Milk Protein-Based Edible Films: Influence on Mechanical, Hydrodynamic, Optical and Antioxidant Properties

Enhancing food safety: A low-cost biosensor for Bacillus licheniformis detection in food products

To enhance food safety, the need for swift and precise detection of B. licheniformis, a bacterium prevalent in various environments, including soil and food products, is paramount. This study presents an innovative and cost-effective bioassay designed to specifically identify the foodborne pathogen, B. licheniformis, utilizing a colorimetric signal approach. The biosensor, featuring a 3D-printed architecture, incorporates a casein-based liquid-proof gelatine film, selectively liquefying in response to the caseinolytic/proteolytic activity of external enzymes from the pathogen. As the sample liquefies, it progresses through a color layer, causing the migration of dye to an absorbent layer, resulting in a distinct positive signal. This bioassay exhibits exceptional sensitivity, detecting concentrations as low as 1 CFU/mL within a 9.3-h assay duration. Notably, this cost-efficient bioassay outperforms conventional methods in terms of efficacy and cost-effectiveness, offering a straightforward solution for promptly detecting B. licheniformis in food samples.

Application of plasma-activated hydrogen peroxide solution synergized with Ag@SiO2 modified polyvinyl alcohol coating for strawberry preservation

To extend the postharvest storage time of strawberries, this study aims to prepare a composite coating using plasma-activated hydrogen peroxide solution (PAH) synergized with nano-Ag@SiO2 by blending method to modify polyvinyl alcohol (PVA) solution. Results showed that the viscosity and the swelling rate of PVA significantly decreased with the addition of Ag@SiO2 at 0.18 %. Meanwhile, the elongation at break and the tensile strength of PVA increased to 0.87 MPa and 214 %. When the addition of Ag@SiO2 was 0.18 % and the composite ratio of PAH to PVA was 1:1, the composites could inactivate the pathogenic bacteria at 2 h. During the storage of strawberries, the initial colony counts on the surface of strawberries could be reduced by about 1 lg CFU/g after coating with the composite film. Moreover, with the extension of the storage time to 7 d, the respiratory intensity, colony counts, and rot index in the strawberries were 65.7 mg/(kg•h), 4.05 log CFU/g, and 38.7 %. Meanwhile, the superoxide dismutase activity and Vc content were 944 U/g and 690 μg/g, respectively. Overall, this study provides ideas and the theoretical basis for applying composite films in fruit preservation.

Preparation and functional characterization of the bio-composite film based on chitosan/polyvinyl alcohol blended with bacterial exopolysaccharide EPS MC-5 having antioxidant activities

In this study, the plate casting method was successfully used to prepare biocomposite films containing EPS from probiotic Enterococcus faecium MC-5 in combination with PVA and chitosan. The findings demonstrated that EPS was uniformly distributed in the film matrices and significantly improved the physicochemical properties of the resulting composite films. The development of intermolecular connections between the polymers was detected by high tensile strength and low water vapour transmission rate. EPS plays an important role in limiting the passage of UV- and visible light radiations through the films. FT-IR analysis was used to determine the molecular compatibility between the functional groups of the blended films made up of chitosan-EPS and PVA-EPS. The TGA results showed that composite films have a significant degree of thermal stability. The presence of amorphous peaks in the composite film was confirmed by XRD analysis. The EPS blended films displayed a greater antioxidant property than the PVA and chitosan films, as determined by DPPH and hydroxyl radical scavenging activities. Interestingly, the EPS-derived films showed enhanced metal chelation activity and strong antibacterial properties against Listeria monocytogenes and Staphylococcus aureus. EPS-based composite films performed better than chitosan and PVA films in terms of degradation rate. The overall functional characteristics of the EPS blended films suggested that they could be used as a packaging material to replace or reduce the use of conventional petroleum-based packaging materials.

