Effects of lactic acid and lauricidin on the survival of Listeria monocytogenes, Salmonella enteritidis and Escherichia coli O157:H7 in chicken breast stored at 4°C

Comparative Effects of Dietary Supplementations with Microencapsulated Sodium Butyrate, Glycerol Monolaurate and Tributyrin on Growth, Immunity, and Gut Health in Black Sea Bream

This study investigates the effects of three dietary additives-microencapsulated sodium butyrate (MSB), glycerol monolaurate (GML), and tributyrin (TB)-on the growth performance, various physiological parameters, gene expression, intestinal morphology, and microflora in Acanthopagrus schlegelii (black sea bream). The experiment utilized a 43.5% soybean meal (SBM) inclusion diet with four isonitrogenous and isoenergetic formulations: a control diet, and diets supplemented with MSB (0.24%), GML (0.04%), or TB (0.22%). The growth trial spanned eight weeks, and triplicate tanks were randomly assigned to each diet, with each tank containing 30 fish, each having an initial weight of 1.55 ± 0.01 g. Key outcomes included measurements of weight gain, specific growth rate, digestive enzyme activity, serum immune markers, antioxidant status, and intestinal morphology and, gut microbiota. Additionally, gene expression and microbiota analysis were conducted on intestinal tissues to assess the impact of these additives on gut health and immune response. The findings revealed that all three additives enhanced growth performance and improved intestinal health and gut microbiota but GML exhibited the most pronounced effects on intestinal barrier function and immune modulation, gene expression, and microflora, followed by MSB and TB. This study provides a comprehensive comparison of MSB, GML, and TB as feed additives for black sea bream, offering insights into their potential for improving fish health and optimizing aquaculture feed formulations.

Effect of dietary supplementation of lauric acid on growth performance, digestive enzymes, serum immune and antioxidant parameters, and intestinal morphology in black sea bream

An eight-week feeding trial was conducted to examine the impact of dietary supplementation with lauric acid (LA) on juvenile black sea bream. A basal diet was formulated containing 19.9% fish meal, while five additional diets were prepared, each supplemented with varying levels of LA: LA1 (0.01%), LA2 (0.02%), LA3 (0.04%), LA4 (0.08%), and LA5 (0.16%), denoted as LA1 through LA5, respectively. Triplicate tanks were randomly allocated to each diet, each containing 20 fish with an initial weight of 1.55 ± 0.02 g. At the conclusion of the trial, the LA3 group exhibited significantly greater final body weight (FBW), weight gain (WG), specific growth rate (SGR), and protein efficiency ratio (PER) compared to the other groups (P < 0.05), while the feed conversion ratio (FCR) was markedly higher in the control group. No significant differences were detected among the groups in terms of initial body weight (IBW), muscle fiber index (MFI), protein productive value (PPV), condition factor (CF), hepatosomatic index (HSI), intraperitoneal fat (IPF), viscerosomatic index (VSI), and survival rate (SR) (P > 0.05). No significant variations were observed among the groups in the proximate compositions of the dorsal muscle and whole body (p > 0.05). Furthermore, no significant differences were observed in serum immune and antioxidant parameters in the midgut and hindgut and digestive enzyme activity (P > 0.05) among the treatment groups. However, the LA3 group demonstrated significantly higher levels of serum immune response markers IgM, C3, and C4 compared to the other groups, while malondialdehyde (MDA) levels were significantly elevated in the control group relative to the others. The LA3 group demonstrated significantly increased fore-intestinal villus height, crypt depth, villus height-to-crypt depth ratio, and goblet cell count per villus compared to the other groups (P < 0.05).

Effect of Dietary Supplementation of Glycerol Monolaurate on Growth Performance, Digestive Enzymes, Serum Immune and Antioxidant Parameters, and Intestinal Morphology in Black Sea Bream

An eight-week feeding trial was conducted to examine the impact of dietary supplementation with glycerol monolaurate (GML) on juvenile black sea bream. A basal diet was formulated containing 24% fish meal, while five additional diets were prepared, each supplemented with varying levels of GML: GML1 (0.01%), GML2 (0.02%), GML3 (0.04%), GML4 (0.08%), and GML5 (0.16%). Triplicate tanks were randomly allocated to each diet, each containing 20 fish with an initial weight of 1.55 ± 0.05 g. By the trial's end, the GML3 group displayed a notably higher final body weight (FBW), weight gain (WG), specific growth rate (SGR), and protein efficiency ratio (PER) compared to the other groups (p < 0.05), but the FCR was significantly higher in the control group. However, no significant differences were observed in the MFI, PPV, CF, HSI, IPF, VSI, or SR among the groups (p > 0.05). Regarding the proximate compositions of the dorsal muscle and whole body, no substantial differences were observed across the groups (p > 0.05). Additionally, there were no significant variations in digestive enzyme activity (p > 0.05), serum immune, or biochemical parameters in the midgut and hindgut among the treatment groups. But in the serum immune response IgM, C3 and C4 were significantly higher in the GML3 group as compared to the other groups (p < 0.05). However, the GML3 group exhibited significantly greater fore-intestinal villus height, crypt depth, villus height per crypt depth, and the number of goblet cells per villus compared to the other groups (p < 0.05). Overall, GML supplementation, particularly GML3, significantly improved growth indicators like the final body weight and intestinal morphology. While certain parameters remained unaffected, these findings suggest GML's potential as a beneficial dietary supplement in fish diets.

Effects of bacterial cellulose/thyme essential oil emulsion coating on the shelf life of chilled chicken meat

BACKGROUND

Bacterial cellulose (BC) is a fiber substance produced by microbial fermentation. It is widely used in the food preservation industry because of its extremely pure texture, high crystallinity and high biocompatibility. In the present study, bacterial cellulose/thyme essential oil (BC/TEO-E) with antibacterial and fresh-keeping functions was prepared by ultrasonic treatment of modified bacterial cellulose for encapsulation of thyme essential oil, which effectively inhibited the spoilage of chilled chicken.

