Preparation, characterization, and properties of chitosan films with cinnamaldehyde nanoemulsions

The effect of Macro and Nano-emulsions of cinnamon essential oil on the properties of edible active films

The effect of Nano-emulsion (NE) and Macro-emulsion (ME) of cinnamon essential oil (CEO) on the properties of carboxymethyl cellulose (CMC)-based films was investigated. MEs (diameters of 242-362 nm) and NEs (diameters of 59-80 nm) of CEO were produced through Ultra-Turrax and Ultrasonication, respectively. The scanning electron microscopy (SEM) and atomic force microscopy (AFM) images showed different morphologies in the films containing ME and NE, also a denser and more uniform microstructure was observed in the NE films in comparison with the ME ones. The higher stability of NE in the CMC matrix, increased the thickness of the resulted films. The water vapor permeability (WVP) was increased from 2.59 × 10-9 g/ms Pa in the control film to 4.43 × 10-9 g/m s Pa in the ME film, and decreased to 1.80 × 10-9 g/ms Pa in the NE film. Adding CEO led to more flexible films with enhanced strain at break (SAB) from 53.56% in the control film to 80% and 94.77% in the ME and NE films, respectively. The antifungal indices against A. niger and M. racemous were 14.16% and 20.82% in the ME films, and were improved to 18.81% and 25% in the NE ones.

Edible Coating and Pulsed Light to Increase the Shelf Life of Food Products

The application of edible coatings (EC) in combination with pulsed light (PL) treatments represents an emerging approach for extending the shelf life of highly perishable but high value-added products, such as fresh-cut fruits and vegetables. The surface of these products would benefit from the protective effects of ECs and the PL decontamination capability. This review describes in detail the fundamentals of both EC and PL, focusing on the food engineering principles in the formulation and application of EC and the delivery of efficient PL treatments and the technological aspects related to the food characterization following these treatments and discussing the implementation of the two technologies, individually or in combination. The advantages of the combination of EC and PL are extensively discussed emphasizing the potential benefits that may be derived from their combination when preserving perishable foods. The downsides of combining EC and PL are also presented, with specific reference to the potential EC degradation when exposed to PL treatments and the screening effect of PL transmittance through the coating layer. Finally, the potential applications of the combined treatments to food products are highlighted, comparatively presenting the treatment conditions and the product shelf-life improvement.

Covalent linkage of bioactive volatiles to a polysaccharide support as a potential approach for preparing active edible coatings and delivery systems for food products

In this study, a potential of covalent linkage approach for developing active edible coatings was examined. Vanillin and trans-cinnamaldehyde were bound to chitosan by Schiff base reaction and reductive amination. The modified polysaccharides were comprehensively characterized and applied as active coatings on fresh-cut melon. The covalent linkage allowed overcoming solubility problems with the lipophilic vanillin and cinnamaldehyde and neutralizing their volatility, producing well-adhered coatings that enhanced fruit quality and storability without sensorial impairment. The attached hydrophobic moieties also provided new polysaccharides with self-assembling ability. Their aggregates were loaded with antimicrobial citral and added to mandarin juice, resulting in up to 6 log CFU/mL microbial count reduction. Thus, the covalent linkage concept offers several advantages, especially when hydrophobic or volatile active agents are used. Further developed, it may become a safe and effective tool for the formation of advanced active edible coatings and delivery vehicles for direct applications on food products.

Preparation, characterization and antimicrobial activity of polyvinyl alcohol/gum arabic/chitosan composite films incorporated with black pepper essential oil and ginger essential oil

Natural materials have attracted increasing attention in wound dressing and food packaging process, which could overcome the serious environmental issues caused by conventional synthetic materials. Essential oils (EOs) such as black pepper essential oil (BPEO) and ginger essential oil (GEO) have extensively been reported for their nutritional and biomedical properties. In this study, biocomposite films based on polyvinyl alcohol (PVA), gum arabic (GA) and chitosan (CS) incorporated with BPEO and GEO were fabricated by solvent casting method. FTIR, XRD, SEM and DSC were performed with mechanical and antimicrobial properties of PVA/GA/CS films with and without BPEO and GEO. The BPEO-PVA/GA/CS film showed heterogeneous rough surface with cavities containing entrapment of BPEO droplets, whereas, the GEO-PVA/GA/CS film showed heterogeneous rough surface with coarseness due to the incorporation of respective EOs. The BPEO and GEO incorporated PVA/GA/CS films were considerable resistant to breakage and flexible with improved heat stability. The BPEO and GEO incorporated PVA/GA/CS films were significantly inhibited the growth of Bacillus cereus, Staphylococcus aureus, Escherichia coli and Salmonella typhimurium. The obtained results have demonstrated that both BPEO and GEO incorporated PVA/GA/CS films are promising alternatives to wound dressing and food packaging materials.

