Technological properties and bacteriocins production by Lactobacillus curvatus 54M16 and its use as starter culture for fermented sausage manufacture

Beyond Conventional Meat Preservation: Saddling the Control of Bacteriocin and Lactic Acid Bacteria for Clean Label and Functional Meat Products

Advancements in food science and technology have paved the way for the development of natural antimicrobial compounds to ensure the safety and quality of meat and meat products. Among these compounds, bacteriocin produced by lactic acid bacteria has gained considerable scientific attention for its ability to preserve the healthy properties of meat while preventing spoilage. This natural preservative is seen as a pioneering tool and a potent alternative to chemical preservatives and heat treatment, which can have harmful effects on the nutritional and sensory qualities of meat. Bacteriocin produced by lactic acid bacteria can be used in various forms, including as starter/protective cultures for fermented meats, purified or partially purified forms, loaded in active films/coatings, or established in encapsulate systems. This review delves into the downstream purification schemes of LAB bacteriocin, the elucidation of their characteristics, and their modes of action. Additionally, the application of LAB bacteriocins in meat and meat products is examined in detail. Overall, the use of LAB bacteriocins holds immense potential to inspire innovation in the meat industry, reducing the dependence on harmful chemical additives and minimizing the adverse effects of heat treatment on nutritional and sensory qualities. This review provides a comprehensive understanding of the potential of bacteriocin produced by lactic acid bacteria as a natural and effective meat preservative.

Effects of Fermentation Temperature, Drying Temperature, Caliber Size, Starter Culture, and Sodium Lactate on Listeria monocytogenes Inactivation During Salami Production

The effect of fermentation and drying temperatures, caliber, and sodium lactate on Listeria monocytogenes inactivation was studied in salami, produced in a pilot scale, inoculated with 107 CFU/g of Listeria innocua ATCC® 33090 as a surrogate microorganism for L. monocytogenes. Fermentation temperature varied between 24 and 30°C, drying temperature between 14 and 20°C, caliber between 5.1 and 13.2 cm, and sodium lactate initial concentrations in salamis were 0 and 2%. L. innocua counts, pH and water activity were determined in salamis over time. Sodium lactate (2%) decreased pH drop and Listeria inactivation during fermentation. Baranyi & Roberts equation was used to fit the experimental data and to estimate, for each test condition, inactivation rate (k), initial (Y0), and final counts of L. innocua (YEND). Total inactivation was calculated as Y0 minus YEND (Y0-YEND). Then, using a Box Benkhen experimental design, a quadratic model for k and a two-factor interaction model (2FI) for Y0 - YEND were obtained as functions of fermentation temperature, drying temperature, and caliber size. The models predicted that maximum k and Y0 -YEND, -2.62 ± 0.14 log10 CFU/g/day and 4.5 ± 0.1 log10 CFU/g, respectively, would be obtained fermenting at 30°C and drying at 20°C regardless of caliber. Drying at 14°C allowed Listeria growth until a water activity (aw) of 0.92 was reached. Therefore, if initial Listeria contamination is high (3 log10 CFU/g), drying at low temperatures will compromise product safety.

Genome-Based Identification and Characterization of Bacteriocins Selectively Inhibiting Staphylococcus aureus in Fermented Sausages

The bacteriocin-producing Lactiplantibacillus plantarum SL47 was isolated from conventional fermented sausages, and the bacteriocin SL47 was purified using ethyl acetate, Sephadex G-25 gel chromatography, and reversed-phase high-performance liquid chromatography (RP-HPLC). Bacteriocin SL47 was identified by HPLC-MS/MS combined with whole-genome sequencing, and the results showed it consisted of plantaricin A, J, K, and N. Further characterization analysis showed that the bacteriocin SL47 was highly thermostable (30 min, 121 °C), pH stable (2-10), sensitive to protease and exhibited broad-spectrum antibacterial ability against Gram-positive and Gram-negative bacteria. The mechanism of action showed that the bacteriocin SL47 increased cell membrane permeability, and 2 × minimum inhibitory concentration (MIC) treatment for 40 min caused apoptosis of Staphylococcus aureus F2. The count of S. aureus in the sausage that was inoculated with L. plantarum SL47 and bacteriocin SL47 decreased by about 64% and 53% of that in the initial stage, respectively. These results indicated the potential of L. plantarum SL47 and bacteriocin SL47 as a bio-preservative in meat products.

