Novel edible coating based on shellac and tannic acid for prolonging postharvest shelf life and improving overall quality of mango

Konjac glucomannan/ carboxylated cellulose nanofiber-based edible coating with tannic acid maintains quality and prolongs shelf-life of mango fruit

Polysaccharide films containing antimicrobial agents have good prospects for application in the fruit industry. However, poor film-forming properties of polysaccharides remain a major challenge. In this work, the konjac glucomannan (KGM) was modified by cross-linking with carboxylated cellulose nanofibers (CNF) to form a composite coating film, and tannic acid (TA) was provided as an active ingredient to improve the antibacterial effect. The optimal formula was: CNF/KGM (w:w) 3.05:10, TA content was 0.40 %, and glycerol content was 0.57 %. KGM/CNF/TA film had good compatibility and a compact structure. The thermal stability and water contact angle of the composite film were higher than those of KGM. Furthermore, the KGM/CNF/TA film reduced the black spot incidence, maintained fruit firmness, decreased ethylene release and respiration rate, increased the antioxidant enzyme activities, and extended the shelf-life of mango. Thus, KGM/CNF/TA is expected to expand polysaccharide/ polymer composite application in the fruit industry.

Challenges in selecting edible coating materials for fruit postharvest preservation and recent advances in edible coating techniques: a review

Fruits are a vital component of a healthy diet, offering essential nutrients and appealing sensory attributes. However, their high perishability leads to significant postharvest losses, which are influenced by factors such as physiological changes, microbial spoilage, and inadequate handling practices. These losses not only reduce fruit quality and marketability but also contribute to increased food waste. Edible coatings have emerged as a promising solution to extend shelf life by forming a protective barrier that reduces moisture loss and prevents microbial spoilage. Despite considerable research into edible coatings, there remains a notable gap in understanding the challenges related to material selection, safety, and scalability. This study critically reviews these challenges and highlights recent advancements in coating technologies. By examining material compatibility, safety concerns, and commercial scalability, the study aims to optimize edible coatings for more sustainable and efficient postharvest fruit preservation.

Protein and polysaccharide edible coatings: A promising approach for fruits preservation - recent advances

Biodegradable packaging, especially edible coatings (EC) for fruit preservation, is a sustainable and eco-friendly approach. ECs, such as polysaccharides and proteins, are widely used in fruit preservation, with a preference for polysaccharides in coating studies. Fundamental EC properties include barrier properties, tensile strength, elongation at break, and UV blocking. Extra materials such as antimicrobial agents, antioxidants, anti-browning agents, and antagonistic microorganisms enhance EC benefits. ECs impact fruit metabolism by reducing malondialdehyde production and enhancing the activities of key enzymes. However, extra materials at high concentrations affect the bonding network of the EC and weaken its structure. Therefore, selecting an appropriate concentration of extra materials is crucial to ensure adequate preservation and safety without affecting sensory properties. Combining coating materials and extra materials to reduce fruit metabolism, maintain fruit quality, inhibit damage pathogens, prevent browning, and provide antioxidants would be an excellent way to promote the green potential of fruit preservation approaches.

Carvacrol enhances antioxidant activity and slows down cell wall metabolism by maintaining the energy level of 'Guifei' mango

BACKGROUND

Postharvest mango fruit are highly susceptible to rapid ripening, softening and senescence, greatly limiting their distribution. In this study, we evaluated the potential effects of carvacrol (0.06 g L-1) on mango (25 ± 1 °C) and the mechanisms by which it regulates antioxidant activity, energy and cell wall metabolism.

RESULTS

The results showed that carvacrol treatment delayed the 'Guifei' mango color transformation (from green to yellow) and the decrease in firmness, titratable acidity, weight loss and soluble solids content, and suppressed the increase in relative conductivity, malondialdehyde content and reactive oxygen species (H2O2 and O2 ·-) as well as enhancing antioxidant activity. In addition, carvacrol treatment increased ascorbic acid and reduced glutathione levels, ascorbate peroxidase, glutathione reductase, monodehydroascorbate reductase and dehydroascorbate reductase activities in mango. Meanwhile, energy level (adenosine triphosphate, adenosine diphosphate, adenosine monophosphate and energy charge) content and energy metabolizing enzyme activities (H+-ATPase, Ca2+-ATPase, succinate dehydrogenasepears and cytochrome C oxidase) were increased on carvacrol treatment, which resulted in the maintenance of higher energy levels. Finally, the application of carvacrol was effective in maintaining firmness and cell wall components by inhibiting the activities of polygalacturonase, cellulase, pectin methyl esterase and β-galactosidase.

CONCLUSION

The current study demonstrates that carvacrol effectively delays the ripening and softening of mangoes by modulating energy metabolism and cell wall dynamics through the attenuation of oxidative stress. © 2024 Society of Chemical Industry.

Tough, antibacterial, antioxidant, antifogging and washable chitosan/nanocellulose-based edible coatings for grape preservation

This study focused on extracting nanocellulose from food processing waste to create a multi-functional edible coating for preserving grapes. Nanocellulose, in the form of short rods with diameters ranging from 30 to 130 nm, was extracted from soy hulls. Edible coatings were then prepared through an ion cross-linking method. Results revealed that the film surfaces and cross-sections were smooth, flat and pore-free, with monomers cross-linked through hydrogen bonding, ester bonds and electrostatic interactions. Further, the incorporation of soy-hull nanocellulose (2 g) effectively improved the mechanical strength (elongation = 281.03 % and tensile strength = 114.88 MPa), barrier properties and antifogging and antibacterial properties (95.55 %) of SCT composite films. Moreover, compared with the control, the SCT-3 coating can extend the shelf life of grapes to 10 d at 25 °C. This study offers a new perspective on the high-value use of agricultural by-products and development of edible films.

