Recent advances in starch-based coatings for the postharvest preservation of fruits and vegetables

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.

Effects of sophorolipids and coconut wax incorporation on the physical, structural, and antibacterial properties of cellulose nanofibers-based Pickering emulsion for cherry tomato preservation

A novel acidic sophorolipid-enhanced cellulose nanofiber-based coconut wax Pickering emulsion (ASL-CCPE) using cellulose nanofibers (CNF) as a stabilizer, lactonic sophorolipids (LSL) as an antimicrobial agent, and acidic sophorolipids (ASL) as a co-stabilizer were developed. Through optimization of the oil phase type, oil-to-water ratio, and ASL content, the emulsion exhibited shear-thinning behavior and elastic gel characteristics, making it suitable for coating applications. After 182 days of storage at room temperature, the emulsion's droplet size remained uniform, with no significant flocculation observed. Compared to CCPE, ASL-CCPE exhibited reduced surface tension and formed a more uniform, dense, and washable coating. Cherry tomatoes coated with ASL-CDPE remained fresh for at least 12 days at room temperature. Furthermore, ASL-CCPE treatment resulted in a 5.10 % reduction in weight loss and a 45.83 % increase in vitamin C content even after 15 days of storage. Additionally, the inclusion of LSL significantly inhibited microbial growth, thus reducing decay. This green, safe, and effective emulsion offers a promising, environmentally friendly approach for fruit and vegetable preservation.

Novel edible coatings pretreatment for enhancing drying performance and physicochemical properties of cherry fruits during multi-frequency ultrasonic vacuum far infrared radiation - Radio frequency vacuum segmented combination drying

To maximize the drying efficiency and physicochemical quality of cherry fruits while minimizing energy consumption, this study investigated the effects of novel edible coatings (sodium carboxymethyl cellulose (CMC-Na) and sodium alginate (SA)) pretreatment combined with multi-frequency ultrasonic vacuum far infrared radiation-radio frequency vacuum (MUSVFIR-RFV) segmented drying on the drying performance and physicochemical properties of cherries. Results demonstrated that MUSVFIR-RFV segmented drying combined with coating pretreatment reduced the drying time by 11.11 ∼ 25.93 % compared to single drying. At a moisture conversion point of 50 %, the process achieved optimal drying performance and energy efficiency. Remarkably, multi-frequency ultrasound outperformed single-frequency ultrasound in terms of energy transfer intensity and uniformity. Physicochemical quality analysis revealed that the combination of CMC-Na or SA coatings with MUSVFIR-RFV segmented drying significantly improved the retention of soluble solids, individual sugar, natural bioactive compounds, TPC, TFC, and antioxidant activities (DPPH, ABTS, and FRAP). Texture and sensory properties showed that the hardness and adhesiveness of coated cherries were reduced, while elasticity, chewiness, and cohesiveness were significantly enhanced. Cherries subjected to (CMC-Na)-(MUSVFIR-RFV) treatment achieved higher scores in texture, crispness, color, sweet taste, appearance, and aroma, with lower bitterness and off-odor, leading to an overall acceptance score of 9.2, which was significantly higher than that of the control. Hierarchical clustering and PCA analysis further validated that the integration of coatings with segmented drying effectively improved the physicochemical quality of dried cherries. The findings provide scientific evidence for the development of efficient drying technologies for cherry, substantiating the potential advantages of combining edible coatings with MUSVFIR-RFV drying in enhancing drying efficiency, quality, and sensory attributes of cherries.