Autochthonous Cultures to Improve Safety and Standardize Quality of Traditional Dry Fermented Meats

Traditional dry fermented meat products are obtained artisanally in many countries, where they represent a gastronomic heritage well distinguished from industrial counterparts. This food category is most often obtained from red meat, a food commodity that is under attack because of evidence of increased risk of cancer and degenerative diseases with high consumption. However, traditional fermented meat products are intended for moderate consumption and gastronomic experience, and, as such, their production must be continued, which would also help safeguard the culture and economy of the geographical areas of origin. In this review, the main risks attributed to these products are considered, and how these risks are reduced by the application of autochthonous microbial cultures is highlighted by reviewing studies reporting the effects of autochthonous lactic acid bacteria (LAB), coagulase negative staphylococci (CNS), Debaryomyces hansenii and Penicillium nalgiovense on microbiological and chemical safety and on sensory attributes. The role of dry fermented sausages as a source of microorganisms that can be beneficial to the host is also considered. From the results of the studies reviewed here it appears that the development of autochthonous cultures for these foods can ensure safety and stabilize sensory characteristics and has the capacity to be extended to a larger variety of traditional products.

Lactic Acid Bacteria and Bacteriocins: Novel Biotechnological Approach for Biopreservation of Meat and Meat Products

Meat and meat products are perishable in nature, and easily susceptible to microbial contamination and chemical deterioration. This not only results in an increased risk to health of consumers, but also causes economic loss to the meat industry. Some microorganisms of the lactic acid bacteria (LAB) group and their ribosomal-synthesized antimicrobial peptides-especially bacteriocins-can be used as a natural preservative, and an alternative to chemical preservatives in meat industry. Purified or partially purified bacteriocins can be used as a food additive or incorporated in active packaging, while bacteriocin-producing cells could be added as starter or protective cultures for fermented meats. Large-scale applications of bacteriocins are limited, however, mainly due to the narrow antimicrobial spectrum and varying stability in different food matrixes. To overcome these limitations, bioengineering and biotechnological techniques are being employed to combine two or more classes of bacteriocins and develop novel bacteriocins with high efficacy. These approaches, in combination with hurdle concepts (active packaging), provide adequate safety by reducing the pathogenicity of spoilage microorganisms, improving sensory characteristics (e.g., desirable flavor, texture, aroma) and enhancing the shelf life of meat-based products. In this review, the biosynthesis of different classes of LAB bacteriocins, their mechanism of action and their role in the preservation of meats and meat products are reviewed.

Taxonomical Identification and Safety Characterization of Lactobacillaceae from Mediterranean Natural Fermented Sausages

Fermented meat products represent an important industrial sector in Europe, particularly in the Mediterranean Countries (MC), where the presence of numerous local productions, still obtained through spontaneous fermentation, is recognized as a formidable treasure chest of unexplored microbial biodiversity. Lactobacillaceae naturally occurring in fifteen spontaneously fermented sausages from MC (Italy, Spain, Croatia, and Slovenia) were isolated and taxonomically characterized using molecular techniques. Additionally, a safety assessment for the presence of antibiotic resistances and biogenic amine (BA) production was performed to determine their suitability as autochthonous starter cultures. Molecular typing, performed using REP-PCR, discriminated 151 strains belonging to Latilactobacillus sakei (59.6%), Latilactobacillus curvatus (26.5%) and Companilactobacillus alimentarius (13.9%). The minimum inhibitory concentrations (MICs) of eight different antibiotics revealed a high resistance to streptomycin (27%), tetracycline (16%), followed by gentamycin (14%) and kanamycin (13%). Interestingly, the results showed a geographical distribution of resistant biotypes. tetM/tetS or ermB genes were identified in only six strains. The amino-biogenic potential of the strains was assessed, confirming the absence of this trait among L. sakei, while a high number of producer strains was found among L. curvatus. On the 151 analyzed strains, 45 demonstrated safety traits for their future use as starter food cultures. These results open the way to further studies on the technological properties of these promising autochthonous strains, strongly linked to the Mediterranean environment.

Natural alternatives for processed meat: Legislation, markets, consumers, opportunities and challenges

Consumers' interest in food with less and/or free from synthetic additives has increased considerably in recent years. In this context, researchers and industries have concentrated efforts on developing alternatives to these compounds. Replacing synthetic additives in meat products is a challenge, given their importance for sensory characteristics and food safety. Complementary technologies combined with the replacement and/or reduction of synthetic additives (hurdle technologies) has been studied focusing on the protection and extension of the shelf life of meat products. This review reports alternatives for replacing and/or reducing the use of synthetic additives in meat derivatives, aiming at the development of more natural and simpler meat products, familiar to consumers and considered clean labels.

Advantages and disadvantages of non-starter lactic acid bacteria from traditional fermented foods: Potential use as starters or probiotics

Traditional fermented foods are a significant source of starter and/or non-starter lactic acid bacteria (nsLAB). Moreover, these microorganisms are also known for their role as probiotics. The potential of nsLAB is huge; however, there are still challenges to be overcome with respect to characterization and application. In the present review, the most important steps that autochthonous lactic acid bacteria isolated from fermented foods need to overcome, to qualify as novel starter cultures, or as probiotics, in food technology and biotechnology, are considered. These different characterization steps include precise identification, detection of health-promoting properties, and safety evaluation. Each of these features is strain specific and needs to be accurately determined. This review highlights the advantages and disadvantages of nsLAB, isolated from traditional fermented foods, discussing safety aspects and sensory impact.

