Survival Of Foodborne Pathogens Research Articles

Survival of Listeria monocytogenes and Salmonella in finishing waxes used for fresh citrus fruits

Citrus fruits are typically waxed before packaging to prevent water loss and extend shelf-life. The survival of Listeria monocytogenes and Salmonella was evaluated in 15 different commercial finishing waxes used for fresh citrus in California. Survival of L. monocytogenes and Salmonella in citrus finishing waxes depended on wax type. Over 24 h at 4 and 22 °C, populations of L. monocytogenes declined more slowly than or equal to Salmonella in all finishing waxes except wax F8 (organic, beeswax based, non-morpholine). Over 24 h of storage at 4 °C, L. monocytogenes populations declined by >4 log (below the detection limit by enrichment, 0.3 log CFU/mL) in waxes F4, F7, F8, and F9. Population declines of 1.2–2.8 log were observed in waxes F5, F10, F11, F13, and F14 and of <1.0 log in waxes F1, F2, F3, F6, F12, and F15. With the exception of waxes F2 (polyethylene based, non-morpholine) and F6 (shellac based, non-morpholine), greater declines of L. monocytogenes were observed over 24 h in most waxes when the storage temperature was increased to 22 °C. During long-term storage at 4 °C, L. monocytogenes declined by >5 log after 5, 10, 20, 30, and 135 days in waxes F3, F1, F15, F12, and F6, respectively. L. monocytogenes populations in all waxes stored at 22 °C fell below the detection limit by enrichment within 20 days except for wax F2. In two separate lots of wax F2, L. monocytogenes populations inoculated at ∼4 or ∼6 log CFU/mL declined by1.6–2.6 log by day 10 and then increased to 5.4 to 5.7 log CFU/mL on day 20. Citrus packinghouse hazard assessments and food safety plans should consider the survival of foodborne pathogens in commercial citrus finishing waxes.

Adhesion to and survival of foodborne pathogens in produce and strategies for their biocontrol

AbstractFoodborne pathogens can cause gastrointestinal infections in consumers and in some cases can even lead to outbreaks. In the last decade, it has been observed that some zoonotic pathogenic bacteria can use plants as secondary hosts. Contamination with foodborne bacteria becomes relevant in foods that are regularly eaten raw, such as lettuce, cilantro, fenugreek, rocket leaves, basil, and so forth, and some fruits such as tomatoes, melons, and green peppers; because the elimination of these pathogenic bacteria is difficult to achieve with conventional sanitization processes. Contamination of produce can occur throughout the entire production chain. In farmlands, pathogenic bacteria can contaminate the seed, mainly when contaminated water is used for irrigation. Later, bacteria can reach other plant tissues such as the stems, leaves, and fruits. Another form of contamination is when the produce is in contact with feces from domestic, production, or wild animals. Additionally, poor handling practices during harvest, packaging, distribution, and sale can contaminate produce. Studies have shown that foodborne pathogens can adhere to produce, sometimes forming a biofilm, and can also be internalized into the plant or fruit, which protects them from sanitation processes. For this reason, in this text we address three biocontrol strategies such as bacteria, lytic bacteriophages, and some fungi, as an alternative approach for the control of both foodborne and plant pathogens. Additionally, the use of these biological agents can represent an advantage for the development of the plant, making them a good strategy to favor yield.