RESULTS

The purified BC, produced by Acetobacter xylinum ATCC 53524, was ultrasonically treated wih different times (0, 30, 60 and 90 min). Transmission electron microscopy, scanning electron microscopy, Fourier transformed infrared spectroscopy, X-ray diffraction, differential scanning calorimetry and zeta potential were used to characterize the structure of BC after ultrasound, showing that BC, treated for 30 min, had the optimal fiber structure, crystallinity (85.8%), thermal stability (347.77 °C) and solution stability (-26.63 ± 1.96 mV). BC/TEO-E was prepared by a homogenizer for the preservation of chilled chicken. Optical microscopy indicated that the BC/TEO-E prepared by 0.5% BC had optimal dispersion and stability, and even no delamination was observed in the emulsion. Compared with other groups (control, 0.5% BC and Tween-E), the total number of colonies and coliforms in chilled chicken treated with 0.5% BC/TEO-E was the lowest during the whole storage period (12 days), indicating that it can effectively inhibit bacterial growth. In addition, total volatile base nitrogen (TVB-N), thiobarbituric acid reactive substances, pH and drip loss results showed that 0.5% BC/TEO-E could effectively inhibit the spoilage of chilled chicken compared to the other treatment groups.

CONCLUSION

All of the results acquired in the present study indicate that BC/TEO-E has a potential application in chilled chicken preservation. © 2024 Society of Chemical Industry.

Inactivation of Salmonella Typhimurium, Escherichia coli, and Staphylococcus aureus in Tilapia Fillets (Oreochromis niloticus) with Lactic and Peracetic Acid through Fogging and Immersion

This study investigated the antimicrobial effects of lactic acid (LA) (3%) and peracetic acid (PA) (300 ppm) on tilapia fillets (Oreochromis niloticus) by fogging (15 min) or by immersion (2 s) in a pool of Escherichia coli (NEWP 0022, ATCC 25922, and a field-isolated strain), Staphylococcus aureus (ATCC 25923 and a field-isolated strain), and Salmonella Typhimurium (ATCC 13311 and ATCC 14028), as well as the effects on the physicochemical characteristics of the fillets. Fogging was effective and the best application method to control S. Typhimurium regardless of the acid used, promoting reductions of 1.66 and 1.23 log CFU/g with PA and LA, respectively. Regarding E. coli, there were significant reductions higher than 1 log CFU/g, regardless of the treatment or acid used. For S. aureus, only immersion in PA showed no significant difference (p < 0.05). For other treatments, significant reductions of 0.98, 1.51, and 1.17 log CFU/g were observed for nebulized PA, immersion, and LA fogging, respectively. Concerning the pH of the samples, neither of the acids used differed from the control. However, treatments with LA, and fogging with PA, reduced the pH compared to immersion in PA. As for color parameters, L* and a* values showed changes regardless of the acid or method used, resulting in an improved perception of fillet quality. These results indicate that fogging and immersion are alternatives for reducing S. Typhimurium, E. coli, and S. aureus in tilapia fillets.

Meta-analysis of citrus-derived additives on chicken meat quality and safety: a comprehensive evaluation of acceptability, physicochemical properties, and microbial contamination

Citrus represents a valuable repository of antioxidant substances that possess the potential for the preservation of meat quality. This meta-analysis aimed to comprehensively assess the impact of citrus additives on the quality and safety of chicken meat. Adhering to the PRISMA protocol, we initially identified 103 relevant studies, from which 20 articles meeting specific criteria were selected for database construction. Through the amalgamation of diverse individual studies, this research provides a comprehensive overview of chicken meat quality and safety, with a specific focus on the influence of citrus-derived additives. Minimal alterations were observed in the nutritional quality of chicken meat concerning storage temperature and duration. The findings demonstrated a significant reduction in aerobic bacterial levels, with Citrus aurantiifolia exhibiting the highest efficacy (P < 0.01). Both extracted and nonextracted citrus components, applied through coating, curing, and marinating, effectively mitigated bacterial contamination. Notably, thiobarbituric acid reactive substances (TBARS) concentrations were significantly reduced, particularly with Citrus hystrix (P < 0.01). Total volatile base nitrogen (TVBN), an indicator of protein degradation, exhibited a decrease, with citrus extract displaying enhanced efficacy (P < 0.01). Chemical composition changes were marginal, except for a protein increase after storage (P < 0.01). Hedonic testing revealed varied preferences, indicating improvements in flavor, juiciness, and overall acceptability after storage (P < 0.01). The study underscores the effectiveness of citrus additives in preserving chicken meat quality, highlighting their antibacterial and antioxidant properties, despite some observed alterations in texture and chemical composition. Citrus additives have been proven successful in 1) mitigating adverse effects on chicken meat during storage, especially with Citrus hystrix exhibiting potent antimicrobial properties, and 2) enhancing the hedonic quality of chicken meat. This research strongly advocates for the application of citrus additives to uphold the quality and safety of chicken meat.

Gelatin/carboxymethyl cellulose edible films: modification of physical properties by different hydrocolloids and application in beef preservation in combination with shallot waste powder

In this work, a gelatin/carboxymethyl cellulose (CMC) base formulation was first modified by using different hydrocolloids like oxidized starch (1404), hydroxypropyl starch (1440), locust bean gum, xanthan gum, and guar gum. The properties of modified films were characterized using SEM, FT-IR, XRD and TGA-DSC before selecting of best-modified film for further development with shallot waste powder. SEM images showed that the rough or heterogeneous surface of the base was changed to more even and smooth depending on the hydrocolloids used while FTIR results demonstrated that a new NCO functional group non-existent in the base formulation was found for most of the modified films, implying that the modification led to the formation of this functional group. Compared to other hydrocolloids, the addition of guar gum into the gelatin/CMC base has improved its properties such as better color appearance, higher stability, and less weight loss during thermal degradation, and had minimal effect on the structure of resulting films. Subsequently, the incorporation of spray-dried shallot peel powder into gelatin/CMC/guar gum was conducted to investigate the applicability of edible films in the preservation of raw beef. Antibacterial activity assays revealed that the films can inhibit and kill both Gram-positive and Gram-negative bacteria as well as fungi. It is noteworthy that the addition of 0.5% shallot powder not only effectively decelerated the microbial growth but also destroyed E. coli during 11 days of storage (2.8 log CFU g-1) and the bacterial count was even lower than that of uncoated raw beef on day 0 (3.3 log CFU g-1).