Shellac-based films/coatings: Progress, applications and future trends in the field of food packaging

As a natural biopolymer from the secretion of insect Laccifer Lacca, shellac shows excellent film-forming ability and safety, making it an attractive material to replace synthetic materials for food packaging. On the basis of an introduction to the structure and properties of shellac, the information on single shellac films/coatings and composite films/coatings of shellac and other bio-based materials such as proteins, polysaccharides, and lipids, including the effects of adding antimicrobial agents (i.e., natural antimicrobials, synthetic antimicrobials, and metal oxide nanoparticles) on films/coatings, was comprehensively summarized. Besides, the current application status of shellac-based films/coatings as preservation packaging for poultry products, fruits, vegetables and other food products was systematically documented. Finally, the future research directions of shellac-based films/coatings such as optimizing shellac concentrations, conducting toxicological evaluation and reducing production costs were discussed. This paper will provide guidance for a systematic understanding of the research advances on shellac-based films/coatings and possible future directions.

Global insights and advances in edible coatings or films toward quality maintenance and reduced postharvest losses of fruit and vegetables: An updated review

Transitioning to safe, nonthermal, and edible strategies for maintaining fruit and vegetable (F&V) quality, reducing postharvest losses (up to 55% annually), and ensuring food security requires extensive research and innovation in postharvest technologies. This review aims to provide an updated understanding of edible coatings or films (ECF), focusing on their role in reducing F&V postharvest losses, based on data from the last 40 years retrieved from the Web of Science database. The global ECF research network is represented by publication trends, majorly researched F&V, key research areas, influential and emerging authors, and global research ranking. The role of ECF in preserving F&V quality has been assessed by examining critical quality parameters, including weight loss, total soluble solids, titratable acidity, ripening, softening, sensory and organoleptic characteristics, browning, chilling injury, and microbial safety. Furthermore, recent advancements in ECF formulations, including nanoscale ingredients and application methodologies, have been critically discussed. Sources, categorization, application strategies, mode of action, functional properties, sustainable development goals (SDGs), challenges, safety, legislations, and future perspectives in ECF research have also been discussed. The key findings indicate that China (20.34%) and the USA (9.94%) are the leading countries in ECF research. Studies have demonstrated ECF's potential in reducing F&V postharvest losses by maintaining quality parameters through advanced nanoscale compositions and methodologies. Notably, ECF research supports multiple SDG targets, including SDGs 2, 3, 8, 9, 12, 13, and 15. Future ECF research should explore 3D-printed coatings, nonflavor-altering components, and potential crosslinking agents to enhance F&V quality and reduce postharvest losses.

Shellac-based materials: Structures, properties, and applications

Shellac stands out among natural polymers as the sole animal-derived resin, boasting a complex polyester composition comprising polyhydroxy long-chain fatty acids and sesquiterpene acids. Its unique attributes include biocompatibility, non-toxicity, distinctive amphiphilicity, superb film-forming and adhesive properties, excellent dielectric properties, rapid drying, and solubility in alkaline solutions while resisting acidic ones. These exceptional qualities have propelled shellac beyond its traditional role as a varnish and decorative material, positioning it as a viable option for diverse applications such as food packaging, pharmaceutical formulations, electronic devices, fiber dyeing, and wood restoration. Furthermore, shellac serves as a crucial carbon source for graphene materials. This review comprehensively explores shellac's contributions to prolonging food shelf life, enhancing the carbon sourcing of graphene materials, facilitating the delivery of active substances, boosting the performance of organic field-effect transistors, enabling environmentally friendly textile dyeing, and providing protective coatings for wood. Additionally, it delves into the current limitations and future directions of shellac's applications. By disseminating this knowledge, we aim to deepen researchers' comprehension of shellac and inspire further exploration, thereby fostering sustainable advancements across various industries.

Hypersensitive quantification of major astringency markers in food and wine by substoichiometric quenching of silicon-rhodamine conjugates

Tannins are chemically diverse polyphenols in plant-derived products that not only show diverse biological activities but also play a crucial role in determining the sensory attributes of food and beverages. Therefore, their accurate and cost-effective quantification is essential. Here, we identified a novel fluorescence quenching mechanism of different synthetic rhodamine fluorophores, with a high selectivity towards tannic acid (TA) and catechin-3-gallate (C3G) compared to a structurally diverse panel of tannins and polyphenols. Specific chemical conjugates of silicon-rhodamine with alkyl linkers attached to bulky apolar moieties had a limit of detection near 500 pM and a linear range spanning 5-100 nM for TA. We validated the assay on 18 distinct red wine samples, which showed high linearity (R2 = 0.92) with methylcellulose precipitation with no interference from anthocyanins. In conclusion, a novel assay was developed and validated that allows the sensitive and selective quantification of major astringency markers abundant in food and beverages.

