Characterization, Release Profile and Antimicrobial Properties of Bioactive Polyvinyl Alcohol-Alyssum homolocarpum Seed Gum- Nisin Composite Film

Sustainable microcrystalline cellulose extracted from biowaste Albezia lebeck L. leaves: Biomass exfoliation and physicochemical characterization

There is a focus on sustainability when manufacturing materials. Utilizing biobased materials and replacing fossil-based products is the main research focus. Bio-composite materials are applied to packaging, filler coatings, and pharmaceuticals. Here, we used the leaves of the agro-waste plant Albizia lebeck L. to extract cellulose. Chemical treatment causing strong acid hydrolysis successfully extracted the cellulose content from the leaves. The cellulose obtained was then strengthened with polylactic acid to make a biobased film for future applications. Fourier transform spectroscopy, scanning electron microscopy, thermal analysis, particle size analysis, visible UV and elemental analysis were all used to characterize the extracted cellulose. SEM and mechanical property analysis were used to check and describe the quality of the reinforced biofilm. The greatest cellulose yield from this raw material was 50.2%. The crystallinity index and crystallite size (CI 70.3% and CS 11.29 nm) were high in the extracted cellulose. The TG (DTG) curve analysis derivative revealed cellulose particle breakdown was initiated around 305.2°C and can endure temperatures up to 600°C. Biofilms reinforced with polylactic acid cellulose (1, 2, 3, and 5% by weight %) exhibited a smooth and parallel surface. As the filler concentration increased, minor agglomeration occurred. The tensile strength of pure polylactic acid (PLA) (34.72 MPa) was extended up to 38.91 MPa for 5% filler. Similarly, Young's modulus also increased to 5.24 MPa. However, the elongation break decreases with the increase of filler content, and the least value of decrease is 7.5 MPa. Concerning prospective implementations, it is expected that the biobased film and cellulose particles will prove to be more functional.

Preliminary Study on a Biocompatible Cellulose Waterborne Polyurethane Composite Membrane

A promising technique for repairing necrotic mucosa of human organs has emerged, in which composite films are used to replace human mucosa. In this work, neutral alpha-amylase corrosion solution with a concentration of 0.40 mg/mL and hydrochloric acid corrosion solution at pH 0.9 were used as simulated oral cavity and gastric fluid environments under the condition of human body temperature. The prepared cellulose film and the cellulose water-based polyurethane composite film (the concentration of water-based polyurethane was 90, 92, 94, 96, or 98%) were mixed in the simulated environment. The composite membrane had a weaker water swelling property (water swelling degree of 4.32%), weaker surface hydrophilicity (water contact angle of 59.05°), and stronger enzyme activity (1.77 U). This functional film composite material is expected to become an ideal substitute for human mucosa.

Effects of nisin and EDTA on morphology and properties of thermoplastic starch and PBAT biodegradable films for meat packaging

Biodegradable active packaging was produced by compounding nisin (3, 6 and 9%) and nisin-ethylenediaminetetraacetic acid (EDTA) (3 and 6%) mixtures with poly(butylene adipate terephthalate) and thermoplastic starch blends (PBAT/TPS) by blown-film extrusion. Nisin and EDTA interacted with polymers, involving CO stretching of ester bonds and increased compatibility. This plasticized the films and modified the crystallinity, surface roughness and thermal relaxation behavior. Barrier properties were improved due to modified hydrophilic-hydrophobic properties, compact structures and crystallites that restricted vapor and oxygen permeation. PBAT/TPS films containing EDTA and nisin effectively inhibited lipid degradation in pork tissues corresponding with stabilizing the CO ester bond of triacylglycerol. Microbial growth was also inhibited, particularly in EDTA-containing films up to 1.4 log. Inactivation of microorganisms stabilized redness and delayed meat discoloration, preserving the quality of packaged pork. Interaction between nisin, EDTA and polymers modified the morphology and film properties and functionalized biodegradable food packaging to inactivate microorganisms.

