Effect of hexanal loaded electrospun fiber in fruit packaging to enhance the post harvest quality of peach

Zein-based nisin-loaded electrospun nanofibers as active packaging mats for control of Listeria monocytogenes on peach

Zein-based nanofibers (NFs) functionalized with nisin (NS), reinforced with montmorillonite nanoclay (nMMT) were fabricated by uniaxial electrospinning (ES) for the first time to preserve yellow peach. Spinnability/viscosity/conductivity optimizations generated porous (95.09%), bead-free, ultrathin (119 nm) NFs of low hydrophobicity (26.05°). Glutaraldehyde (GTA) crosslinking fostered positive outcomes of tensile strength (1.23 MPa), elongation (5.0%), hydrophobicity (99.46°), surface area (201.38 m2.g-1), pore size (2.88 nm), thermal stability (Tmax = 342 °C), antioxidant/cytotoxic activities in optimized NFs that released NS sustainably according to Korsmeyer-Peppas model indicating a Fickian diffusion mechanism with R2 = 0.9587. The novel NFs inhibited growth of Listeria monocytogenes/aerobic mesophilic populations in peach after 4 days of abusive storage, evincing their robustness in food contact applications. Simultaneously, quality parameters (moisture/texture/browning/total soluble solids/pH) and peach physical appearance were maintained for up to 8 days, endorsing the practical value of zein-based NFs as a non-thermal postharvest intervention for prolonging fruits storage life.

In-situ enzyme-initiated production of hexanal from sunflower oil and its release from double emulsion electrospun bio-active membranes

The aim of the presented study was to evaluate the release of the enzymatically initiated production of hexanal from double emulsion electrospun bio-active membranes at a temperature of fruit storage. Among different formulations of water-in-oil (W1/O) primary emulsions, the emulsion composed of 12% w/v Tween20 and 0.1 M NaCl in water (W1) and 6% of poly(glycerol) poly(ricinoleate) dissolved in sunflower oil (O) using W1/O ratio of 80/20 (w/w) (Tween20-NaCl/6% PGPR) was selected, for further incorporation of enzymes, based on the lowest average droplet size (391.0 ± 15.6 nm), low polydispersity index (0.255 ± 0.07), and good gravitational stability also after 14 days. Both enzymes, lipase and lipoxygenase are needed to produce hexanal (up to 58 mg/L). Additionally, double emulsions were prepared with sufficient conductivity and viscosity using different W1/O to W2 ratios for electrospinning. From the selected electrospun membrane, up to 4.5 mg/L of hexanal was released even after 92 days.

One-pot co-crystallized hexanal-loaded ZIF-8/quaternized chitosan film for temperature-responsive ethylene inhibition and climacteric fruit preservation

Controlling ethylene production and microbial infection are key factors to prolong the shelf life of climacteric fruit. Herein, a nanocomposite film, hexanal-loaded ZIF-8/CS (HZCF) with "nano-barrier" structure, was developed by a one-pot co-crystallized of ZIF-8 in situ growth on quaternized chitosan (CS) and encapsulation of hexanal into ZIF-8 via microporous adsorption. The resultant film realized the temperature responsive release of hexanal via the steric hindrance and hierarchical pore structure as "nano-barrier", which can inhibit ethylene production in climacteric fruit on demand. Based on this, the maximum ethylene inhibition rate of HZCF was up to 52.6 %. Meanwhile, the film exhibits excellent antibacterial, mechanical, UV resistance and water retention properties, by virtue of the functional synergy between ZIF-8 and CS. Contributed to the multifunctional features, HZCF prolonged the shelf life of banana and mango for at least 16 days, which is 8 days longer than that of control fruit. More strikingly, HZCF is washable and biodegradable, which is expected to replace non-degradable plastic film. Thus, this study provides a convenient novel approach to simplify the encapsulation of active molecule on metal-organic frameworks (MOFs), develops a packaging material for high-efficient freshness preservation, and helps to alleviate the survival crisis caused by food waste.

