Food stabilizing potential of nisin Z produced by wild Lactococcus lactis subsp. lactis from raw milk and some fermented products

Effect of cheese-making and ripening processes on the anti-Clostridium activity of Lactococcus strains

Lactic acid bacteria (LAB) can produce bacteriocins that exert an antimicrobial activity against Clostridium spp. responsible for late blowing defects (LBD) in cheese. This study aimed to evaluate the influence of cheese-making and ripening temperature and salt concentration on the LAB bacteriocin production to enable their effective use in dairy chain. Five Lactococcus strains (Lc. cremoris FT27 and Lc. lactis N16, N26, SV77 and VC106) with anti-Clostridium activity were selected for their ability to produce bacteriocin at the optimal growth temperature (30 °C) and in temperature conditions resembling those of the uncooked and semi-cooked cheese-making. At optimal growth condition the bacteriocin titre resulted to be strain-dependent (from 2.4 to 3.3 log10 IU/mL), differently at temperatures applied during the cheese-making process only one strain (Lc. lactis VC106) was able to produce a high amount of bacteriocins (2.8 and 2.9 log10 IU/mL, respectively. During the period that simulated the ripening process at 10 °C, the bacteriocin titre of Lc. lactis VC106 declined progressively (1.6 and 1.9 log10 IU/mL after 170 days), but remained above the threshold required to inhibit the LBD. Our findings provide new evidence of how cheese-making and ripening processes adversely affect the bacteriocins synthesis and, consequently, the anti-Clostridium activity. Lc. lactis VC106 showed an antimicrobial activity comparable to that obtained at optimal growth temperature suggesting that this strain could provide a useful tool to inhibit spoilage bacteria in the dairy chain.

Enhancement of sausages shelf life using natural antimicrobials and propolis extract

The present work assessed the impacts of nisin (200 mg/kg) and nisin-nanoparticles (NNPs; 200 mg/kg) in combination with propolis ethanolic extract (PEE; 1% and 3%) on quality and stability of sausage during refrigerated period. The treated meat batters were mechanically stuffed into polyamide casings, packaged in vacuum conditions and analyzed at days 1, 15, 30 and 45. Sausages treated with combined NNPs and PEE displayed higher total phenolic content (2.14-5.41 mg GAE/g DM), pH values (5.27-5.80) and sensory scores (3.70-3.93) with low hardness (34.9-37.7 kg m/s2) and TBARS values (1.41-2.85 mg MDA/kg) throughout keeping period. At day 45, treated samples with 200 mg/kg NNPs + 3% PEE indicated 0.28 Log CFU/g reduction in TVC, 0.16 CFU/g in Clostridium perfringens, 0.23 in E. coli, 0.65 in Staphylococcus aureus, and 0.37 CFU/g in mold and yeast count compared with control (120 ppm nitrite). Hence, this work aims to assess the performance of nisin compounds + PEE in the quality improvement of frankfurter-type sausage kept for 45 days (4 °C) to produce novel and practical nitrite substitutes.

The clinical praxis of bacteriocins as natural anti-microbial therapeutics

In recent decades, the excessive use of antibiotics has resulted in a rise in antimicrobial drug resistance (ADR). Annually, a significant number of human lives are lost due to resistant infectious diseases, leading to around 700,000 deaths, and it is estimated that by 2050, there could be up to 10 million casualties. Apart from their possible application as preservatives in the food sector, bacteriocins are gaining acknowledgment as potential clinical treatments. Not only this, these antimicrobial peptides have revealed in modulating the host immune system producing anti-inflammatory and anti-modulatory responses. At the same time, due to the ever-increasing global threat of antibiotic resistance, bacteriocins have gained attraction among researchers due to their potential clinical applications. Bacteriocins as antimicrobial peptides, represent one of the most important natural defense mechanisms among bacterial species, particularly lactic acid bacteria (LAB), that can fight against infection-causing pathogens. In this review, we are highlighting the potential of bacteriocins as novel therapeutics for inhibiting a wide range of clinically relevant and multi-drug-resistant pathogens (MDR). We also highlight the effectiveness and potential applications of current bacteriocin treatments in combating antimicrobial resistance (AMR), thereby promoting human health.

Synthesis and Characterization of a Novel Chitosan-Based Nanoparticle-Hydrogel Composite System Promising for Skin Wound Drug Delivery

As a natural preservative, nisin is widely used in the food industry, while its application in biomedicine is limited due to its susceptibility to interference from external conditions. In this study, a nanoparticle-hydrogel composite system was designed to encapsulate and release nisin. Nisin nanoparticles were identified with a smooth, spherical visual morphology, particle size of 122.72 ± 4.88 nm, polydispersity coefficient of 0.473 ± 0.063, and zeta potential of 23.89 ± 0.37 mV. Based on the sample state and critical properties, three temperature-sensitive hydrogels based on chitosan were ultimately chosen with a rapid gelation time of 112 s, outstanding reticular structure, and optimal swelling ratio of 239.05 ± 7.15%. The composite system exhibited the same antibacterial properties as nisin, demonstrated by the composite system's inhibition zone diameter of 17.06 ± 0.83 mm, compared to 20.20 ± 0.58 mm for nisin, which was attributed to the prolonged release effect of the hydrogel at the appropriate temperature. The composite system also demonstrated good biocompatibility and safety, making it suitable for application as short-term wound dressings in biomedicine due to its low hemolysis rate of less than 2%. In summary, our nanoparticle-based hydrogel composite system offers a novel application form of nisin while ensuring its stability, thereby deepening and broadening the employment of nisin.

Natural Antimicrobials in Dairy Products: Benefits, Challenges, and Future Trends

This review delves into using natural antimicrobials in the dairy industry and examines various sources of these compounds, including microbial, plant, and animal sources. It discusses the mechanisms by which they inhibit microbial growth, for example, by binding to the cell wall's precursor molecule of the target microorganism, consequently inhibiting its biosynthesis, and interfering in the molecule transport mechanism, leading to cell death. In general, they prove to be effective against the main pathogens and spoilage found in food, such as Escherichia coli, Staphylococcus aureus, Bacillus spp., Salmonella spp., mold, and yeast. Moreover, this review explores encapsulation technology as a promising approach for increasing the viability of natural antimicrobials against unfavorable conditions such as pH, temperature, and oxygen exposure. Finally, this review examines the benefits and challenges of using natural antimicrobials in dairy products. While natural antimicrobials offer several advantages, including improved safety, quality, and sensory properties of dairy products, it is crucial to be aware of the challenges associated with their use, such as potential allergenicity, regulatory requirements, and consumer perception. This review concludes by emphasizing the need for further research to identify and develop effective and safe natural antimicrobials for the dairy industry to ensure the quality and safety of dairy products for consumers.