Recent advances in biopolymeric antioxidant films and coatings for preservation of nutritional quality of minimally processed fruits and vegetables

Functionalized cellulose nanocrystals reinforced polysaccharide matrix for the preparation of active packaging for perishable fruits preservation

Polysaccharide-based films have received increasing attention as promising candidates for petrochemical plastics. However, they are highly brittle, poorly hydrophobic and without antibacterial activity, while current films used to address these issues often struggle to manage the balance between these properties. To achieve a balance of several performance indices of the films, functionalized dialdehyde cellulose nanocrystals (DCNCs) were prepared to activate pectin-based films. Structural characterization including dynamic light scattering techniques (DLS), scanning electron microscope (SEM), atomic force microscope (AFM), attenuated total reflection Fourier-transform infrared (ATR-FTIR) spectrometer and x-ray diffraction (XRD) demonstrated that DCNCs were homogeneously dispersed in the pectin polysaccharide matrix and tightly cross-linked through hydrogen bonding interactions, which promoted the stable formation of high-performance composite films. Compared to pure pectin film, the composite film has better tensile strength (23.09 MPa), water contact angle (WCA, 91.23°), water vapor permeability (WVP, 1.02 × 10-12 g/cm·s·Pa), and exhibit excellent UV-resistance, DPPH radical scavenging capacity (27.04 %) and antibacterial activity that significantly extended the shelf life of strawberries (5 d). Furthermore, DCNCs can be used to enhance the mechanical strength (4.15-23.46 MPa), WVP (1.55-5.21 × 10-12 g/cm·s·Pa) and WCA (59.46°-61.03°) of various polysaccharide-based films, which validates their universality. This work effectively improves and balances the several properties of polysaccharide-based films, creating more opportunities for the wide application of polysaccharide-based films, such as food preservation packaging.

A Current Trend in Efficient Biopolymer Coatings for Edible Fruits to Enhance Shelf Life

In recent years, biopolymer coatings have emerged as an effective approach for extending the shelf life of edible fruits. The invention of biopolymer coverings has emerged as an innovation for extending fruit shelf life. Natural polymers, like chitosan, alginate, and pectin, are used to create these surfaces, which have several uses, including creating a barrier that prevents water evaporation, the spread of living microbes, and respiratory movement. These biopolymer coatings' primary benefits are their environmental friendliness and lack of damage. This study highlights the advancements made in the creation and usage of biopolymer coatings, highlighting how well they preserve fruit quality, reduce post-harvest losses, and satisfy consumer demand for natural preservation methods. This study discusses the usefulness of the biopolymer coating in terms of preserving fruit quality, reducing waste, and extending the product's shelf life. Biopolymer coatings' potential as a sustainable solution for synthetic preservatives in the fruit sector is highlighted as are formulation process advances that combine natural ingredients and environmental implications. This essay focuses on the essential methods, such as new natural additives, as well as the environmental effect of biopolymer coatings, which are safe and healthy commercial alternatives.

Inhibition Mechanism of Water-Soluble Chitosan-Curdlan Composite Coating on the Postharvest Pathogens of Serratia marcescens and Pseudomonas syringae in Cherry Tomatoes

Cherry tomatoes, a very popular fruit, are highly susceptible to microbial infestation, which cause significant economic losses. In order to preserve cherry tomatoes better, we treat them with a Chitosan (CTS) and Curdlan (CUR) composite coating. The lowest inhibitory concentration of CTS/CUR composite coating on Serratia marcescens and Pseudomonas syringae, the growth curves, and the changes of the cell lysis rate were determined to explore the inhibitory mechanism of CTS/CUR composite coating on Serratia marcescens and Pseudomonas syringae and the microscopic morphology of Serratia marcescens and Pseudomonas syringae was observed using scanning electron microscopy at the same time. The results showed that the CTS/CUR composite coating could effectively inhibit the growth of Serratia marcescens and Pseudomonas, and the inhibitory effect reflected the concentration-dependent characteristics. The electron microscopy results indicated that the inhibition of Serratia marcescens and Pseudomonas syringae by the CTS/CUR composite coating might originate from its disruptive effect on the cell wall and cell membrane of the bacterium.