An Acyl Carrier Protein Gene Affects Fatty Acid Synthesis and Growth of Hermetia illucens

Acyl carrier protein (ACP) is an acyl carrier in fatty acid synthesis and is an important cofactor of fatty acid synthetase. Little is known about ACP in insects and how this protein may modulate the composition and storage of fatty acids. We used an RNAi-assisted strategy to study the potential function of ACP in Hermetia illucens (Diptera: Stratiomyidae). We identified a HiACP gene with a cDNA length of 501 bp and a classical conserved region of DSLD. This gene was highly expressed in the egg and late larval instars and was most abundant in the midgut and fat bodies of larvae. Injection of dsACP significantly inhibited the expression level of HiACP and further regulated the fatty acid synthesis in treated H. illucens larvae. The composition of saturated fatty acids was reduced, and the percentage of unsaturated fatty acids (UFAs) was increased. After interfering with HiACP, the cumulative mortality of H. illucens increased to 68.00% (p < 0.05). H. illucens growth was greatly influenced. The development duration increased to 5.5 days, the average final body weights of larvae and pupae were decreased by 44.85 mg and 14.59 mg, respectively, and the average body lengths of larvae and pupae were significantly shortened by 3.09 mm and 3.82 mm, respectively. The adult eclosion rate and the oviposition of adult females were also severely influenced. These results demonstrated that HiACP regulates fatty acid content and influences multiple biological processes of H. illucens.

Emerging Trends for Nonthermal Decontamination of Raw and Processed Meat: Ozonation, High-Hydrostatic Pressure and Cold Plasma

Meat may contain natural, spoilage, and pathogenic microorganisms based on the origin and characteristics of its dietary matrix. Several decontamination substances are used during or after meat processing, which include chlorine, organic acids, inorganic phosphates, benzoates, propionates, bacteriocins, or oxidizers. Unfortunately, traditional decontamination methods are often problematic because of their adverse impact on the quality of the raw carcass or processed meat. The extended shelf-life of foods is a response to the pandemic trend, whereby consumers are more likely to choose durable products that can be stored for a longer period between visits to food stores. This includes changing purchasing habits from “just in time” products “for now” to “just in case” products, a trend that will not fade away with the end of the pandemic. To address these concerns, novel carcass-decontamination technologies, such as ozone, high-pressure processing and cold atmospheric plasma, together with active and clean label ingredients, have been investigated for their potential applications in the meat industry. Processing parameters, such as exposure time and processing intensity have been evaluated for each type of matrix to achieve the maximum reduction of spoilage microorganism counts without affecting the physicochemical, organoleptic, and functional characteristics of the meat products. Furthermore, combined impact (hurdle concept) was evaluated to enhance the understanding of decontamination efficiency without undesirable changes in the meat products. Most of these technologies are beneficial as they are cost-effective, chemical-free, eco-friendly, easy to use, and can treat foods in sealed packages, preventing the product from post-process contamination. Interestingly, their synergistic combination with other hurdle approaches can help to substitute the use of chemical food preservatives, which is an aspect that is currently quite desirable in the majority of consumers. Nonetheless, some of these techniques are difficult to store, requiring a large capital investment for their installation, while a lack of certification for industrial utilization is also problematic. In addition, most of them suffer from a lack of sufficient data regarding their mode of action for inactivating microorganisms and extending shelf-life stability, necessitating a need for further research in this area.

Chicken Skin Decontamination of Thermotolerant Campylobacter spp. and Hygiene Indicator Escherichia coli Assessed by Viability Real-Time PCR

Thermotolerant Campylobacter spp. are fecal contaminants of chicken meat with serious implications for human health. E. coli is considered as hygiene indicator since, in contrast to Campylobacter. spp., the bacterium is generally present in the avian gut. Stress exposure may transiently cease bacterial division. Therefore, colony forming units (CFU) may underestimate the infection risk of pathogens. We developed a viability real-time PCR (v-qPCR) for the quantification of viable E. coli targeting the uidA gene, encoding β-glucuronidase, which is usually detected for phenotypic species identification. The short- and long-term effects of decontaminating chicken skin on the survival of both C. jejuni and an ESBL-producing E. coli were evaluated by CFU and v-qPCR. The results showed that freezing and storage in cool conditions are potentially underestimated by CFU but not by v-qPCR. The effect of treatment with peroxyacetic acid on survival was consistently detected by CFU and v-qPCR. v-qPCR analysis detected bacterial survival upon the application of lactic acid, which awaits further analysis. Interestingly, both bacteria showed similar kinetics of inactivation upon the application of reduction strategies, suggesting that E. coli might be a complementary hygiene indicator. We conclude that v-qPCR can improve food safety under the consideration of some limitations.

Effects of Chitosan and Duck Fat-Based Emulsion Coatings on the Quality Characteristics of Chicken Meat during Storage

Chicken meat is a popular food commodity that is widely consumed worldwide. However, the shelf-life or quality maintenance of chicken meat is a major concern for industries because of spoilage by microbial growth. The aim of this study was to evaluate the effects of chitosan and duck fat-based emulsion coatings on the quality characteristics and microbial stability of chicken meat during refrigerated storage. The coated chicken meat samples were as follows: control (non-coated), DFC0 (coated with duck fat), DFC0.5 (coated with duck fat and 0.5% chitosan), DFC1 (coated with duck fat and 1% chitosan), DFC2 (coated with duck fat and 2% chitosan), and SOC2 (coated with soybean oil and 2% chitosan). The results showed that the apparent viscosity and coating rate were higher in DFC2 than in other groups. Physicochemical parameters (pH, color, and Warner-Bratzler shear force) were better in DFC2 than those in other groups during 15 days of storage. Moreover, DFC2 delayed lipid oxidation, protein deterioration, and growth of microorganisms during storage. These data suggest that chitosan-supplemented duck fat-based emulsion coating could be used to maintain the quality of raw chicken meat during refrigerated storage.