Application of Liposome Encapsulating Lactobacillus curvatus Extract in Cosmetic Emulsion Lotion

Probiotic extracts have various positive attributes, such as antioxidant, tyrosinase inhibitory, and antimicrobial activity. Lactobacillus curvatus produces bacteriocin, which activates the lipid membrane structure and has potential as a natural preservative for cosmetic emulsions. In this study, L. curvatus extract was encapsulated in liposomes and formulated as an oil-in-water (O/W) emulsion. Radical scavenging activity, tyrosinase inhibition, and challenge tests were conducted to confirm the liposome activity and the activity of the applied lotion emulsion. The liposome-encapsulated extract had a relatively high absolute ζ-potential (52.53 > 35.43), indicating its stability, and 96% permeability, which indicates its potential as an active agent in lotion emulsions. Characterization of emulsions containing the liposomes also indicated a stable state. The liposome-encapsulated extract exhibited a higher radical scavenging activity than samples without the extract and non-encapsulated samples, and the functionality was preserved in the lotion emulsion. The tyrosinase inhibition activity of the lotion emulsion with the liposome-encapsulated extract was similar to that of the non-treated extract. Candida albicans and Aspergillus niger were also inhibited in the challenge test with the lotion emulsions during storage. Collectively, these findings indicate that the liposome-encapsulated extract and the lotion containing the encapsulated extract have potential applicability as natural preservatives.

Bacteriocin producing microbes with bactericidal activity against multidrug resistant pathogens

BACKGROUND

Bacteriocins are proteins or peptides synthesized by bacteria that show inhibitory or killing activities against various bacteria. Bacteriocins are mainly considered for effective alternatives to different commercial antibiotics, preservatives in the food and pharmaceutical industries.

OBJECTIVES

To screen and analyze novel bacteriocin-producing bacteria from the fermented food shidal for antibacterial activity against food pathogens and their molecular interactions studied through computationally.

METHODS

In this study, a strain Lactobacillus plantarum LA21 was isolated from the fermented food shidal identified based on morphological, biochemical, and 16S rDNA gene sequencing. The potent bacterium was subjected to improve bacteriocins production and characterized. Antimicrobial activity against drug-resistant bacteria and minimum inhibitory concentration (MIC) were determined. The bacteriocin was treated with proteolytic enzymes, and the mechanism of action on food pathogens was analyzed. Molecular docking studies were carried out as GLIDE module in the maestro tool of Schrodinger Software.

RESULTS

Bacteriocin was effective against pathogens such as Bacillus pumilus, Bacillus amyloliquefaciens, Staphylococcus aureus, and Listeria monocytogenes, with the most negligible MIC value was detected in L. monocytogenes. Furthermore, the depleted viability of bacterial cells indicated bacteriocin-induced cell lysis in L. monocytogenes via bactericidal activity. In addition, proteolytic enzyme digested bacteriocins revealed bacteriocin-like substances. Finally, molecular docking was performed to study the interactions between the targets and bacteriocins, results in relative intense contact with minimally 3 Å distance.

CONCLUSIONS

The characteristic features of these bacteriocin-like molecules revealed that L. plantarum LA21 is a novel bacteriocin-producing bacterial strain to prepare novel antimicrobial drugs, feed additives or preservatives for future use in livestock and food industries.

Antibacterial Activity of Pediocin and Pediocin-Producing Bacteria Against Listeria monocytogenes in Meat Products

One of the most important challenges in the food industry is to produce healthy and safe food products, and this could be achieved through various processes as well as the use of different additives, especially chemical preservatives. However, consumer awareness and concern about chemical preservatives have led researchers to focus on the use of natural antimicrobial compounds such as bacteriocins. Pediocins, which belong to subclass IIa of bacteriocin characterized as small unmodified peptides with a low molecular weight (2.7-17 kDa), are produced by some of the Pediococcus bacteria. Pediocin and pediocin-like bacteriocins exert a broad spectrum of antimicrobial activity against Gram-positive bacteria, especially against pathogenic bacteria, such as Listeria monocytogenes through formation of pores in the cytoplasmic membrane and cell membrane dysfunction. Pediocins are sensitive to most protease enzymes such as papain, pepsin, and trypsin; however, they keep their antimicrobial activity during heat treatment, at low temperatures even at -80°C, and after treatment with lipase, lysozyme, phospholipase C, DNase, or RNase. Due to the anti-listeria activity of pediocin on the one hand and the potential health hazards associated with consumption of meat products on the other hand, this review aimed to investigate the possible application of pediocin in preservation of meat and meat products against L. monocytogenes.