Antimicrobial polysaccharide hydrogels embedded with methyl-β-cyclodextrin/thyme oil inclusion complexes for exceptional mechanical performance and chilled chicken breast preservation

While hydrogels have potential for food packaging, limited research on hydrogels with excellent mechanical performance and antibacterial activity for preserving chicken breasts. Herein, we created antibacterial hydrogels by embedding methyl-β-cyclodextrin/thyme oil inclusion complexes (MCD/TO-ICs) into a polyvinyl alcohol matrix containing dendrobium polysaccharides and guar gum in varying ratios using freeze-thaw cycling method. The resulting hydrogels exhibited a more compact structure than those without MCD/TO-ICs, enhancing thermal stability and increasing glass transition temperature due to additional intermolecular interactions between polymer chains that inhibited chain movement. XRD analysis showed no significant changes in crystalline phase, enabling formation of a 3D network through abundant hydrogen bonding. Moreover, the hydrogel demonstrated exceptional durability, with a toughness of 350 ± 25 kJ/m3 and adequate tearing resistance of 340 ± 30 J/m2, capable of lifting 3 kg weight, 1200 times greater than the hydrogel itself. Additionally, the hydrogels displayed excellent antimicrobial activity and antioxidant properties. Importantly, the hydrogels effectively maintained TVB-N levels and microbial counts within acceptable ranges, preserving sensory properties and extending the shelf life of chilled chicken breasts by four days. This study highlights the potential of MCD/TO-IC-incorporated polysaccharide hydrogels as safe and effective active packaging solutions for preserving chilled chicken in food industry.

Study on the Properties of PLA- and PP-Based Films for Food Applications Incorporating Orange Peel Extract from Agricultural by-Products

The aim of this work was to develop active packaging based on polypropylene (PP) and polylactic acid (PLA) matrices using a high value by-product extracted from orange peel as an active compound for food packaging applications. Different films with and without orange peel extract (OPE) based on PP and PLA were obtained via cast extrusion and characterized in terms of their mechanical, thermal, optical, and sealing properties. The films obtained were transparent, but when OPE was incorporated, the transmittance spectrum decreased, causing slight coloration. Mechanical properties were affected by the incorporation of OPE, as elongation at break and tensile strength increased in the cross-direction of the PP film, although the main differences found were related to the polymer itself. In addition, sealing strength also increased via the incorporation of OPE in the PP matrix. However, thermal properties were not affected by OPE in the PP matrix but slightly decreased stability in PLA. Regarding antimicrobial activity in in vitro studies, no inhibition of the growth of Listeria innocua, Saccharomyces cerevisiae, Aspergillus niger, or Escherichia coli was observed. Finally, antioxidant activity was observed in in vitro studies with 2,2-Diphenyl-1picrylhydrazyl (DPPH) radical. The results of this study showed that the obtention of materials with OPE incorporated into the PLA and PP matrix is feasible. The new materials obtained can be used for applications of oxidation-sensitive fresh products.

Recent advances in modified starch based biodegradable food packaging: A review

This study reviews the importance of resistant starch (RS) as the polymer of choice for biodegradable food packaging and highlights the RS types and modification methods for developing RS from native starch (NS). NS is used in packaging because of its vast availability, low cost and film forming capacity. However, application of starch is restricted due to its high moisture sensitivity and hydrophilic nature. The modification of NS into RS improves the film forming characteristics and extends the applications of starch into the formulation of packaging. The starch is blended with other bio-based polymers such as guar, konjac glucomannan, carrageenan, chitosan, xanthan gum and gelatin as well as active ingredients such as nanoparticles (NPs), plant extracts and essential oils to develop hybrid biodegradable packaging with reduced water vapor permeability (WVP), low gas transmission, enhanced antimicrobial activity and mechanical properties. Hybrid RS based active packaging is well known for its better film forming properties, crystalline structures, enhanced tensile strength, water resistance and thermal properties. This review concludes that RS, due to its better film forming ability and stability, can be utilized as polymer of choice in the formulation of biodegradable packaging.