Mechanical Properties of Protein-Based Food Packaging Materials

The quality and safety of food products greatly depend on the physiochemical properties of the food packaging material. There is an increasing trend in the utilization of protein-based biopolymers for the preparation of edible films and coating due to their film-forming properties. Various studies have reported the preparation of protein-based edible films with desirable mechanical and barrier properties. The mechanical attributes of the protein-based food packaging materials can be enhanced by incorporating various components in the film composition such as plasticizers, surfactants, crosslinkers, and various bioactive compounds, including antimicrobial and antioxidant compounds. This review article summarizes the recent updates and perspective on the mechanical attributes such as Tensile Strength (TS), Elongation at Break (EAB), and Young’s Modulus (YM) of edible films based on different proteins from plants and animal sources. Moreover, the effects of composite materials such as other biopolymers, bioactive compounds, essential oils, and plasticizers on the mechanical properties of protein-based edible films are also discussed.

Strategies for Exploiting Milk Protein Properties in Making Films and Coatings for Food Packaging: A Review

Biopolymers of different natures (carbohydrates, proteins, etc.) recovered from by-products of industrial processes are increasingly being studied to obtain biomaterials as alternatives to conventional plastics, thus contributing to the implementation of a circular economy. The food industry generates huge amounts of by-products and waste, including unsold food products that reach the end of their shelf life and are no longer usable in the food chain. Milk proteins can be easily separated from dairy waste and adapted into effective bio-based polymeric materials. Firstly, this review describes the relevant properties of milk proteins and the approaches to modifying them for subsequent use. Then, we provide an overview of recent studies on the development of films and coatings based on milk proteins and, where available, their applications in food packaging. Comparisons among published studies were made based on the formulation as well as production conditions and technologies. The role of different additives and modifiers tested for the performances of films and coatings, such as water vapor permeability, tensile strength, and elongation at break, were reviewed. This review also outlines the limitations of milk-protein-based materials, such as moisture sensitivity and brittleness. Overall, milk proteins hold great potential as a sustainable alternative to petroleum-based polymers. However, their use in food packaging materials at an industrial level remains problematic.

Wheat gluten-based coatings and films: Preparation, properties, and applications

Effective food packaging that can protect foodstuffs from physical, chemical, and biological damage and maintain freshness and quality is essential to the food industry. Wheat gluten shows promise as food packaging materials due to its edibility, biodegradability, wide availability, low cost, film-forming potential, and high resistance to oxygen. The low mechanical properties and poor water permeability of wheat gluten coatings and films limit their wide applications; however, some inferior properties can be improved through various solutions. This work presents a comprehensive review about wheat gluten-based coatings and films, including their formulation, processing methods, properties, functions, and applications. The mechanical and water resistance properties of coatings and films can be reinforced through wheat gluten modification, combinations of different processing methods, and the incorporation of reinforcing macromolecules, antioxidants, and nanofillers. Antioxidants and antimicrobial agents added to wheat gluten can inhibit microbial growth on foodstuffs, maintain food quality, and extend shelf life. Performances of wheat gluten-based coatings and films can be further improved to expand their applications in food packaging. Current research gaps are identified. Future research is needed to examine the optimal formulation and processing of wheat gluten-based coatings and films and their performance.

Whey Protein Films for Sustainable Food Packaging: Effect of Incorporated Ascorbic Acid and Environmental Assessment

The management of food waste and by-products has become a challenge for the agri-food sector and an example are whey by-products produced in dairy industries. Seeking other whey valorisation alternatives and applications, whey protein films for food packaging applications were developed in this study. Films containing different amounts (0, 5, 10, and 15 wt%) of ascorbic acid were manufactured via compression-moulding and their physicochemical, thermal, barrier, optical, and mechanical properties were analysed and related to the film structure. Additionally, the environmental assessment of the films was carried out to analyse the impact of film manufacture. Regarding physicochemical properties, both FTIR and water uptake analyses showed the presence of non-covalent interactions, such as hydrogen bonding, between whey protein and ascorbic acid as band shifts at the 1500-1700 cm^-1 region as well as a water absorption decrease from 380% down to 240% were observed. The addition of ascorbic acid notably improved the UV-Vis light absorbance capacity of whey protein films up to 500 nm, a relevant enhancement for protecting foods susceptible to UV-Vis light-induced lipid oxidation. In relation to the environmental assessment, it was concluded that scaling up film manufacture could lead to a reduction in the environmental impacts, mainly electricity consumption.

