Improving nisin production by encapsulated Lactococcus lactis with starch/carboxymethyl cellulose edible films

The physicochemical properties of Cassava Starch/Carboxymethyl cellulose sodium edible film incorporated of Bacillus and its application in salmon fillet packaging

Edible film is now a trend in the food packaging industry. In this study, edible films were prepared by adding two Bacillus spp. (Bacillus amyloliquefaciens Y11 and Bacillus velezensis Y12) to a cassava starch and carboxymethyl cellulose sodium matrix. The structural, physicochemical, and biological characteristics of the film were analyzed, and its application in salmon preservation was explored. The film had a dense structure and no pores, indicating that its polymeric components were compatible with each other. The addition of Bacillus spp. increased the antioxidant activity of the film and its ability to eliminate hydroxyl radicals (84.57% and 91.86%, respectively). The film also showed good antibacterial activity against several pathogens and underwent complete degradation in natural soil within 12 days. The film significantly reduced the total coliform count of salmon and extended its shelf life by 3 days, demonstrating its value as a food-packaging material.

A water-resistant egg white/chitosan/pectin blending film with spherical-linear molecular interpenetrating network strengthened by multifunctional tannin-nisin nanoparticles

Edible films are effective alternatives to plastic packaging, however, the hydrophilicity of edible films based on protein and polysaccharide limits the application. Therefore, we fabricated a water-stable hybrid film with a linear-spherical interpenetrating molecular topology network using egg white (EW), chitosan (CS), and pectin. Meanwhile, the nisin-tannin acid self-assembly complex nanoparticles were employed as a multifunctional cross-linker, antibacterial and antioxidant agent to improve the performance of films. The FTIR, XRD, and SEM analysis revealed that the conformation and crystalline structure rearrangement of chitosan induced by the alkaline environment provided by egg white enhanced the network structure of films, effectively avoided the addition of modifying reagents. The proposed hybrid films exhibited excellent properties, with EW/TNPCS3 showing the best overall performance. The water contact angle (WCA) increased to 105.27 ± 1.62°, and its dissolution and swelling rates were significantly lower than pure egg white and pure chitosan films. Moreover, tannin-nisin (TN) nanoparticles endowed the films with excellent antimicrobial activity against the common Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Thus, the prepared blending films have great application potential in food preservation, especially to maintain stable performance in high humidity environment.

A comprehensive review on starch-based sustainable edible films loaded with bioactive components for food packaging

Biopolymers like starch, a renewable and widely available resource, are increasingly being used to fabricate the films for eco-friendly packaging solutions. Starch-based edible films offer significant advantages for food packaging, including biodegradability and the ability to extend shelf life. However, they also present challenges such as moisture sensitivity and limited barrier properties compared to synthetic materials. These limitations can be mitigated by incorporating bioactive components, such as antimicrobial agents or antioxidants, which enhance the film's resistance to moisture and improve its barrier properties, making it a more viable option for food packaging. This review explores the emerging field of starch-based sustainable edible films enhanced with bioactive components for food packaging applications. It delves into fabrication techniques, structural properties, and functional attributes, highlighting the potential of these innovative films to reduce environmental impact and preserve food quality. Key topics discussed include sustainability issues, processing methods, performance characteristics, and potential applications in the food industry. The review provides a comprehensive overview of current research and developments in starch-based edible films, presenting them as promising alternatives to conventional food packaging that can help reduce plastic waste and environmental impact.