Recent advancements in polysaccharides, proteins and lipids based edible coatings to enhance guava fruit shelf-life: A review

Fresh fruits are highly needed for the health benefits of human beings because of the presence of high content of natural nutrition in the form of vitamins, minerals, antioxidants, and other phenolic compounds. However, some nutritional fruits such as guava are climacteric in nature with very less post-harvest shelf-life because of the ripening in a very short period and possibility of microbial infections. Thus security of natural nutrients is a serious concern in order to properly utilize guava without generating a huge amount of waste. Among reported various methods for the enhancement of fruits shelf-life, the application of edible coatings with antimicrobial activities on the outer surface of fruits have attracted significant attention because of their eco-friendly nature, easy applicability, high efficacy, and good durability. In recent years, researchers are paying more and more attention in the development of antimicrobial edible coatings to enhance the post-harvest shelf-life of guava using polysaccharides, protein and lipids. In this review, basic approaches and recent advancements in development of antimicrobial and edible coatings on guava fruit by the application of polysaccharides and protein and lipids along with the combination of nanomaterials are summarized. In addition, improvements in basic properties of edible coatings to significantly control the permeation of gases (O2/CO2) by the optimization of coating components as well as delay in ripening process are reviewed and discussed.

Development of a novel, sustainable, cellulose-based food packaging material and its application for pears

This study aimed to develop a cellulose-based active food packaging material using paper, a biodegradable, sustainable, recyclable, renewable, and relatively low-cost material. For electrospray coating, fulvic acid (FA), which has antioxidant and antimicrobial properties, and sericin (S) were used as an active agent and a carrier medium, respectively. Solutions prepared at various concentrations and ratios of FA and S were analyzed, the properties of the active packaging material were examined, and the effect on the quality of pears was studied. The optimum conditions of electrospraying for minimum droplet size and maximum antibacterial effect were 0.8 g/mL concentration of solutions, 1:1 FA:S ratio, 20 kV voltage, 0.75 mL/h flow rate, and 23 cm collector-needle tip distance. FA had static, lethal, and inhibitory effects on Pseudomonas syringae and P. digitatum, the common pathogenic microorganisms on pears. The antioxidant activity of FA was higher than that of S (872.96 mM vs. 239.36 mM). At the end of the 90-day storage period, pears stored in the active packaging material at 7 °C and 90% RH showed better preserved color and texture, matured later, had a lower antimicrobial load, and were more appreciated in sensory evaluation than other samples.

Evaluation of a Fish Gelatin-Based Edible Film Incorporated with Ficus carica L. Leaf Extract as Active Packaging

The significant concerns associated with the widespread use of petroleum-based plastic materials have prompted substantial research on and development of active food packaging materials. Even though fish gelatin-based films are appealing as active food packaging materials, they present practical production challenges. Therefore, this study aimed to develop an edible film using Ficus carica L. leaf extract (FLE), as it is affordable, accessible, and has superoxide anion radical scavenging action. This edible film was produced by adding FLE to mackerel skin gelatin at varied concentrations (2.5-10% w/w). The results showed that adding FLE to gelatin films significantly affected the tensile strength (TS), elongation at break (EAB), transmittance and transparency, solubility, water vapor permeability (WVP), antioxidant activity, and antibacterial activity. Among all the samples, the most promising result was obtained for the edible film with FLE 10%, resulting in TS, EAB, solubility, WVP, antioxidant activity, and antibacterial activity against S. aureus and E. coli results of 2.74 MPa, 372.82%, 36.20%, 3.96 × 10-11 g/msPa, 45.49%, 27.27 mm, and 25.10 mm, respectively. The study's overall findings showed that fish gelatin-based films incorporated with FLE are promising eco-friendly, biodegradable, and sustainable active packaging materials.

