Nisin Diffusion Research Articles

Diffusion kinetics of nisin from composite coatings reinforced with nano-rhamnosomes

This study evaluated the release kinetics of nisin encapsulated in rhamnolipid functionalized liposomes (rhamnosomes), which were further embedded in κ-carrageenan/hydroxypropyl methylcellulose (κ-CR/HPMC) based composite coatings. Release kinetics was analysed in various food simulants e.g. lipophilic (D1) and hydrophilic (A) for 10 days at 4 °C and 25 °C. Thus, diffusion exponent (n), diffusion constant (k), and correlation coefficient (R2) from the power-law model, diffusion coefficient (D) from Fick's second law of diffusion and partition (K) coefficient were evaluated. Diffusion of nisin from nano-active packaging (NAP) was higher for simulant D1 (50% ethanol) than simulant A (10% ethanol) at both temperatures. Partition coefficient values confirmed higher affinity of nisin for rhamnosomes nano-carrier systems (RS-NCS) embedded in biopolymeric coatings than the food simulants. Moreover, the developed NAP exhibited broad-spectrum antimicrobial activity against Gram-positive and Gram-negative foodborne pathogens (L. monocytogenes and E. coli) due to the synergistic effect of nisin and functionalized component of rhamnosomes (rhamnolipids). Thus, these novel RS-NCS embedded NAP can be used as an effective bioactive strategy for improved food preservation during extended shelf-life.

Properties of nisin incorporated ZrO2/poly (vinyl alcohol)-wheat gluten antimicrobial barrier films

ABSTRACTThe properties of manufactured nisin-ZrO2/poly (vinyl alcohol)-wheat gluten (ZPWG) films were characterized. The formation of hydrogen bonds among the PVA, WG, and ZrO2 units were detected and caused a decrease in the film crystallinity. Also, the degradation rate was increased with WG content. As expected, the addition of WG and ZrO2 influenced the light transmission, tensile properties, gas permeability and water vapor permeability of the films. Nisin-loaded films presented a low initial burst release of the antimicrobial agent, followed by a gradual release. The initial diffusion of nisin (Mt/M∞<2/3) from the ZPWG film was formulated by the Fickian diffusion equation, showing a linear relationship (R2 > 0.998) between Mt/M∞ and t1/2, and the diffusion coefficient D increased with increasing WG content. Antimicrobial activity testing of nisin-ZPWG films with 40 wt% WG showed excellent inhibitory activity against Staphylococcus aureus, indicating its potential as a new active food packaging material.

Release Profile and Antimicrobial Activity of Nisin Control-released from Agar Gel Foods

The release profiles of nisin from nisin-incorporating gel foods and the antimicrobial activities of the gels on the growth of Brochothrix thermosphacta in an aqueous system containing the gels have been investigated. A linear regression model was applied to determine the diffusion coefficient (D) for the diffusion of nisin in the gel. The antimicrobial activities of nisin released from 1, 2 and 3% (w/v) agar gels on the growth of B. thermosphacta in a broth medium with and without nisin were investigated. The D decreased from 1.2×10-2 to 8.2×10-3 and 6.4×10-3 cm2/s as the agar concentration in the gel increased from 1 to 2 and 3% (w/v), demonstrating the diffusion rate in the gels can be controlled by the agar concentration in gel. The agar gel incorporating nisin inhibited the B. thermosphacta growth in the broth medium by prolonging the lag phase. The growth inhibition was enhanced by the addition of nisin in the medium. The results of this study exhibited that the gel food is a feasible nisin delivery system with a controlled release achieved by the adjustment of agar concentration in the system, demonstrating the potential of nisin-incorporating gel for preserving particulate-containing drinks.

Release Kinetics of Nisin from Chitosan-Alginate Complex Films.