Development and physicochemical characterization of chitosan hydrochloride/sulfobutyl ether-β-cyclodextrin nanoparticles for cinnamaldehyde entrapment

In this work, the cinnamaldehyde (CA) loaded nanoparticles were synthesized by directly cross-linking chitosan hydrochloride (CSH) and sulfobutyl ether-β-cyclodextrin (SBE-β-CD). The CA/SBE-β-CD inclusion complex was firstly prepared, and its highest encapsulation efficiency (EE) was 86.34%. Field Emission Scanning Electron Microscope results indicated that the inclusion complex showed massive aggregates with a coarse and fluffy texture and irregular surface. Then, the inclusion complex interacted with CSH to form nanoparticles. The EE of CA in nanoparticles was improved. Atomic force microscopy showed the nanoparticles had regular and spherical morphology. Fourier transform infrared spectroscopy analysis demonstrated that CA was mainly encapsulated in the inner place of CSH/SBE-β-CD nanoparticles (CSNs). The enhanced thermal stability of the nanoparticles was found in differential scanning calorimeter. X-ray diffraction implied that CA-CSNs existed in the amorphous state. CA-CSNs had excellent slow release property. Further, the bacteriostatic effect of CA-CSNs was much better than that of CA and CSNs. All the results indicated that CSNs can be used as a promising carrier to encapsulate CA. PRACTICAL APPLICATIONS: CA is an effective antimicrobial and generally recognized as Safe-GRAS. CA also exhibits many other bioactivities and has been commonly used for digestive, cardiovascular and immune system diseases. However, CA is easy to be oxidized and volatilized during storage for poor water solubility. The nanoencapsulations display the capacities of enhancing solubility of bioactive compounds, protecting them from degradation, and prolonging their residence. In this manuscript, CA loaded nanoparticles were investigated. The results suggested that the nanoencapsulation could benefit for improving water solubility and stability of CA. This strategy could be helpful for its application and development in food preservation.

Encapsulation Systems for Antimicrobial Food Packaging Components: An Update

Antimicrobially active packaging has emerged as an effective technology to reduce microbial growth in food products increasing both their shelf-life and microbial safety for the consumer while maintaining their quality and sensorial properties. In the last years, a great effort has been made to develop more efficient, long-lasting and eco-friendly antimicrobial materials by improving the performance of the incorporated antimicrobial substances. With this purpose, more effective antimicrobial compounds of natural origin such as bacteriocins, bacteriophages and essential oils have been preferred over synthetic ones and new encapsulation strategies such as emulsions, core-shell nanofibres, cyclodextrins and liposomes among others, have been applied in order to protect these antimicrobials from degradation or volatilization while trying to enable a more controlled release and sustained antimicrobial action. On that account, this article provides an overview of the types of antimicrobials agents used and the most recent trends on the strategies used to encapsulate the antimicrobial agents for their stable inclusion in the packaging materials. Moreover, a thorough discussion regarding the benefits of each encapsulation technology as well as their application in food products is presented.

Design of Bioinspired Emulsified Composite European Eel Gelatin and Protein Isolate-Based Food Packaging Film: Thermal, Microstructural, Mechanical, and Biological Features

The study focused on the elaboration and the characterization of blend biofilms based on European eel skin gelatin (ESG) and protein isolate (EPI) and the assessment of European oil (EO) incorporation effect on their properties. Data displayed that the incorporation of EPI and EO to the gelatin formulation decreased the lightness and yellowness of composite and emulsified films, respectively, compared to ESG film. Moreover, ESG films exhibited improved mechanical properties than EPI films. FTIR analysis, all incorporated films with EO at the ratio 1:4 (oil/polymer) revealed similar characteristic bands as in free-oil films. Further, the SEM images of 100% ESG and 100% EPI films showed a smooth and homogenous structure, whereas the cross-section of blend film (at a ratio 50:50) displayed a rougher microstructure. In addition, emulsified film ESG100 revealed a smooth and homogeneous microstructure compared to that prepared using EPI/ESG 50/50 ratio. Furthermore, EPI or EO addition into the ESG matrix enhanced the blend films antioxidant activities.