Carbon dot/g-C3N4-mediated self-activated antimicrobial nanocomposite films for active packaging applications

A novel carbon dot/g-C3N4 nanocomposite (CCN) exhibiting enhanced photocatalytic activity was developed and used as a photoactive nanofiller to construct corn starch/carboxymethyl cellulose (CS/CMC)-based functional films. The morphologies and structures of the CCN-CS/CMC composite films were investigated with scanning electron microscopy, Fourier transform infrared spectroscopy and X-ray diffraction. The effects of the CCN on the physicochemical properties and antibacterial activities of the films were analyzed. The properties of the films were optimized with the addition of CCN (0.20 mg/mL), and the tensile strength of the film was increased to 11.9 MPa and the water contact angle was increased to 103.39°. The optimal active film showed > 99.9 % antibacterial efficiencies against Escherichia coli and Staphylococcus aureus under visible light and prolonged the shelf lives of bananas for more than four days compared to the 4-day shelf life of the control. This work provides a novel route for developing antimicrobial active packaging.

Use of fenugreek seed gum in edible film formation: major drawbacks and applicable methods to overcome

Researching on potential biopolymer sources with the aim of developing edible films with better mechanical and barrier properties has become innovative as it would be a key factor to minimize the use of synthetic polymers in food packaging. Therefore, different biopolymers such as galactomannan have been gaining attention recently. Fenugreek seed gum is a rich source of galactomannan which is minimally researched on its applicability in edible film making. The degree of galactose substitution and polymerization are the main factors that determine the functional properties of galactomannan. A strong and cohesive film matrix cannot be produced from fenugreek seed gum as its molecular interaction is weakened due to the high galactose substitution with a high galactose/mannose ratio, 1:1. Structural modifications of galactomannan in fenugreek seed gum will lead to films with the required mechanical properties. Hence, this review summarizes recent scientific studies on the limitations of fenugreek seed gum as a film forming agent and the specific modification techniques that can be applied in order to increase its film forming capability and performance.

Biopolymer-Based Sustainable Food Packaging Materials: Challenges, Solutions, and Applications

Biopolymer-based packaging materials have become of greater interest to the world due to their biodegradability, renewability, and biocompatibility. In recent years, numerous biopolymers-such as starch, chitosan, carrageenan, polylactic acid, etc.-have been investigated for their potential application in food packaging. Reinforcement agents such as nanofillers and active agents improve the properties of the biopolymers, making them suitable for active and intelligent packaging. Some of the packaging materials, e.g., cellulose, starch, polylactic acid, and polybutylene adipate terephthalate, are currently used in the packaging industry. The trend of using biopolymers in the packaging industry has increased immensely; therefore, many legislations have been approved by various organizations. This review article describes various challenges and possible solutions associated with food packaging materials. It covers a wide range of biopolymers used in food packaging and the limitations of using them in their pure form. Finally, a SWOT analysis is presented for biopolymers, and the future trends are discussed. Biopolymers are eco-friendly, biodegradable, nontoxic, renewable, and biocompatible alternatives to synthetic packaging materials. Research shows that biopolymer-based packaging materials are of great essence in combined form, and further studies are needed for them to be used as an alternative packaging material.

Sodium alginate/carboxymethyl starch/κ-carrageenan enteric soft capsule: Processing, characterization, and rupture time evaluation

Although gelatin has good characteristics in preparing soft capsules, its noticeable shortcomings force researchers to further develop substitutes for gelatin soft capsules. In this paper, sodium alginate (SA), carboxymethyl starch (CMS) and κ-carrageenan (κ-C) were used as matrix materials, and the formula of the co-blended solution was screened through rheological method. In addition, films of the different blends were characterized by thermogravimetry analysis, SEM, FTIR, X-ray, water contact angle and mechanical properties. The results showed that κ-C had strong interaction with CMS and SA and the mechanical properties of capsule shell were greatly improved by the addition of κ-C. When the ratio of CMS/SA/κ-C was 2:0.5:1.5, the microstructure of the film was more dense and uniform. In addition, this formula had the best mechanical properties and adhesion properties, and was more suitable for the production of soft capsules. Finally, a novel plant soft capsule was successfully prepared by dropping method, and its appearance and rupture properties met the requirements of enteric soft capsules. In simulated intestinal juice, the soft capsule was almost completely degraded within 15 min, and it was superior to the gelatin soft capsule. Therefore, this study provides an alternative formula for preparing enteric soft capsules.