Active Food Packaging Made of Biopolymer-Based Composites

Food packaging plays a vital role in protecting food products from environmental damage and preventing contamination from microorganisms. Conventional food packaging made of plastics produced from unrenewable fossil resources is hard to degrade and poses a negative impact on environmental sustainability. Natural biopolymers are attracting interest for reducing environmental problems to achieve a sustainable society, because of their abundance, biocompatibility, biodegradability, chemical stability, and non-toxicity. Active packaging systems composed of these biopolymers and biopolymer-based composites go beyond simply acting as a barrier to maintain food quality. This review provides a comprehensive overview of natural biopolymer materials used as matrices for food packaging. The antioxidant, water barrier, and oxygen barrier properties of these composites are compared and discussed. Furthermore, biopolymer-based composites integrated with antimicrobial agents-such as inorganic nanostructures and natural products-are reviewed, and the related mechanisms are discussed in terms of antimicrobial function. In summary, composites used for active food packaging systems can inhibit microbial growth and maintain food quality.

Chitosan-Sodium Caseinate Composite Edible Film Incorporated with Probiotic Limosilactobacillus fermentum: Physical Properties, Viability, and Antibacterial Properties

Single-use synthetic plastics that are used as food packaging is one of the major contributors to environmental pollution. Hence, this study aimed to develop a biodegradable edible film incorporated with Limosilactobacillus fermentum. Investigation of the physical and mechanical properties of chitosan (CS), sodium caseinate (NaCas), and chitosan/sodium caseinate (CS/NaCas) composite films allowed us to determine that CS/NaCas composite films displayed higher opacity (7.40 A/mm), lower water solubility (27.6%), and higher Young's modulus (0.27 MPa) compared with pure CS and NaCas films. Therefore, Lb. fermentum bacteria were only incorporated in CS/NaCas composite films. Comparison of the physical and mechanical properties of CS/NaCas composite films incorporated with bacteria with those of control CS/NaCas composite films allowed us to observe that they were not affected by the addition of probiotics, except for the flexibility of films, which was improved. The Lb. fermentum incorporated composite films had a 0.11 mm thickness, 17.9% moisture content, 30.8% water solubility, 8.69 A/mm opacity, 25 MPa tensile strength, and 88.80% elongation at break. The viability of Lb. fermentum after drying the films and the antibacterial properties of films against Escherichia coli O157:H7 and Staphylococcus aureus ATCC 29213 were also evaluated after the addition of Lb. fermentum in the composite films. Dried Lb. fermentum composite films with 6.65 log₁₀ CFU/g showed an inhibitory effect against E. coli and S. aureus (0.67 mm and 0.80 mm inhibition zone diameters, respectively). This shows that the Lb.-fermentum-incorporated CS/NaCas composite film is a potential bioactive packaging material for perishable food product preservation.

Milk protein-based active edible packaging for food applications: An eco-friendly approach

Whey and casein proteins, in particular, have shown considerable promise in replacing fossil-based plastics in a variety of food applications, such as for O₂ susceptible foods, thereby, rendering milk proteins certainly one of the most quality-assured biopolymers in the packaging discipline. Properties like excellent gas barrier properties, proficiency to develop self-supporting films, adequate availability, and superb biodegradability have aroused great attention toward whey and other milk proteins in recent years. High thermal stability, non-toxicity, the ability to form strong inter cross-links, and micelle formation, all these attributes make it a suitable material for outstanding biodegradability. The unique structural and functional properties of milk proteins make them a suitable candidate for tailoring novel active package techniques for satisfying the needs of the food and nutraceutical industries. Milk proteins, especially whey proteins, serve as excellent carriers of various ingredients which are incorporated in films/coatings to strengthen barrier properties and enhance functional properties viz. antioxidant and antimicrobial. In this review, the latest techniques pertaining to the conceptualization of active package models/ systems using milk proteins have been discussed. Physical and other functional properties of milk protein-based active packaging systems are also reviewed. This review provides an overview of recent applications of milk protein-sourced active edible packages in the food packaging business.