Hardening Properties of Cheeses by Latilactobacillus curvatus PD1 Isolated from Hardened Cheese-Ddukbokki Rice Cake

Hardening of cheese is one of major issues that degrade the quality of Home Meal Replacement (HMR) foods containing cheese such as Cheese-ddukbokki rice cake (CD, stir-fried rice cakes with shredded cheese). The quality of cheese, such as pH, proteolytic, and flavor properties, depends on various lactic acid bacteria (LAB) used in cheese fermentation. The hardening of cheese is also caused by LAB. In this study, various LAB strains were isolated from CD samples that showed rapid hardening. The correlation of LAB with the hardening of cheese was investigated. Seven of the CD samples with different manufacturing dates were collected and tested for hardening properties of cheese. Among them, strong-hardening of cheese was confirmed for two samples and weak-hardening was confirmed for one sample. All LAB in two strong-hardening samples and 40% of LAB in one weak-hardening sample were identified as Latilactobacilluscurvatus. On the other hand, most LAB in normal cheese samples were identified as Leuconostoc mesenteroides and Lactobacillus casei. We prepared cheese samples in which L. curvatus (LC-CD) and L. mesenteroides (LM-CD) were most dominant, respectively. Each CD made of the prepared cheese was subjected to quality test for 50 days at 10 °C. Hardening of cheese with LC-CD dominant appeared at 30 days. However, hardening of cheese with LM-CD dominant did not appear until 50 days. The pH of the LC-CD was 5.18 ± 0.04 at 30 days, lower than that of LM-CD. The proteolytic activity of LC-CD sample was 2993.67 ± 246.17 units/g, higher than that of LM-CD sample (1421.67 ± 174.5 units/g). These results indicate that high acid production and high protease activity of L. curvatus might have caused hardening of cheese.

Nitrite reduction in fermented meat products and its impact on aroma

Fermented meat products are important not only for their sensory characteristics, nutrient content and cultural heritage, but also for their stability and convenience. The aroma of fermented meat products is unique and its formation mechanisms are not completely understood; however, the presence of nitrite and nitrate is essential for the development of cured aroma. The use of nitrite and nitrate as curing agents in meat products is based on its preservation activity. Even though their presence has been associated with several risks due to the formation of nitrosamines, their use is guarantee due to their antimicrobial action against Clostridium botulinum. Recent trends and recommendations by international associations are directed to use nitrite but at the minimum concentration necessary to provide the antimicrobial activity against Clostridium botulinum. This chapter discuss the actual limits of nitrite and nitrite content and their role as curing agents in meat products with special impact on dry fermented products. Regulatory considerations, antimicrobial mechanisms and actual trends regarding nitrite reduction and its effect on sensory and aroma properties are also considered.

Functional Characteristics of Lactobacillus and Yeast Single Starter Cultures in the Ripening Process of Dry Fermented Sausage

Dry fermented sausage is popular among the world because of its rich nutrition and unique flavor. Starter cultures play an important role in the quality of dry fermented sausage. In this study, probiotics lactic acid bacteria Lactobacillus delbrueckii N102, Latilactobacillus sakei H1-5, Debaryomyces hansenii Y4-1, and Wickerhamomyces anomalus Y12-3 were isolated from food-borne materials. The physicochemical properties, microbial populations, TBARS, lipolysis, proteolysis, and volatile flavor compounds of dry fermented sausages with different starter cultures were evaluated comparatively during the ripening process. The results showed that both L. delbrueckii N102 and L. sakei H1-5 grow well and could rapidly reduce the pH value of the products. At the same time, they could significantly reduce the number of Enterobacter putrefaciens, so as to ensure the safety of the products. In addition, the strains N102 promoted the formation of flavor compounds 2,3-butanedione, 3-hydroxy-2-butanone, and carnosine, whereas taurine content of batch H1-5 was significantly increased, while yeast y4-1 and y12-3 could also grow faster in sausage and promoted the esters and alcohols formation such as ethyl acetate and linalool, with the formation of γ-aminobutyric acid by y4-1. Compared with lactic acid bacteria, yeasts showed to contribute more in flavor formation and effective inhibition of lipid oxidation. The starter cultures played different roles in flavor contribution and had obvious differentiation in the ripening process of dry fermented sausage.

Latilactobacillus curvatus: A Candidate Probiotic with Excellent Fermentation Properties and Health Benefits

Latilactobacillus curvatus is a candidate probiotic that has been included in the list of recommended biological agents for certification by the European Food Safety Authority. According to the published genomic information, L. curvatus has several genes that encode metabolic pathways of carbohydrate utilization. In addition, there are some differences in cell surface complex related genes of L. curvatus from different sources. L. curvatus also has several genes that encode bacteriocin production, which can produce Curvacin A and Sakacin P. Due to its ability to produce bacteriocin, it is often used as a bioprotective agent in fermented meat products, to inhibit the growth of a variety of pathogenic and spoilage bacteria. L. curvatus exerts some probiotic effects, such as mediating the production of IL-10 by dendritic cells through NF-κB and extracellular regulated protein kinases (ERK) signals to relieve colitis in mice. This review is the first summary of the genomic and biological characteristics of L. curvatus. Our knowledge on its role in the food industry and human health is also discussed, with the aim of providing a theoretical basis for the development of applications of L. curvatus.