Zein Multilayer Electrospun Nanofibers Contain Essential Oil: Release Kinetic, Functional Effectiveness, and Application to Fruit Preservation

In this study, sequential electrospinning was employed to produce a multilayer film consisting of zein nanofibers (Z) and Zataria multiflora essential oil (ZMEO) with different layers. The layers include: Z (without ZMEO), Z1 (one layer of Z + ZMEO), Z3 (three layers of Z + ZMEO), and Z5 (five layers of Z + ZMEO). Then, the effect of this antimicrobial packaging was investigated in relation to increasing the shelf life of strawberries at 4 °C for 12 days. The scanning electron microscopy (SEM) images of the fibers demonstrated a uniform and smooth structure without any beads. The use of Fourier transform infrared (FTIR) and Differential scanning calorimetry (DSC) showed that ZMEO was physically encapsulated into multilayer Z, resulting in an enhancement in thermal stability. The multilayer film showed a sustained release pattern of the encapsulated ZMEO for Z3, lasting for 90 h, and Z5, lasting for 180 h. This was in contrast to the rapid release within 50 h observed with Z film. The release kinetics for Z5 showed a good correlation with both the Higuchi and Korsmeyer-Peppas models, while for Z1 and Z3 films, Fickian diffusion was identified as the underlying mechanism. The findings of this study indicated that the multilayer film released ZMEO through a combination of diffusion and polymeric erosion. During a 12-day period of cold storage, strawberries that were treated with Z5 showed significant preservation of their anthocyanin (32.99%), antioxidant activity (25.04%), weight loss (24.46%), titratable acidity (11.47%), firmness (29.67%), and color (10.17%) compared to the control sample. The findings indicated that the sequential electrospinning technique used to create the multilayer nanofibrous film could be used in various fields, such as bioactive encapsulation, controlled release, antimicrobial packaging, and food preservation.

One pot synthesis of hydrophobic nanochitin aerogel via tert-butyl alcohol/water binary solvents as antibacterial and renewable oil superabsorbent

In this study, hydrophobic nanochitin aerogels are synthesized via one-pot synthesis strategy and subsequent freeze-drying technique, employing nanochitin, hexanal and formaldehyde as primary components. The tert-butyl alcohol (TBA)/water binary solvents are found efficient for well mixing of hydrophilic nanochitin and hydrophobic hexanal, which is fundamental for fabricating hydrophobic aerogels with water contact angle as high as 105°. Schiff base reaction between amino groups in nanochitin and aldehyde groups in hexanal is believed to be the main reason for the successful hydrophobization of nanochitin aerogels. Additionally, formaldehyde is employed to enhance the mechanical properties of aerogels via ice templated crosslinking technique. Nanochitin aerogels prepared in this work possess surface area as high as 237 m2 g-1, which are believed benefiting from the TBA/water binary solvents with lower density, smaller ice crystal and convenience in freeze-drying. The ultralow density, ultrahigh porosity, and hydrophobicity nature also lead to the advanced oil adsorption (as high as 210 g g-1) of nanochitin aerogels. The simple preparation process, nature sustainability and excellent adsorption performance is believed rendering nanochitin aerogels as a viable alternative for the remediation of oil spills.

Tracing the volatilomic fingerprint of grape pomace as a powerful approach for its valorization

The huge amount of grape pomace (GP) generated every year worldwide, particularly in Europe, creates negative impacts at the economic and environmental levels. As far as we know, scarce research has been done on the volatilomic fingerprint of GP. To meet consumer demand for healthy foods, there is a growing interest in the characterization of particular volatile organic metabolites (VOMS) in GP that can be used for industrial applications, including the food industry. In this study, the volatilomic fingerprint of GP obtained from different Vitis vinifera L. grapes was established by solid phase microextraction (HS-SPME) combined to gas chromatography-mass spectrometry (GC-MS), to explore the properties of most dominant VOMs in a context of its application on marketable products. A total of 52 VOMs belonging to different chemical families were identified. Alcohols, carbonyl compounds, and esters, are the most dominant, representing 38.8, 29.3, and 24.2% of the total volatile profile of the investigated GP, respectively. Esters (e.g., isoamyl acetate, hexyl acetate, ethyl hexanoate) and alcohols (e.g., 3-methyl butan-2-ol, hexan-1-ol) can be used as flavoring agents with potential use in the food industry, and in the cosmetic industry, for fragrances production. In addition, the identified terpenoids (e.g., menthol, ylangene, limonene) exhibit antioxidant, antimicrobial, and anticancer, biological properties, among others, boosting their potential application in the pharmaceutical industry. The obtained results revealed the potential of some VOMs from GP to replace synthetic antioxidants, colorants, and antimicrobials used in the food industry, and in the cosmetic and pharmaceutical industry, meeting the increasing consumer demand for natural alternative compounds.