Survival of Foodborne Pathogens in Low and Nonalcoholic Craft Beer

Breweries and beverage companies have recently been interested in creating innovative beer varieties that deviate from traditional beer styles, with either low-alcohol content <2.5% alcohol by volume (ABV) or the absence of alcohol altogether (<0.5% ABV). Traditional beers (up to 10% ABV) contain numerous intrinsic and extrinsic factors preventing pathogens from proliferation or propagation. Physiochemical properties such as a low pH, presence of ethanol and hop acids, limited oxygen, and specific processing techniques, including wort boiling, pasteurization, filtration, cold storage, and handling, all contribute to microbial stability and safety. The potential change or absence in one or more of these antimicrobial hurdles can render the final product susceptible to pathogen survival and growth. In this study, the effect of pH, storage temperature, and ethanol concentration on the growth or die-off of foodborne pathogens in low and nonalcoholic beers was evaluated. pH and ethanol concentrations were adjusted from their initial values of 3.65 and <0.50% ABV to pHs 4.20, 4.60, and 4.80; and 3.20 ABV, respectively. The samples were inoculated with individual five-strain cocktails of E. coli O157:H7, S. enterica, and L. monocytogenes, then stored at two different temperatures (4 and 14°C) for 63 days. Microbial enumeration was performed using selective agar with incubation at 35°C. Results showed that nonalcoholic beers allowed for pathogen growth and survival, as opposed to the low-alcoholic ones. E. coli O157:H7 and S. enterica grew approximately 2.00 log at 14°C, but no growth was observed at 4°C. L. monocytogenes was more susceptible and fell at, or below, the detection limit rapidly in all the conditions tested. The results show that storage temperature is critical in preventing the growth of pathogens. pH did not appear to have a significant effect on the survival of pathogens (p < 0.05). This challenge study demonstrates the need for beverage manufacturers to prioritize and maintain food safety plans along with practices specific to low- and nonalcoholic beer manufacturers.

Microbiological effect of complete replacement of nitrites/nitrates with starter cultures in traditional raw-dried fermented sausage “Lukanka Panagyurska”

The article is focused on microbiological safety of the traditional raw-dried meat product “Lukanka Panagyurska”, produced by a starter cultures, containing Lactiplantibacillus plantarum GLP3 and Debaryomyces hansenii ATCC 36239 instead of using nitrates/nitrites. The aim of the study was to demonstrate that the starter cultures had a similar or better preservative effect as the traditional nitrates transformed into nitrites in the drying-ripening phase. The effect of the same starter cultures, produced by two different technological approaches on the survival of foodborne pathogens (Salmonella Typhimurium, Listeria monocytogenes, Escherichia coli and Clostridium perfringens) was examined. The study showed the presence of the lactic acid microorganisms at every stage of the production process of the raw-dried meat product. Zoonotic pathogens as S. Typhimurium and L. monocytogenes and sanitary indicator bacteria as E. coli and C. perfringens were combined to control the levels of pathogen inactivation. The preservative effect of the starter cultures resulting from lactic acid fermentation was more effective in comparison to that of nitrites/nitrates. The experiments proved that the microbiological safety of the raw-dried meat product was improved in comparison with the popular practice of adding nitrates/nitrites as a preservative.

Antifungal activity of human gut lactic acid bacteria against aflatoxigenic Aspergillus flavus MTCC 2798 and their potential application as food biopreservative

AbstractWith the enhanced use of chemical preservatives and the survival of foodborne pathogens, lactic acid bacteria and its metabolic product have received increased attention as a potential food preservative. Even though the antibacterial property of lactic acid bacteria is well known, its antifungal property and application in food preservation have not been widely exploited. Considering these facts, this study was conducted to investigate the antifungal properties of three human gut lactic acid bacterial isolates, Lactobacillus plantarum AL1, Lactobacillus fermentum AL2, and Weissella confusa AL3 antifungal activity of the isolates were studied against the aflatoxigenic Aspergillus flavus MTCC 2798, using the agar overlay method and inhibition of fungal mycelium (co‐culture method). These LAB isolates were also potent producers of antimicrobial compounds like lactic acid, hydrogen peroxide, and diacetyl. GC–MS analysis of the methanolic extract of the three LAB isolates detected two antifungal bioactive compounds like cyclo (leucyloprolyl) and 1,2‐benzenedicarboxylic acid in extracts. The hemolysis results provided an important insight that the human gut lactic acid bacteria can be used as protective cultures in the biopreservation. The antifungal activity of human gut LAB AL1, AL2, and AL3 against aflatoxigenic Aspergillus flavus MTCC 2798 and its ability extend the shelf life of peanuts prove as a natural preservative for food products.