Combining carvacrol and nisin in biodegradable films for antibacterial packaging applications

In this work, the feasibility of antibacterial biopolymeric films containing carvacrol (CRV) and a nisin commercial formulation (Nis) for potential food packaging applications was investigated. As polymer matrix, a commercial biodegradable polymer formulation of Mater-Bi (MB) was chosen due to its significant food packaging applications. CRV and Nis were chosen due to their well-established antibacterial properties and their potential synergistic effect. MB/CRV, MB/Nis, and MB/CRV/Nis systems were produced by melt mixing and compression molding. The mechanical properties of the films were evaluated by tensile tests. Differential scanning calorimetry was assessed aiming at investigating the effect of the two compounds and their mixture on the thermal properties of MB. The release profile of CRV and Nis from the MB-based films was evaluated in water at 4 °C by UV-Vis measurements and it was fitted with a power-law model. The antibacterial activity of MB-based films was tested in vitro against Listeria monocytogenes, Salmonella enteritidis, Escherichia coli, and Staphylococcus aureus. The combination of CRV and Nis strongly affected the properties of the MB-based films and ensured higher antibacterial activity if compared to MB/CRV and MB/Nis systems.

Incorporation and antimicrobial activity of nisin Z within carrageenan/chitosan multilayers

An antimicrobial peptide, nisin Z, was embedded within polyelectrolyte multilayers (PEMs) composed of natural polysaccharides in order to explore the potential of forming a multilayer with antimicrobial properties. Using attenuated total reflection Fourier transform infrared spectroscopy (ATR FTIR), the formation of carrageenan/chitosan multilayers and the inclusion of nisin Z in two different configurations was investigated. Approximately 0.89 µg cm-2 nisin Z was contained within a 4.5 bilayer film. The antimicrobial properties of these films were also investigated. The peptide containing films were able to kill over 90% and 99% of planktonic and biofilm cells, respectively, against Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA) strains compared to control films. Additionally, surface topography and wettability studies using atomic force microscopy (AFM) and the captive bubble technique revealed that surface roughness and hydrophobicity was similar for both nisin containing multilayers. This suggests that the antimicrobial efficacy of the peptide is unaffected by its location within the multilayer. Overall, these results demonstrate the potential to embed and protect natural antimicrobials within a multilayer to create functionalised coatings that may be desired by industry, such as in the food, biomaterials, and pharmaceutical industry sectors.

Application of soy protein isolate and cassava starch based film solutions as matrix for ionic encapsulation of carrot powders

Research into characterization and storage stability of carrot powders encapsulated in soy protein isolate and cassava starch based film solutions via ionic gelation method was performed. Carotene a major antioxidant presents in carrot powders plays a beneficial role in preventing some health problems such as cancer, and cardiovascular/coronary heart diseases. Consequently, the carotene contains a hydrocarbon with an unsaturated double bond or its oxygen derivatives, which makes it unstable and sensitive to moisture, heat, oxygen, light, and acid. There is therefore the need for encapsulation of this nutritive and healthy component of carrot powders to extend its stability. Film solutions required for encapsulation of the carrot powders were prepared from soy protein isolate, cassava starch and their combinations, and were as well categorized into plasticized and non-plasticized using glycerol in combination with sorbitol as plasticizer. Ionic encapsulation was achieved using sodium alginate for gelation of carrot powder beads in 5% calcium chloride solution for curing. Distinction in gelation features of the film solutions as a result of blend compositions as well as the addition of plasticizers substantially influenced the quality criteria of encapsulated carrot powder beads such as encapsulation efficiency, encapsulation yield, moisture content, hygroscopicity, particle size, and also their sensory qualities. Their values varied between 70.93-82.59%, 70.35-75.35%, 9.88-13.04%, 40.00-49.00 g/100 g, and 2.18-2.64 mm respectively. 100% soy protein isolate based film solution performed much better than 100% cassava starch based film solutions in preventing degradation of carotene content of the encapsulated carrot powder beads. Plasticization of the membrane solutions caused greater carotene degradation. Combination of soy-protein isolate (50%) and cassava starch (50%) composite based film solutions gave the best protection for carotene degradation having shelf life of 106 days while plasticized cassava starch based was the least with the shelf life of 13 days which is closed to that of the control (carrot powders).

