Effect of chitosan and alginate based coatings enriched with pomegranate peel extract to extend the postharvest quality of guava (Psidium guajava L.)

Sodium carboxymethyl cellulose hydrogels containing montmorillonite-NaClO2 for postharvest preservation of Chinese bayberries

Owing to their lack of outer skin, Chinese bayberries are highly susceptible to mechanical damage during picking, which accelerates bacterial invasion and rotting, shortening their shelf life. In this study, montmorillonite (MMT) was used to absorb an aqueous sodium chlorite solution embedded in a carboxymethyl cellulose sodium hydrogel after freeze drying, and the hydrogel was crosslinked by Al3+ ions. Al3+ hydrolyzed to produce H+, creating an acidic environment within the hydrogel and reacting with NaClO2 to slowly release ClO2. We prepared a ClO2 slow-release hydrogel gasket with 0.5 wt% MMT-NaClO2 and investigated its storage effect on postharvest Chinese bayberries. Its inhibition rates against Escherichia coli and Listeria monocytogenes were 98.84% and 98.96%, respectively. The results showed that the gasket preserved the appearance and nutritional properties of the berries. The antibacterial hydrogel reduced hardness loss by 26.57% and ascorbic acid loss by 46.36%. This new storage method could also be applicable to other fruits and vegetables.

An alginate-based edible coating containing lactic acid bacteria extends the shelf life of fresh strawberry (Fragaria × ananassa Duch.)

Edible coatings, formulated with sodium alginate and various strains of lactic acid bacteria, were evaluated for their effectiveness in extending the shelf life and mitigating microbial risks associated with strawberries. This study specifically employed strains of Lacticaseibacillus paracasei, Lacticaseibacillus rhamnosus, and Lacticaseibacillus plantarum as antimicrobial agents. Through physicochemical property analysis, the alginate-based antimicrobial coating proved most effective in reducing the strawberry weight loss rate, decay index, and ascorbic acid degradation. Over time, all treatments exhibited increased fungal growth. However, strawberries treated with alginate and lactic acid bacteria recorded lower final colony formation counts-6.82 log CFU/g for SA + LPC, 6.04 log CFU/g for SA + LGG, and 6.26 log CFU/g for SA + LP-compared to 8.73 log CFU/g in the control group. In terms of bacterial resistance under gastrointestinal conditions, L. paracasei demonstrated the highest survival rate post-simulated gastric fluid exposure, while L. plantarum showed the greatest resilience post-simulated intestinal fluid exposure. These findings underscore the efficacy of alginate-based antimicrobial coatings in not only enhancing the storage quality of strawberries but also ensuring microbial safety and potential benefits for gut health.

Application of Natural Functional Additives for Improving Bioactivity and Structure of Biopolymer-Based Films for Food Packaging: A Review

The global trend towards conscious consumption plays an important role in consumer preferences regarding both the composition and quality of food and packaging materials, including sustainable ones. The development of biodegradable active packaging materials could reduce both the negative impact on the environment due to a decrease in the use of oil-based plastics and the amount of synthetic preservatives. This review discusses relevant functional additives for improving the bioactivity of biopolymer-based films. Addition of plant, microbial, animal and organic nanoparticles into bio-based films is discussed. Changes in mechanical, transparency, water and oxygen barrier properties are reviewed. Since microbial and oxidative deterioration are the main causes of food spoilage, antimicrobial and antioxidant properties of natural additives are discussed, including perspective ones for the development of biodegradable active packaging.

Postbiotics-enriched flaxseed mucilage coating: A solution to improving postharvest quality and shelf life of strawberry