Biodegradable Active Packaging Enriched with Essential Oils for Enhancing the Shelf Life of Strawberries

The strawberry (Fragaria ananassa) is a nutrient-rich fruit with high content of health-beneficial compounds. However, strawberries are susceptible to mechanical damage and microbiological contamination which can cause changes in fruit sensory properties. These changes consequently effect on ripening and shelf life of the strawberry. In recent years, essential oils (EOs) have been famous for their antimicrobial and antioxidant properties and are promising ecological alternatives to chemical antimicrobial substances. Nowadays, active packaging is one of several techniques developed for slowing down the metabolic processes of fresh fruits. Poly(lactic acid) (PLA) is one of the several polymers suitable for encapsulation EOs, whereas at the same time represent non-toxic, biodegradable, and compostable polymer derived from renewable resources. Suitable packaging prolongs the shelf life of fruit, keeps the products at the highest possible nutrition level, improves quality, and attracts customer attention. In the current study, we encapsulated EOs (lemongrass and oregano) into a PLA and poly(3-hydroxybutyrate) (PHB) packaging film and explored their antimicrobial and antioxidant properties. Moreover, biochemical and quality parameters for strawberry preservation and shelf-life extension were also assessed. Our tested active packaging film with EOs was proven to be useful for postharvest quality maintenance and shelf-life extension of strawberries, with PLA/PHB/ATBC + 5% lemongrass EO being slightly better than PLA/PHB/ATBC + 5% oregano EO.

Triggered and controlled release of bioactives in food applications

Bioactive compounds (e.g., nutraceuticals, micronutrients, antimicrobial, antioxidant) are added to food products and formulations to enhance sensorial/nutritional attributes and/or shelf-life. Many of these bioactives are susceptible to degradation when exposed to environmental and processing factors. Others involve in undesirable interactions with food constituents. Encapsulation is a useful tool for addressing these issues through various stabilization mechanisms. Besides protection, another important requirement of encapsulation is to design a carrier that predictably releases the encapsulated bioactive at the target site to elicit its intended functionality. To this end, controlled release carrier systems derived from interactive materials have been developed and commercially exploited to meet the requirements of various applications. This chapter provides an overview on basic controlled and triggered release concepts relevant to food and active packaging applications. Different approaches to encapsulate bioactive compounds and their mode of release are presented, from simple blending with a compatible matrix to complex multiphase carrier systems. To further elucidate the mass transport processes, selected diffusion and empirical release kinetic models are presented, along with their brief historical significance. Finally, interactive carriers that are responsive to moisture, pH, thermal and chemical stimuli are presented to illustrate how these triggered release mechanisms can be useful for food applications.

Electrospun Nanofibers: Current Progress and Applications in Food Systems

Electrospinning has the advantages of simple manufacturing equipment, a low spinning cost, wide range of spinnable materials, and a controllable mild process, which can continuously fabricate submicron or nanoscale ultrafine polymer fibers without high temperature or high pressure. The obtained nanofibrous films may have a large specific surface area, unique pore structure, and easy-to-modify surface characteristics. This review briefly introduces the types and fiber structures of electrospinning and summarizes the applications of electrospinning for food production (e.g., delivery systems for functional food, filtration of beverages), food packaging (e.g., intelligent packaging, antibacterial packaging, antioxidant packaging), and food analysis (e.g., pathogen detection, antibiotic detection, pesticide residue detection, food compositions analysis), focusing on the advantages of electrospinning applications in food systems. Furthermore, the limitations and future research directions of the technique are discussed.

