the method can be scaled to industrial levels.

THE PROBLEMS OF MEAT PRODUCTS THERMAL TREATMENT

The main problems of meat products thermal treatment have been considered and analysed in the paper. Analysis of the existing research papers suggests that the main attention is devoted to the influence of temperature value and time of processing on the physical, chemical, microbiological and organoleptic indicators of the product. The influence on the protein and fat components of raw meat has been described as well as the changes in the meat product structure under the influence of temperature have been pointed out. The important impact of thermal treatment on the changes in proteins at heating, including solubility and hydration of the proteins, has been examined. The paper analyses the microbiota screening before and after thermal treatment. Special attention was paid to the impact of temperature on microbiota as it is an important indicator of a meat product safety. Methods and purpose of thermal treatments as well as the advantages and drawbacks of each method were considered. Formation of tastiness properties of the product depending on the methods and thermal cycling was emphasized. Submitted is the analysis of the factors that influence the product mass losses under the impact of high temperature. The dependence conditions of a meat product quality on the thermal cycle were also analysed. Attention is paid to alternative methods of thermal heating as well as their influence on ready product quality and safety. Substantial contribution of Odesa National Academy of Food Technologies to solving problems of the conventional thermal treatment of meat products was shown, same as a possibility of bringing a product to cooking readiness without application of high temperature. The main content of the paper includes analysis of the methods and thermal treatment cycles existing in the world and proves importance of the temperature control and cooking time which influence safety, quality and yield of the product.

Survival of Salmonella spp. in minced meat packaged under vacuum and modified atmosphere

The effect of different modified atmosphere packaging regimes on the behavior of Salmonella spp. on minced meat was studied. Minced meat was experimentally contaminated with a Salmonella spp. cocktail (S. Enteritidis, S. Typhimurium, S. Infantis and S. Arizonae), packaged under vacuum or modified atmosphere with initial headspaces containing 20%O2/50%CO2/30%N2 and 20%O2/30%CO2/50%N2) and stored at 3±1°C for 12 days. Samples were analyzed for Salmonella spp., viable and lactic acid bacteria count every third day. Salmonella spp. counts decreased during storage in all packaging types, with reductions of about 1.5logCFU/g. A significant difference (p<0.01) was noted between Salmonella spp. counts in meat packaged in vacuum and modified atmospheres, although there was no significant difference in Salmonella spp. count between meat packaged in 50%CO2, and meat packaged in 30%CO2. At the end of the study, there were significant differences (p<0.01; p<0.05) in total viable and lactic acid bacterial counts between meat packaged in vacuum and modified atmosphere, and the lowest counts were noted in meat packaged in modified atmosphere with 50%CO2.

Chicken fillets subjected to UV-C and pulsed UV light: Reduction of pathogenic and spoilage bacteria, and changes in sensory quality

We have compared the efficacy of continuous ultraviolet (UV-C) (254 nm) and pulsed UV light in reducing the viability of Salmonella Enteritidis, Listeria monocytogenes, Staphylococcus aureus, enterohemorrhagic Escherichia coli, Pseudomonas spp., Brochothrix thermospacta, Carnobacterium divergens, and extended-spectrum β-lactamase producing E. coli inoculated on chicken fillet surface. Fluences from 0.05 to 3.0 J/cm2 (10 mW/cm2, from 5 to 300 s) used for UV-C light resulted in average reductions from 1.1 to 2.8 log cfu/cm2. For pulsed UV light, fluences from 1.25 to 18.0 J/cm2 gave average reductions from 0.9 to 3.0 log cfu/cm2. A small change in the odor characterized as sunburnt and increased concentration of volatile compounds associated with burnt odor posed restrictions on the upper limit of UV treatment, however no sensory changes were observed after cooking the meat. Treatments under modified atmosphere conditions using a UV permeable top film gave similar or slightly lower bacterial reductions.

PRACTICAL APPLICATIONS

Ultraviolet (UV) light may be used for decontaminating the surface of food products and reduce viability of pathogenic and spoilage bacteria. Exposure of raw chicken fillet surface to various doses of continuous UV-C or pulsed UV light proposed in the present work represent alternatives for microbiological improvement of this product. Chicken fillets can be treated in intact packages covered with UV permeable top film, thus avoiding recontamination of the meat. UV-C light treatment is a low cost strategy with low maintenance, whereas pulsed UV light involves more elaborate equipment, but treatment times are short and less space is required. Both methods can be helpful for producers to manage the safety and quality of chicken fillets.

Synergistic Effect of the Lactoperoxidase System and Cinnamon Essential Oil on Total Flora andSalmonellaGrowth Inhibition in Raw Milk

Despite its antibacterial and antipathogenic effects, the heat treatment of milk induces undesirable changes that can be noted in the overall properties of ultrahigh temperature (UHT) milk, such as changes in nutritional and organoleptic properties. Our goal is to find new nonthermal antibacterial technologies for the preservation of raw milk (RM). This study investigates the possible synergistic effect of using a combination of the lactoperoxidase system (LS) and 3 μg mL−1of cinnamon essential oil (cinnamon EO) to inactivate the total flora of milk andSalmonellaHadar (S. Hadar). The LS was activated with 30 mg L−1sodium percarbonate and 14 mg L−1of sodium thiocyanate. Using this approach, we obtained a synergistic effect with a complete inhibition of the activity of the total flora of the milk andS.Hadar after 12 hours at 25°C. In addition, the attainment of synergy was defined when the inhibitory effect of the two compounds together was greater than the effect observed by each compound added alone. Moreover, the monitoring of the synergistic effect at 4°C for 5 days showed complete inhibition of total flora for 3 days and forS. Hadar it was up to 5 days. To summarize, the current study clearly identified a new inhibitory combination that may be used in food-based applications.