Understanding protection from SARS-CoV-2 using metabolomics

The COVID-19 pandemic is still raging in most countries. Although the recent mass vaccination campaign has opened a new chapter in the battle against SARS-CoV-2, the world is still far from herd immunity. There is an urgent need to identify healthy people at high risk of contracting COVID-19, as well as supplements and nutraceuticals that can reduce the risk of infection or mitigate symptoms. In the present study, a metabolic phenotype that could protect individuals from SARS-CoV-2 infection or predispose them to developing COVID-19 was investigated. Untargeted metabolomics was performed on serum samples collected from 51 healthcare workers who were in good health at the beginning of the COVID-19 outbreak in Italy, and who were later exposed to the same risk of developing COVID-19. Half of them developed COVID-19 within three weeks of the blood collection. Our results demonstrate the presence of a specific signature associated with protection from SARS-CoV-2. Circulating monolaurin, which has well-known antiviral and antibacterial properties, was higher in protected subjects, suggesting a potential defensive role against SARS-CoV-2 infection; thus, dietary supplements could boost the immune system against this infection. In addition, our data demonstrate that people with higher levels of cholesterol are at higher risk of developing COVID-19. The present study demonstrates that metabolomics can be of great help for developing personalized medicine and for supporting public healthcare strategies. Studies with larger cohorts of subjects are necessary to confirm our findings.

In vitro Antibacterial Effect of Polyglycerol Monolaurates against Gram-Bacteria and Understanding the Underlying Mechanism

Polyglycerol monolaurates are generally recognized as safe food additives and are commonly used as food emulsifiers. In this study, the antimicrobial effect of four polyglycerol monolaurates on two Gram-positive bacteria (Staphylococcus aureus and Bacillus subtilis) and two Gram-negative bacteria (Escherichia. coli and Pseudomonas aeruginosa) were investigated. The minimum inhibitory concentration (MIC) of diglycerol monolaurate (PG2ML), triglycerol monolaurate (PG3ML), hexaglycerol monolaurate (PG6ML), and decaglycerol monolaurate (PG10ML) against S. aureus was 0.16, 0.32, 0.63, and 1.25 mg/mL, respectively. The MIC of PG2ML, PG3ML, PG6ML, and PG10ML against B. subtilis was 0.32, 0.63, 1.25, and 3.75 mg/mL, respectively. No apparent antimicrobial effect of these four polyglycerol monolaurates on E. coli and P. aeruginosa was observed even up to 10.00 mg/mL. The underlying mechanism was investigated by assessing cell membrane permeability, the integrity of cell membrane, and morphology. We concluded that polyglycerol monolaurates might eliminate Gram-positive bacteria by disrupting the cell membrane, thereby increasing cell membrane permeability, releasing the cellular contents, and altering the cell morphology.

Bactericidal effect of glycerol monolaurate complex disinfectants on Salmonella of chicken

Glycerol monolaurate (GML) is a monoglycerol ester of the fatty lauric acids, which has a wide-spectrum antimicrobial capacity, but fails to inactivate Gram-negative bacteria, especial Salmonella. To enhance the population reduction rate of GML for Salmonella, this reagent was combined with three disinfectants: lactic acid (LA), cetylpyridinium chloride (CPC), and trisodium phosphate (TSP), which can present acid, neutral, and alkaline in solution, respectively. The results showed that the 1% GML and a complex disinfectant (0.5% GML-0.025% LA) could powerfully inactivate Salmonella. Their population reduction rates respectively were able to achieve 99.92% and 98.29% with the vortex treatment, indicating that the vortex treatment could improve GML to destruct the outer membrane of Salmonella. During the simulation test of the soaking and rinse processing of chicken, for a short time (0 h), the effect of 0.5% GML-0.025% LA compound was better and more suitable for instantaneous inactivation than others, while for a long time (4 h), 1% GML exhibited a better bactericidal effect, which indicated it to be more suitable for long-term bacteriostasis. The characterization of color and texture for chicken samples were determined using Colormeter Ci7600, TA.XT Plus and Hyper-spectral Imager, which demonstrated that all samples treated by these complex disinfectants were not significantly different from untreated group. In conclusion, GML is a potential and superior disinfectant for the chicken process.

Study of the bacterial profile of raw milk butter, made during a challenge test with Listeria monocytogenes, depending on cream maturation temperature

Bacteria can play different roles and impart various flavors and characteristics to food. Few studies have described bacterial microbiota of butter. In this study, next-generation sequencing was used to determine bacterial content of raw milk butter, processed during a challenge test, depending on cream maturation temperature and on the presence or not of L. monocytogenes. Two batches were produced. pH and microbiological analyses were conducted during cream maturation and butter storage. DNA was also isolated from all samples for 16S rRNA amplicon sequencing analysis. For butter made from cream matured at 14 °C, a growth potential of L. monocytogenes of - 1.72 log cfu/g was obtained. This value corresponds to the difference between the median of counts at the end of storage and the median of counts at the beginning of storage. This butter (pH value of 4.75 ± 0.04) was characterized by a dominance of Lactococcus. The abundance of Lactococcus was significantly higher in inoculated samples than in control samples (p value < 0.05). Butter made from cream matured at 4 °C (pH value of 6.81 ± 0.01) presented a growth potential of 1.81 log cfu/g. It was characterized by the abundance of psychrotrophic bacteria mainly Pseudomonas. This study demonstrated that cream maturation temperature impacts butter microbiota, affecting thus product's characteristics and its ability to support or not the growth of pathogens like L. monocytogenes.