Application of chitosan/Nano-TiO₂/Daisy essential oil composite film for the preservation of Actinidia arguta: Inhibition of spoilage microorganisms and induction of resistance

This study explores the inhibitory effects of a chitosan/nano-TiO₂/Daisy Essential Oil (CSTD) composite film on spoilage microorganisms affecting Actinidia arguta. Owing to its high nutritional value and water content, Actinidia arguta is highly susceptible to microbial spoilage, leading to a significantly shortened shelf life. Traditional chemical preservation methods are ineffective against microbial spoilage and raise concerns about safety and environmental sustainability, highlighting the demand for natural, effective alternatives. Chitosan, a natural polysaccharide, shows promise due to its biocompatibility and biodegradability. However, its mechanical, antimicrobial, and antioxidant properties require enhancement. To address these limitations, this study incorporates nano-TiO₂ and Daisy Essential Oil into chitosan to develop a composite film. Key spoilage microorganisms of Actinidia arguta were isolated and identified, with Rhizopus stolonifera reported for the first time as one of the spoilage organisms. The composite film demonstrated significant inhibitory effects against Escherichia coli, Staphylococcus aureus, Bacillus subtilis, Bacillus amyloliquefaciens, Aspergillus niger, Neopestalotiopsis clavispora, Aspergillus piperis, and Rhizopus stolonifera. Resistance induction experiments further revealed that CSTD effectively delayed oxidative stress and enzymatic degradation linked to fruit spoilage, significantly extending the shelf life of Actinidia arguta. These findings provide theoretical support for developing effective preservation techniques for Actinidia arguta.

Application of Smart Packaging in Fruit and Vegetable Preservation: A Review

The application of smart packaging technology in fruit and vegetable preservation has shown significant potential with the ongoing advancement of science and technology. Smart packaging leverages advanced sensors, smart materials, and Internet of Things (IoT) technologies to monitor and regulate the storage environment of fruits and vegetables in real time. This approach effectively extends shelf life, enhances food safety, and reduces food waste. The principle behind smart packaging involves real-time monitoring of environmental factors, such as temperature, humidity, and gas concentrations, with precise adjustments based on data analysis to ensure optimal storage conditions for fruits and vegetables. Smart packaging technologies encompass various functions, including antibacterial action, humidity regulation, and gas control. These functions enable the packaging to automatically adjust its internal environment according to the specific requirements of different fruits and vegetables, thereby slowing the growth of bacteria and mold, prolonging freshness, and retaining nutritional content. Despite its advantages, the widespread adoption of smart packaging technology faces several challenges, including high costs, limited material diversity and reliability, lack of standardization, and consumer acceptance. However, as technology matures, costs decrease, and degradable smart packaging materials are developed, smart packaging is expected to play a more prominent role in fruit and vegetable preservation. Future developments are likely to focus on material innovation, deeper integration of IoT and big data, and the promotion of environmentally sustainable packaging solutions, all of which will drive the fruit and vegetable preservation industry toward greater efficiency, intelligence, and sustainability.

Green fabrication of biomass-derived carbon dots and bio-based coatings: Potential of enhancing postharvest quality on Chinese flowering cabbage

The objective of this study was to develop a bio-nanocomposite coating (CQSC) by combining chitosan quaternary ammonium salt (CQAS) and sericin (SC) with biomass-derived carbon dots (CDs) to extend the shelf life of Chinese flowering cabbage (CFC). The effects of different concentrations of CDs (0.2, 0.4, 0.6, 0.8, and 1.0 mg/mL) on the physicochemical, structural, and functional activity of nanocomposite particles were evaluated. CQAS exhibited strong inhibitory effects against Escherichia coli and Bacillus subtilis. Moreover, the application of CQSC on CFC significantly reduced mass losses, slowed the increase in lignin content, maintained ascorbic acid and chlorophyll levels, inhibited the growth of microorganisms, and preserved the unique texture and aroma of CFC during storage at 10 °C compared with uncoated CFC. The results will contribute to the further development of CDs coatings to improve the postharvest preservation effect of fruits and vegetables.