Understanding the release kinetics of antimicrobials from polymer films is important in the design of effective antimicrobial packaging films. The release kinetics of nisin (30 mg/film) from chitosan-alginate polyelectric complex films prepared using various fractions of alginate (33%, 50%, and 66%) was investigated into an aqueous release medium. Films containing higher alginate fractions showed significantly lower (P < 0.05) degree of swelling in water. Total amount of nisin released from films into an aqueous system decreased significantly (P < 0.05) with an increase in alginate concentration. The mechanism of diffusion of nisin from all films was found to be Fickian, and diffusion coefficients varied from 0.872 × 10-9 to 8.034 ×10-9 cm2 /s. Strong complexation was confirmed between chitosan and alginate polymers within the films using isothermal titration calorimetry and viscosity studies, which affects swelling of films and subsequent nisin release. Complexation was also confirmed between nisin and alginate, which limited the amount of free nisin available for diffusion from films. These low-swelling biopolymer complexes have potential to be used as antimicrobial packaging films with sustained nisin release characteristics.

Diffusion and Antibacterial Properties of Nisin-Loaded Chitosan/Poly (L-Lactic Acid) Towards Development of Active Food Packaging Film

Nisin-loaded chitosan/poly (L-lactic acid) (nisin-CS/PLLA) antimicrobial films were prepared by coating method. The structure and mechanical properties of nisin carrier CS/PLLA films were investigated, and the antibacterial behavior of nisin-CS/PLLA against Staphylococcus aureus ATCC6538 was assessed. Furthermore, the diffusion behaviors of nisin from films were evaluated by diffusion kinetics and thermodynamics, and the diffusion efficiency was investigated as a function of CS/PLLA ratio, pH, and ionic strength. When CS/PLLA ratio was at 1:1 (w/w) and above, a notable enhancement was observed in the tensile strength with the increase of PLLA content, while the elongation at break was decreased slightly at the same time. However, a significant decrease in tensile strength and elongation at break were present when the CS/PLLA ratio was below 1:1. There existed intermolecular hydrogen bonds between CS and PLLA molecules. The diffusion of nisin from film was strongly dependent on pH and ionic strength. The thermodynamic parameters (ΔH o , ΔS o , and ΔG o ) indicated that the diffusion process of nisin from film was spontaneous and endothermic. From diffusion and antimicrobial activity results, nisin-CS/PLLA films revealed well-controlled release and better antimicrobial activity against S. aureus, which may have potential as a novel active food packaging film.

Kinetics and functional effectiveness of nisin loaded antimicrobial packaging film based on chitosan/poly(vinyl alcohol)

The aim of this study was to evaluate the kinetics and functional effectiveness of Nisin loaded chitosan/poly(vinyl alcohol) (Nisin–CS/PVA) as an antibacterial packaging film. The films were prepared by coating method and Staphylococcus aureus (S. aureus, ATCC6538) was used as test bacterium. The intermolecular hydrogen bonds between CS and PVA molecules were confirmed. The elasticity of films was significantly improved by the incorporation of PVA, and the film could also bear a relative high tensile strength at 26.7MPa for CS/PVA=1/1. As CS/PVA ratio decreased, the water vapor permeability (WVP) decreased and reached its minimum value 0.983×10−10gm−1s−1 at CS/PVA=1/1, meanwhile, oxygen permeability (OP) increased but still lower than 0.91cm3μmm−2d−1kPa−1 for CS/PVA=1/1 as the CS/PVA ratio was above 1:1. The initial diffusion of nisin (Mt/M∞<2/3) from CS/PVA film could be well described by the Fickian diffusion equation. Owing to the positively charged nisin at pH below isoelectric point (pI, 8.8) and its increasing dissolubility in water as the pH reduced, the diffusion of nisin from the films strongly depended on pH and ionic strength besides CS/PVA ratio and temperature. Moreover, the thermodynamic parameters suggested the spontaneous and endothermic diffusion of nisin from the films. The resulting data can provide some valuable information for the design of film in structure and ingredient.