Cascading effects of composts and cover crops on soil chemistry, bacterial communities and the survival of foodborne pathogens.

AimsRecent foodborne disease outbreaks have caused farmers to re‐evaluate their practices. In particular, concern that soil amendments could introduce foodborne pathogens onto farms and promote their survival in soils has led farmers to reduce or eliminate the application of animal‐based composts. However, organic amendments (such as composts and cover crops) could bolster food safety by increasing soil microbial diversity and activity, which can act as competitors or antagonists and reduce pathogen survival.Methods and ResultsLeveraging a study of a 27‐year experiment comparing organic and conventional soil management, we evaluate the impacts of composted poultry litter and cover crops on soil chemistry, bacterial communities and survival of Salmonella enterica and Listeria monocytogenes. We found that bacterial community composition strongly affected pathogen survival in soils. Specifically, organic soils managed with cover crops and composts hosted more macronutrients and bacterial communities that were better able to suppress Salmonella and Listeria. For example, after incubating soils for 10 days at 20°C, soils without composts retained fourfold to fivefold more Salmonella compared to compost‐amended soils. However, treatment effects dissipated as bacterial communities converged over the growing season.ConclusionsOur results suggest that composts and cover crops may be used to build healthy soils without increasing foodborne pathogen survival.Significance and Impact of the StudyOur work suggests that animal‐based composts do not promote pathogen survival and may even promote bacterial communities that suppress pathogens. Critically, proper composting techniques are known to reduce pathogen populations in biological soil amendments of animal origin, which can reduce the risks of introducing pathogens to farm fields in soil amendments. Thus, animal‐based composts and cover crops may be a safe alternative to conventional fertilizers, both because of the known benefits of composts for soil health and because it may be possible to apply amendments in such a way that food‐safety risks are mitigated rather than exacerbated.

Antimicrobial potential of kombucha against foodborne pathogens

The survival of foodborne pathogens under stressful food processing conditions and in host’s gastrointestinal tract has been widely reported to cause the outbreak of human diseases. Generally, antibiotics have been used to elimi-nate the microbial flora of foodborne pathogens. However, the overuse of antibiotics has contributed to the emergence and spread of multi-drug-resistant foodborne pathogens. Kombucha is a beverage prepared by fermenting sugared tea or other substrates with a symbiotic culture of yeasts and bacteria, and has been proved to fight food-borne pathogens and affect gastrointestinal microbial flora to prevent foodborne illnesses. In this context, this review primarily focused on microbiological and chemical compositions of kombucha obtained by fermenting different substrates. It further discussed the antimicrobial activity of kombucha, as well as potential antimicrobial agents found in kombucha, and the limitations of kombucha in the food industry. In addition, the need for developing antimicrobial agents from kombucha has been discussed for potential applications. The information provided in this review indicates that kombucha could serve as an alternative approach to control pathogens in place of using antibiotics.

Models for factors influencing pathogen survival in low water activity foods from literature data are highly significant but show large unexplained variance

Factors that control pathogen survival in low water activity foods are not well understood and vary greatly from food to food. A literature search was performed to locate data on the survival of foodborne pathogens in low-water activity (<0.70) foods held at temperatures <37 °C. Data were extracted from 67 publications and simple linear regression models were fit to each data set to estimate log linear rates of change. Multiple linear stepwise regression models for factors influencing survival rate were developed. Subset regression modeling gave relatively low adjusted R2 values of 0.33, 0.37, and 0.48 for Salmonella, E. coli and L. monocytogenes respectively, but all subset models were highly significant (p < 1.0e-9). Subset regression models showed that Salmonella survival was significantly (p < 0.05) influenced by temperature, serovar and strain type, water activity, inoculum preparation method, and inoculation method. E. coli survival was significantly influenced by temperature, water activity, and inoculum preparation. L. monocytogenes survival was significantly influenced by temperature, serovar and strain type, and inoculum preparation method. While many factors were highly significant (p < 0.001), the high degrees of variability show that there is still much to learn about the factors which govern pathogen survival in low water activity foods.