Green Extraction of Antioxidant Fractions from Humulus lupulus Varieties and Microparticle Production via Spray-Drying

The formulation of polymeric microparticles to encapsulate bioactive compounds from two hop varieties (Nugget and Perle) using sequential green extraction processes was performed. The technologies used were ultrasound-assisted extraction (UAE) and pressurized hot water (PHW) extraction. Liquid phases were analyzed for total phenolic content (~2%), antioxidant activity (IC50, DPPH: 3.68 (Nugget); 4.46 (Perle) g/L, TEAC (~4-5%), FRAP (~2-3%), and reducing power (~4%)), protein content (~1%), oligosaccharide content (~45%), and for structural features. The fractions obtained from UAE were selected to continue with the drying process, achieving the maximum yield at 120 °C (Perle) and 130 °C (Nugget) (~77%). Based on these results, the formulation of polymeric microparticles using mannitol as the carrier was performed with these fractions. The production yield (~65%), particle size distribution (Perle: 250-750 µm and Nugget: ~100 µm), and rheological features (30-70 mPa s at 0.1 s-1) were the parameters evaluated. The UAE extracts from hop samples processed using a sustainable aqueous treatment allowed the formulation of microparticles with a suitable yield, and morphological and viscosity properties adequate for potential food and non-food applications.

Multi-Component Biodegradable Materials Based on Water Kefir Grains and Yeast Biomasses: Effect of the Mixing Ratio on the Properties of the Films

The use of biopolymeric materials is restricted for some applications due to their deficient properties in comparison to synthetic polymers. Blending different biopolymers is an alternative approach to overcome these limitations. In this study, we developed new biopolymeric blend materials based on the entire biomasses of water kefir grains and yeast. Film-forming dispersions with varying ratios of water kefir to yeast (100/0, 75/25, 50/50 25/75 and 0/100) underwent ultrasonic homogenisation and thermal treatment, resulting in homogeneous dispersions with pseudoplastic behaviour and interaction between both biomasses. Films obtained by casting had a continuous microstructure without cracks or phase separation. Infrared spectroscopy revealed the interaction between the blend components, leading to a homogeneous matrix. As the water kefir content in the film increased, transparency, thermal stability, glass transition temperature and elongation at break also increased. The thermogravimetric analyses and the mechanical tests showed that the combination of water kefir and yeast biomasses resulted in stronger interpolymeric interactions compared to single biomass films. The ratio of the components did not drastically alter hydration and water transport. Our results revealed that blending water kefir grains and yeast biomasses enhanced thermal and mechanical properties. These studies provided evidence that the developed materials are suitable candidates for food packaging applications.

Effect of ferulic acid derivative concentration on the release kinetics, antioxidant capacity, and thermal behaviour of different polymeric films

Ferulic acid displays poor thermal resistance during extrusion and compression moulding, slow 2,2-diphenyl-1-picrylhydrazyl (DPPH) reaction kinetics, and undetected release from polylactide (PLA) and polyhydroxyalkanoates (PHA)-based films into polar media. Thus, in this study, a ferulic acid derivative Bis-O-dihydroferuloyl-1,4-butanediol (BDF) was used as an active additive (up to 40 w%) in PLA, poly(3-hydroxybutyrate) (PHB), and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) matrices to produce blends by extrusion. These blends were then used to prepare films by solvent casting. The BDF displayed good stability with 86-93% retention. The release kinetics in Food Simulant A revealed higher BDF release amounts (1.16-3.2%) for PHA-based films as compared to PLA. The BDF displayed faster DPPH reaction kinetics as compared to ferulic acid. The PHA-based films containing BDF displayed > 80% of DPPH inhibition. The growth of crystals inside polymer matrix had a nucleation effect which reduced the glass transition temperature of the films.