Eugenol and Aloe vera blended natural wax-based coating for preserving postharvest quality of Kaji lemon (Citrus jambhiri)

Edible coatings on fruits and vegetables preserve postharvest quality by reducing water loss and lowering respiration, and metabolic activities. The primary objectives of this study were to develop composite coating formulations using natural waxes (carnauba and shellac wax), eugenol nanoemulsion, and Aloe vera gel, and assess the potential impacts of the coating formulations on the postharvest quality and shelf-life of the Kaji lemon. The results show that eugenol nanoemulsion and Aloe vera gel enhanced the physico-chemical, antimicrobial and antioxidant properties of the developed coating. Notably, the fruits coated with optimized nanocomposite of wax with eugenol and aloe vera gel inclusion (SW + CW/EuNE-20/AVG-2) showed the lowest weight loss (16.56%), while the coatings of wax with only aloe vera gel (SW + CW/AVG-2) exhibited the highest firmness (48 N), in contrast to the control fruit, which had 27.33% weight loss and 9.6 N firmness after 28 days of storage, respectively.

Respiration-Triggered Release of Cinnamaldehyde from a Biomolecular Schiff Base Composite for Preservation of Perishable Food

One-third of the food produced worldwide is wasted annually and never consumed, of which ≈ 40-50% are perishable vegetables and fruits (VFs). Although various methods are proposed to reduce this loss, high manufacturing costs and food safety concerns pose significant challenges for the preservation of VFs. Herein, a respiration-triggered, self-saving strategy for the preservation of perishable products based on a biomolecular Schiff base composite fabricated by imidization of chitosan and cinnamaldehyde (CS-Cin) is reported. Ripening of VFs produces acid moisture and triggers a Schiff base reaction in CS-Cin, permitting the release of volatile Cin into the storage space. This enables versatile preservation by placing CS-Cin on the side without the need to touch the food, like the desiccant packet in a food packaging bag, while the rotting of VFs is retarded in a self-saving manner. As a result, the lifetimes of broccoli and strawberries are extended from 2 to 8 days. Furthermore, CS-Cin with restored preservative properties can be repeatedly recycled from used CS via imidization with Cin. Compared with conventional techniques, the preservatives are easy to use, versatile, and cost-effective, and the respiration-responsive release of Cin empowers a self-saving approach toward the smart preservation of perishable food.

Recent Highlights in Sustainable Bio-Based Edible Films and Coatings for Fruit and Vegetable Applications

The present review paper focuses on recent developments in edible films and coatings made of base compounds from biological sources, namely plants, animals, algae, and microorganisms. These sources include by-products, residues, and wastes from agro-food industries and sea products that contribute to sustainability concerns. Chitosan, derived from animal biological sources, such as crustacean exoskeletons, has been the most studied base compound over the past three years. Polysaccharides typically constitute no more than 3-5% of the film/coating base solution, with some exceptions, like Arabic gum. Proteins and lipids may be present in higher concentrations, such as zein and beeswax. This review also discusses the enrichment of these bio-based films and coatings with various functional and/or bioactive compounds to confer or enhance their functionalities, such as antimicrobial, antioxidant, and anti-enzymatic properties, as well as physical properties. Whenever possible, a comparative analysis among different formulations was performed. The results of the applications of these edible films and coatings to fruit and vegetable products are also described, including shelf life extension, inhibition of microbial growth, and prevention of oxidation. This review also explores novel types of packaging, such as active and intelligent packaging. The potential health benefits of edible films and coatings, as well as the biodegradability of films, are also discussed. Finally, this review addresses recent innovations in the edible films and coatings industry, including the use of nanotechnologies, aerogels, and probiotics, and provides future perspectives and the challenges that the sector is facing.

Preparation and characterization of lotus root starch based bioactive edible film containing quercetin-encapsulated nanoparticle and its effect on grape preservation

The present work aimed to develop a novel bioactive edible film prepared by adding quercetin-encapsulated carboxymethyl lotus root starch nanoparticles (QNPs)，gellan gum and lotus root starch. The physicochemical characteristics, preservation effect and mechanism on grapes of the prepared film were investigated. SEM results showed that QNPs (5 %) were dispersed uniformly within lotus root starch matrix, indicating the formation of a stable composite nanoparticle film. In addition, the incorporation of QNPs (5 %) effectively improved the mechanical strength, thermal stability, barrier property and antioxidant activity of QNPs/starch film. Moreover, compared with the control, the QNPs/starch (5 %) film showed effective preservation effect on grapes during 21 days of storage at room temperature, based on the characterization by grape appearance, weight loss, firmness, and titratable acidity. Further studies found that QNPs/starch (5 %) film could exhibit enhanced antioxidant activity and potent anti-fungal ability against Botrytis cinerea, thus extending grape shelf life. In conclusion, the obtained QNPs/starch (5 %) film presented a promising application as an edible packing material for fruit preservation by antioxidant and preventing Botrytis cinerea contamination.

Layer by layer application of chitosan and carboxymethyl cellulose coatings delays ripening of mango fruit by suppressing cell wall polysaccharides disassembly