Technological Feature Assessment of Lactic Acid Bacteria Isolated from Cricket Powder's Spontaneous Fermentation as Potential Starters for Cricket-Wheat Bread Production

The bacterial community profile of cricket powder highlighted the presence of four main genera: Bacteroides spp., Parabacteroides spp., Lactococcus spp., and Enterococcus spp. The spontaneous fermentation of cricket powder allowed for the isolation and characterization of seven lactic acid bacteria strains belonging to six species: Latilactobacillus curvatus, Lactiplantibacillus plantarum, Latilactobacillus sakei, Lactococcus garvieae, Weissella confusa, and Enterococcus durans. The strains were characterized and selected according to different technological properties. L. plantarum CR L1 and L. curvatus CR L13 showed the best performance in terms of general aminopeptidase activity, acidification, and growth rate in MRS broth and in dough with cricket powder and wheat flour, as well as robustness during consecutive backslopping. Thus, they were used as starter-mixed to produce sourdough to manufacture bread fortified with 20% cricket powder. The addition of cricket powder led to a significant increase of protein (up to 94%) and lipid content, from 0.7 up to 6 g/100 g of bread. Spontaneous fermentation represents a source of microbial diversity that can be exploited in order to obtain potential starters for food with innovative ingredients. Edible insects powder can be successfully added in leavened baked goods to enhance their nutritional value.

Principles and applications of non-thermal technologies and alternative chemical compounds in meat and fish

Conventional methods of food preservation have demonstrated several disadvantages and limitations in the efficiency of the microbial load reduction and maintain food quality. Hence, non-thermal preservation technologies (NTPT) and alternative chemical compounds (ACC) have been considered a high promissory replacer to decontamination, increasing the shelf life and promoting low levels of physicochemical, nutritional and sensorial alterations of meat and fish products. The combination of these methods can be a potential alternative to the food industry. This review deals with the most critical aspects of the mechanisms of action under microbial, physicochemical, nutritional and sensorial parameters and the efficiency of the different NTPT (ultrasound, high pressure processing, gamma irradiation and UV-C radiation) and ACC (peracetic acid, bacteriocins, nanoparticles and essential oils) applied in meat and fish products. The NTPT and ACC present a high capacity of microorganisms inactivation, ensuring low alterations level in the matrix and high reduction of environmental impact. However, the application conditions of the different methods as exposition time, energy intensity and concentration thresholds of chemical compounds need to be specifically established and continuously improved for each matrix type to reduce to the maximum the physicochemical, nutritional and sensorial changes. In addition, the combination of the methods (hurdle concept) may be an alternative to enhance the matrix decontamination. In this way, undesirable changes in meat and fish products can be further reduced without a decrease in the efficiency of the decontamination.

Isolation, Identification and Antimicrobial Activity of Unprecedented Lactic Acid Bacterial Isolates from Honeybees

BACKGROUND AND OBJECTIVE

Lactic acid bacteria are generally recognized as safe that could be beneficial for several uses in food industry to get their health benefits. The present study was focused on the isolation and identification of some new lactic acid bacteria that might be naturally occurred in the honeybees stomach and tried to explore their benefits.

MATERIALS AND METHODS

Twenty five isolates of lactic acid bacteria were isolated from the stomach of three different types of Egyptian bees (Apis mellifera lamarckii ), Carniolan bees (A.m. carnica) and hybrid Carniolan bees. Identification of isolates was carried out based on phenotypical tests and carbohydrate assimilation using API50 CHL and 16S rDNA sequencing.

RESULTS

In the present study, the results emphasized Lactobacillus plantarum to be the predominant species (62.5%), other strains were identified as Pediococcus pentosaceus (12.5%), Lactobacillus pentosus (12.5%) and Lactobacillus sakei (12.5%). Eight of 25 isolates showed a potential antibacterial activity especially against Salmonella senftenberg strain. The novel isolates (HBMSS1, HBMSS3, HBMSS4, HBMSS5, HBMSS6 and HBMSS8) showed a significant antimicrobial activity against C. botulinum, E. coli, S. Senftenberg and S. epidermidis as food borne pathogens and P. larvae and M. plutonius as honeybee pathogens.

CONCLUSION

These promising findings might be beneficial for discovering novel preservatives in food industry and substitution of antibiotic drugs used in the treatment of honeybees' infection.