Inactivation of Listeria monocytogenes , Escherichia coli O157:H7, and Salmonella spp. on dates by antimicrobial washes

Dates are a low moisture ready-to-eat fruit that are popular both globally and in the United States. The harvesting and post-harvest handling of dates could result in the contamination of common produce-associated foodborne pathogens including E. coli O157:H7, Listeria monocytogenes, and Salmonella spp. In this study, the efficacy of antimicrobial washes for the reduction of foodborne pathogen populations was evaluated as a post-harvest mitigation step. Peracetic acid (PAA, 75 ppm), ethanol (EtOH, 70%), lactic acid (LA, 2.5%), trans-cinnamaldehyde (TC, 2%), and pomegranate peel extract (1%, PPE) were used to develop five antimicrobial washes: 75 ppm PAA; 75 ppm PAA + 70% EtOH; 75 ppm PAA + 2.5% LA; 75 ppm PAA + 70% EtOH + 2% trans-cinnamaldehyde (TC); and 75 ppm PAA + 1% PPE. For whole dried dates, a 60 s treatment with 75 ppm PAA significantly reduced pathogen populations by 4.08 to 4.96 log CFU/g. Specifically, for E. coli O157:H7, populations were reduced by 7.25 log CFU/g on dates when treated for 60 s with either 75 ppm PPA + 70% EtOH or with 75 ppm PPA + 70% EtOH + 2% TC. No significant reductions in pathogen populations were observed on the fresh whole dates for any of the sanitizer treatments. In addition, all three pathogens were capable of survival on pitted date pieces during storage at 4°C for 31 days; no significant reduction for any pathogen was observed. The results of this study provide data on the survival of these three foodborne pathogens on fresh and dried dates and can aid in the risk assessment of this food product. Practical applications This study provides the basis for a preventive control with the ability to reduce foodborne pathogenic bacteria populations between 1.34 and 7.25 log CFU/g on fresh and dried dates. An antimicrobial wash implemented as a preventative control will greatly increase the confidence a manufacturer may have in date products used in RTE foods. Survival of foodborne pathogens on dates can aid in its risk assessment.

Growth and Survival of Foodborne Pathogens during Soaking and Drying of Almond (Prunus dulcis) Kernels

The practice of soaking almonds prior to consumption is popular both commercially and at home. The food safety implications of soaking almonds was investigated through analysis of blogs and videos (n = 85 recipes) to identify both the reasons for soaking almonds and the common practices employed. Among the recipes analyzed, the most common reasons for soaking almonds (94.1%) were perceived benefits such as improved digestion and nutrient uptake. Most recipes (34.1%) suggested soaking at "room temperature" for times that ranged from 4 to 24 h or, more commonly, "overnight" (51.8%). Postsoaking drying instructions were provided in 40 recipes (47.1%). Among those providing a drying temperature (31.8%), 85% specified 66°C and lower. To evaluate the growth of foodborne pathogens during almond soaking, separate cocktails of Escherichia coli O157:H7, Listeria monocytogenes, and Salmonella enterica were inoculated onto raw almonds or into the soak water (almonds-to-water ratios of 1:1 and 1:3 [w/v]). Populations were monitored during soaking at 15, 18, and 23°C for up to 24 h, and during postsoak drying at 66°C for 14 h (for Salmonella only). At 15°C and a 1:1 almond:water ratio, no significant population increase (P > 0.05) was observed between 0 and 24 h for any of the pathogens. At 18°C, increases of 0.63, 1.70, and 0.88 log CFU per sample were observed over 24 h for populations of E. coli O157:H7, L. monocytogenes, and Salmonella, respectively. Populations of E. coli O157:H7, L. monocytogenes, and Salmonella increased by 3.48, 3.22, and 3.94 log CFU per sample, respectively, after 24 h at 23°C. When soaked almonds were dried for 14 h at 66°C, moisture and water activity decreased from 40 to ∼6% and 0.99 to 0.60, respectively, but no significant reduction in Salmonella populations was observed. Recommendations for using shorter times (<8 h) and cooler temperatures (≤15°C) should reduce the potential for foodborne pathogens, if present, to grow during soaking of almonds.