Assessing Compositional and Quality Parameters of Unconcentrated and Refractive Window Concentrated Milk Based on Color Components

In this study, a multiple linear regression equation was developed to measure and predict quality parameters of unconcentrated and concentrated milk based on color components. The viscosity, density, pH, moisture, and fat content could be measured using image processing technology. The multiple linear regression model had a good fitting on experimental data considering the limited errors (0.00–1.12%), standard deviation (0.000–0.043), and root mean square error (0.0007–0.3721). Therefore, these models can be used to predict the quality parameters of milk, including fat percentage, pH, viscosity, density, and moisture content, based on color components of unconcentrated and concentrated milk. The maximum and minimum of color change were 12.28 and 5.96, respectively. The values of browning index were also well-predicted and were within the standard limits. The non-destructive and quick procedure that proposed in this study showed a percentage of accuracy in assessing and predicting the quality parameters milk based on color components. Overall, the color correlates with different compositional and physical characteristics, and provide a possible internet of things (IoT)-based approach to accompany the conventional approaches in the future after further evaluation at large scale for various types of milks subjected to various processes.

The Influence of the Structure of Selected Polymers on Their Properties and Food-Related Applications

Every application of a substance results from the macroscopic property of the substance that is related to the substance’s microscopic structure. For example, the forged park gate in your city was produced thanks to the malleability and ductility of metals, which are related to the ability of shifting of layers of metal cations, while fire extinguishing powders use the high boiling point of compounds related to their regular ionic and covalent structures. This also applies to polymers. The purpose of this review is to summarise and present information on selected food-related biopolymers, with special attention on their respective structures, related properties, and resultant applications. Moreover, this paper also highlights how the treatment method used affects the structure, properties, and, hence, applications of some polysaccharides. Despite a strong focus on food-related biopolymers, this review is addressed to a broad community of both material engineers and food researchers.

Preparation and Characterization of New Electrospun Poly(lactic acid) Nanofiber Antioxidative Active Packaging Films Containing MCM-41 Mesoporous Molecular Sieve Loaded with Phloridzin and Their Application in Strawberry Packaging

Health concerns about food safety have increased in recent years. In order to ensure the safety and increase the shelf-life of food, many methods have been used to slow down the oxidation rate of food fat. In order to solve this problem, a new type of antioxidant-active packaging has emerged. Poly(lactic acid) (PLA) films containing phloridzin adsorbed on to an MCM-41 mesoporous molecular sieve were prepared by electrostatic spinning, using PLA as a film-forming substrate, phloridzin as an antioxidant, and MCM-41 as the adsorption and controlled release carrier. The physical properties of the new films—including microscopic structure, water vapor transmission rate, and fresh-keeping effects, as well as the mechanical, thermal, antioxidant, and antibacterial properties—were studied. When the mass ratio of MCM-41 to phloridzin is 1:2, the nanofiber membrane achieves a 53.61% free-radical scavenging rate and better antibacterial performance (85.22%) due to the high content of phloridzin (30.54%). Additionally, when the mass ratio of the molecular sieve to phloridzin is 1:2 and 3:4 (with the best antibacterial performance of 89.30%), the films significantly delay lipid oxidation in the strawberry packaging, allowing the fresh-keeping time to be extended to up to 21 days before mildew appears. In this study, an MCM-41 mesoporous molecular sieve was used to load phloridzin for the first time. The packaging film with phloridzin, MCM-41, and poly(lactic acid) were used as the raw materials and electrospinning technology was used to prepare the packaging film with antioxidant activity. The packaging film was used for the first time in the packaging of strawberries.