Silica nanoparticles loaded with caffeic acid to optimize the performance of cassava starch/sodium carboxymethyl cellulose film for meat packaging

Cassava starch/sodium carboxymethyl cellulose (CC) was used as the substrate to create a multipurpose food packaging film, and caffeic acid@silica nanoparticles (C@SNPs) was added. The encapsulation rate of caffeic acid in C@SNPs was 84.7 ± 0.97 %. According to SEM pictures, the nanoparticles were evenly dispersed throughout the film and exhibited good compatibility with the other polymers. C@SNPs was added, which enhanced the physical characteristics of film and decreased its water solubility. The best mechanical and oxygen barrier qualities among them are found in the C@SCC_5:1 film, whose tensile strength rises from 7.17 MPa to 15.44 MPa. The C@SCC_5:1 film has scavenging rates of 95.43 % and 84.67 % against ABTS and DPPH free radicals, respectively, and CA can be released continuously in various food systems. In addition, the antibacterial rate of E. coli O157:H7 and S. aureus of C@SCC_5:1 film in meat was 99.9 %, and it can effectively delay lipid oxidation and pH rise. In conclusion,C@SCC_5:1 film is a new type of antibacterial and antioxidant food packaging material.

The Antioxidant Activity and Protection of Probiotic Bacteria in the In Vitro Gastrointestinal Digestion of a Blueberry Juice and Whey Protein Fermentation System

Blueberries have received great attention due to the health effects of their bioactive compounds, such as antioxidant, antitumor, and anti-obesity properties. Probiotics also have these health-promoting benefits. However, these biological activities may be affected by the processs of gastrointestinal digestion, which decreases their functionality. This study aimed to use a more convenient method to improve the blueberries’ antioxidant activity and protective effects on probiotic cells by fermentation with whey protein, and to explore the possible mechanisms underlying these effects. This result showed that the total phenolic content, anthocyanin content, reducing power, DPPH radical scavenging capacity, and probiotic cells’ survival in a blueberry juice and whey protein fermentation system were enhanced in a model of in vitro gastrointestinal digestion. The bioactive compounds in blueberry juice interacted with whey protein, as shown through FTIR. The stability of phenolic compounds was enhanced, and the release of functional compounds in the mixture fermentation system was delayed through CLSM. Interactions between bioactive compounds in blueberries, whey protein, and bacterial surface proteins, glycoproteins or polysaccharides during fermentation were studied by SDS-PAGE. Thus, the stability of bioactive activities in the mixed system after fermentation was strengthened by the interaction. The mixed fermentation system has promising potential for improving antioxidant activity and protecting probiotic cells.

Novel gellan gum-based probiotic film with enhanced biological activity and probiotic viability: Application for fresh-cut apples and potatoes

A novel probiotic film based on gellan gum (GN), cranberry extract (CE), and Lactococcus lactis (LA) was developed in the present study. The fluorescence and SEM image results showed that GN/CE film containing LA was successfully fabricated. The incorporation of LA significantly enhanced the antibacterial activity of the film. The presence of CE strengthened the antioxidant activity and LA survivability in the film. The combination of LA (0-1.0 %) and CE (0.5-1.0 %) improved the mechanical property of the film through the formation of density structure. The best comprehensive properties were obtained with the film containing 2.0 %LA and 0.5 %CE. The GN/2.0 %LA/0.5 %CE film also showed the optimal preservation effect on fresh-cut potatoes and apples. Hence, GN/2.0 %LA/0.5 %CE probiotic film has proved to be suitable for fruit and vegetable preservation.

