Inhibition of Listeria monocytogenes in vitro and in goat milk by liposomal nanovesicles containing bacteriocins produced by Lactobacillus sakei subsp. sakei 2a

Essential Oils and Their Combination with Lactic Acid Bacteria and Bacteriocins to Improve the Safety and Shelf Life of Foods: A Review

The use of plant extracts (e.g., essential oils and their active compounds) represents an interesting alternative to chemical additives and preservatives applied to delay the alteration and oxidation of foods during their storage. Essential oils (EO) are nowadays considered valuable sources of food preservatives as they provide a healthier alternative to synthetic chemicals while serving the same purpose without affecting food quality parameters. The natural antimicrobial molecules found in medicinal plants represent a possible solution against drug-resistant bacteria, which represent a global health problem, especially for foodborne infections. Several solutions related to their application on food have been described, such as incorporation in active packaging or edible film and direct encapsulation. However, the use of bioactive concentrations of plant derivatives may negatively impact the sensorial characteristics of the final product, and to solve this problem, their application has been proposed in combination with other hurdles, including biocontrol agents. Biocontrol agents are microbial cultures capable of producing natural antimicrobials, including bacteriocins, organic acids, volatile organic compounds, and hydrolytic enzymes. The major effect of bacteriocins or bacteriocin-producing LAB (lactic acid bacteria) on food is obtained when their use is combined with other preservation methods. The combined use of EOs and biocontrol agents in fruit and vegetables, meat, and dairy products is becoming more and more important due to growing concerns about potentially dangerous and toxic synthetic additives. The combination of these two hurdles can improve the safety and shelf life (inactivation of spoilage or pathogenic microorganisms) of the final products while maintaining or stabilizing their sensory and nutritional quality. This review critically describes and collects the most updated works regarding the application of EOs in different food sectors and their combination with biocontrol agents and bacteriocins.

Nanostructured Antimicrobials for Quality and Safety Improvement in Dairy Products

In the food sector, one of the most important economic activities is the dairy industry, which has been facing many challenges in order to meet the increasing demand by consumers for natural and minimally processed products with high quality. In this sense, the application of innovative and emerging technologies can be an interesting alternative, for example, the use of nanotechnology in packaging and as delivery systems. This technology has the potential to improve the quality and safety of dairy products, representing an interesting approach for delivering food preservatives and improving the mechanical, barrier and functional properties of packaging. Several applications and promising results of nanostructures for dairy product preservation can be found throughout this review, including the use of metallic and polymeric nanoparticles, lipid-based nanostructures, nanofibers, nanofilms and nanocoatings. In addition, some relevant examples of the direct application of nanostructured natural antimicrobials in milk and cheese are presented and discussed, as well as the use of milk agar as a model for a preliminary test. Despite their high cost and the difficulties for scale-up, interesting results of these technologies in dairy foods and packaging materials have promoted a growing interest of the dairy industry.

Antimicrobial peptide-based materials: opportunities and challenges

The multifunctional properties of antimicrobial peptides (AMPs) make them attractive candidates for the treatment of various diseases. AMPs are considered alternatives to antibiotics due to the rising number of multidrug-resistant...

A Systematic Review on Nanoencapsulation Natural Antimicrobials in Foods: In Vitro versus In Situ Evaluation, Mechanisms of Action and Implications on Physical-Chemical Quality

Natural antimicrobials (NA) have stood out in the last decade due to the growing demand for reducing chemical preservatives in food. Once solubility, stability, and changes in sensory attributes could limit their applications in foods, several studies were published suggesting micro-/nanoencapsulation to overcome such challenges. Thus, for our systematic review the Science Direct, Web of Science, Scopus, and Pub Med databases were chosen to recover papers published from 2010 to 2020. After reviewing all titles/abstracts and keywords for the full-text papers, key data were extracted and synthesized. The systematic review proposed to compare the antimicrobial efficacy between nanoencapsulated NA (nNA) and its free form in vitro and in situ studies, since although in vitro studies are often used in studies, they present characteristics and properties that are different from those found in foods; providing a comprehensive understanding of primary mechanisms of action of the nNA in foods; and analyzing the effects on quality parameters of foods. Essential oils and nanoemulsions (10.9–100 nm) have received significant attention and showed higher antimicrobial efficacy without sensory impairments compared to free NA. Regarding nNA mechanisms: (i) nanoencapsulation provides a slow-prolonged release to promote antimicrobial action over time, and (ii) prevents interactions with food constituents that in turn impair antimicrobial action. Besides in vitro antifungal and antibacterial, nNA also demonstrated antioxidant activity—potential to shelf life extension in food. However, of the studies involving nanoencapsulated natural antimicrobials used in this review, little attention was placed on proximate composition, sensory, and rheological evaluation. We encourage further in situ studies once data differ from in vitro assay, suggesting food matrix greatly influences NA mechanisms.