This research aimed to assess the effects of flaxseed mucilage (Mu) coatings supplemented with postbiotics (P) obtained from Lactobacillus acidophilus LA-5 on various physical, biochemical, and microbial characteristics of strawberry fruits. Strawberry fruits were immersed for 2 min in Mu2.5 (2.5 % mucilage in distilled water), Mu5 (5 % mucilage in distilled water), P-Mu2.5 (2.5 % mucilage in undiluted postbiotics) and P-Mu5 (5 % mucilage in undiluted postbiotics) solutions and were stored at 4 °C and 85 RH for 12 days. All coatings were effective in reducing fungal count compared to the uncoated control fruits. Mu5 coating exhibited the highest efficacy, reducing fungal count by 2.85 log10 CFU/g, followed by Mu2.5 (1.47 log10 CFU/g reduction) and P-Mu2.5 groups (0.90 log10 CFU/g reduction). The fruits coated with edible coatings showed significant delays in the change of weight loss, pH, and total soluble solids as compared to the uncoated fruits. The coating containing postbiotics i.e., P-Mu5 also showed a significant increase in the total phenolic contents, total flavonoid content, antioxidant capacity, and total anthocyanin content at the end of storage relative to the uncoated fruits. Thus, Mu and P-Mu coatings may be a useful approach to maintaining the postharvest quality of strawberry fruits during cold storage.

The Preservation Effect of Chitosan-hawthorn Leaf Extract Coating on Strawberries

Strawberries rapidly deteriorate postharvest, necessitating effective measures to extend their shelf life. This study focused on developing an eco-friendly chitosan-based protective film for strawberry preservation. Strawberries were treated with a coating solution containing varying concentrations of hawthorn leaf extract (HLE) (0.4%, 0.7%, and 1.0%), 1.5% chitosan (CH), and 1% acetic acid. The results demonstrated that coating strawberry fruit with 1% CH-HLE notably delayed fruit spoilage. In-depth analysis revealed that, compared with the uncoated strawberry fruits, the 1% CH-HLE coating effectively reduced weight loss, the respiration intensity, malondialdehyde (MDA) levels, and superoxide anion (O2·-) production. Additionally, the coated strawberries exhibited improved firmness, total soluble solids (TSS), vitamin C (Vc) content, titratable acidity (TA), and total phenolic compound (TPC) content. The enzyme activities of superoxide dismutase (SOD) and catalase (CAT) in the CH-HLE-coated strawberries were greater than those in their uncoated counterparts. The application of a 1% CH-HLE coating successfully delayed spoilage and extend the shelf life of the strawberries by approximately 4-5 days. These findings suggest that CH-HLE has significant potential as a resource for protecting fruits and vegetables, offering an environmentally sustainable solution for postharvest preservation.

Postharvest Physiology and Handling of Guava Fruit

Guavas are typical tropical fruit with high nutritional and commercial value. Because of their thin skin and high metabolic rate, guavas are highly susceptible to water loss, physical damage, and spoilage, severely limiting their shelf-life. Guavas can typically only be stored for approximately one week at room temperature, making transportation, storage, and handling difficult, resulting in low profit margins in the industry. This review focuses on the physiological and biochemical changes and their molecular mechanisms which occur in postharvest guavas, and summarizes the various management strategies for extending the shelf-life of these sensitive fruits by means of physical and chemical preservation and their combinations. This review also suggests future directions and reference ideas for the development of safe and efficient shelf-life extension techniques.

Improved sustained-release properties of ginger essential oil in a Pickering emulsion system incorporated in sodium alginate film and delayed postharvest senescence of mango fruits

The insufficient water vapor barrier and mechanical capacity of sodium alginate (SA) film limited its application in fruit preservation. Herein, cellulose nanocrystals (CNCs) were used to stabilize Pickering emulsion. Then, we prepared SA composite films. Ginger essential oil (GEO) was loaded as antimicrobials and antioxidants. Finally, the application on mangos were investigated. Compared to coarse emulsion, Pickering emulsion and its film-formation-solution showed more stable system and larger droplet size. The emulsion significantly changed the properties of SA film. Specifically, CNCs improved the thermal, tensile, and barrier properties of the film and GEO enhanced the ultraviolet-visible light barrier capacity. Additionally, the SA/CNC film possessed a homogeneous micromorphology which had a sustained-release effect on GEO, thus maintaining high postharvest quality and long-term bioavailability for mangos. In conclusion, the film prepared via Pickering emulsion showed satisfactory properties which had great potential in fruit preservation.

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.