Triggered and controlled release of active gaseous/volatile compounds for active packaging applications of agri-food products: A review

Gaseous and volatile active compounds are versatile to enhance safety and preserve quality of agri-food products during storage and distribution. However, the use of these compounds is limited by their high vapor pressure and/or chemical instability, especially in active packaging (AP) applications. Various approaches for stabilizing and controlling the release of active gaseous/volatile compounds have been developed, including encapsulation (e.g., into supramolecular matrices, polymer-based films, electrospun nonwovens) and triggered release systems involving precursor technology, thereby allowing their safe and effective use in AP applications. In this review, encapsulation technologies of gases (e.g., CO₂ , ClO₂ , SO₂ , ethylene, 1-methylcyclopropene) and volatiles (e.g., ethanol, ethyl formate, essential oils and their constituents) into different solid matrices, polymeric films, and electrospun nonwovens are reviewed, especially with regard to encapsulation mechanisms and controlled release properties. Recent developments on utilizing precursor compounds of bioactive gases/volatiles to enhance their storage stability and better control their release profiles are discussed. The potential applications of these controlled release systems in AP of agri-food products are presented as well.

Electrospun nanofibers food packaging: trends and applications in food systems

Food safety is a bottleneck problem. In order to provide information about advanced and unique food packaging technique, this study summarized the advancements of electrospinning technique. Food packaging is a multidisciplinary area involving food science, food engineering, food chemistry, and food microbiology, and the interest in maintaining the freshness and quality of foods has grown considerably. For this purpose, electrospinning technology has gained much attention due to its unique functions and superior processing. Sudden advancements of electrospinning have been rapidly incorporated into research. This review summarized some latest information about food packaging and different materials used for the packaging of various foods such as fruits, vegetables, meat, and processed items. Also, the use of electrospinning and materials used for the formation of nanofibers are discussed in detail. However, in food industry, the application of electrospun nanofibers is still in its infancy. In this study, different parameters, structures of nanofibers, features and fundamental properties are described briefly, while polymers fabricated through electrospinning with advances in food packaging films are described in detail. Moreover, this comprehensive review focuses on the polymers used for the electrospinning of nanofibers as packaging films and their applications for variety of foods. This will be a valuable source of information for researchers studying various polymers for electrospinning for application in the food packaging industry.

Activated release of hexanal and salicylaldehyde from imidazolidine precursors encapsulated in electrospun ethylcellulose-poly(ethylene oxide) fibers

Hexanal and salicylaldehyde are naturally-occurring antimicrobial volatiles from edible plants known for their efficacy for post-harvest preservation of fruits and vegetables. Due to their volatility and susceptibility to oxidation, these volatiles must be encapsulated within a carrier to control their release, especially when applied in modified atmnosphere and active packaging applications. In this study, salicylaldehyde precursor (SP; 1,3-dibenzylethane-2-hydroxyphenyl imidazolidine) and hexanal precursor (HP) were synthetized through a Schiff base reaction between these aldehydes and N,N’-dibenzylethane-1,2-diamine. The structure of SP was confirmed using nuclear magnetic resonance and attenuated total reflection-Fourier transform infrared (FTIR) spectroscopies. SP and HP, separately and in combinations, were encapsulated within ethylcellulose–poly(ethylene oxide) (EC–PEO) nonwoven membranes, using a free-surface electrospinning technique. Scanning electron microscopy showed that the morphology of the fibers varied substantially with SP and HP ratio. Specific interactions between SP and HP with the polymers were not detected from the FTIR spectroscopy analysis, suggesting that the precursors were mainly physically entrapped within the EC–PEO fiber matrix. Headspace gas chromatography showed that the release of hexanal and salicylaldehyde could be activated by contacting the precursor-containing electrospun nonwoven with an acidified agarose gel containing 0.003–0.3 M of citric acid. The delivery system can be promising for controlled release of hexanal and salicylaldehyde to extend the shelf-life of fruits and vegetables.