Plasma activated water-induced formation of compact chicken myofibrillar protein gel structures with intrinsically antibacterial activity

The poor gel strength and microbial infection of conventional chicken myofibrillar protein (CMP) gels have severely limited the application. Here, plasma activated water (PAW) instead of normal water was used to prepare CMP gels. PAW prepared by treating deionized water with plasma jet was incubated with CMPs and followed by heating to prepare CMP gels. Effects of PAW on CMP gels were assessed in terms of basic physicochemical properties, network structure, and antibacterial activity. The results showed that PAW treatment accelerated the aggregation of CMPs and increased the strength and water holding capacity of CMP gels. Due to the presence of NO and NO₂ free radicals in PAW, the prepared CMP gels were endowed with antibacterial activity against Salmonella Enteritidis and Staphylococcus aureus. The new method of PAW-induced CMP gels will have the prospect of improving the quality of gels and extending the shelf life of chicken gel products.

Listeria monocytogenes inhibition by lactic acid bacteria and coliforms in Brazilian fresh white cheese

INTRODUCTION

Minas fresh cheese (MFC), a Brazilian white cheese, is one of the most popular cheeses nationwide. Studies have shown that Listeria monocytogenes occurrence in this product is generally low, while high populations of coliforms can be found. This study aimed to evaluate the influence of coliforms in the behavior of L. monocytogenes in MFC.

METHODS

Pasteurized milk was inoculated with L. monocytogenes and coliforms, and the acidification was made by lactic acid or by the addition of a starter culture. The cheeses of each production were divided into 3 groups and stored at 5 ºC, 12 ºC and cycles of 5 ºC followed by 25 ºC. In predetermined days, samples were taken and L. monocytogenes, coliforms and lactic acid bacteria populations were evaluated, besides the pH, water activity (aw), titratable acidity and NaCl concentration.

RESULTS

The inhibition of L. monocytogenes in the presence of coliforms was observed (p < 0.05), except for those samples prepared with lactic acid and stored at temperature cycles. The values of pH and aw were not sufficiently low to cause inhibition; however, titratable acidity was higher in cheeses containing coliforms. In vitro tests containing lactic acid and L. monocytogenes showed that the bacterium is sensitive to concentration of lactic acid ≥ 0.3%, indicating that lactic acid produced by coliforms strongly influences the population of L. monocytogenes.

CONCLUSIONS

Thus, it can be concluded that coliforms negatively impact populations of L. monocytogenes in MFC. We strongly recommend that producers of MFC adopt good hygiene practices to not only avoid contamination with L. monocytogenes, but also coliforms.

Glycerol monolaurate nanocapsules for biomedical applications: in vitro toxicological studies

The glycerol monolaurate (GML) is a surfactant used in the food industry and has potent antimicrobial activity against many microorganisms; however, the use of GML is not expanded due its high melting point and poor solubility in water. The aim of the study was to produce, characterize, and evaluate in vitro the cytotoxicity of GML and GML nanocapsules. The GML nanocapsules were produced and characterized by a mean diameter, zeta potential, and polydispersity index. The cytotoxicity was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), lactate dehydrogenase (LDH) release, thiobarbituric acid reactive substances (TBARS), and hemolytic activity. The genotoxicity was verified by comet assay. The physicochemical parameters showed a mean diameter of 192.5 ± 2.8 nm, a polydispersity index of 0.061 ± 0.018, and a zeta potential about - 21.9 ± 1 mV. The viability test demonstrated the protector effect of GML nanocapsule compared with the GML on peripheral blood mononuclear cells (PBMC) and VERO cells (isolated from kidney epithelial cells extracted from an African green monkey). A reduction in lipid peroxidation and lactate dehydrogenase release in GML nanocapsule-exposed cells compared with GML treated cells was observed. The damage on erythrocytes was addressed in treatment with GML, while the treatment with GML nanocapsules did not cause an effect. Moreover, the comet assay showed that the GML-caused genotoxicity and GML nanocapsules do not demonstrate damage. The study showed the reduction of toxicity of GML nanocapsules by many methods used in antimicrobial therapy.

Glycerol monolaurate in the diet of broiler chickens replacing conventional antimicrobials: Impact on health, performance and meat quality

Glycerol monolaurate (GML), known as lauric acid, is a chemical compound formed from lauric acid and glycerol that presents strong antimicrobial activity. Therefore, our hypothesis is that MGL can replace conventional antimicrobials, being a new alternative to poultry farming. The aim of this study was to evaluate whether the addition of GML as a replacement for antibiotics could have positive effects on health and performance of broiler chickens. For this, 240, one-day-old, Cobb 500 broiler chicks were weighed and randomly distributed into four groups with four repetitions each (n = 15). The control group, T0, received a basal diet containing antibiotic (60 ppm of bacitracin), while the T100, T200, and T300 groups received a basal diet supplemented with 100, 200, and 300 mg/kg of GML, respectively. The birds were weighed at intervals of seven days, as well as at the end of the experiment (day 42). Blood samples were collected for evaluating animal health, stool for counting bacteria and coccidian, as well as muscle (chest) to measure meat quality, respectively. At the end of the experiment (day 42), body weight, weight gain, and daily weight gain of broiler chickens in the T300 group were higher than the T0 group (P < 0.05). Indeed, feed conversion was lower compared to T0. Animals that received diets containing GML showed lower amounts of Eimeria spp. oocysts on day 42 in comparison to the control group. Low total bacterial counts on day 21 of the experiment were also observed in the treated groups. Conversely, plasma levels of total protein, globulins, uric acid, and glucose were higher in animals that received GML when compared to the control group. It was also observed higher carcass yields in the breast muscle of the T100 group when compared to other groups. Lower water holding capacity was observed in breast meat of animals of the groups T100, T200, and T300 when compared to T0. Histopathological findings were compatible with coccidiosis, and the degree of these lesions did not differ among groups. Based on these results, GML in the diets of broiler chickens, showing potent antimicrobial effect, growth promoter capacity, and lack of toxicity. Therefore, GML is a promising alternative to replace conventional antimicrobials used in the diets of broiler chickens.

Coconut Bio-yoghurt Phytochemical-chemical and Antimicrobial-microbial Activities

BACKGROUND AND OBJECTIVE

Coconut flour is known to be highly nutritious flour and contains high dietary fiber. The aim of this study was to make "bio-yoghurt beverage grafted with coconut flour and containing probiotic bacteria which is recommended as a functional milk product.