Enhancing Postharvest Quality and Antioxidant Capacity of Blue Honeysuckle cv. 'Lanjingling' with Chitosan and Aloe vera Gel Edible Coatings during Storage

This study investigated the impact of chitosan (CH, 1%) and aloe vera gel (AL, 30%) edible coatings on the preservation of blue honeysuckle quality during a 28-day storage at -1 °C. Coating with CH, AL, and CH+AL led to notable enhancements in several key attributes. These included increased firmness, total soluble solids, acidity, pH, and antioxidant capacity (measured through DPPH, ABTS, and FRAP assays), as well as the preservation of primary (ascorbic acid) and secondary metabolites (TPC, TAC, and TFC). The TAC and TFC levels were approximately increased by 280% and 17%, respectively, in coated blue honeysuckle after 28 d compared to uncoated blue honeysuckle. These coatings also resulted in reduced weight loss, respiration rate, color, abscisic acid, ethylene production, and malondialdehyde content. Notably, the CH+AL treatment excelled in preserving secondary metabolites and elevating FRAP-reducing power, demonstrating a remarkable 1.43-fold increase compared to the control after 28 days. Overall, CH+AL exhibited superior effects compared to CH or AL treatment alone, offering a promising strategy for extending the shelf life and preserving the quality of blue honeysuckle during storage.

Efficacy of chitosan nanoparticles and wax coatings on maintaining post-harvest quality of "Murcott" mandarins

Because of its high degree of biodegradability, chitosan is widely used as a component in food packaging. However, its poor physical properties, such as permeability, limit its applicability. Consequently, applying nano chitosan is regarded as the most effective solution to this issue. In the current study, we studied the effect of using different materials in the coating process on the quality of "Murcott" mandarin during cold storage. We used different concentrations of nano chitosan (50 and 100 ppm) without wax and 100 ppm nano chitosan with wax. We investigated the impact of these compounds on the chemical composition and quality of fruits. The most successful treatment for preventing weight loss from discarded fresh fruit was a combination of wax and 100 ppm nano chitosan. This combination also prevented the deterioration of vitamin C, maintained the fruit pulp, and preserved the fruit's superior taste during cold storage and shelf life. It also maintains a better total soluble solids and total acidity level than other treatments. In addition, the activity of antioxidant enzymes and the total number of antioxidants indicates no degradation of plant tissues compared to those not coated with nano chitosan. It also reduces the microbial load on the coated fruits. Consequently, this coating combination could suggest prolonging post-harvest life and increasing the marketing period of mandarin fruits.

Worldwide productivity and research trend on fruit quality: a bibliometric study

Introduction

As one of the important sources of food for human beings, fruits have been extensively studied. To better guide basic and applied research, it is urgent to conduct a systematic analysis of these studies based on extensive literature collection.

Methods

Based on the Web of Science Core Collection database, this study uses R language and CiteSpace to conduct bibliometric analysis and data mining on the literatures related to fruit quality from January 2013 to June 2023.

Results

The results indicated that among various fruits, tomatoes have been most frequently studied with special interests in photosynthesis, fruit development, and molecular breeding. The research direction primarily focused on fruit resistance and storage characteristics. Among the indicators related to fruit quality, antioxidant activity has the highest co-occurrence with other indicators of fruit quality, especially with nutrients such as anthocyanins, phenolic substances, sugars, and fruit firmness.

Discussion

Currently, adaptation to stress and antioxidant activity are recognized as prominent research focal points in this field. Fruit morphology, particularly fruit size, irrigation methods, application of molecular technology, and infection prevention, represent potential areas of interests in future research on fruit quality.

Physical stability, microstructure and antimicrobial properties of konjac glucomannan coatings enriched with Litsea cubeba essential oil nanoemulsion and its effect on citruses preservation