On-demand removable hydrogel film derived from gallic acid-phycocyanin and polyvinyl alcohol for fruit preservation

Postharvest spoilage of fruits accounts for significant losses ranging between 20 %-30 %, leading to considerable resource wastage and economic downturns. The development of an effective fresh-keeping packaging material is of paramount importance. This study introduces an innovative on-demand removable active fruit fresh-keeping film (GPP), created by embedding a GP (gallic acid-phycocyanin) fiber mesh hydrogel with functional properties into a polyvinyl alcohol (PVA) matrix. The resultant GPP hydrogel-based film demonstrates outstanding UV and water vapor barrier capabilities, mechanical stability, resistance to external mechanical stress, universal surface adhesion, antibacterial efficacy, and on-demand removal attributes, while being devoid of potential toxicity hazards. Utilizing grapes and blueberries as representative fruits, it is shown that the GPP hydrogel film significantly preserves the fruits' hardness, pH, total soluble solids content (TSS), and minimizes the rate of weight loss, thereby prolonging the shelf life to 13 days for grapes and 20 days for blueberries at ambient temperature. These results underscore the potential of this hydrogel-based film as an invaluable material for fruit preservation within the food industry.

Preservative for High Antioxidant and Antimicrobial Activity and Low Toxicity

There is an urgent need for highly efficacious and minimally toxic preservatives for vegetables and fruits to ensure extended freshness and safety. Using natural polymer starch as the matrix, we produced nicotinated starch-ethylamine (NSA) based on N,N'-carbonyldiimidazole (CDI) acting as the catalyst and 2-chloroethylaminehydrochloride as the nucleophile. To strengthen the antimicrobial and antioxidant activity, NSA was reacted with three different cinnamic acids to prepare starch derivatives bearing cinnamyl (CNSA, DNSA, and ENSA). With a grafting rate of 27%, ENSA demonstrated notable antioxidant capability reaching ∼85% at 1.6 mg/mL. Also, it displayed inhibitory indices of 88.14%, 89.11%, and 77.90% against Botrytis cinerea, Phomopsis asparagi, and Glomerella cingulate, respectively, at a concentration of 1.0 mg/mL. The cytotoxicity test showed that the 293T cell survival ratio reached 101.5%. In addition, the sample was able to extend the shelf life of the cherry tomatoes by three days. This study has successfully developed a novel starch-based preservative for fruits and vegetables that not only possesses excellent antioxidant and antimicrobial properties but also effectively extends the shelf life of produce, demonstrating its broad application prospects in the field of fruit and vegetable storage and preservation.

Calcium alginate-encapsulated propolis microcapsules: Optimization, characterization, and preservation effects on postharvest sweet cherry

The increasing consumption of fresh fruits and vegetables has led to the development of eco-friendly and active preservation materials which have slow-release effect of antioxidant/antifungal agents. The propolis microcapsules (PM), utilizing calcium alginate as the wall material, incorporating ethanolic extract of propolis (EEP) as the core material, were prepared by ionic gelation method and conducted a investigation of its characteristics After optimization by single factor experiment and theoretical response models, PM which was prepared by dropping 9.3 g L-1 100 mL sodium alginate solution containing 9.8 mL EEP into 0.22 mol L-1 calcium chloride solution showed an encapsulation efficiency of 69.29±1.12 %. Prepared microcapsules were spherical with a dense surface which protected propolis well from the environment, retained a large number of bio-active compounds and improve thermal stability of propolis. Moreover, the microcapsules exhibited good slow-release effect and good inhibitory influence on the development of Alternaria Alternata growth which the colony diameter of the control was 41.38 % higher than the treatment at day six. With 5.0 g PM placed in the small non-woven bag in the application on sweet cherries with non-direct contact method, the decay rate and weight loss of fruits were reduced by 47.5 % and 17.6 %, concurrently the PM also effectively maintain the good appearance, hardness, antioxidant capacity by slowing the reduction in the content of total phenols, flavonoids and enzymatic activities. Therefore, the PM with superior antioxidant and antifungal capacity have the great potential to design as a practical active materials for fruits preservation.