Carboxymethylcellulose reinforced starch films and rapid detection of spoiled beverages

The integrity of the packaging of a liquid foodstuff makes it difficult to detect spoilage. Therefore, it is important to develop a sensitive, fast and real-time material for liquid food detection. CMC, as lignocellulose derivatives and starch are widely used in the food industry. In this study, starch films with pH-responsive properties are successfully prepared from full-component starch and corn amylopectin (CA) by adding CMC. The effects of CMC on the mechanical properties, morphology characteristics, physical and chemical structures, stability and pH responsiveness of the starch films are analyzed. The starch/CMC-1.0 g composite films display good electrical conductivity and reduce the resistance of the composite film by two orders of magnitude. The composite films have pH response ability; in the simulation of orange juice spoilage experiment, the CA/CMC composite film has a more sensitive current response and was more suitable for the application to liquid food quality detection. Additionally, the starch/CMC composite films have potential applications for rapid detection and real-time monitoring of the safety of liquid food.

Novel Features of Cellulose-Based Films as Sustainable Alternatives for Food Packaging

Packaging plays an important role in food quality and safety, especially regarding waste and spoilage reduction. The main drawback is that the packaging industry is among the ones that is highly dependent on plastic usage. New alternatives to conventional plastic packaging such as biopolymers-based type are mandatory. Examples are cellulose films and its derivatives. These are among the most used options in the food packaging due to their unique characteristics, such as biocompatibility, environmental sustainability, low price, mechanical properties, and biodegradability. Emerging concepts such as active and intelligent packaging provides new solutions for an extending shelf-life, and it fights some limitations of cellulose films and improves the properties of the packaging. This article reviews the available cellulose polymers and derivatives that are used as sustainable alternatives for food packaging regarding their properties, characteristics, and functionalization towards active properties enhancement. In this way, several types of films that are prepared with cellulose and their derivatives, incorporating antimicrobial and antioxidant compounds, are herein described, and discussed.

Fabrication of Chitosan/Hydroxyethyl Cellulose/TiO2 Incorporated Mulberry Anthocyanin 3D-Printed Bilayer Films for Quality of Litchis

In this study, a bilayer antibacterial chromogenic material was prepared using chitosan (CS) and hydroxyethyl cellulose (HEC) as inner substrate, mulberry anthocyanins (MA) as a natural tracer, and titanium dioxide nanoparticles (nano-TiO₂)/CS:HEC as a bacteriostatic agent for the outer layer. By investigating their apparent viscosity and suitability for 3D printing links, the optimal ratio of the substrates was determined to be CS:HEC = 3:3. Viscosity of the CH was moderate. The printing process was consistent and exhibited no breakage or clogging. The printed image was highly stable and not susceptible to collapse and diffusion. Scanning electron microscopy and infrared spectroscopy indicated that intermolecular binding between the substances exhibited good compatibility. Titanium dioxide nanoparticles (nano-TiO₂) were evenly distributed in the CH and no agglomeration was observed. The inner film fill rates affected the overall performance of the chromogenic material, with strong inhibitory effects against Escherichia coli and Staphylococcus aureus at different temperatures, as well as strong color stability. The experimental results indicated that the double-layer antibacterial chromogenic material can, to a certain extent, extend the shelf life of litchi fruit and determine the extent of its freshness. Therefore, from this study, we can infer that the research and development of active materials have a certain reference value.

An insight to potential application of synbiotic edible films and coatings in food products

Edible films and coatings have gained significant consideration in recent years due to their low cost and decreasing environmental pollution. Several bioactive compounds can be incorporated into films and coatings, including antioxidants, antimicrobials, flavoring agents, colors, probiotics and prebiotics. The addition of probiotics to edible films and coatings is an alternative approach for direct application in food matrices that enhances their stability and functional properties. Also, it has been noted that the influence of probiotics on the film properties was dependent on the composition, biopolymer structure, and intermolecular interactions. Recently, the incorporation of probiotics along with prebiotic compounds such as inulin, starch, fructooligosaccharide, polydextrose and wheat dextrin has emerged as new bioactive packaging. The simultaneous application of probiotics and prebiotics improved the viability of probiotic strains and elevated their colonization in the intestinal tract and provided health benefits to humans. Moreover, prebiotics created a uniform and compact structure by filling the spaces within the polymer matrix and increased opacity of edible films. The effects of prebiotics on mechanical and barrier properties of edible films was dependent on the nature of prebiotic compounds. This review aims to discuss the concept of edible films and coatings, synbiotic, recent research on synbiotic edible films and coatings as well as their application in food products.