Survival of Foodborne Pathogens in Homemade Fig and Mulberry Vinegars

This work reports the survival status of Listeria monocytogenes, Escherichia coli O157:H7, Staphylococcus aureus and Salmonella Typhimurium in homemade fig and mulberry vinegar. Each pathogen was separately inoculated in vinegar samples at approximately 7 log CFU/mL. The survival status of pathogens was examined at 20°C for 0, 15, 30 and 60 min, and 4, 8 and 24 h. The residual populations after 24 h were below detection limit for all species assayed. S. Typhimurium was much more sensitive to mulberry vinegar ( 6 log reduction in 30 min) than it is to fig vinegar ( 6 log reduction in 24 h). L. monocytogenes had an overall quite different behaviour, being the most sensitive species to fig vinegar ( 6 log reduction in 4 h) while being the most resistant one to mulberry vinegar ( 6 log reduction in 24 h). The total phenolic content of fig vinegar (767 mg GAE/L) was higher than mulberry vinegar (557.5 mg GAE/L). The results exhibited that antimicrobial activity of vinegar is mainly related to the contact time, test pathogen and physicochemical properties of vinegar.

Survival of common foodborne pathogens on dried apricots made with and without sulfur dioxide treatment

To fill the current knowledge gap in the survival of foodborne pathogens on dried fruits, this study monitored the survival of three common pathogens on dried apricots. Sun-dried apricots made with (DAS) and without sulfur dioxide (DANS) treatments were used and were inoculated using a dry (sand) or a wet (phosphate-buffered saline, PBS) carrier. The survival of Shiga-toxin-producing Escherichia coli (STEC), Salmonella spp. and Listeria monocytogenes (LM) on inoculated dried apricots was monitored for three months during ambient temperature storage. When dried apricots were inoculated with the wet carrier, all three pathogens survived the 48- hour drying period. After drying and during ambient temperature storage, the number of culturable pathogen cells decreased as the storage time increased. Among all three pathogens, STEC survived with higher culturable numbers for a longer period of time than the other two pathogens on DANS over the 90-day storage period. When pathogens were inoculated via the dry carrier, Salmonella survived with higher culturable numbers among three pathogens on DANS, indicating its enhanced survivability after being dried on sand and exposed to stress conditions before inoculation. In addition, regardless of the inoculation carriers, pathogens survived for longer periods of time or with higher levels on DANS, indicating the antimicrobial properties of free SO2 contained in DAS. In summary, based on the results of this study, pathogens can survive on dried fruits; factors affecting pathogen survival include the types of test pathogens, inoculation methods, and the use of sulfur dioxide.

Survival of foodborne pathogens on stainless steel soiled with different food residues

Insufficient and ineffective cleaning practices can cause food residues to remain in kitchen and can facilitate bacterial attachment and persistence by protective films. The present study investigated the survival of five major foodborne pathogens on stainless steel coupons, in the presence of cooked rice, whole eggs, and soymilk. Foodborne pathogens showed different survival rates by desiccation and disinfection depending on food residues. Overall, the pathogens showed stronger survival than the control at 0.13-3.97 log CFU/coupon with 5% residues, and at 0.75-5.29 log CFU/coupon with 50% residues. Staphylococcus aureus was not affected by the food residue with showing the least difference in concentration, while Escherichia coli O157:H7 showed the most significant increase by food residue. The cells with cooked rice were observed using FE-SEM, and demonstrated bacterial binding or embedment. All results suggest that food safety can be practically ensured by food residue types and appropriate cleaning and disinfectants.