Mango is a climacteric fruit that ripens quickly after harvest due to its climacteric nature. Edible coatings have been reported to delay the ripening of various harvested fruit. The efficacy of the applied edible coatings could be improved by using in combination as a layer-by-layer (LBL) approach. So, the influence of LBL application of chitosan (CH) and carboxymethyl cellulose (CMC) was studied on mangoes during postharvest storage at 15 °C for 20 days. Mangoes were coated with monolayers of CH (1 % w/v) and CMC (1 % w/v) as well as LBL application of CH and CMC and were compared with control. The treatment of mangoes with CH and CMC-based LBL treatment resulted in lower decay percentage and weight loss along with higher total chlorophyll pigments and suppressed total carotenoid accumulation. The LBL application of CH and CMC showed lower activity of chlorophyll degrading such as chlorophyllase (CPS), pheophytinase (Phe), Mg-dechalatase (MGD) and chlorophyll degrading peroxidase (Chl-POD) enzymes as well as reduced changes in b*, a* and L* along with a suppressed increase in ethylene (EP) and CO2 production (CPR) rates having higher antioxidant such as catalase (CAT), ascorbate peroxidase (APX), peroxidase (POD) and superoxide dismutase (SOD) enzymes activity. In addition, mangoes coated with LBL treatment of CH and CMC exhibited lower water-soluble pectin (WSP) and higher protopectin (PP) having higher concentrations of chelate soluble (CSP) and sodium carbonate-soluble pectin (SCP). Similarly, LBL-coated mangoes showed significantly higher hemicellulose (HCLS) and cellulose (CLS) contents in contrast with control. It was observed that mangoes coated with CH and CMC-based LBL coating exhibited higher flesh firmness and showed suppressed cellulase (CS), pectin methylesterase (PME), polygalacturonase (PG) and β-galactosidase (β-Gal) enzymes activity. The concentrations of total soluble solids and ripening index were markedly lower and titratable acidity was higher in the LBL-based coating treatment in comparison with control. In conclusion, LBL treatment based on CH and CMC coatings could be used for the delay of ripening and softening of harvested mangoes.

Valorizing pomegranate wastes by producing functional silver nanoparticles with antioxidant, anticancer, antiviral, and antimicrobial activities and its potential in food preservation

The food sector generates massive amounts of waste, which are rich in active compounds, especially polyphenols; therefore, valorizing these wastes is a global trend. In this study, we produce silver nanoparticles from pomegranate wastes, characterized by enhanced antioxidant, anticancer, antiviral, and antimicrobial properties and investigated their potential to maintain the fruit quality for sixty days in market. The pomegranate waste-mediated silver nanoparticles (PPAgNPs) were spherical shape (measured by TEM), 20 nm (Zeta sizer), negatively charged -25.98 mV (Zeta potential), and surrounded by active groups (FTIR). The PPAgNPs scavenged 94 % of DPPH radicals and inhibited the growth of pathogens, i.e., Staphylococcus aureus, Listeria monocytogenes, Campylobacter jejuni, Salmonella typhi and Candida with inhibition zones diameters (16-45 mm). They impeded the development of breast and colon cancer cell lines by 80 and 78 %, increased the activity of apoptosis marker caspase 3, and inhibited 82 % of COVID-19. The PPAgNPs were added to the rat diet at 80, 160, and 320 µg/kg levels. PPAgNPs administered at a concentration of 160 µg/kg in the rat diet resulted in the best growth performance, normal liver and kidney parameters (p = 0.029-0.038), lowered lipid profile, malondialdhyde (MDA), and raised glutathion reduced (GSH), total protein (TP). Also, the reduced gene expression of Interleukin 6 (IL-6) and Tumor necrosis factor alpha (TNF-α) in albino rats' serum indicates the anti-inflammatory effect of PPAgNPs. PPAgNPs developed a functional coating to preserve mandarin fruit for 60 days by dipping technique. The active coat containing PPAgNPs can effectively preserve the fruit for 60 days.

Gas barrier coating based on cellulose nanocrystals and its preservation effects on mango

Mango is the "king of tropical fruits" because of its attractive appearance, delicious taste, rich aroma, and high nutritional value. However, mango keeps fast metabolizing after harvest, leading to water loss, starch conversion into sugar, texture softening, and decay. Here, a gas barrier coating based on cellulose nanocrystals (CNCs) is proposed to control the post-harvest metabolism of mango. The results of gas barrier permeability show that CNCs enhance the barrier ability of the chitosan (CS) membrane on mango by 202 % and 63 % for oxygen and water vapor, respectively. The gas-barrier coating reduces the climb in pH and the decrease in firmness by 84.9 % and 45.8 %, respectively, decelerating the conversion process from starch to sugar. Besides, introducing clove essential oil (CEO), the CEO mainly adsorbs and crystalizes on the hydrophobic facets of CNCs, presenting high compatibility, increases the antibacterial rate to nearly 100 %. As a consequence, the preservation period of the mango coated by the CNC-based membrane is at least 7-day longer than the control group. Such a gas-barrier coating based on eco-friendly composites must have excellent potential in the preservation of mango, and even for other tropical fruits.

Tannic Acid and Ca2+ Double-Crosslinked Alginate Films for Passion Fruit Preservation

In this study, the interaction of different concentrations of tannic acid (TA) (10%, 20%, and 30% w/w) and Ca2+ with alginate (SA) was utilized to create double-crosslinked SA films. The resulting films were evaluated for their optical, mechanical, water resistance, and barrier properties, and their microstructure and intermolecular interactions were also characterized. The SA films containing 20% TA showed the best mechanical properties, with an observed increase in tensile strength of 22.54%. In terms of water vapor permeability, the SA film containing 30% TA exhibited the highest barrier property, which was 25.36% higher than that of the pure SA film. Moreover, TA demonstrated a strong UV absorption ability, resulting in a nearly 0% UV transmittance of the SA film at 280 nm. It can be seen that SA films containing 20% TA have excellent barrier and mechanical properties, and the development of such films will be applied to the storage and packaging of fresh food. It is worth noting that this work also investigated the effect of SA coatings containing different concentrations of TA on the preservation of passion fruits for 7 days. The results revealed that passion fruits treated with SA coatings containing a 30% TA concentration maintained a better appearance on the 7th day and had the lowest weight loss and crumpling indices of approximately 8.98% and 2.17, respectively, compared to the other treatment groups. Therefore, based on the overall results, the addition of 30% TA to SA coatings proved to be more effective and can be considered a promising approach for delaying fruit senescence and decay.