MATERIALS AND METHODS

Chemical, phytochemical studies and antimicrobial activity have been performed on coconut flour which was used to make the beverage. Bio-yoghurt beverages made with different ratios of coconut flour (0, 2, 4 and 6%) were chemical, microbiological and sensory tested when fresh and during storage for 15 days of cold storage.

RESULTS

Chemical composition of coconut flour showed reasonable contents of moisture, ash, fat, fatty acids, protein, crude fiber, total solids, total phenols and antioxidants. Coconut flour showed antibacterial activity against some foodborne pathogenic bacteria. The addition of coconut flour to make bio-yoghurt beverages increased its contents of total solids, protein, ash, fiber, acidity, antioxidant activity, total phenols, improved yoghurt sensory and rheological properties especially when probiotic bacteria were used. The results did not reveal any significant differences (p>0.05), between the bacterial counts of yoghurt starter culture, Lactobacillus rhamnosus, Lactobacillus casei in yoghurt control (without coconut) and bio-yoghurt treatments (with coconut), during cold storage. Moulds and yeasts were not detected in all bio-yoghurt treatments; meanwhile they appeared in yoghurt control after 15 days indicating coconut antifungal activity and subsequently a period of time to save more for this drink. All bio-yoghurt beverages with different ratios of coconut flour were sensory accepted and showed more favorable properties, particularly for the viscosity.

CONCLUSION

A new functional dairy product of bio-yoghurt beverage contain coconut flour high fiber content was prepared with probiotic bacteria and showed good chemical, microbiological and sensory/rheological properties.

Physical and Chemical Methods for the Reduction of Biological Hazards in Animal Feeds

Feed for livestock animals have been under increased scrutiny as a vector for pathogenic bacteria leading to human illnesses. Control of these pathogenic bacteria in animal feeds can be controlled via physical and chemical means. Physical methods can include thermal processing, including irradiation, pelleting, and extrusion. Chemical mitigation can be accomplished through the inclusion of various additives, including formaldehyde, organic acids, essential oils, or medium chain fatty acids. While physical and chemical interventions can help mitigate risk of pathogens contaminating finished animal feeds, the implementation of a biosecurity plan at the feed mill can help prevent pathogens from entering or spreading throughout the facility.

Modeling the Combined Effect of Pressure and Mild Heat on the Inactivation Kinetics of Escherichia coli, Listeria innocua, and Staphylococcus aureus in Black Tiger Shrimp (Penaeus monodon)

The high-pressure inactivation of Escherichia coli, Listeria innocua, and Staphylococcus aureus was studied in black tiger shrimp (Penaeus monodon). The processing parameters examined included pressure (300 to 600 MPa) and temperature (30 to 50°C). In addition, the pressure-hold period (0 to 15 min) was investigated, thus allowing both single-pulse pressure effects (i.e., zero holding time) and pressure-hold effects to be explored. E. coli was found to be the most sensitive strain to single-pulse pressure, followed by L. innocua and lastly S. aureus. Higher pressures and temperatures resulted in higher destruction rates, and the value of the shape parameter (β') accounted for the downward concavity (β' > 1) of the survival curves. A simplified Weibull model described the non-linearity of the survival curves for the changes in the pressure-hold period well, and it was comparable to the original Weibull model. The regression coefficients (R2), root mean square error (RMSE), accuracy factor (Af ), bias factor (Bf ), and residual plots suggested that using linear models to represent the data was not as appropriate as using non-linear models. However, linear models produced good fits for some pressure-temperature combinations. Analogous to their use in thermal death kinetics, activation volume (Va ) and activation energy (Ea ) can be used to describe the pressure and temperature dependencies of the scale parameter (δ, min), respectively. The Va and Ea values showed that high pressure and temperaturefavored the inactivation process, and S. aureus was the most baro-resistant pathogen.

Effects of malic acid or/and grapefruit seed extract for the inactivation of common food pathogens on fresh-cut lettuce

This study investigated the antimicrobial activity of malic acid (MA), grapefruit seed extract (GSE), and combined (MA+GSE) treatment against Escherichia coli O157:H7, Salmonella Typhimurium, and Listeria monocytogenes on fresh-cut lettuce. The antimicrobial effects of 1% MA and 0.5% GSE alone and in combination (1% MA+0.5% GSE) were tested on artificially inoculated lettuce during storage at 5°C for 14 days. The maximum reductions of E. coli O157:H7, S. Typhimurium, and L. monocytogenes were 4.96, 4.80, and 3.95 log CFU/g observed with MA+GSE during storage for 14 days, respectively. MA+GSE showed the greatest reduction against in E. coli O157:H7 and L. monocytogenes. These results indicate that the combined treatment was more effective than MA and GSE alone treatment. Therefore, it suggests that MA + GSE could be used as an effective intervention method for improving microbiological safety of fresh-cut lettuce.

Evaluating Chemical Mitigation of Salmonella Typhimurium ATCC 14028 in Animal Feed Ingredients

Salmonella Typhimurium is a potential feed safety hazard in animal feed ingredients. Thermal mitigation of Salmonella spp. during rendering is effective but does not eliminate the potential for cross-contamination. Therefore, the objective of this experiment was to evaluate the effectiveness of chemicals to mitigate postrendering Salmonella Typhimurium ATCC 14028 contamination in rendered proteins over time. Treatments were arranged in a 6 × 4 factorial with six chemical treatments and four rendered protein meals. The chemical treatments included (i) control without chemical treatment, (ii) 0.3% commercial formaldehyde product, (iii) 2% essential oil blend, (iv) 2% medium chain fatty acid blend, (v) 3% organic acid blend, and (vi) 1% sodium bisulfate. The four rendered protein meals included (i) feather meal, (ii) blood meal, (iii) meat and bone meal, and (iv) poultry by-product meal. After matrices were chemically treated, they were inoculated with Salmonella Typhimurium ATCC 14028, stored at room temperature, and enumerated via plate counts on days 0, 1, 3, 7, 14, 21, and 42 postinoculation. The Salmonella concentration in ingredients treated with medium chain fatty acid and commercial formaldehyde were similar to one another (P = 0.23) but were 2 log lower than the control (P < 0.05). Ingredients treated with organic acids and essential oils also had lower Salmonella concentrations than the control (P < 0.05). Time also played a significant role in Salmonella mitigation, because all days except days 14 and 21 (P = 0.92) differed from one another. Rendered protein matrix also affected Salmonella stability, because concentrations in meat and bone meal and blood meal were similar to one another (P = 0.36) but were greater than levels in feather meal and poultry by-product meal (P < 0.05). In summary, chemical treatment and time both mitigated Salmonella Typhimurium ATCC 14028, but their effectiveness was matrix dependent. Time and chemical treatment with medium chain fatty acids or a commercial formaldehyde product were most effective at mitigating Salmonella Typhimurium ATCC 14028 in rendered protein meals.