Food preservatives influence biofilm formation, gene expression and small RNAs in Salmonella enterica

Salmonella enterica is major foodborne pathogens. Salmonella persists in the food chain due to its ability to produce biofilms under different conditions. One of the biggest challenges in biofilm research is reproducing real food industry conditions. Also, food microbiologists have the challenge of elucidating the role of small RNAs (sRNAs) in the survival of foodborne pathogens in the food chain. This study evaluated food preservatives (sodium nitrite, sodium sulfite and sodium acetate-citric acid) effect on biofilm formation of ten S. enterica strains on two surfaces (polystyrene and stainless steel). The effects of preservatives on transcription of biofilm- and virulence-related genes and sRNAs were evaluated. All Salmonella strains produced biofilm in all the conditions evaluated. However, sodium sulfite reduced biofilm formation by Salmonella in both surfaces tested. Food preservatives influenced biofilm- and virulence-related genes and sRNAs transcription. This study highlights that Salmonella strains can produce biofilms in the presence of food preservatives, representing a public health problem. Fully understanding what metabolic pathways are modified by the presence of preservatives could allow developing new control strategies to prevent foodborne pathogens persistence in the food chain by using effective combinations of preservatives.

Survival of foodborne pathogens on commercially packed table grapes under simulated refrigerated transit conditions

We examined the survival of Listeria monocytogenes, Escherichia coli O157:H7, and Salmonella enterica Thompson inoculated on commercially packed table grapes under simulated refrigerated transit conditions (1.1 ± 0.5 °C; 90% RH). Grapes were placed in perforated polyethylene cluster bags, within a commercial expanded polystyrene box equipped with either a SO2-generating pad; a perforated polyethylene box liner; a SO2-generating pad and a box liner; or none of them. L. monocytogenes was most sensitive to SO2-generating pad. SO2-generating pad or SO2-generating pad with box liner inactivated this pathogen completely on day 12 following the inoculation. S. enterica Thompson displayed a similar cold sensitivity as L. monocytogenes, but was more resistant to SO2-generating pad than L. monocytogenes. While SO2-generating pad eliminated S. enterica Thompson on day 20, a combination of box liner with SO2-generating pad inactivated this pathogen completely on day 13. E. coli O157:H7 had the highest tolerance to transit temperature and to SO2-generating pad; SO2-generating pad inactivated this pathogen completely on Day 20. Our data suggest that use of SO2-generating pad combined with box liner is effective in reducing foodborne pathogens L. monocytogenes and S. enterica Thompson, while the use of SO2-generating pad alone was more effective on E. coli O157:H7.

Viable microbial loads on citrus carpoplane during packhouse processing and survival of foodborne pathogens in reconstituted postharvest fungicides

AbstractThis study investigated microbial population shifts on citrus carpoplane and the impact of irrigation and packhouse processing water in four commercial farms. Samples included oranges (n = 450) and water (n = 230). Mean microbial concentrations ranging from 1.6 to 3.6 log colony forming units (CFU)/cm2 were detected on unwashed fruit and were reduced at least by 2.0 log CFU/cm2 for bacteria, 0.8 log CFU/cm2 for fungi and 1.3 log CFU/cm2 for yeasts during washing with disinfectants and/or fungicides. Occasional spikes in concentration (mostly for bacteria) were observed following some packing steps including washing, fungicide treatment, waxing, and final packing. Evaluation of Escherichia coli O157:H7 and S. Typhimurium survival in fungicides typically used during packhouse processing showed them to be susceptible to guazatine, imazalil, philabuster, and ortho‐phenyl phenate. Both tested pathogens were able to survive in thiabendazole, fludioxinil and pyremethanil, except for S. Typhimurium in fludioxinil where it died within 4 hr of incubation.Practical applicationsUnderstanding the impact of current intervention strategies on the ecological balance of the citrus carpoplane may provide a more durable approach to reduced losses and spoilage and in developing crop‐specific management systems for food safety assurance. Our study showed process‐by‐process changes in microbial loads naturally present on healthy citrus fruit at harvest. Washing baths containing a sanitizing agent consistently reduced initial microbial loads on the citrus carpoplane. Further, potential survival of E. coli O157:H7 and S. Typhimurium in currently registered commercial postharvest fungicides, was demonstrated. The pesticide fludioxinil was observed to be effective against, S. Typhimurium providing some potential use as a kill step agent, which, however, needs further investigation.