Exploring adequate CO2 elevation for optimum tomato growth and yield under protected cultivation

The adequate elevation of CO2 concentrations (e [CO2]) could not be assessed by constrained analysis of comparative experimental study for optimum plant growth and yield with improved fruit quality owing to the lack of conjunctive investigation of plant parametric responses. Instead, the principal component analysis (PCA) and technique for order preference by similarity to ideal solution (TOPSIS) assessed and quantified the parametric plant responses to identify the adequate level of e [CO2] for optimum plant growth and yield. In this study, tomato plants were grown under an ambient CO2 (a [CO2], 500 μmol mol-1) and three e [CO2] (700, 850 and 1000 μmol mol-1): named EC700, EC850 and EC1000, respectively, in autumn-winter (AW) 2020 and spring summer (SS) 2021 growing seasons to investigate and evaluate the plant parametric responses under e [CO2]. The tomato plant's response with maximum transportability of biomass to fruits was observed under 700 μmol mol-1. The plant height, stem diameter and LAI were enhanced compared to a [CO2] at the optimum level under 1000 μmol mol-1 (by 50.53, 20.98 and 44.44%) and 700 μmol mol-1 (by 22.41, 12.09 and 26.88%) in Aw 2020; Ss 2021, respectively. The optimum yield was increased under 700 μmol mol-1 by 73.95% and 55.58% in Aw 2020; Ss 2021, respectively. EC700 was ranked as a priority by TOPSIS with 0.632 and 0.694 plant response performance index in Aw 2020; Ss 2021, respectively, to get optimum tomato growth, yield, water use efficiency and fruit quality. The results of this study are beneficial for commercial greenhouse crop production by fumigating the adequate level of e [CO2], to reduce the cost of CO2 fertigation, enhance the yield and save the water quantity.

Tannic Acid Interfacial Modification of Prochloraz Ethyl Cellulose Nanoparticles for Enhancing the Antimicrobial Effect and Biosafety of Fungicides

With the poorly soluble and intrinsically unstable feature, prochloraz (Pro) was confronted with lower bioavailability in the crop defense against fungal erosion. Therefore, it was a challenging project to explore the innovative antifungal compound delivery system for improving bioavailability. The superior adhesive fungicide formulation was supposed to be an efficient pathway to enhance transmembrane permeability and biological activity. According to abundant phenolic hydroxyl groups, tannic acid (TA) was an ideal modified adhesive biomaterial to improve interfacial interactions. The fundamental purpose of this research was focused on the synergistic mechanism of TA-interfacial-modified Pro-ethyl cellulose (EC) nanoparticles for improving bioavailability and biosafety. In the stability test, TA-modified Pro-EC nanoparticles had the capacity to reduce Pro initial release burst, extending a persistent validity and improving anti-photodegradation property. The toxicity index of Pro-EC and Pro-EC-TA was approximately 2.93-fold and 4.96-fold that of Pro technical against Fusarium graminearum (F. graminearum), respectively. Compared with nonmodified EC nanoparticles, TA-modified EC nanoparticles obtained eminent transmembrane permeability and superior adherence ability to F. graminearum, for hydroxyl and carboxyl groups of TA to enhance interaction with target cell membranes. The contents of cellular reactive oxygen species induced by Pro-EC and Pro-EC-TA nanoparticles were about 2.31 times and 3.00 times that of the control check (CK), respectively. Compared to the CK group, the membrane potential and ergosterol values of F. graminearum treated with Pro-EC-TA nanoparticles were drastically reduced by 74.91 and 56.20%, respectively. In the biosafety assay, the maximum half-lethal concentration value of the TA-modified Pro-EC nanoparticles indicated that the acute toxicity of the Pro-EC-TA nanoparticles to adult zebrafish was approximately 8.34-fold reduced compared to that of the Pro technical. These findings demonstrated that the successful interfacial modification of Pro-EC nanoparticles with TA was a highly efficient, environmentally safe, and promising alternative for sustainable agricultural application, thus making the fungicide formulation process more simplified, easier fabrication, and lower cost.

Preparation and Characterization of a Novel Artemisia Oil Packaging Film and Its Application in Mango Preservation

In this work, a new food packaging film was synthesized via blending Artemisia oil (AO) into soybean protein isolate (SPI) and gelatin (Gel) for the postharvest storage of mango. The morphological architecture and mechanical properties of the films were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometer (XRD), and other technologies. The results show that the prepared films had relatively flat surfaces with good mechanical properties. AO enhanced the light-blocking ability of the film, increased the hydrophobicity, and affected the moisture content and water solubility of the film to a certain extent. Furthermore, the antioxidant performance and antifungal (Colletotrichum gloeosporioides) capacity of the films increased with higher AO concentration due to the presence of the active components contained in AO. During mango storage applications, the films showed good freshness retention properties. The above results indicate that SPI-Gel films containing AO have excellent physicochemical and application properties and have great potential in the field of food packaging.