Controlled Release Study on Bifidocin A from a Polyvinyl Alcohol/Chitosan Blend Particle-Based Biodegradable and Active Packaging Coupled with Mechanistic Assessment and Experimental Modeling

On the basis of PVA-CS, which is incorporated with Bifidocin A, anti-microbial biodegradable films were prepared, characterized by their abilities to control the Bifidocin A's total release rate into foods as needed for packaging of active foods. This study aimed to explore the anti-microbial effects and release kinetics of active substances in polyvinyl alcoholchitosan (PVA-CS) particle composite films added with Bifidocin A. Pseudomonas fluorescens was used as indicator bacteria to evaluate the anti-microbial activity of the films. Fick's law, power law and negative exponential growth model were applied to further study the release kinetics of Bifidocin A. The results revealed that the composite films of PVA and CS had better mechanical properties and anti-microbial activity when the content of Bifidocin A was 50% with 1:1 PVA/CS, but it impairs the structure of the film, which can be resolved by including a suitable amount of grycerol. The anti-microbial was released faster at higher temperature and concentration of Bifidocin A, and the diffusion coeffcients increased significantlywith the increase of temperature and concentration. According to the thermodynamic parameters, the release of Bifidocin A was endothermic and spontaneous. High correlation factors (R² > 0.99) were acquired by fitting the release data of the Bifidocin A with the negative exponential growth model. The potential of Bifidocin A to deliver from the films into the food analog appropriately at low temperatures favored the obtained active films to be applied on food packaging, especially suitable for refrigerated foods.

Integrated Phenotypic-Genotypic Analysis of Latilactobacillus sakei from Different Niches

Increasing attention has been paid to the potential probiotic effects of Latilactobacillus sakei. To explore the genetic diversity of L. sakei, 14 strains isolated from different niches (feces, fermented kimchi, and meat products) and 54 published strains were compared and analyzed. The results showed that the average genome size and GC content of L. sakei were 1.98 Mb and 41.22%, respectively. Its core genome mainly encodes translation and transcription, amino acid synthesis, glucose metabolism, and defense functions. L. sakei has open pan-genomic characteristics, and its pan-gene curve shows an upward trend. The genetic diversity of L. sakei is mainly reflected in carbohydrate utilization, antibiotic tolerance, and immune/competition-related factors, such as clustering regular interval short palindromic repeat sequence (CRISPR)-Cas. The CRISPR system is mainly IIA type, and a few are IIC types. This work provides a basis for the study of this species.

Lipid-Based Nanostructures for the Delivery of Natural Antimicrobials

Encapsulation can be a suitable strategy to protect natural antimicrobial substances against some harsh conditions of processing and storage and to provide efficient formulations for antimicrobial delivery. Lipid-based nanostructures, including liposomes, solid lipid nanoparticles (SLNs), and nanostructured lipid nanocarriers (NLCs), are valuable systems for the delivery and controlled release of natural antimicrobial substances. These nanostructures have been used as carriers for bacteriocins and other antimicrobial peptides, antimicrobial enzymes, essential oils, and antimicrobial phytochemicals. Most studies are conducted with liposomes, although the potential of SLNs and NLCs as antimicrobial nanocarriers is not yet fully established. Some studies reveal that lipid-based formulations can be used for co-encapsulation of natural antimicrobials, improving their potential to control microbial pathogens.