Pathogen Reductions during Traditional Fermentation and Drying of Pork Salamis

ObjectivesTraditionally-processed meat products produced without thermal processing are common in European countries and are increasing in popularity in the United States. Processors are met with the challenge of creating these high-quality products while ensuring food safety. The purpose of this study was to validate the safety of a process to produce a traditional fermented and dried salami. This experiment investigated the impact of casing type and an antimicrobial intervention on the survival of foodborne pathogens in a salami product made with minimal ingredients.Materials and MethodsPork butts were cubed and experimentally-inoculated with ∼8 log10 CFU/ml of 3 strains each of E. coli O157:H7 (EC), Salmonella spp. (S), and L. monocytogenes (LM). The cubes were either sprayed with water (CTRL) or a 2.5% antimicrobial solution (TRT) prior to grinding through a 6-mm plate. Dry ingredients and starter culture were thoroughly mixed into the ground pork before being stuffed into ∼50 mm natural, collagen, and fibrous casings (N = 192). The salamis were subjected to fermentation (72 h), drying (28 d), and packaging (28 d). Salami samples were collected every 24 h until the end of fermentation. During drying and packaging, salami sampes were collected weekly.ResultsThere was no significant difference between the CTRL and TRT sausages for bacteria populations for EC (p = 0.1645), S (p = 0.3746), or LM (p = 0.1762) for the 60 d sampling period. There was also no significant difference in bacteria reductions between casings types within each treatment (p > 0.05). Intitial levels of pathogens were 8.36, 8.40, and 8.72 log10 CFU/g for EC, S, and LM, respectively. Following the treatments, bacteria populations in CTRL sausages decreased by 3.20, 0.38, and 0.12 log10 CFU/g for EC, S, and LM, respectively. Bacteria populations decreased in TRT sausages decreased by 2.40, 0.34, and 0.19 log10 CFU/g for EC, S, and LM. Following fermentation and drying, EC populations decreased 1.50 to 3.19 log10 CFU/g; S populations decreased 3.03 to 3.45 log10 CFU/g; and LM populations decreased 2.69 to 4.56 log10 CFU/g in both CTRL and TRT sausages. A 5 log10 reduction was achieved for S and LM by the end of packaging, but a combination of treatment and casing type did not achieve a 5 log10 reduction of EC by the end of packaging.ConclusionThis study validated the safety of a fermented pork salami manufactured without a heat treatment or additional lethality steps following fermentation and drying for salamis produced in collagen and fibrous casings.