Influence of homopolysaccharide-producing lactic acid bacteria on the spreadability of raw fermented sausages (onion mettwurst)

The purpose of the study was to investigate the effect of a reduced pH value (5.1 instead of 5.5 to 5.6) on the properties of highly perishable, spreadable raw fermented sausages (onion mettwurst) with or without the addition of homopolysaccharide (HoPS)-producing lactic acid bacteria (LAB). Hence, sausages with HoPS-producing LAB and a pH value of 5.1 were produced and compared to sausages (pH 5.1) produced with a non-exopolysaccharide (EPS)-forming strain (Lactobacillus sakei TMW 1.2037). Microbial growth and pH values were monitored during processing (24 °C for 48 hr, 10 °C for 24 hr) and storage (14 days at 0 to 2 °C). Furthermore, fat (Weibull-Stoldt) and EPS contents were determined in the final products. Sausages were characterized using texture profile and sensory analysis. The fat contents ranged from 16% to 19% and the determined EPS concentrations ranged from 0.17 to 0.59 g/kg for L. sakei TMW 1.411 and Lactobacillus curvatus TMW 1.1928 and from 0.67 to 1.58 g/kg for L. curvatus TMW 1.51. The strains L. sakei TMW 1.411 and L. curvatus TMW 1.51 reduced the hardness of the samples significantly (P < 0.05) compared to the control samples. Regarding spreadability and mouthfeel, sausages containing an EPS-forming culture were rated slightly better than the control samples and the taste was not negatively influenced. PRACTICAL APPLICATION: This study clearly demonstrated that it is promising to apply HoPS-producing LAB to maintain the spreadability of pH-reduced (pH 5.1) spreadable raw fermented onion mettwurst, which may prospectively give the opportunity to increase the safety of this highly perishable product.

Production of Bioactive Peptides from Lactic Acid Bacteria: A Sustainable Approach for Healthier Foods

Traditional fermented foods where lactic acid bacteria (LAB) are present have been associated with beneficial effects on human health, and some of those benefits are related to protein-derived products. Peptides produced by LAB have attracted the interest of food industries because of their diverse applications. These peptides include ribosomally produced (bacteriocins) and protein hydrolysates by-products (bioactive peptides), which can participate as natural preservatives and nutraceuticals, respectively. It is essential to understand the biochemical pathways and the effect of growth conditions for the production of bioactive peptides and bacteriocins by LAB, in order to suggest strategies for optimization. LAB is an important food-grade expression system that can be used in the simultaneous production of peptide-based products for the food, animal, cosmetic, and pharmaceutical industries. This review describes the multifunctional proteinaceous compounds generated by LAB metabolism and discusses a strategy to use a single-step production process, using an alternative protein-based media. This strategy will provide economic advantages in fermentation processes and will also provide an environmental alternative to industrial waste valorization. New technologies that can be used to improve production and bioactivity of LAB-derived peptides are also analyzed.

Purification and biochemical characteristics of the microbial extracellular protease from Lactobacillus curvatus isolated from Harbin dry sausages

This study investigates the purification and biochemical characteristics of the protease secreted by Lactobacillus curvatus R5, which was isolated from Harbin dry sausages. The optimized fermentation conditions were fermentation time 36 h, initial pH 6 and fermentation temperature 37 °C. An extracellular protease was purified using ammonium sulfate precipitation, ion-exchange layer and gel filtration. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) analysis showed that molecular weight of the purified protease was 45.3 kDa. Protease produced by L. curvatus R5 reached a higher relative protease activity at pH 6, 40 °C, and the purified protease exhibited pH and thermal stability at pH 6 and 40 °C. The microbial protease activity can be inhibited by ethylene diamine tetraacetic acid disodium salt (EDTA). The V_max and K_m of the protease were 53 mg/min and 15.9 mg/mL, respectively. SDS-PAGE reflects the ability of the protease to hydrolyse myofibrillar protein and sarcoplasmic protein, especially on myosin heavy chain, actin, myosin light chain and phosphorylase. The 3D structure and the Ramachandran plot of L. curvatus R5 protease was obtained by homology modelling. The Ramachandran plot analysis revealed that the purified protease was composed of 366 amino acids, and its residues in favoured, allowed, generously allowed and disallowed regions were 84.6%, 11.3%, 3.2% and 0.9% residues, respectively. Molecular docking showed that the substrate actin bound to the protease active site by hydrogen bonding and hydrophobic interaction. This research provides a basis for understanding the enzymatic properties of L. curvatus R5 protease. In conclusion, L. curvatus R5 can be used as a starter culture or protease-producing strain to inoculate Harbin dry sausages.

Preservation of Meat Products with Bacteriocins Produced by Lactic Acid Bacteria Isolated from Meat

Bacteriocins are ribosomal-synthesized antimicrobial peptides that inhibit the growing of pathogenic and/or deteriorating bacteria. The most studied bacteriocin-producing microorganisms are lactic acid bacteria (LAB), as they have great potential application in food biopreservation, since the majority have GRAS (Generally Recognized as Safe) status. The LAB-producing bacteriocins and/or bacteriocins produced by these bacteria have been widely studied, with the emphasis on those derived from milk and dairy products. On the other hand, isolates from meat and meat products are less studied. The objective of this review is to address the main characteristics, classification, and mechanism of action of bacteriocins and their use in food, to highlight studies on the isolation of LAB with bacteriocinogenic potential from meat and meat products and also to characterize, purify, and apply these bacteriocins in meat products. In summary, most of the microorganisms studied areLactococcus,Enterococcus,Pediococcus, andLactobacillus, which produce bacteriocins such as nisin, enterocin, pediocin, pentocin, and sakacin, many with the potential for use in food biopreservation.