Controlled release of nisin from HPMC, sodium caseinate, poly-lactic acid and chitosan for active packaging applications

Biodegradable polymers with distinct composition can be used as antimicrobial carriers. To judge their relative efficiency as antimicrobial carriers, release rates of fluorescently labeled nisin Z from hydroxypropyl methylcellulose (HPMC), chitosan (CTS), sodium caseinate (SC) and polylactic acid (PLA) films were evaluated at 4 and 40°C in water–ethanol solution. Nisin diffusion coefficient (D) indicated that DCTS<DPLA<DSC<DHPMC. Temperature increase significantly increased nisin release from SC and HPMC films due to glass transition and hydrophilic nature. Partition coefficients (K) followed the same trend but were below 1, except for HPMC at 40°C, which implies that, at equilibrium, a lower amount of nisin was liberated in water–ethanol solution. A higher antibacterial effect against Listeria monocytogenes CIP 82110 and Staphylococcus aureus CIP 4.83 was observed with HPMC and SC films containing nisin due to strong interactions (hydratation) between the medium and the film. However, HPMC, CTS, SC packaging films could progressively release nisin to sustain an anti-bacterial effect and can be favorably used for prolonging shelf life of packed food.

Development and evaluation of active packaging for sliced mozzarella preservation

AbstractAntimicrobial films were formed by the incorporation of nisin (NI), natamycin (NA) and a combination of both (NI + NA) into cellulose polymer. Film efficacies were evaluated in vitro against Staphylococcus aureus ATCC 6538, Listeria monocytogenes ATCC 15313, Penicillium sp. and Geotrichum sp. The films were also evaluated on sliced mozzarella cheese against moulds and yeasts, Staphylococcus sp. and psychrotrophic bacteria. Mechanical and microscopic properties of the films and the diffusion of the antimicrobial agents from the film to the cheese were also evaluated. Films containing NI showed an antimicrobial effect in vitro against S. aureus and L. monocytogenes, while films containing NA were effective in vitro against Penicillium sp. and Geotrichum sp. By the ninth day of storage at 12 ± 2°C, the count of yeasts and moulds on cheese covered with films containing NA decreased 2 log10 units compared with the count on cheese with control films. NI film did not show an effect against Staphylococcus sp., but it was effective against psychrotrophic bacteria for 6 days of storage of the cheese. The incorporation of antimicrobial compounds decreased the resistance and elongation of the films and caused changes in their molecular conformation. NI diffusion from the films to the cheese was not detected; however, time‐dependent diffusion of NA from the film containing NI + NA was measured. The incorporation of NI and NA together in the films did not show an effect. The film containing NA showed potential for application as active food packaging for sliced mozzarella cheese. Copyright © 2008 John Wiley &amp; Sons, Ltd.

Evaluation of antimicrobial peptide nisin as a safe vaginal contraceptive agent in rabbits: in vitro and in vivo studies.

In the midst of the global epidemics of both unwanted pregnancies and sexually transmitted infections (STIs), options that provide protection are ideal. In the present study, nisin, a known antimicrobial peptide, was evaluated for safety and contraceptive potential in vitro and in vivo in the rabbit. A concentration of 400 microg nisin per ml was found to be spermicidal in vitro, and the effect was dose and time dependent. In vivo studies indicated that intravaginal application of 1 mg nisin blocked conception in rabbits. Repeated application of nisin (50 mg/animal per day) in rabbits for 14 consecutive days did not cause local inflammation or damage to the vaginal epithelium. In addition, the rate of diffusion of nisin into the blood via the vaginal mucosal epithelium, and its clearance from the circulation was found to be rapid. No treatment-related changes were observed in the reproductive performance of rabbits after cessation of treatment. Furthermore, no changes were observed in the gestation period, subsequent growth and survival of neonates in these animals. When male rats were given nisin orally for 13 consecutive weeks, no effect was observed on reproductive performance. The number of pups born, survival and growth of pups were unaltered. The affinity studies of nisin revealed that spermatozoa are more susceptible to nisin than red blood cells and vaginal epithelial cells. We suggest that nisin with spermicidal and antimicrobial properties could serve as a safe vaginal contraceptive for future therapeutic interventions in STIs.