Janus hydrogel loaded with a CO2-generating chemical reaction system: Construction, characterization, and application in fruit and vegetable preservation

In this study, we inserted a dynamic chemical reaction system that can generate CO2 into Janus hydrogel (JH) to develop a multidimensional preservation platform that integrates hygroscopicity, antibacterial activity, and modified atmospheric capacity. The double gel system developed using sodium alginate/trehalose at a 1:1 ratio effectively encapsulated 90% of citric acid. Furthermore, CO2 loss was avoided by separately embedding NaHCO3/cinnamon essential oil and citric acid microcapsules into a gelatin pad to develop JH. Freeze-dried JH exhibited a porous and asymmetric structure, very strongly absorbing moisture, conducting water, and rapidly releasing CO2 and essential oils. Furthermore, when preserving various fruits and vegetables in practical settings, JH provided several preservation effects, including color protection, microbial inhibition, and antioxidant properties. Our study findings broaden the application of JH technology for developing chemical reaction systems, with the resulting JH holding substantial promise for cold chain logistics.

A review on polysaccharide-based jelly: Gell food

The prevalence of gel foods in the food industry has grown significantly due to their high water content, low calorie content, and ability to enhance satiety. This review focuses on jelly powder, the earliest form of gel food in the current food industry. Jelly is the earliest form of the gel-food, dating back to the Northern Song dynasty in China, and it relies on gelatinizing and aging of starch to form a gel. With the development of technology, jelly gradually evolved to rely on gel form of food additives. Jelly is divided into starch jelly and non-starch jelly according to their different gel formation. The development status of the two kinds of jelly is also summarized. Additionally, the current research status of these materials is summarized to broaden the understanding of gel food and offer valuable insights for future research in this field.

Biopolymers as Sustainable and Active Packaging Materials: Fundamentals and Mechanisms of Antifungal Activities

Developing bio-based and biodegradable materials has become important to meet current market demands, government regulations, and environmental concerns. The packaging industry, particularly for food and beverages, is known to be the world's largest consumer of plastics. Therefore, the demand for sustainable alternatives in this area is needed to meet the industry's requirements. This review presents the most commonly used bio-based and biodegradable packaging materials, bio-polyesters, and polysaccharide-based polymers. At the same time, a major problem in food packaging is presented: fungal growth and, consequently, food spoilage. Different types of antifungal compounds, both natural and synthetic, are explained in terms of structure and mechanism of action. The main uses of these antifungal compounds and their degree of effectiveness are detailed. State-of-the-art studies have shown a clear trend of increasing studies on incorporating antifungals in biodegradable materials since 2000. The bibliometric networks showed studies on active packaging, biodegradable polymers, films, antimicrobial and antifungal activities, essential oils, starch and polysaccharides, nanocomposites, and nanoparticles. The combination of the development of bio-based and biodegradable materials with the ability to control fungal growth promotes both sustainability and the innovative enhancement of the packaging sector.

Edible chitosan-based Pickering emulsion coatings: Preparation, characteristics, and application in strawberry preservation

The long-term application of plant essential oils in food preservation coatings is limited by their poor water solubility and high volatility, despite their recognized synergistic antimicrobial effects in postharvest fruit preservation. To overcome these limitations, a Pickering emulsion loaded with thyme essential oil (TEO) was developed by utilizing hydrogen bonding and electrostatic interactions to induce cross-linking of chitosan particles. This novel emulsion was subsequently applied in the postharvest storage of strawberries. The shear-thinning behavior (flow index <1) and elastic gel-like characteristics of the emulsion made it highly suitable for spray application. Regarding TEO release, the headspace concentration of TEO increased from 0.21 g/L for pure TEO to 1.86 g/L after two instances of gas release due to the stabilizing effect of the chitosan particles at the oil-water interface. Notably, no phase separation was observed during the 10-day storage of the emulsion. Consequently, the emulsion was successfully employed for the postharvest storage of strawberries, effectively preventing undesirable phenomena such as weight loss, a decrease in firmness, an increase in pH, and microbial growth. In conclusion, the developed Pickering emulsion coating exhibits significant potential for fruit preservation applications, particularly for extending the shelf life of strawberries.