Fabrication and characterization of natural polyphenol and ZnO nanoparticles loaded protein-based biopolymer multifunction electrospun nanofiber films, and application in fruit preservation

To extend the shelf life of sweet cherries (Prunus avium L.) and considering the environmental problems caused by traditional packaging materials, novel Zein/Gelatin-proanthocyanidins-zinc oxide nanoparticles (ZE/GE-PC-ZnO) and Zein/Gelatin-gallic acid-zinc oxide nanoparticles (ZE/GE-GA-ZnO) protein-based composite nanofiber films were prepared by electrospinning. According to the results, ZE/GE-PC-ZnO and ZE/GE-GA-ZnO films' contact angles were higher than those of Zein/Gelatin film by 28.91% and 21.27%, and their antioxidant activities were 5 and 9 times higher, respectively. Moreover, ZE/GE-PC-ZnO film showed good inhibitory activity against B. cinerea. On the eleventh day of the cherry packaging test, compared to unwrapped cherries, the losses of weight and firmness of wrapped fruit were reduced by more than 20% and 60%, respectively. Respiration time was delayed by 5 days, and the peak of ethylene release was decreased by nearly half. In conclusion, these two nanofiber films were viable packaging materials that fulfilled global strategies for green development.

Biopolymer Food Packaging Films Incorporated with Essential Oils

Petroleum-based packaging materials are typically nonbiodegradable, which leads to significant adverse environmental and health issues. Therefore, developing novel efficient, biodegradable, and nontoxic food packaging film materials has attracted increasing attention from researchers. Due to significant research and advanced technology, synthetic additives in packaging materials are progressively replaced with natural substances such as essential oils (EOs). EOs demonstrate favorable antioxidant and antibacterial properties, which would be an economical and effective alternative to synthetic additives. This review summarized the possible antioxidant and antimicrobial mechanisms of various EOs. We analyzed the properties and performance of food packaging films based on various biopolymers incorporated with EOs. The progress in intelligent packaging materials has been discussed as a prospect of food packaging materials. Finally, the current challenges regarding the practical application of EOs-containing biopolymer films in food packaging and areas of future research have been summarized.

Development of Composite Edible Coating from Gelatin-Pectin Incorporated Garlic Essential Oil on Physicochemical Characteristics of Red Chili (Capsicum annnum L.)

Red chili is a climacteric fruit that still undergoes respiration after harvest. During storage, it is susceptible to mechanical, physical, and physiological damage and decay incidence, therefore a method is needed to protect it so that the quality losses can be minimized. One way this can be achieved is by applying edible coatings that can be made from hydrocolloids, lipids, or composites of both, in addition to antimicrobial agents that can also be added to inhibit microbial growth. In this study, we detail the application of an edible coating made of gelatin composite from tilapia fish skin, which has a transparent color and good barrier properties against O₂, CO₂, and lipids. To increase its physicochemical and functional qualities, it must be modified by adding composite elements such as pectin as well as hydrophobic ingredients such as garlic essential oil. This study was conducted to determine the effect of a gelatin-pectin composite edible coating (75:25, 50:50, 25:75), which was incorporated with garlic essential oil (2% and 3%) on the physicochemical properties of red chili at room temperature (±29 °C), RH ± 69%) for 14 days. The best treatment was the 50-50% pectin-gelatin composite, which was incorporated with garlic essential oil with a concentration of 2 and 3%. This treatment provided a protective effect against changes in several physicochemical properties: inhibiting weight loss of 36.36 and 37.03%, softening of texture by 0.547 and 0.539 kg/84 mm², maintaining acidity of 0.0087 and 0.0081%, maintaining vitamin C content of 2.237 and 2.349 mg/gr, anti-oxidant activity (IC₅₀) 546.587 and 524.907; it also provided a protective effect on chili colors changing to red, and retains better total dissolved solid values.

Polyhydroxybutyrate (PHB) produced from red grape pomace: Effect of purification processes on structural, thermal and antioxidant properties

Red grape pomace was used as a source for poly(3-hydroxybutyrate) (PHB) production, which was then subject to a range of purification processes. The different PHB biopolymers were characterized for chemical structure, crystallinity, thermal properties, colour, release of compounds into different food simulants and antioxidant inhibition, and comparisons were made with a commercially available PHB. An increase in purification steps did not have a significant effect on the high thermal stability of the extracted biopolymer, but it decreased the degree of crystallinity and the presence of amino acids and aromatic compounds. With additional purification, the PHB powders also whitened and the number of components released from the biopolymer into food simulants decreased. The released compounds presented antioxidant inhibition, which has not been previously reported in the literature or with commercially available polyhydroxyalkanoates. This is of great interest for food packaging and biomedical industries where the addition of antioxidant additives to improve PHB functional properties may not be necessary and could be avoided.