Porous electrospun poly(ε-caprolactone)/gelatin nanofibrous mat containing cinnamon for wound healing application: in vitro and in vivo study

In this study, cinnamon (cin) was loaded into poly(ε-caprolactone)/gelatin (PCL/Gel) nanofibrous matrices in order to fabricate an appropriate mat to improve wound healing. Mats were fabricated from PCL/COLL [1:1 (w/w)] solution with 1, 5 and 25% (w/v) of cinnamon. Prepared mats were characterized with regard to their microstructure, mechanical properties, porosity, surface wettability, water-uptake capacity, water vapor permeability, blood compatibility, microbial penetration and cellular response. The fabricated mats with and without cinnamon were used to treat the full-thickness excisional wounds in Wistar rats. The results indicated that the amount of cinnamon had a direct effect on porosity, mechanical properties, water uptake capacity, water contact angle, water vapor transmission rate and cell proliferation. In addition, the results of in vivo study indicated that after 14 days, the wounds which were treated with PCL/Gel 5%cin had better wound closure (98%) among other groups. Our results suggest that the cinnamon can be used as a suitable material for wound healing.

The Impact of Cross-linking Mode on the Physical and Antimicrobial Properties of a Chitosan/Bacterial Cellulose Composite

The bacteriostatic performance of a chitosan film is closely related to its ionic and physical properties, which are significantly influenced by the mode of cross-linking. In the current work, chitosan with or without bacterial cellulose was cross-linked with borate, tripolyphosphate, or the mixture of borate and tripolyphosphate, and the composite films were obtained by a casting of dispersion. Mechanical measurements indicated that different modes of cross-linking led to varying degrees of film strength and elongation increases, while the films treated with the borate and tripolyphosphate mixture showed the best performance. Meanwhile, changes in the fractured sectional images showed a densified texture induced by cross-linkers, especially for the borate and tripolyphosphate mixture. Measurements of Fourier transform infrared showed the enhanced interaction between the matrix polymers treated by borate, confirmed by a slight increase in the glass transitional temperature and a higher surface hydrophobicity. However, the reduced antimicrobial efficiency of composite films against E. coli, B. cinerea, and S. cerevisiae was obtained in cross-linked films compared with chitosan/bacterial cellulose films, indicating that the impact on the antimicrobial function of chitosan is a noteworthy issue for cross-linking.

Development and Characterization of Chitosan Microparticles-in-Films for Buccal Delivery of Bioactive Peptides

Nowadays, bioactive peptides are used for therapeutic applications and the selection of a carrier to deliver them is very important to increase the efficiency, absorption, release, bioavailability and consumer acceptance. The aim of this study was to develop and characterize chitosan-based films loaded with chitosan microparticles containing a bioactive peptide (sequence: KGYGGVSLPEW) with antihypertensive properties. Films were prepared by the solvent casting method, while the microparticles were prepared by ionic gelation. The final optimized chitosan microparticles exhibited a mean diameter of 2.5 µm, a polydispersity index of 0.46, a zeta potential of +61 mV and a peptide association efficiency of 76%. Chitosan films were optimized achieving the final formulation of 0.79% (w/v) of chitosan, 6.74% (w/v) of sorbitol and 0.82% (w/v) of citric acid. These thin (±0.100 mm) and transparent films demonstrated good performance in terms of mechanical and biological properties. The oral films developed were flexible, elastic, easy to handle and exhibited rapid disintegration (30 s) and an erosion behavior of 20% when they came into contact with saliva solution. The cell viability (75–99%) was proved by methylthiazolydiphenyl-tetrazolium bromide (MTT) assay with TR146 cells. The chitosan mucoadhesive films loaded with peptide–chitosan microparticles resulted in an innovative approach to perform administration across the buccal mucosa, because these films present a larger surface area, leading to the rapid disintegration and release of the antihypertensive peptide under controlled conditions in the buccal cavity, thus promoting bioavailability.

A review on applications of chitosan-based Schiff bases

Biopolymers have become very attractive as they are degradable, biocompatible, non-toxic and renewable. Due to the intrinsic reactive amino groups, chitosan is vibrant in the midst of other biopolymers. Using the versatility of these amino groups, various structural modifications have been accomplished on chitosan through certain chemical reactions. Chemical modification of chitosan via imine functionalization (RR'CNR″; R: alkyl/aryl, R': H/alkyl/aryl and R″: chitosan ring) is significant as it recommends the resultant chitosan-based Schiff bases (CSBs) for the important applications in the fields like biology, catalysis, sensors, water treatment, etc. CSBs are usually synthesized by the Schiff condensation reaction between chitosan's amino groups and carbonyl compounds with the removal of water molecules. In this review, we first introduce the available synthetic approaches for the preparation of CSBs. Then, we discuss the biological applications of CSBs including antimicrobial activity, anticancer activity, drug carrier ability, antioxidant activity and tissue engineering capacity. Successively, the applications of CSBs in other fields such as catalysis, adsorption and sensors are demonstrated.