Potential use of ultrasound to promote fermentation, maturation, and properties of fermented foods: A review

Conventional food fermentation is time-consuming, and maturation of fermented foods normally requires a huge space for long-term storage. Ultrasound is a technology that emerged in the food industry to improve the efficacy of food fermentation and presents great potentials in maturation of fermented foods to produce fermented foods with high quality. Proliferation of microorganisms was observed along with promoted enzyme activities and metabolic performance when treated by a short-term ultrasonication (<30 min) at a relatively low-power (≤100 W). Additionally, ultrasound at a high-power level (≥100 W) was highlighted to promote the maturation of fermented foods through promoting Maillard reaction, oxidation, esterification, and proteolysis. As a result of promoted fermentation and maturation, texture, color, flavor and taste of fermented foods were improved. All the reviewed studies have indicated that ultrasound at the proper conditions would be a promising technique to produce fermented foods with high-quality.

Micro/nanoencapsulation strategy to improve the efficiency of natural antimicrobials against Listeria monocytogenes in food products

Listeria monocytogenes (Lm), the etiological agent of listeriosis diseases in humans, is a serious pathogenic microorganism threatening the food safety especially in ready-to-eat food products. Adhesion on both biotic and abiotic surfaces is making it a potential source of contamination by Lm. Also, this bacterium has become more tolerant in food processing conditions, including in the presence of adverse conditions such as cold and dehydration. One of the attractive and effective methods to inhibit the growth of Lm in the food products is using natural antimicrobial agents, which can be a suitable alternative to synthetic preservatives for producing organic food products. The use of pure natural antimicrobials has some limitations including low stability against harsh conditions, low solubility and absorption, and un-controlled release, which can decrease their functions. These limitations have been overcome by using new advanced encapsulation techniques, which have boosted the anti-listerial activity of natural agents. Therefore, the current paper is aiming to review the results of recent studies conducted on using natural antimicrobials added directly or as encapsulated forms into the food formulation to control the growth of Lm. The information of current study can be used by the researchers as well as the food companies for the optimization of food formulations through encapsulation strategies to control Lm and potentially produce safe foods for the consumers.

Preparation of phosphatidylcholine nanovesicles containing bacteriocin CAMT2 and their anti-listerial activity

A novel bacteriocin CAMT2, produced by Bacillus amyloliquefaciens ZJHD3-06, has potential as a natural biopreservative for the control of food-borne spoilage and pathogenic bacteria. To avoid interaction of CAMT2 with components of food that may adversely impact its antibacterial activity, CAMT2 was encapsulated into nanovesicles prepared from soybean phosphatidylcholine. The encapsulation of CAMT2 exhibited a limited impact on functional structure and crystallinity of bacteriocin CAMT2, but a high anti-listerial activity in agar, and increase its stability in food at refrigeration temperature (4 °C). The results also showed that both encapsulated and free CAMT2 had good anti-listerial effect in skim milk at refrigeration temperature. However, encapsulated CAMT2 performed better than free CAMT2 against Listeria in whole milk. These results showed that nano-encapsulation is an effective method of protecting bacteriocin from fat in milk and retaining its antimicrobial efficacy.

Advances in Lipid and Metal Nanoparticles for Antimicrobial Peptide Delivery

Antimicrobial peptides (AMPs) have been described as excellent candidates to overcome antibiotic resistance. Frequently, AMPs exhibit a wide therapeutic window, with low cytotoxicity and broad-spectrum antimicrobial activity against a variety of pathogens. In addition, some AMPs are also able to modulate the immune response, decreasing potential harmful effects such as sepsis. Despite these benefits, only a few formulations have successfully reached clinics. A common flaw in the druggability of AMPs is their poor pharmacokinetics, common to several peptide drugs, as they may be degraded by a myriad of proteases inside the organism. The combination of AMPs with carrier nanoparticles to improve delivery may enhance their half-life, decreasing the dosage and thus, reducing production costs and eventual toxicity. Here, we present the most recent advances in lipid and metal nanodevices for AMP delivery, with a special focus on metal nanoparticles and liposome formulations.