Effect of Bacillus cereus peptide conjugated with nanoporous silica on inactivation of Listeria monocytogenes in apple juice, as an ecofriendly preservative

Bacteriocins are ribosomally synthesized antimicrobial proteins/peptides. They are of great interest in the food processing industries as potential natural preservative agent to control food-borne pathogens. Bacillus spp. are one among the potential probiotics receiving more attention since they produce a broad spectrum of antimicrobial bioactive peptides. In this study, a small-scale medium composition and bioprocessing parameters were statistically optimized to increase the yield of bacteriocin namely cerein from Bacillus cereus NS02 showing antagonism against a wide range of food-borne pathogens. The cerein was partially purified, characterized, and evaluated for their optimal reaction condition. It was subjected to surface adsorption onto food-grade silica to evaluate its maximal adsorption, reached at 4 h, 40 °C, pH 6-7, and at the initial concentration of 200 AU mL^-1. The effectiveness of silica-adsorbed and silica-free cerein was checked in Listeria monocytogenes inoculated fresh apple juice and demonstrated biopreservative activity. In juice treated with silica-cerein, the colony forming unit (CFU) was found to be less in count on the 15th day of storage at 4 °C whereas, free-cerein was found to contain 3.8 log CFU mL^-1. While, on the same day of storage, the control juice contained the strength of 14.6 log CFU mL^-1. Based on the above, this study concludes that the identified heat stable low molecular weight peptide cerein from B. cereus NS02 could serve as a potential biopreservative with effective antilisterial activity in the food system. However, a more detailed study is required to determine if their quality change especially the effect of cerein in organoleptic and nutritional properties of food beyond their addition is necessary, before it is to be exploited as an ecofriendly biopreservative.

Modeling of starter cultures growth for improved Thai sausage fermentation and cost estimating for sausage preparation and transportation

The purpose of this study was to improve Thai fermented sausage flavor by adding starter cultures (i.e., Pediococcus pentosaceus, Pediococcus acidilactici, Weissella cibaria, Lactobacillus plantarum, Lactobacillus pentosus, and Lactobacillus sakei) as compared with naturally fermented sausage. The predictive mathematical models for growth of P. acidilactici and natural lactic acid bacteria (LAB) in Thai fermented sausage were developed to obtain specific prepared sausage quality. Furthermore, comparisons of sausage preparation and transportation cost between nonrefrigerated and refrigerated trucks were studied. The concentration of 3-methyl-butanoic acid synthesized from LAB inoculated sausage was higher than in the control sample which contributed to the flavor forming. Moreover, the proposed unstructured kinetic models of Thai fermented sausage substrates and products describing the consumption of total protein and glucose, and the production of nonprotein nitrogen responsible for flavor enhancer, lactic acid and formic acid concentration were successfully fitted with two selected experimental data sets of the in situ fermentation of Thai fermented sausage. Finally, the transportation of inoculated sausages in a nonrefrigerated truck by combining fermentation process and transportation was more cost efficient for delivering sausages in a long distance.

In Vivo Assessment of Immunogenicity and Toxicity of the Bacteriocin TSU4 in BALB/c Mice

Bacteriocin TSU4 is a novel antimicrobial peptide isolated from Catla catla gut isolate Lactobacillus animalis TSU4. It has been reported for its potential antimicrobial activity against fish pathogens and food spoilage bacteria. In vivo safety evaluation is necessary to determine its immunogenicity, toxicity, and importance in real-life applications. The present study was designed to evaluate the immunogenicity, acute and sub-chronic toxicity of bacteriocin TSU4 in BALB/c mice to ensure its safety in industrial application. Male BALB/c mice were administered intraperitoneally for immunogenicity assessment, by oral gavage with 50, 100, and 200 mg/kg/body weight for acute test and 0.5 mg/kg/day dose of bacteriocin TSU4 for sub-chronic toxicity test. Neither mortality nor any infections were observed during experimental period. There was no major increase in antibody titer during the immunogenicity test, and no mortality was observed during acute or sub-chronic toxicity tests. The LD₅₀ value of bacteriocin TSU4 was found to be higher than 200 ± 0.45 mg/kg. No significant change in the serum biochemical markers, histopathological analysis and visual observation in spleen sizes was observed. These findings revealed that bacteriocin TSU4 is a non-immunogenic, safe, non-toxic, and could be a potential candidate for industrial applications in food preservation and aquaculture industries.