Advances in postharvest technologies to extend the storage life of minimally processed fruits and vegetables

Minimally processed fresh produce is one of the fastest growing segments of the food industry due to consumer demand for fresh, healthy, and convenient foods. However, mechanical operations of cutting and peeling induce the liberation of cellular contents at the site of wounding that can promote the growth of pathogenic and spoilage microorganisms. In addition, rates of tissue senescence can be enhanced resulting in reduced storage life of fresh-cut fruits and vegetables. Chlorine has been widely adopted in the disinfection and washing procedures of fresh-cut produce due to its low cost and efficacy against a broad spectrum of microorganisms. Continuous replenishment of chlorine in high organic wash water can promote the formation of carcinogenic compounds such as trihalomethanes, which threaten human and environmental health. Alternative green and innovative chemical and physical postharvest treatments such as ozone, electrolyzed water, hydrogen peroxide, ultraviolet radiation, high pressure processing, and ultrasound can achieve similar reduction of microorganisms as chlorine without the production of harmful compounds or compromising the quality of fresh-cut produce.

The influence of ultrasonic treatment on the growth of the strains of Salmonella enterica subs. typhimurium

This study proposes the destruction of pathogenic bacteria with the use of ultrasound waves because the more commonly used thermal processing methods often result in lowering the nutritional value of food. The study presents the impact of ultrasound of 20, 40 and 100 kHz frequencies and the power of 10.5 W/cm2 on the growth of the strain of Salmonella enterica subs. typhimurium. The tests were carried out both in chilled and non-chilled treatment mediums, with an average bacterial population >105 and >108 CFU/cm3. The total inactivation of Salmonella spp. was observed in the tests in the low-population non-chilled treatment medium after sonication at 20 and 40 kHz for 30 min, and in high bacterial population at 20 kHz for 30 min. A reduction in the average number of bacteria was reported in the low-population non-chilled medium after 15 min of sonication at 20, 40 and 100 kHz; after 15 min of sonication at 20 and 100 kHz of the material of high bacterial population; and in the low-population chilled treatment mediums after 15 and 30 min at 20 kHz. The samples with inactivated bacteria and those with reduced bacterial counts maintained the same levels when stored at 4 °C for 24 and 48 h. Bacteria inactivation obtained after sonication lasted for up to 48 h in storage at 21 °C. For the samples with reduced bacterial counts stored at 21 °C, a rise in the average number of bacteria was recorded.

Outbreaks and factors influencing microbiological contamination of fresh produce

Fresh fruits and vegetables are nutritionally well-recognised as healthy components in diets. The microbiological foodborne outbreaks associated with the consumption of fresh produce have been increasing. Salmonella spp., Escherichia coli O157:H7, Staphylococcus aureus, Campylobacter spp. and Listeria monocytogenes are the most common pathogens that contaminate fresh produce. This review discusses recent foodborne outbreaks linked to fresh produce, factors that affect microbiological contamination and measures that could be adopted to reduce the foodborne illnesses. © 2016 Society of Chemical Industry.

Evaluation of the effectiveness of ozone as a sanitizer for fish experimentally contaminated with Salmonella sp

Abstract Salmonellosis is a major public health problem related to food contamination and ensuing food poisoning. Brazilian resolution RDC nº 12/2001 of the Brazilian National Health Surveillance Agency (ANVISA) established the absence of Salmonella in 25 g of fish for consumption. However, the significant increase in the occurrence of fish contamination by Salmonella and other pathogenic bacteria shows that the currently applied strategies are not sufficient and that, in addition to the implementation of good health practices, the application of new sanitizer technologies in the fish industry is also necessary. In this context, the present study evaluated the effectiveness of ozone in an aqueous medium as a sanitizer for Salmonella contaminated fish. The experiment was carried out using a completely randomized design with eight treatments and five replicates, giving a total of 40 experimental units. Each sample consisted of three fishes, totalizing 120 fishes. The treatments consisted of different combinations of temperature and water-dissolved ozone (O3) concentrations (21 °C × 0.35 ppm; 20 °C × 0.45 ppm; 21 °C × 0.60 ppm; 20 °C × 0.80 ppm; 19 °C × 1.7 ppm; 6 × 5.1 ppm; 4 °C × 7.2 ppm; and 2 °C × 9.1 ppm). Colossoma macropomum (Tambaqui) samples were experimentally infected with Salmonella typhymurium (ATCC 14028) and immersed in water with the different treatments. After three minutes, the fish samples were collected and subjected to qualitative Salmonella analyses. The ozone tests were not efficient in eradicating Salmonella under the experimental conditions presented here, indicating the need for the identification of effective sanitizers in order to meet the determinations of Brazilian law.

The use of ECAS in plant protection: a green and efficient antimicrobial approach that primes selected defense genes

The use of highly polluting chemicals for plant and crop protection is one of the components of the negative environmental impact of agricultural activities. In the present paper, an environmentally friendly alternative to pesticide application has been studied, based on the so-called electrochemically activated solutions (ECAS). Experiments have been carried out, by applying ECAS having different contents of active ingredients, on tobacco plants at a laboratory scale and on apple trees at fruit garden scale. The results, accumulated during a couple of years, have shown that properly selected dilute solutions of chlorides, once activated by an electrochemical treatment, exhibit a very effective protecting action of plants, irrespective of their nature. Extension of the research has shown that the observed effect is the result of two distinct factors: the expected anti-microbial action of the electrochemically synthesized oxidants, and an unexpected priming of immune plant defenses, which is clearly due to the treatment with ECAS. Interestingly, the repetition of ECAS application triggers an even stronger activation of defense genes. No oxidative damages, due to the use of the activated solutions, could be detected.