Post-harvest ripening affects drying behavior, antioxidant capacity and flavor release of peach via alteration of cell wall polysaccharides content and nanostructures, water distribution and status

Effect of post-harvest ripening on cell wall polysaccharides nanostructures, water status, physiochemical properties of peaches and drying behavior under hot air-infrared drying was evaluated. Results showed that the content of water soluble pectins (WSP) increased by 94 %, while the contents of chelate-soluble pectins (CSP), Na₂CO₃-soluble pectins (NSP) and hemicelluloses (HE) decreased during post-harvest ripening by 60 %, 43 %, and 61 %, respectively. The drying time increased from 3.5 to 5.5 h when the post-harvest time increased from 0 to 6 days. Atomic force microscope analysis showed that depolymerization of hemicelluloses and pectin occurred during post-harvest ripening. Time Domain -NMR observations indicated that reorganization of cell wall polysaccharides nanostructure changed water spatial distribution and cell internal structure, facilitated moisture migration, and affected antioxidant capacity of peaches during drying. This leads to the redistribution of flavor substances (heptanal, n-nonanal dimer and n-nonanal monomer). The current work elucidates the effect of post-harvest ripening on the physiochemical properties and drying behavior of peaches.

Effects of Volatile Flavour Compound Variations on the Varying Aroma of Mangoes 'Tainong' and 'Hongyu' during Storage

The aroma, taste, and flavour profiles of mango cultivars vary, directly influencing their marketability and consumer acceptance. In this study, we explored the effects of volatile organic compounds (VOCs) on the distinct aromas of two mango cultivars during storage using GC-IMS and HS-SPME-GC-MS combined with OPLS-DA analysis. Our findings revealed that the terpene and aldehyde contents were higher in the 'Tainong' mango cultivar, compared to the 'Hongyu' mango, while the ester content was lower. The aroma was attributed to the presence of terpinolene, 2-nonenal, delta-carene, and alpha-phellandrene in the early stages of storage, and later-between 5 and 11 days-to ethyl acetate, ethyl butyrate, and ethyl propanoate. Further analysis of characteristic VOCs using OPLS-DA demonstrated and explained the strong grassy aroma of the 'Tainong' mango, and the strong fruity and sweet aromas of the 'Hongyu' mango. Additionally, esters mainly accumulated during the later periods of storage, especially propyl butyrate, which was produced and accumulated when fruit quality deteriorated in the later storage period. Our study provides a theoretical basis for detecting mango VOCs during storage to determine the appropriate marketing time for the two mango cultivars and enables informed consumer choice.

Research Progress on Mango Post-Harvest Ripening Physiology and the Regulatory Technologies

Mango (Mangifera indica L.) is an important tropical fruit with a delicate taste, pleasant aroma, and high nutritional value. In recent years, with the promotion of the rural revitalization strategy and the development of the poverty alleviation industry, China has gradually become an important mango producer. However, the short shelf life of mango fruit, the difficulty in regulating the postharvest quality, and the lack of preservation technology are the main problems that need to be solved in China's mango industry. In this paper, the physiological changes and mechanisms of mango during postharvest ripening were summarized, including sugar and acid changes, pigment synthesis and accumulation, and aroma formation and accumulation. The physical, chemical, and biological technologies (such as endogenous phytohormones, temperature, light, chemical preservatives, and edible coatings) commonly used in the regulation of mango postharvest ripening and their action principles were emphatically expounded. The shortcomings of the existing mango postharvest ripening regulation technology and physiological mechanism research were analyzed in order to provide a reference for the industrial application and development of mango postharvest.

Encapsulation of Bioactive Compounds for Food and Agricultural Applications

This review presents an updated scenario of findings and evolutions of encapsulation of bioactive compounds for food and agricultural applications. Many polymers have been reported as encapsulated agents, such as sodium alginate, gum Arabic, chitosan, cellulose and carboxymethylcellulose, pectin, Shellac, xanthan gum, zein, pullulan, maltodextrin, whey protein, galactomannan, modified starch, polycaprolactone, and sodium caseinate. The main encapsulation methods investigated in the study include both physical and chemical ones, such as freeze-drying, spray-drying, extrusion, coacervation, complexation, and supercritical anti-solvent drying. Consequently, in the food area, bioactive peptides, vitamins, essential oils, caffeine, plant extracts, fatty acids, flavonoids, carotenoids, and terpenes are the main compounds encapsulated. In the agricultural area, essential oils, lipids, phytotoxins, medicines, vaccines, hemoglobin, and microbial metabolites are the main compounds encapsulated. Most scientific investigations have one or more objectives, such as to improve the stability of formulated systems, increase the release time, retain and protect active properties, reduce lipid oxidation, maintain organoleptic properties, and present bioactivities even in extreme thermal, radiation, and pH conditions. Considering the increasing worldwide interest for biomolecules in modern and sustainable agriculture, encapsulation can be efficient for the formulation of biofungicides, biopesticides, bioherbicides, and biofertilizers. With this review, it is inferred that the current scenario indicates evolutions in the production methods by increasing the scales and the techno-economic feasibilities. The Technology Readiness Level (TRL) for most of the encapsulation methods is going beyond TRL 6, in which the knowledge gathered allows for having a functional prototype or a representative model of the encapsulation technologies presented in this review.