Design, Development, and Characterization of Imiquimod-Loaded Chitosan Films for Topical Delivery

Aldara™ (5% w/w imiquimod) topical cream is approved by the US FDA for the treatment of superficial basal cell carcinoma. However, the cream formulation suffers from dose variability, low drug availability due to the incomplete release, and poor patient compliance. To achieve sustained and complete release of imiquimod, chitosan films were prepared by casting using propylene glycol as a plasticizer. Chitosan films had appropriate physicochemical characteristics for wound dressing and excellent content uniformity and maintained the original physical form of imiquimod. Films were capable of releasing a defined dose of imiquimod over a period of 7 days. The bioactivity of imiquimod was not affected by its entrapment in chitosan matrix as indicated by the results of in vitro growth inhibition assay. In addition, the film formulation showed significantly (p ˂ 0.05) higher drug accumulation in the skin when compared to commercial cream formulation.

Effects of Chitosan-Based Coatings Enriched with Cinnamaldehyde on Mandarin Fruit cv. Ponkan during Room-Temperature Storage

The current work aimed to evaluate the efficacy of four coating formulations—chitosan coating (CH), 0.5% cinnamaldehyde + chitosan (0.5% CI–CH), 1.0% cinnamaldehyde + chitosan (1.0% CI–CH), and 1.5% cinnamaldehyde + chitosan (1.5% CI–CH)—on fresh mandarin fruit cv. Ponkan quality maintenance (weight loss, decay rate, total soluble solids, titratable acidity, vitamin C, color index, malondialdehyde, and antioxidant activity) over 100 days of storage at 20 °C. Compared to the control, chitosan treatment effectively reduced the decay and weight loss rates of mandarin fruit cv. Ponkan during storage at room temperature, delayed the decline of nutritional quality in fruits, increased the antioxidant capacity, and inhibited the accumulation of malondialdehyde (MDA). In comparison to chitosan coating, 1.5% CI–CH did not improve the fruit storage effect, but inhibited the normal color change of fruits and increased the accumulation of MDA. Both 0.5% CI–CH and 1.0% CI–CH effectively reduced the rate of fruit decay, improved the quality of fruits after harvest, and delayed fruit aging. Our study suggests that 0.5% CI–CH and 1.0% CI–CH might be good formulations for maintaining the quality of mandarin fruit cv. Ponkan during room-temperature storage.

Chitosan, gelatin and methylcellulose films incorporated with tannic acid for food packaging

In this work, chitosan, gelatin and methylcellulose films incorporated with tannic acid (TA) were synthesised, characterised and applied for the first time to preserve cherry tomatoes (Solanum lycopersicum var. cerasiforme) and grapes (Vitis vinifera). The addition of TA at 15% (w/w) increased the transparency value of biopolymer films. The highest increment of transparency value was obtained for MC-TA film, increased from 0.572 to 4.73 A/mm. Based on antimicrobial study, the addition of TA improved the antibacterial properties of biopolymers against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The ability of films to preserve both fruits was evaluated in a 14-day preservation study. The application of biopolymer films treated with TA has decreased the weight loss and browning index of fruits, as compared to control films. A significant reduction in the weight loss of cherry tomatoes wrapped with chitosan (from 21.3 to 19.6%), gelatin (from 22.1 to 15.5%) and methylcellulose (26.2 to 20.5%) films were obtained following TA treatment. Overall, results obtained from this study highlight the effects of TA on physiochemical properties of biopolymer films and their ability to preserve fruits.

Mechanical, barrier, and color properties of banana starch edible films incorporated with nanoemulsions of lemongrass ( Cymbopogon citratus) and rosemary ( Rosmarinus officinalis) essential oils

Edible films are among the most promising fields in food science over the last decade due to their versatility (they can be made from a wide array of materials) and because they can be used as carriers of different active substances, like antioxidants, antimicrobial agents, and essential oils from plants. In the case of the essential oils, their inclusion in edible films is limited by their low water solubility. Nanoemulsions are thermodynamically stable and transparent systems that can be used as a way of incorporating essential oils into edible film matrices. In this paper, we developed lemongrass and rosemary essential oil nanoemulsions by using a low-energy method, observing the effect of the surfactant/oil ratio in their physicochemical properties. Then we studied the effect of the nanoemulsions concentration incorporated into banana starch edible films. We observed that essential oils' nanoemulsions have a plasticizing effect increasing the film's water vapor permeability, transparency, and elongation at break, while the hydrophobic nature of the essential oils lead to a decrease in their water solubility.