Controlled Diffusion of an Antimicrobial Peptide from a Biopolymer Film

Research in the safety of processed food has focused on performing antimicrobial edible films as a novel way to suppress pathogenic bacteria such as Listeria monocytogenes and Staphylococcus aureus. Previous studies have developed an antimicrobial polysaccharide edible film, incorporating the bacteriocin nisin, active against a large spectrum of Gram-positive bacteria. The film effectiveness is based on both nisin desorption from the film and its diffusion in food products. In the present work, nisin molecular transfer in agarose gel was investigated and apparent diffusion coefficients were calculated. Fick's second law well represented both nisin desorption from the film and its diffusion in agarose gel. The coefficient values for free nisin diffusion varied between 1.92 × 10−11 and 8.14 × 10−11m2 s−1 for temperatures between 5 and 22°C. When nisin was added to the film, nisin transfer into agarose gel was slowed due to a desorption effect. This result indicated that nisin interacted with film components which induced partial retention of nisin in food surface. This is interesting because it would improve food safety by reducing aero-anaerobic pathogenic bacteria growth at food surfaces.

Experimental study and modeling of nisin diffusion in agarose gels

Research in safety of processed food has focused on the use of anti-microbial compounds to suppress pathogenic bacteria growth such as Listeria monocytogenes and Staphylococcus aureus. Previous studies developed an anti-microbial edible film, incorporating the bacteriocin nisin. Nisin effectiveness was based on both nisin desorption from the film and its diffusion in the food product. In this present work, and as a preliminary study, nisin diffusion in agarose gel was investigated. The apparent diffusion coefficients were calculated, taking into account factors influencing the diffusion rates such as nisin concentration, diffusion time and temperature. Influence of agarose content on nisin diffusion was also evaluated. As a result, Fick’s second law well represented nisin diffusion in agarose gel. In 3% (w/w) gel, the diffusion coefficient values varied between 1.92 × 10 −11 and 8.14 × 10 −11 m 2 s −1 for temperatures ranged between 5.4 and 22.3 °C. Diffusion phenomena satisfied Arrhenius relationship. Agarose content from 3% to 6% did not have any effect on nisin diffusion. However, agarose content of 8% significantly reduced nisin diffusion in agarose gel cylinders.

Nisin Diffusion in Protein Films: Effects of Film Type and Temperature

ABSTRACT: Protein films [cast corn zein (CCZ), heat‐pressed corn zein (HPCZ), cast wheat gluten (CWG), and heat‐pressed wheat gluten (HPWG)] were studied at different exposure temperatures (5, 25, 35, and 45 °C) to determine nisin diffusion in aqueous model systems. Kinetics of nisin diffusion in protein films followed a Fickian diffusion model. The CCZ had the lowest nisin diffusivity and highest nisin retention. Diffusivities in HPCZ, CWG, and HPWG films were not significantly different. Temperature dependence of nisin diffusion in all films followed an Arrhenius model, which indicated no morphological changes within 5 to 45 °C. The activation energy for nisin diffusion in corn‐zein films was higher than that in wheat‐gluten films.

Properties of nisin‐incorporated polymer coatings as antimicrobial packaging materials

AbstractNisin was incorporated into binder solutions of acrylic polymer and vinyl acetate‐ethylene co‐polymer, and then coated on to paper. Diffusive migration of incorporated nisin and the antimicrobial activity of the polymer coatings were investigated in order to understand the way of controlling nisin migration and the extent of microbial suppression by the coated paper. Vinyl acetate–ethylene co‐polymer exhibited a faster rate and higher degree of migration into aqueous food simulant solutions compared to acrylic polymer, and also exhibited a higher degree of suppression against Micrococcus flavus ATCC 10240 inoculated into the microbial medium. Addition of NaCl, sugar and citric acid to water significantly reduced the rate of diffusion of nisin in the case of acrylic polymer, while only slight change was observed due to the additive for vinyl acetate‐ethylene co‐polymer. The simulant type slightly affected the equilibrated migration level of nisin. When the nisin‐incorporated coatings were in contact with pasteurized milk and orange juice at 10°C, significant suppression of total aerobic bacteria and yeasts was observed without any noticeable difference between the two types of coatings. Copyright © 2002 John Wiley &amp; Sons, Ltd.