Metabolomic Analysis on the Mechanism of Nanoselenium Biofortification Improving the Siraitia grosvenorii Nutritional and Health Value

Nanoselenium (nano-Se) foliar application is crucial for enhancing plant health. However, the mechanism by which nano-Se biofortification promotes the nutritional components of Siraitia grosvenorii remains unclear. In this study, nano-Se foliar application increased the carbohydrate and amino acid contents, including glucose (23.6%), fructose (39.7%), sucrose (60.6%), tryptophan (104.5%), glycine (85.9%), tyrosine (78.4%), phenylalanine (60.1%), glutamic acid (63.4%), and proline (52.5%). Nano-Se application enhanced apigenin (3.8 times), syringic acid (0.7 times), and 4-hydroxy-3,5-dimethoxycinnamic acid (1.4 times) of the phenylpropane biosynthesis pathways. Importantly, the SgCDS (31.1%), CYP-P450 (39.1%), and UGT (24.6%) were induced by nano-Se, which enhanced the mogroside V content (16.2%). Compared to the control, nano-Se treatment dramatically enhanced aromatic substances, including 2-butanone (51.9%), methylpropanal (146.3%), n-nonanal dimer (141.7%), pentanal (52.5%), and 2-pentanone (46.0%). In summary, nano-Se improves S. grosvenorii quality by increasing nutrients and volatile organic compounds and adjusting the phenylpropane pathway.

A novel approach for authentication of shellac resin in the shellac-based edible coatings: Contain shellac or not in the fruit wax preservative coating

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A novel approach based on targeted metabolomics for the authentication of shellac resin in shellac-based coating solution was established for the first time.

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The authentication of shellac resin was skillfully transformed by means of taking monomer compounds constituting shellac resin (fatty acids and terpenic acids) as targeted metabolites.

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The feasibility of the authenticated approach of shellac resin in commercial coating solution products for fruit preservation was verified by taking common metabolites as the biomarkers.

As an edible coating substrate, the detection of shellac resin has always been an intractable problem. In this paper, an authentication method of shellac resin in shellac-based edible coatings was established. Results showed that the authentication of shellac resin could be skillfully transformed as the identification of 13 targeted metabolites which were monomer compounds of shellac resin. The 13 targeted metabolites were further divided into 6 differential metabolites and 7 common metabolites with the metabonomic method and difference analysis of targeted metabolite contents. Then, four commercial soi-disant shellac-based coating solutions were selected to verify the feasibility of this method, and 7 common metabolites were detected in only one commercial sample, highly consistent with the results of shellac resin. All the above results indicated that the targeted metabolomics approach established in this study could provide a scientific basis for the qualitative authentication of shellac resin in the preservation coating.

Potential of engineered nanostructured biopolymer based coatings for perishable fruits with Coronavirus safety perspectives

Fresh fruits are prioritized needs in order to fulfill the required health benefits for human beings. However, some essential fruits are highly perishable with very short shelf-life during storage because of microbial growth and infections. Thus improvement of fruits shelf-life is a serious concern for their proper utlization without generation of huge amount of fruit-waste. Among various methods employed in extension of fruits shelf-life, design and fabrication of edible nanocoatings with antimicrobial activities have attracted considerable interest because of their enormous potential, novel functions, eco-friendly nature and good durability. In recent years, scientific communities have payed increased attention in the development of advanced antimicrobial edible coatings to prolong the postharvest shelf-life of fruits using hydrocolloids. In this review, we attempted to highlight the technical breakthrough and recent advancements in development of edible fruit coating by the application of various types of agro-industrial residues and different active nanomaterials incorporated into the coatings and their effects on shelf-life of perishable fruits. Improvements in highly desired functions such as antioxidant/antimicrobial activities and mechanical properties of edible coating to significantly control the gases (O2/CO2) permeation by the incorporation of nanoscale natural materials as well as metal nanoparticles are reviewed and discussed. In addition, by compiling recent knowledge, advantages of coatings on fruits for nutritional security during COVID-19 pandemic are also summarized along with the scientific challenges and insights for future developments in fabrication of engineered nanocoatings.

Effect of vacuum impregnation assisted probiotics fermentation suspension on shelf life quality of freshly cut lotus root

Probiotic fermentation suspension was used to extend the shelf life of freshly cut lotus root for the first time, which played a dual role of biological protection and quality maintenance. Fermentation suspension contained lactic acid bacteria (8-9 log CFU/mL) was prepared from juice of lotus root and used to immerse samples under atmospheric pressure and vacuum. Probiotic fermentation suspension inhibited microorganism and the activity of polyphenol oxidase (PPO), peroxidase (POD) and phenylalanine ammonia lyase (PAL), which slowed down the physiological reaction and was beneficial to maintain the color and hardness of tissues. Lactic acid bacteria antagonized other microorganisms, and metabolic acid production played a continuous role in preservation during storage. The vacuum was helpful for the fermentation suspension to be fully impregnated into samples. The probiotic fermentation suspension had a significant inhibitory effect on E.coli O157:H7, and extended lotus root shelf life from 3 to 9 days.

A new method for shellac binder detection in ancient building mortars

Shellac, also known as lac, is composed mainly of aleuritic acid.

Development of hydroxypropyl methylcellulose film with xanthan gum and its application as an excellent food packaging bio-material in enhancing the shelf life of banana

A novel film composed of xanthan gum (XG) and hydroxypropyl methylcellulose (HPMC) was prepared (XH). The films were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy (SEM). The light transmittance, mechanical properties and water vapor transmission rate (WVTR) indicated the good compatibility between XG and HPMC with hydrogen-bond interaction and XG had a significant effect on the chemical structure, crystalline texture and microstructure of the XH composite film. The best XH sample with optimum XG concentration of 2 g/L was used as food packaging via coating onto banana, whereby the weight loss rate on banana was able to decreased from 25 ± 3% (without XH coating) to 16 ± 4% (with XH coating). Consequently, the release of flavor substances was also decreased. Banana shelf life has qualitatively improved with XH composite film for food preservation and affirmed the uses in food packaging applications.