Development and Characterization of Pullulan-Carboxymethyl Cellulose Blend Film for Packaging Applications

Edible packaging materials have widespread applications in pharmaceutical industries. In this study, the physical, thermal, colour, mechanical, and water barrier properties of a novel edible film based on pullulan (PUL) and carboxymethyl cellulose (CMC) were investigated. The blend films were made by the solution casting method with 3 g of total solid content. The following percentages of 100/0, 75/25, 50/50, 25/75, and 0/100 were used to prepare the films. Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), and thermogravimetric analysis (TGA) were used to analyze the interaction between PUL and CMC. At the level of 75/25 percentage of PUL, CMC film showed the lowest EAB% (5.55%), the highest values for TS (17.30 MPa), WVP value ( $4.12\times {10}^{-10}$  g m-1s-1Pa-1), and water contact angle of 63.43°. By increasing the CMC concentration, blend films became slightly greenish and yellowish but appeared transparent with UV blocking ability. This study reveals that 75/25 (PUL/CMC) blend film has a good potential that can be used in producing edible packaging films to protect the quality of pharmaceutical products with interesting specifications.

Breeding of a High-Nisin-Yielding Bacterial Strain and Multiomics Analysis

Nisin is a green, safe and natural food preservative. With the expansion of nisin application, the demand for nisin has gradually increased, which equates to increased requirements for nisin production. In this study, Lactococcus lactis subsp. lactis lxl was used as the original strain, and the compound mutation method was applied to induce mutations. A high-yielding and genetically stable strain (Lactobacillus lactis A32) was identified, with the nisin titre raised by 332.2% up to 5089.29 IU/mL. Genome and transcriptome sequencing was used to analyse A32 and compare it with the original lxl strain. The comparative genomics results show that 107 genes in the A32 genome had mutations and most base mutations were not located in the four well-researched nisin-related operons, nisABTCIPRK, nisI, nisRK and nisFEG: 39 single-nucleotide polymorphisms (SNPs), 34 insertion mutations and 34 deletion mutations. The transcription results show that the expression of 92 genes changed significantly, with 27 of these differentially expressed genes upregulated, while 65 were downregulated. Our findings suggest that the output of nisin increased in L. lactis strain A32, which was accompanied by changes in the DNA replication-related gene dnaG, the ABC-ATPase transport-related genes patM and tcyC, the cysteine thiometabolism-related gene cysS, and the purine metabolism-related gene purL. Our study provides new insights into the traditional genetic mechanisms involved nisin production in L. lactis, which could provide clues for a more efficient metabolic engineering process.

Essential Oil-Containing Polysaccharide-Based Edible Films and Coatings for Food Security Applications

The wastage of food products is a major challenge for the food industry. In this regard, the use of edible films and coatings have gained much attention due to their ability to prevent the spoilage of the food products during handling, transport, and storage. This has effectively helped in extending the shelf-life of the food products. Among the various polymers, polysaccharides have been explored to develop edible films and coatings in the last decade. Such polymeric systems have shown great promise in microbial food safety applications. The inclusion of essential oils (EOs) within the polysaccharide matrices has further improved the functional properties of the edible films and coatings. The current review will discuss the different types of polysaccharides, EOs, methods of preparing edible films and coatings, and the characterization methods for the EO-loaded polysaccharide films. The mechanism of the antimicrobial activity of the EOs has also been discussed in brief.