Combined inhibitory effect of nisin with EDTA against Listeria monocytogenes in soy-protein edible coating on turkey frankfurters stored at 4°C and 10°C

Several food contamination outbreaks are linked to Listeria monocytogenes. More effective methods are needed to prevent the growth and recontamination of L. monocytogenes on ready-to-eat (RTE) food products. Therefore, the objectives of this study were to evaluate the inhibitory activities of nisin (10,000 IU/mL), EDTA (sodium Ethylenediaminetetraacetic acid: 1.6 mg/mL), and the combination of nisin (10,000 IU/mL) with EDTA 1.6 mg/mL either in brain-heart-infusion (BHI) media at 37°C for 72 h or in soy-protein edible coating on the surface of full-fat commercial turkey frankfurters against the cell populations of approximately 106 colony forming units (CFU/mL) of L. monocytogenes. The surface-inoculated frankfurters were dipped into soy-protein film forming solutions with and without the addition of antimicrobial agents [(nisin (10,000 IU) or EDTA (0.16%) or the combination)] and stored at either 4°C or 10°C. The inhibitory effects of edible coatings were evaluated on a weekly basis for 45 d. The greatest inhibitory activities of 6 log cycle reductions of L. monocytogenes were found when nisin was combined with EDTA and eliminated 6 log cycles of L. monocytogenes in both systems. In the combined nisin (10,000 IU) with EDTA (0.16%) treatment, the L. monocytogenes population was reduced to undetectable levels after 15 h or 7 d incubation in BHI at 37°C or on turkey frankfurters stored at 4°C and 10°C, respectively. This research has demonstrated that the use of an edible film coating containing nisin with EDTA is a promising means of controlling the growth and recontamination of L. monocytogenes on RTE meat products

Inhibitory activity against Listeria monocytogenes by soy-protein edible film containing grape seed extract, nisin, and malic acid

The frequent outbreaks of food-borne illness necessitate development of intervention strategies, including the use of natural antimicrobials. Listeria monocytogenes is one of the most important bacterial pathogens that recently has caused a significant number of outbreaks. With the aim of finding potent natural agents that can minimize pathogen contamination concerns, this study evaluated the inhibitory activities against L. monocytogenes of grape seed extract (GSE), malic acid (M), nisin (N), and combinations thereof incorporated into soy-protein edible films. Soyprotein films with/without addition of antimicrobial agents (GSE: 1%, Nisin: 10,000 IU/g, Malic acid: 1%, and their combinations) were prepared and evaluated for anti-listerial activities. The highest inhibitory activity after 1 h incubation at 25°C was found in the treatment containing GSE, nisin, and malic acid, which produced reductions of log 3.7 colony-forming units (CFU)/ ml as compared to control film without the addition of antimicrobial agents. These data demonstrated that the GSE, nisin, and malic acid combination incorporated into soy-protein edible films is very effective in inhibiting L. monocytogenes growth at 25°C and has potential for applications on a variety of food products to help prevent L. monocytogenes contamination and growth

Evaluation of Physicochemical and Antioxidant Properties of Peanut Protein Hydrolysate

Peanut protein and its hydrolysate were compared with a view to their use as food additives. The effects of pH, temperature and protein concentration on some of their key physicochemical properties were investigated. Compared with peanut protein, peanut peptides exhibited a significantly higher solubility and significantly lower turbidity at pH values 2–12 and temperature between 30 and 80°C. Peanut peptide showed better emulsifying capacity, foam capacity and foam stability, but had lower water holding and fat adsorption capacities over a wide range of protein concentrations (2–5 g/100 ml) than peanut protein isolate. In addition, peanut peptide exhibited in vitro antioxidant properties measured in terms of reducing power, scavenging of hydroxyl radical, and scavenging of DPPH radical. These results suggest that peanut peptide appeared to have better functional and antioxidant properties and hence has a good potential as a food additive

Colorants in Cheese Manufacture: Production, Chemistry, Interactions, and Regulation

Colored Cheddar cheeses are prepared by adding an aqueous annatto extract (norbixin) to cheese milk; however, a considerable proportion (∼20%) of such colorant is transferred to whey, which can limit the end use applications of whey products. Different geographical regions have adopted various strategies for handling whey derived from colored cheeses production. For example, in the United States, whey products are treated with oxidizing agents such as hydrogen peroxide and benzoyl peroxide to obtain white and colorless spray‐dried products; however, chemical bleaching of whey is prohibited in Europe and China. Fundamental studies have focused on understanding the interactions between colorants molecules and various components of cheese. In addition, the selective delivery of colorants to the cheese curd through approaches such as encapsulated norbixin and microcapsules of bixin or use of alternative colorants, including fat‐soluble/emulsified versions of annatto or beta‐carotene, has been studied. This review provides a critical analysis of pertinent scientific and patent literature pertaining to colorant delivery in cheese and various types of colorant products on the market for cheese manufacture, and also considers interactions between colorant molecules and cheese components; various strategies for elimination of color transfer to whey during cheese manufacture are also discussed

Bioactive Functional Nanolayers of ChitosanLysine Surfactant with Single- and Mixed-Protein-Repellent and Antibiofilm Properties for Medical Implants

[Image: see text] Medical implant-associated infections resulting from biofilm formation triggered by unspecific protein adsorption are the prevailing cause of implant failure. However, implant surfaces rendered with multifunctional bioactive nanocoatings offer a promising alternative to prevent the initial attachment of bacteria and effectively interrupt biofilm formation. The need to research and develop novel and stable bioactive nanocoatings for medical implants and a comprehensive understanding of their properties in contact with the complex biological environment are crucial. In this study, we developed an aqueous stable and crosslinker-free polyelectrolyte–surfactant complex (PESC) composed of a renewable cationic polysaccharide, chitosan, a lysine-based anionic surfactant (77KS), and an amphoteric antibiotic, amoxicillin, which is widely used to treat a number of infections caused by bacteria. We successfully introduced the PESC as bioactive functional nanolayers on the “model” and “real” polydimethylsiloxane (PDMS) surfaces under dynamic and ambient conditions. Besides their high stability and improved wettability, these uniformly deposited nanolayers (thickness: 44–61 nm) with mixed charges exhibited strong repulsion toward three model blood proteins (serum albumin, fibrinogen, and γ-globulin) and their competitive interactions in the mixture in real-time, as demonstrated using a quartz crystal microbalance with dissipation (QCM-D). The functional nanolayers with a maximum negative zeta potential (ζ: −19 to −30 mV at pH 7.4), water content (1628–1810 ng cm(–2)), and hydration (low viscosity and elastic shear modulus) correlated with the mass, conformation, and interaction nature of proteins. In vitro antimicrobial activity testing under dynamic conditions showed that the charged nanolayers actively inhibited the growth of both Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria compared to unmodified PDMS. Given the ease of fabrication of multifunctional and charged biobased coatings with simultaneous protein-repellent and antimicrobial activities, the limitations of individual approaches could be overcome leading to a better and advanced design of various medical devices (e.g., catheters, prosthetics, and stents)