Effect of Chitosan Coatings with Cinnamon Essential Oil on Postharvest Quality of Mangoes

Mango (Mangifera indica Linn.) is a famous climacteric fruit containing abundant flavor and nutrients in the tropics, but it is prone to decay without suitable postharvest preservation measures. In this study, the chitosan (CH)-cinnamon essential oil (CEO) Pickering emulsion (CH-PE) coating was prepared, with cellulose nanocrystals as the emulsifier, and applied to harvested mangoes at the green stage of maturity. It was compared with a pure CH coating and a CH-CEO emulsion (CH-E) coating, prepared with the emulsifier Tween 80. Results showed that the CH-PE coating had a lower water solubility and water vapor permeability than the other coatings, which was mainly due to electrostatic interactions, and had a better sustained-release performance for CEO than the CH-E coating. During mango storage, the CH-PE coating effectively improved the appearance of mangoes at 25 °C for 12 d by reducing yellowing and dark spots, and delayed water loss. Hardness was maintained and membrane lipid peroxidation was reduced by regulating the activities of pectin methyl esterase, polygalacturonase, and peroxidase. In addition, the nutrient quality was improved by the CH-PE coating, with higher contents of total soluble solid, titratable acid, and ascorbic acid. Therefore, the CH-PE coating is promising to comprehensively maintain the postharvest quality of mangoes, due to its enhanced physical and sustained-release properties.

Coating Process Optimization and Self-Healing Performance Evaluation of Shellac Microcapsules Coated with Melamine/Rice Husk Powder

To explore the implication of the coating process on the comprehensive properties of water-based coating containing shellac microcapsules coated with melamine/rice husk powder on the Tilia cordata surface, the optical properties, mechanical properties, liquid resistance, aging resistance, chemical composition, and microstructure of the coating were analyzed comprehensively. After the best coating process was determined, compared with the coating without microcapsules, the self-repairing performance of the water-based coating containing shellac microcapsules coated with melamine/rice husk powder was explored via aging resistance test and scratch test. The results showed that the best comprehensive performance of the coating was obtained by three times primer, two times finish, and 6.0% shellac microcapsules coated with melamine/rice husk powder added in the primer. The coating with shellac microcapsules had significant stability, aging resistance, and self-healing performance, which can repair cracks in a certain period of time and inhibit the formation of cracks. At the core wall ratio of 0.75, the shellac which plays a role of the repair agent as the core material can effectively fill the microcracks in the coating to repair by flowing from the broken microcapsule because it can be physically cured at room temperature. The modification of waterborne coatings with shellac microcapsules coated with melamine/rice husk powder contributes the improved self-repairing properties of surface coatings containing heterogeneous natural polymer composites.

A Gas-Permeation Controllable Packaging Membrane with Porous Microspheres as Gas "Switches" for Efficient Preservation of Litchi

Food wastage represented by the deterioration of perishable food like fruits and vegetables is a serious global problem with tremendous ethical, financial, and environmental costs. The atmosphere (CO₂ and O₂) has a crucial role in food storage and can regulate physiological food metabolism and microbial growth. Modified atmosphere packaging (MAP) is a promising method used to extend shelf life and preserve the quality of perishable food; yet, its use depends on the specific gas permeability and selectivity of polymer membranes to generate an atmosphere desirable for storage. In this study, we established and validated a new plant leaf-mimetic shellac-based MAP membrane embedded with chitosan porous microspheres loaded with antimicrobial tannic acid (TA-CPM) as gas "switches" for regulating O₂ and CO₂ permeability and CO₂/O₂ selectivity. The effects of different amounts of TA-CPM added into the hybrid membranes were examined for litchi preservation at room temperature. Our results showed that this hybrid TA-CPM/shellac packaging membrane could regulate the internal CO₂ and O₂ concentrations and the CO₂/O₂ ratio within the packages containing litchis by adjusting the addition amount of TA-CPM. The 0.05% TA-CPM/shellac and 0.10% TA-CPM/shellac packages, especially 0.05% TA-CPM/shellac, generated a more desirable CO₂ and O₂ atmosphere for litchi preservation compared with controls, which was reflected by the delaying of browning and rotting, maintaining of the natural color of the litchi pericarp, preservation of pulp quality, inhibition of polyphenol oxidase and guaiacol peroxidase activities, and reduction of oxidative cell damage in litchis. The results suggested that 0.05% TA-CPM/shellac and 0.10% TA-CPM/shellac packaging membranes, especially 0.05% TA-CPM/shellac, could generate an ideal atmosphere for litchi storage at room temperature, demonstrating that this permeation-controlled hybrid membrane has great potential in food preservation and other applications requiring a modified atmosphere.

Recent advances in portable devices for fruit firmness assessment

Fruit firmness is of vital importance in various links of the fruit supply chain, such as determining harvest time, choosing packaging and transportation methods, regulating storage conditions and predicting shelf life. Portable devices are useful tools to perform on-site measurements of fruit firmness to guide production, optimize processing procedures, improve handling practices and formulate supply strategies. This paper reviews the recent advances in the design and development of portable devices to evaluate fruit firmness based on sensing mechanical, sonic, vibrational and optical properties of fruits. The principle, structure, composition, application and performance of different portable devices are presented. Since each sensor has its merits and limitations, the integration of multiple microsensors to develop a miniaturized, low-cost and facile-operation device may achieve higher sensing performance in determining fruit firmness.