Effects of Bioactive Packaging Films Incorporated with Bifidocin A on Microbial Reduction and Quality Parameters of Chill-Stored Spanish Mackerel (Scomberomorus niphonius) Fillets

To evaluate the potential of bifidocin A for preservation of fresh Spanish mackerel fillets, the bioactive packaging films incorporated with bifidocin A (1 × minimal inhibition concentration (MIC), 2 × MIC and 4 × MIC) were developed, and their effects on the microbiological and physicochemical properties and sensory profile of mackerel fillets at refrigerated storage were investigated. Results showed that the incorporation of bifidocin A in cellulosic matrix films did not affect the thickness and elongation of the films, but reduced slightly the tension strength. The films incorporated with 2 × MIC and 4 × MIC bifidocin A presented a broad spectrum of activity against most tested bacteria, including some fish-borne specific spoilage bacteria such as Pseudomonas fluorescens, Shewanella putrefaciens, Brochothrix thermosphacta, and Micrococcus luteus, and maintained their 100% activity for 28 days during storage at 4°C. The bioactive packaging films incorporated with bifidocin A could generally suppress the growth of microflora, especially Pseudomonas and Enterobacteriaceae, as well as substantially inhibit the accumulation of total volatile basic nitrogen (TVB-N), thiobarbituric acid reactive substances (TBARS) and hypoxanthine, during chilled mackerel fillets storage. Overall, from a microbiological and physicochemical point of view, a much more effective treatment was achieved with 4 × MIC bifidocin A, extending the shelf life to 12 days and maintaining the relatively low TVB-N value (≤13.2 mg/100 g), TBARS value (≤0.45 mg MDA/kg), and K-value (≤32.8%), as well as a relatively high sensory score (≥7.1) during the whole storage. Hence, the bioactive packaging films incorporated with bifidocin A could be a promising hurdle technology and alternative to conventional processes used for improving the safety and quality of chilled mackerel fillets.

Advances and challenges in liposome digestion: Surface interaction, biological fate, and GIT modeling

During the past 50 years, there has been increased interest in liposomes as carriers of pharmaceutical, cosmetic, and agricultural products. More recently, much progress has been made in the use of surface-modified formulas in experimental food matrices. However, before the viability and the applications of nutrients in liposomal form in the edible field can be determined, the digestion behavior along the human gastrointestinal tract (GIT) must be clarified. In vitro digestion models, from static models to dynamic mono-/bi-/multi-compartmental models, are increasingly being developed and applied as alternatives to in vivo assays. This review describes the surface interactions of liposomes with their encapsulated ingredients and with external food components and updates the biological fate of liposomes after ingestion. It summarizes current models for the human stomach and intestine that are available and their relevance in nutritional studies. It highlights limitations and challenges in the use of these models for liposomal colloid system digestion and discusses crucial factors, such as enzymes and bile salts, that affect liposomal bilayer degradation.

Prevalence of ectoparasite infestations in owned dogs in Kwara State, Nigeria

In Nigeria, dogs are the common companions in many households and, harbor wide range of ectoparasites of severe zoonotic potentials. A cross sectional survey was conducted to examine the prevalence, intensity and risk factors of ectoparasite infestation among the owned dogs in Kwara state, Nigeria. A total of 333 dogs were screened for ectoparasites, and questionnaires were applied to obtain information regarding; age, sex, breeds, coat colour and management practices by dog owners. Two hundred and seventy one (81.4%) dogs were infested with at least one species of ectoparasite and multiple infestations recorded mostly among the female dogs. Six species of ectoparasites of three taxa were identified: ticks (Rhipicephalus sanguineus sensu lato, Haemaphysalis leachii and Amblyomma variegatum), fleas (Ctenocephalides canis and C. felis) and louse (Heterodoxus spiniger). R. sanguineus s.l. was the most prevalent (70.3%) followed by C. felis (42.1%) and H. spiniger (30.0%). Intensities of C. felis, H. spiniger and R. sanguineus s.l infestations were significantly higher in female and younger dogs (p < 0.001). Ectoparasites occurrence varied with breed and coat colour of host. A high prevalence of ectoparasite infestation recorded is at variance with the knowledge of dogs' owners in this study area. Therefore, intervention based on provision of veterinary clinics and prevention and management of parasite infestation in endemic area would mitigate the possible health hazard associated with the ectoparasitic infestation of dogs.