Bacteriocinogenic LAB Strains for Fermented Meat Preservation: Perspectives, Challenges, and Limitations

Over the last decades, much research has focused on lactic acid bacteria (LAB) bacteriocins because of their potential as biopreservatives and their action against the growth of spoilage microbes. Meat and fermented meat products are prone to microbial contamination, causing health risks, as well as economic losses in the meat industry. The use of bacteriocin-producing LAB starter or protective cultures is suitable for fermented meats. However, although bacteriocins can be produced during meat processing, their levels are usually much lower than those achieved during in vitro fermentations under optimal environmental conditions. Thus, the direct addition of a bacteriocin food additive would be desirable. Moreover, safety and technological characteristics of the bacteriocinogenic LAB must be considered before their widespread applications. This review describes the perspectives and challenges toward the complete disclosure of new bacteriocins as effective preservatives in the production of safe and "healthy" fermented meat products.

Purification and Characterization of a Novel Anti-Campylobacter Bacteriocin Produced by Lactobacillus curvatus DN317

The lactic acid bacteria (LAB) microbiota of Saudi chicken ceca was determined. From 60 samples, 204 isolates of lactic acid bacteria were obtained. Three isolates produced antimicrobial activities against Campylobacter jejuni, Listeria monocytogenes, and Bacillus subtilis. The isolate DN317, which had the highest activity against Campylobacter jejuni ATCC 33560, was identified as Lactobacillus curvatus (GenBank accession numbers: KX353849 and KX353850). Full inhibitory activity was observed after a 2-h incubation with the supernatant at pH values between 4 and 8. Only 16% of the activity was conserved after a treatment at 121 °C for 15 min. The use of proteinase K, pepsin, chymotrypsin, trypsin, papain, and lysozyme drastically reduced the antimicrobial activity. However, lipase, catalase, and lysozyme had no effect on this activity. The active peptide produced by Lactobacillus curvatus DN317 was purified by precipitation with an 80% saturated ammonium sulfate solution, and two steps of reversed phase HPLC on a C18 column. The molecular weight of this peptide was 4448 Da as determined by MALDI-ToF. N-terminal sequence analysis using Edman degradation revealed 47 amino acid residues (UniProt Knowledgebase accession number C0HK82) revealing homology with the amino acid sequences of sakacin P and curvaticin L442. The antimicrobial activity of the bacteriocin, namely curvaticin DN317, was found to be bacteriostatic against Campylobacter jejuni ATCC 33560. The use of microbial antagonism by LAB is one of the best ways to control microorganisms safely in foods. This result constitutes a reasonable advance in the antimicrobial field because of its potential applications in food technology.

Impact of Lactobacillus curvatus 54M16 on microbiota composition and growth of Listeria monocytogenes in fermented sausages

Lactobacillus curvatus 54M16 produced bacteriocins sak X, sak T_α, sak T_β and sak P. The aim of this study was to investigate the anti-listerial activity of the bacteriocins-producing strain against Listeria monocytogenes in vitro co-culture experiments and during the manufacture of fermented sausages. In MRS broth, Lb. curvatus 54M16 was able to inhibit L. monocytogenes to undetectable levels after 48 h at 20 °C or 5 days at 15 °C. Anti-listerial activity was lower during the production of fermented sausages with pathogen inoculation at levels of approximately 4 Log CFU g^-1. However, total inhibition of L. monocytogenes native to the raw ingredients was achieved over the course of the fermentation. Moreover, 16S rRNA-based analysis revealed the ability of Lb. curvatus 54M16 to dominate and affect the bacterial ecosystem, whereas spoilage-associated bacterial genera, such as Brochothrix, Psychrobacter, Pseudomonas and some Enterobacteriaceae, were found until the end of ripening in sausages without Lb. curvatus 54M16. The use of the bacteriocins-producing Lb. curvatus 54M16 in fermented sausages could be an important contribution to product safety, provided that eco-physiological factors and other preservation methods are maintained at levels required for the inhibition of pathogens in controlled conditions.

Technological aspects of horse meat products - A review

Horse meat and its products can be considered as a food with a high nutritional value. However, due to cases of economically motivated food adulteration by the intentional addition of horse meat beef products in recent years, horse meat has become a controversial issue. Consumer confidence in meat products and the meat industry has diminished, although consumers consider the differences between the food content and the label as the major issue rather than the safety and nutritional characteristics of horse meat. The elaboration of meat products from horse meat (e.g. "cecina", dry-cured loin, salami, bressaola and pâté) is also an interesting alternative to other traditional meat products such as dry-cured pork hams, pork sausages and liver pâtés. In this review, the technological aspects, safety and storage stability of meat products elaborated from horse meat will be addressed by highlighting the nutritional and sensory aspects of these meat products. We aim to improve the existing knowledge about horse meat in the view of recent scandals.