Inactivation of murine norovirus-1 and hepatitis A virus on fresh meats by atmospheric pressure plasma jets

In the current study, inactivation effect of atmospheric pressure plasma (APP) jets (10s-20min) was investigated against murine norovirus (MNV-1), as a norovirus (NoV) surrogate and hepatitis A virus (HAV) associated with three types of fresh meats (beef loin, pork shoulder and chicken breast). The quality characteristics of fresh meats, such as surface color, moisture content and thiobarbituric acid reactive substance (TBARS) were also examined. After 5-20min of treatment with APP jets, the reduction in MNV-1 titers (initial inoculums of 10⁷ plaque-forming units (PFU)) were >2log₁₀PFU/mL in the three types of meat. After 5-20min treatment with APP jets, the reduction in HAV titers (initial inoculums of 10⁶PFU) were >1log₁₀PFU/mL in the three types of meat. There was no significant difference (p>0.05) in the L*, a*, and b* values for APP jet treatment times below 5min. Furthermore, there was no significant difference (p>0.05) in the water content (%) value for treatment times under 5min. Although the TBARS values gradually increased with increase in APP jet treatment times, these TBA values were below 1.0mgMA/kg (an indicator of meat rancidity). The results of the current study indicate that 5min of APP jet treatment showed >99% reduction (2log₁₀PFU/mL) of MNV-1 titer and >90% reduction (1log₁₀PFU/mL) of HAV titer without concomitant changes in meat quality; thus, this procedure can be considered in fresh meat production, processing and distribution processes to enhance fresh meat safety.

Fumaric Acid and Slightly Acidic Electrolyzed Water Inactivate Gram Positive and Gram Negative Foodborne Pathogens

Sanitizing effectiveness of slightly acidic electrolyzed water (SAEW) and fumaric acid (FA) at different dipping temperatures (25-60 °C), times (1-5 min), and concentrations (5-30 ppm for SAEW and 0.125%-0.5% for FA) on pure cultures of two Gram positive pathogens Staphylococcus aureus (SA) and Listeria monocytogenes (LM) and two Gram negative pathogens Escherichia coli O157:H7 (EC) and Salmonella Typhimurium (ST) was evaluated. FA (0.25%) showed the strongest sanitizing effect, demonstrating complete inactivation of EC, ST, and LM, while SA was reduced by 3.95-5.76 log CFU/mL at 25-60 °C, respectively, after 1 min of treatment. For SAEW, the complete inactivation was obtained when available chlorine concentration was increased to 20 ppm at 40 °C for 3 and 5 min. Moreover, Gram positive pathogens have been shown to resist to all treatment trends more than Gram negative pathogens throughout this experiment. Regardless of the different dipping temperatures, concentrations, and times, FA treatment was more effective than treatment with SAEW for reduction of foodborne pathogens. This study demonstrated that application of FA in food systems may be useful as a method for inactivation of foodborne pathogens.

Combined effects of chlorine and thiamine dilauryl sulfate on reduction of Listeria monocytogenes in chicken breast and development of predictive growth models

The inhibitory effect of chlorine (50, 100, and 200 mL/kg) and thiamine dilauryl sulfate (TDS: 100, 500, and 1,000 mg/kg) on Listeria monocytogenes in chicken breast was investigated. Also, predictive growth models as a function of chlorine and TDS concentration, and storage temperature (4, 10, and 15°C) were developed using a polynomial model. Listeria monocytogenes counts were significantly (P < 0.05) different in samples treated with sterile distilled water and combinations of chlorine and TDS. The maximum reduction effect was 0.5 log cfu/g by combined treatment of 200 mL/kg chlorine and 1,000 mg/kg TDS. The largest synergistic effect was 0.38 log cfu/g by combined treatment of 100 mL/kg chlorine and 1,000 mg/kg TDS. The primary models that were developed to obtain the specific growth rates (SGR) and lag time (LT) had good fitness (R(2) > 0.91) determined by the reparameterized Gompertz equation. The secondary polynomial models were calculated by nonlinear regression analysis. In the validation of the developed models, the bias factor (Bf) and accuracy factor (Af) for SGR were 0.54 and 1.84, respectively, whereas those for LT were 0.97 and 1.04, respectively. In quality analysis, chlorine and TDS did not change the color or texture of chicken breast meat during storage at 4°C for 7 d. Thus, our findings indicate that a combined treatment of 100 mL/kg chlorine and 1,000 mg/kg TDS appears to an effective method into reduce L. monocytogenes in broiler carcasses with no negative effects on color and textural quality. The predictive models were in good agreement with the validation and may be used to predict L. monocytogenes growth in chicken breast.

Combined effects of high pressure processing and addition of soy sauce and olive oil on safety and quality characteristics of chicken breast meat

This study was conducted to evaluate the combined effect of high pressure (HP) with the addition of soy sauce and/or olive oil on the quality and safety of chicken breast meats. Samples were cut into 100 g pieces and 10% (w/w) of soy sauce (SS), 10% (w/w) of olive oil (OO), and a mixture of both 5% of soy sauce and 5% olive oil (w/w) (SO) were pressurized into meat with high pressure at 300 or 600 MPa. Cooking loss was lower in OO samples than SS samples. With increased pressure to 600 MPa, the oleic acid content of OO samples increased. The total unsaturated fatty acids were the highest in SO and OO 600 MPa samples. Lipid oxidation was retarded by addition of olive oil combined with HP. The addition of olive oil and soy sauce followed by HP decreased the amount of volatile basic nitrogen during storage and reduced the population of pathogens. Sensory evaluation indicated that the addition of olive oil enhanced the overall acceptance and willingness to buy. In conclusion, the combination of HP with the addition of soy sauce and/or olive oil is an effective technology that can improve chemical, health, sensory qualities and safety of chicken breast.