Control de crecimiento de Listeria monocytogenes en co- cultivo con Lactobacillus plantarum

Listeria monocytogenes (Lm) es un patógeno emergente causante de enfermedades transmitidas por alimentos de consumo masivo principalmente cárnicos y lácteos. Actualmente se buscan diferentes estrategias para su control, entre ellas compuestos naturales producidos por otros microorganismos como  ácidos orgánicos y otros compuestos como lactoferrina, lisozima y bacteriocinas, estas últimas producidas por especies de bacterias como Lactobacillus plantarum (Lp). El objetivo de esta investigación fue determinar el efecto de cepas de Lp aisladas de suero costeño sobre el control de crecimiento de L. monocytogenes inoculada en co-cultivos. Se realizaron curvas de crecimiento para Lm, Lp 60-1 y Lp 62-1 y co-cultivos de cada Lp con Lm.  La cinética de crecimiento fue evaluada determinando la viabilidad durante 24h en agares selectivos. La tasa de crecimiento de L. monocytogenes inoculada como control en leche UHT y en co-cultivos, presentaron diferencias significativas (p<0,05) entre los tratamientos, evidenciando que el control alcanzó un valor promedio de tasa de crecimiento mayor (μmax =0,65 h-1), que el obtenido para los co-cultivos  con Lp 60-1 y Lp 62-1 (μmax =0,22 h-1 y μmax =0,27 h-1 respectivamente). La mayor diferencia fue alcanzada en el co cultivo con Lp  60-1, obteniendo el menor valor promedio de tasa de crecimiento de Lm. Los resultados demuestran la eficiencia de las cepas de Lp (60-1 y 62-1) para el control de crecimiento de Lm en leche UHT comercial, siendo esta una alternativa  para reducir el uso de aditivos químicos durante la producción de lácteos.

Lighting the anaerobic digestion process in rural areas: obtainment of struvite from bovine manure digestate

The objective of this research was to obtain struvite from digested matter from a bio rural digester fed with bovine manure. To determine operating variables to recover struvite (PO43- and NH4+ ions), researchers developed an experiment design in which they evaluated the combined effect of the Mg2+: PO43- molar ratio (1.5:1; 2.5:1 and 3.5:1), reaction time (10, 50 and 90 min) and stirring speed (100, 450 and 800 rpm). The recovery rates obtained were 55±4.94 % and 58±7.72 % for NH4+ and PO43- respectively. The favorable conditions were 1.5 molar ratio, 50 minute reaction time and 450 rpm stirring speed. Struvite crystal formation and composition were confirmed using petrographic microscopy and infrared radiation. Struvite yield was 295.75 mg /l from digestate employed.

Application of Bacteriocins and Protective Cultures in Dairy Food Preservation

In the last years, consumers are becoming increasingly aware of the human health risk posed by the use of chemical preservatives in foods. In contrast, the increasing demand by the dairy industry to extend shelf-life and prevent spoilage of dairy products has appeal for new preservatives and new methods of conservation. Bacteriocins are antimicrobial peptides, which can be considered as safe since they can be easily degraded by proteolytic enzymes of the mammalian gastrointestinal tract. Also, most bacteriocin producers belong to lactic acid bacteria (LAB), a group that occurs naturally in foods and have a long history of safe use in dairy industry. Since they pose no health risk concerns, bacteriocins, either purified or excreted by bacteriocin producing strains, are a great alternative to the use of chemical preservatives in dairy products. Bacteriocins can be applied to dairy foods on a purified/crude form or as a bacteriocin-producing LAB as a part of fermentation process or as adjuvant culture. A number of applications of bacteriocins and bacteriocin-producing LAB have been reported to successful control pathogens in milk, yogurt, and cheeses. One of the more recent trends consists in the incorporation of bacteriocins, directly as purified or semi-purified form or in incorporation of bacteriocin-producing LAB into bioactive films and coatings, applied directly onto the food surfaces and packaging. This review is focused on recent developments and applications of bacteriocins and bacteriocin-producing LAB for reducing the microbiological spoilage and improve safety of dairy products.

Nanostructures for delivery of natural antimicrobials in food

Natural antimicrobial compounds are a topic of utmost interest in food science due to the increased demand for safe and high-quality foods with minimal processing. The use of nanostructures is an interesting alternative to protect and delivery antimicrobials in food, also providing controlled release of natural compounds such as bacteriocins and antimicrobial proteins, and also for delivery of plant derived antimicrobials. A diversity of nanostructures are capable of trapping natural antimicrobials maintaining the stability of substances that are frequently sensitive to food processing and storage conditions. This article provides an overview on natural antimicrobials incorporated in nanostructures, showing an effective antimicrobial activity on a diversity of food spoilage and pathogenic microorganisms.