Pathogen Reductions during Traditional Fermentation and Drying of Pork Salamis

ObjectivesTraditionally-processed meat products produced without thermal processing are common in European countries and are increasing in popularity in the United States. Processors are met with the challenge of creating these high-quality products while ensuring food safety. The purpose of this study was to validate the safety of a process to produce a traditional fermented and dried salami. This experiment investigated the impact of casing type and an antimicrobial intervention on the survival of foodborne pathogens in a salami product made with minimal ingredients.Materials and MethodsPork butts were cubed and experimentally-inoculated with ∼8 log10 CFU/ml of 3 strains each of E. coli O157:H7 (EC), Salmonella spp. (S), and L. monocytogenes (LM). The cubes were either sprayed with water (CTRL) or a 2.5% antimicrobial solution (TRT) prior to grinding through a 6-mm plate. Dry ingredients and starter culture were thoroughly mixed into the ground pork before being stuffed into ∼50 mm natural, collagen, and fibrous casings (N = 192). The salamis were subjected to fermentation (72 h), drying (28 d), and packaging (28 d). Salami samples were collected every 24 h until the end of fermentation. During drying and packaging, salami sampes were collected weekly.ResultsThere was no significant difference between the CTRL and TRT sausages for bacteria populations for EC (p = 0.1645), S (p = 0.3746), or LM (p = 0.1762) for the 60 d sampling period. There was also no significant difference in bacteria reductions between casings types within each treatment (p > 0.05). Intitial levels of pathogens were 8.36, 8.40, and 8.72 log10 CFU/g for EC, S, and LM, respectively. Following the treatments, bacteria populations in CTRL sausages decreased by 3.20, 0.38, and 0.12 log10 CFU/g for EC, S, and LM, respectively. Bacteria populations decreased in TRT sausages decreased by 2.40, 0.34, and 0.19 log10 CFU/g for EC, S, and LM. Following fermentation and drying, EC populations decreased 1.50 to 3.19 log10 CFU/g; S populations decreased 3.03 to 3.45 log10 CFU/g; and LM populations decreased 2.69 to 4.56 log10 CFU/g in both CTRL and TRT sausages. A 5 log10 reduction was achieved for S and LM by the end of packaging, but a combination of treatment and casing type did not achieve a 5 log10 reduction of EC by the end of packaging.ConclusionThis study validated the safety of a fermented pork salami manufactured without a heat treatment or additional lethality steps following fermentation and drying for salamis produced in collagen and fibrous casings.

Effect of Temperature and Nutrient Concentration on Survival of Foodborne Pathogens in Deciduous Fruit Processing Environments for Effective Hygiene Management

Temperature and good sanitation practices are important factors for controlling growth of microorganisms. Fresh produce is stored at various temperatures to ensure quality and to prolong shelf life. When foodborne pathogens survive and grow on fresh produce at storage temperatures, then additional control strategies are needed to inactivate these pathogens. The aim of this study was to determine how temperatures associated with deciduous fruit processing and storage facilities (0.5, 4, and 21°C) affect the growth and/or survival of Escherichia coli O157:H7, Listeria monocytogenes , Salmonella enterica subsp. enterica serovar Typhimurium, and Staphylococcus aureus under different nutrient conditions (nutrient rich and nutrient poor) and on simulated contact surfaces (vinyl coupons). Information on the growth and survival of foodborne pathogens at specific deciduous fruit processing and storage temperatures (0.5°C) is not available. All pathogens except E. coli O157:H7 were able to survive on vinyl coupons at all temperatures. L. monocytogenes proliferated under both nutrient conditions independent of temperature. S. aureus was the pathogen least affected by nutrient conditions. The survival of foodborne pathogens on the vinyl coupons, a model system for studying surfaces in fruit preparation and storage environments, indicates the potential for cross-contamination of deciduous fruit products under poor sanitation conditions. Foodborne pathogens that can proliferate and survive at various temperatures under different nutrient conditions could lead to fruit cross-contamination. Temperature mismanagement, which could allow pathogen proliferation in contaminated fruit packing houses and storage environments, is a concern. Therefore, proper hygiene and sanitation practices, removal of possible contaminants, and proper food safety management systems are needed to ensure food safety.

Survival of foodborne pathogens in unripe grape products

Antibacterial effects of unripe grape products (verjuice and sour grape sauce) which are particularly rich in antioxidants and organic acids were evaluated. Survival of Escherichia coli, Listeria monocytogenes, Salmonella Typhimurium and Staphylococcus aureus which were inoculated in unripe grape products at different inoculum doses (2 and 6 log CFU/mL) was determined. All the samples were kept at room temperature (approximately 25 °C) for 0, 5, 15 and 30 min after inoculation with pathogens, separately. The unripe grape products which were inoculated at low inoculum dose inhibited all tested pathogens in 5 min, while it took 15 min for high inoculum dose. The pH, titratable acidity (tartaric acid %) and total sugar content values of the samples were between 2.14–2.74, 2.29–7.10% and 1.19–17.65 g/L, respectively. It was concluded that unripe grape products are microbiologically safe products and they have self-protection systems even when they were contaminated with pathogens at high levels.