The Optimization of Gelatin Extraction from Chicken Feet and the Development of Gelatin Based Active Packaging for the Shelf-Life Extension of Fresh Grapes

Synthetic plastics are causing serious environmental and health problems due to which the concept of developing biodegradable food packaging has gained considerable attention. In this study, extraction of gelatin from chicken feet was optimized followed by characterization of gelatin. Chicken feet gelatin was used to develop biodegradable nanocomposite films by the incorporation of chitosan (CS) and zinc oxide (ZnO) nanoparticles (NPs). Gelatin nanocomposite films were used to increase the shelf-life of fresh grapes by determining the browning index, weight loss, and microbial profile of fresh grapes. A high yield (7.5%) of gelatin and Bloom strength (186 g) were obtained at optimized extraction conditions (pretreatment with 4.2% acetic acid and extraction at 66 °C for 4.2 h). Electrophoretic analysis of gelatin revealed the presence of α (130–140 kDa) and β chains (195–200 kDa), whereas a Fourier transformed infrared (FTIR) spectrometer confirmed the presence of amide A and B and amide I, II, and III. Incorporation of ZnO NPs in a gelatin–CS matrix improved the barrier and the mechanical and the thermal properties of films. Gelatin nanocomposite films with 0.3% ZnO NPs significantly reduced the weight loss (23.88%) and the browning index (53.33%) of grapes in comparison to control treatments. The microbial count in artificially inoculated grapes wrapped in gelatin nanocomposite films remained below 4 log CFU/mL until the fifth storage day in comparison to control treatments. The gelatin from poultry byproducts such as chicken feet can serve as an efficient biopolymer to develop biodegradable food packaging to enhance the shelf-life of perishable food products.

Development and characterization of sodium alginate/tea tree essential oil nanoemulsion active film containing TiO2 nanoparticles for banana packaging

To improve the postharvest quality and reduce the anthracnose of bananas, the sodium alginate (SA)/tea tree essential oil nanoemulsion (TEON) based bilayer films incorporated with different contents of TiO₂ nanoparticles were fabricated in this work. The developed TEON presented satisfactory DPPH scavenging activity (65.5 ± 1.8%) and antifungal capability (90.5 ± 5.8%). The microscopy images of the cross-section of the films indicated that the bilayer films with well-cross-linked were developed successfully. Notably, the addition of a certain content of TiO₂ to SA greatly improved the UV blocking and water vapor and oxygen barrier properties of the developed film. However, the barrier property of the film was decreased when the TiO₂ content further increased to 4.0 mg/100 mg of SA. The retention of TEO under visible and UV light in the bilayer film was respectively prolonged to 24 days and 32 h when the addition of TiO₂ content was 2.0 mg/100 mg of SA. Finally, the postharvest quality and anthracnose of banana fruits were significantly improved by SA-TiO₂ + SA-TEON film-forming solution treatments. Results from the present work might open up new insights into the approaches of postharvest quality improvement of bananas.

Single and Combined Effect of Mild-Heat Treatment and Alginate Coatings on Quality Preservation of Minimally Processed Bunching Green Onions

Bunching green onion is an Allium species that has been widely used in food flavorings and seasonings. This vegetable experiences a rapid loss of quality during storage due to physiological changes and microbial spoilage. In the current work, the single and combined effect of mild-heat treatment (55 °C for 60 s) and alginate edible coatings on the quality preservation of minimally processed bunching green onions was studied. Control and treated samples were stored at 4 °C for 15 days and examined periodically in terms of their respiration rate, weight loss, pH, soluble solids content, firmness, total polyphenol content, antioxidant activity, microbial count, decay ratio, and overall visual quality. The results showed that the combination of mild heat and alginate edible coatings was the most effective approach to slow down the respiration rate and the incidence of decay in the minimally processed bunching green onions. In addition, the treatments with alginate coating alone or combined with mild-heat treatment showed the best performance for maintaining the overall visual quality of the products during the storage.