Long-Term Antibacterial Effect of Electrospun Polyvinyl Alcohol/Polyacrylate Sodium Nanofiber Containing Nisin-Loaded Nanoparticles

Response Surface Methodology (RSM) was used to assess the optimal conditions for a Water/Oil/Water (W/O/W) emulsion for encapsulated nisin (EN). Nano-encapsulated nisin had high encapsulation efficiencies (EE) (86.66 ± 1.59%), small particle size (320 ± 20 nm), and low polydispersity index (0.27). Biodegradable polyvinyl alcohol (PVA) and polyacrylate sodium (PAAS) were blended with EN and prepared by electrospinning. Scanning electron microscopy (SEM) revealed PVA/PAAS/EN nanofibers with good morphology, and that their EN activity and mechanical properties were enhanced. When the ultrasonication time was 15 min and 15% EN was added, the nanofibers had optimal mechanical, light transmittance, and barrier properties. Besides, the release behavior of nisin from the nanofibers fit the Korsemeyer–Peppas (KP) model, a maximum nisin release rate of 85.28 ± 2.38% was achieved over 16 days. At 4 °C, the growth of Escherichia coli and Staphylococcus aureus was inhibited for 16 days in nanofibers under different ultrasonic times. The application of the fiber in food packaging can effectively inhibit the activity of food microorganisms and prolong the shelf life of strawberries, displaying a great potential application for food preservation.

Bio-based antimicrobial packaging from sugarcane bagasse nanocellulose/nisin hybrid films

Bio-based nanomaterials with antimicrobial functions hold promise in replacing petroleum-based packaging for food preservation. A nanocellulose-based hybrid film with antimicrobial properties was developed from sugarcane bagasse and nisin. Cellulose nanofibrils (CNFs) were prepared from sugarcane bagasse pulp by mechanical grinding, and mixed with nisin to prepare CNFs/nisin nanohybrid films. The concentration of nisin has a remarkable influence on the mechanical, light transmission, gas barrier, and antimicrobial properties of these films. CNFs/nisin hybrid films with 1920 mg/L nisin exhibit good light transmission, relatively high tensile strength, low oxygen permeability, and low water vapor transmission rates. This hybrid film was used as a liner of low-density polyethylene plastic packaging for ready-to-eat ham; it completely inhibited Listeria monocytogenes during 7 days of storage at 4 °C. Such novel CNFs/nisin nanohybrid films are expected to expand the application of bagasse nanocellulose in active packaging for food preservation.

Thermodynamic Properties and State Diagram of Gum Ghatti-Based Edible Films: Effects of Glycerol and Nisin

In this present study, the thermodynamic and thermal properties of glycerol and nisin-incorporated gum ghatti (GG, Anogeissus latifolia)-based films were determined. The films exhibited type III isotherm behaviors. Moisture content (MC) of films was increased with increasing water activity (aw) and decreased with higher temperature. The incorporation of glycerol and nisin increased the sorption ability of GG films. The net isosteric heat of adsorption (qst) and differential entropy (Sd) were decreased with increasing MC, showing an exponential negative correlation between them. Spreading pressure (φ) was increased with increasing aw, but decreased with higher temperature. This incorporation of glycerol and nisin increased the qst, Sd and φ of the GG films. The sorption behaviors were enthalpy-driven and non-spontaneous processes. The glass transition temperature (Tg), critical MC and aw of the films were decreased, and increased respectively with the incorporation of glycerol and nisin. This work provides a theoretical basis for the application of edible films in fresh food preservation.