Controlling Vibrio vulnificus and spoilage bacteria in fresh shucked oysters using natural antimicrobials

This study evaluated the efficacy of grape seed extract (GE), citric acid (CA) and lactic acid (LA) on the inactivation of Vibrio vulnificus and inherent microflora in fresh shucked oysters. The minimum inhibitory concentration (MIC) of GE, CA or LA against V. vulnificus was determined. Furthermore, the shucked oysters were artificially inoculated with V. vulnificus. The inoculated shucked oysters (25 g) were then dipped in 250 ml GE, CA or LA solutions for 10 min. The population of V. vulnificus in shucked oysters was determined. The effects of the treatments with GE, CA or LA solutions on the inherent microbiota in fresh shucked oysters during storage at 5°C for 20 days were also studied. The MICs of GE, CA or LA against V. vulnificus were 10.0, 5.0 or 1.0 mg ml(-1), respectively. The concentrations of 500, 300 or 150 mg ml(-1) GE, CA or LA solutions were needed to reduce the population of V. vulnificus to below the detection level (1.0 log g(-1)). Treatment with 500, 300, 150 mg ml(-1) GE, CA or LA significantly reduced the initial inherent microbiota in fresh shucked oysters, and inherent levels were significantly (P < 0.05) lower than the control sample throughout refrigerated storage for 20 days.

SIGNIFICANCE AND IMPACT OF THE STUDY

Oysters filter large volume of seawater during their feeding activities that concentrate bacteria such as Vibrio vulnificus in their body. The presence of V. vulnificus in oysters has a serious impact on public health and international trade. There is increasing concern over the use of chemical preservatives. Furthermore, the food industry is looking for new natural preservation methods. This study indicated that lactic acid and citric acid wash solutions could offer an inexpensive, natural and strong approach to control V. vulnificus and spoilage bacteria in fresh shucked for the oyster industry.

E. coli O157:H7 and other toxigenic strains: the curse of global food distribution

It is estimated that there are approximately 76 million illnesses, 325,000 hospitalizations, and 5,200 deaths in the US each year attributed to foodborne outbreaks with a total cost of 10-83 billion US dollars a year. While the rates of foodborne disease have remained relatively constant over the last few years, there have been large outbreaks associated with either a component of commercially prepared food or outbreaks that span between states or even countries. With the world population expecting fresh produce year round, organic produce, and exotic foods, these global outbreaks have the potential to increase in number and severity. There needs to be a means to both rapidly identify these outbreaks, screen our food supply, as well as prevent these outbreaks. This article will discuss the global nature of this problem associated with our food and water supply as well as explain potential ways to solve this international problem.

Modulation of cell surface hydrophobicity and attachment of bacteria to abiotic surfaces and shrimp by Malaysian herb extracts

The use of simple crude water extracts of common herbs to reduce bacterial attachment may be a cost-effective way to control bacterial foodborne pathogens, particularly in developing countries. The ability of water extracts of three common Malaysian herbs (Andrographis paniculata, Eurycoma longifolia, and Garcinia atroviridis) to modulate hydrophobicity and attachment to surfaces of five food-related bacterial strains (Bacillus cereus ATCC 14576, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 10145, Salmonella Enteritidis ATCC 13076, Staphylococcus aureus ATCC 25923) were determined. The bacterial attachment to hydrocarbon assay was used to determine bacterial hydrophobicity. Staining and direct microscopic counts were used to determine attachment of bacteria to glass and stainless steel. Plating on selective media was used to determine attachment of bacteria to shrimp. All extracts were capable of either significantly ( P < 0.05) increasing or decreasing bacterial surface hydrophobicity, depending on the herb extract and bacteria combination. Bacterial attachment to all surfaces was either significantly (P < 0.05) increased or decreased, depending on the herb extract and bacteria combination. Overall, hydrophobicity did not show a significant correlation (P > 0.05) to bacterial attachment. For specific combinations of bacteria, surface material, and plant extract, significant correlations (R > 0.80) between hydrophobicity and attachment were observed. The highest of these was observed for S. aureus attachment to stainless steel and glass after treatment with the E. longifolia extract (R = 0.99, P < 0.01). The crude water herb extracts in this study were shown to have the potential to modulate specific bacterial and surface interactions and may, with further work, be useful for the simple and practical control of foodborne pathogens.

Comparison of nitroethane, 2-nitro-1-propanol, lauric acid, Lauricidin® and the Hawaiian marine algae, Chaetoceros, for potential broad-spectrum control of anaerobically grown lactic acid bacteria

The gastrointestinal tract of bovines often contains bacteria that contribute to disorders of the rumen, and may also contain foodborne or opportunistic human pathogens as well as bacteria capable of causing mastitis in cows. Thus there is a need to develop broad-spectrum therapies that are effective while not leading to unacceptably long antibiotic withdrawal times. The effects of the CH(4)-inhibitors nitroethane (2 mg/mL), 2-nitro-1-propanol (2 mg/mL), lauric acid (5 mg/mL), the commercial product Lauricidin® (5 mg/mL), and a finely ground product of the Hawaiian marine algae, Chaetoceros (10 mg/mL), were compared in pure cultures of Streptococcus agalactia, Enterococcus faecium, Streptococcus bovis, and in a mixed lactic acid rumen bacterial culture. Lauricidin® and lauric acid exhibited the most bactericidal acidity against all bacteria. These results suggest potential animal health benefits from supplementing cattle diets with lauric acid or Lauricidin® to improve the health of the rumen and help prevent shedding of human pathogens.