This study purposed to develop konjac glucomannan (KGM) based antimicrobial coatings containing Litsea cubeba essential oil nanoemulsion (LNE) for citruses preservation. Physical stability, rheological, structural and antimicrobial properties of the coating solutions were investigated, along with the release characteristics of Litsea cubeba essential oil (LCO). Results showed that the coating solutions displayed shear thinning behavior. The oil droplets were distributed homogeneously in KGM phase with good stability. The coating structure became loose with increasing LNE content due to LNE interfering with molecular interactions and entanglement of KGM. The coating solutions showed stronger antibacterial activity against Escherichia coli than against Staphylococcus aureus and were effective in inhibiting the growth of Penicillium italicum on citrus surfaces. KGM-LNE 10 negatively affected citruses due to phytotoxicity caused by high levels of LCO. LCO was released slowly and continuously from the coatings, and its release was faster in deionized water than in an ethanol-water solution. KGM-LNE 2.5 coated citruses had the least weight loss, the greatest hardness, and kept the minimum changes in total soluble solids, total acid and vitamin C content, implying that KGM-LNE 2.5 best maintained the quality of citruses. The findings suggest that KGM-based coatings containing LNE have high potential for citruses preservation.

Development and characterization of pomegranate peel extract-functionalized jackfruit seed starch-based edible films and coatings for prolonging the shelf life of white grapes

In the current research, the pomegranate peel extract of varying concentrations (0.02, 0.04, 0.06, 0.08, and 0.1 g/mL) were incorporated into jackfruit seed starch (5 % w/w) based edible films and coatings for the evaluation their effects on the mechanical, physical, barrier and thermal properties. Furthermore, the effects of the optimized edible coating were investigated on the postharvest shelf life of white grapes at room storage (30 ± 5 °C, RH = 70 ± 5 %) conditions for up to 8 days. The obtained results showed a significant increment in thickness (p ≤ 0.05) with higher concentration (0.1 g/mL) of pomegranate peel extract (PPE), total phenolic content (959.33 ± 43.36 mg/100 g) and antioxidant activity (87.35 ± 1.64 %) of the prepared edible films but have negative impacts on the water vapor permeability (2.82 × 10-6 ± 6.48 × 10-7 g-1h-1pa-1) and oxygen permeability (1.62 × 10-14 ± 9.32 × 10-15 cm3·cm/cm2·s·cmHg), solubility (23.24 ± 3.21 %), and tensile strength (1.60 ± 0.43 MPa). The edible film enriched with 0.4 g/mL of PPE showed higher thermal stability in terms of glass transition temperature (98.2 ± 0.21 °C) and peak temperature (110.3 ± 0.35 °C). Additionally, the application of coating treatment significantly maintains the postharvest shelf life of white grapes throughout the storage period.

Understanding the effects of chitosan, chia mucilage, levan based composite coatings on the shelf life of sweet cherry

Sweet cherry (Prunus avium L.) fruits are prone to quality and quantity loss in shelf-life conditions and cold storage due to their short post-harvest life. Until now efforts have been made to extend the shelf life of the sweet cherry. However, an efficient and commercially scalable process remains elusive. To contribute to this challenge, here in this study, biobased composite coatings consisting of chitosan, mucilage, and levan, were applied on sweet cherry fruits and tested for postharvest parameters in both market and cold storage conditions. Results demonstrated that the shelf life of sweet cherries can be extended until the 30^th day while retaining important post-harvest properties like decreased weight loss, fungal deterioration, increased stem removal force, total flavonoid, l-ascorbic acid, and oxalic acid. Given the cost-effectiveness of the polymers used, the findings of this study indicate the feasibility of extending the shelf-life of sweet cherries on a larger scale.

The combination treatment of chlorogenic acid and sodium alginate coating could accelerate the wound healing of pear fruit by promoting the metabolic pathway of phenylpropane

Water loss and microbial infection induced by mechanical injury are the main sources of harvested loss of fruits and vegetables. Plenty studies have shown that regulating phenylpropane-related metabolic pathways can effectively accelerate wound healing. The combination treatment of chlorogenic acid and sodium alginate coating on postharvest wound healing of pear fruit were investigated in this work. The result shows combination treatment reduced weight loss and disease index of the pears, enhanced texture of healing tissues, maintained the integrity of cell membrane system. Moreover, chlorogenic acid increased the content of total phenols and flavonoids, and ultimately leads to the accumulation of suberin poly phenolic (SPP) and lignin around wound cell wall. Activities of phenylalanine metabolism-related enzymes (PAL, C4H, 4CL, CAD, POD and PPO) in wound-healing tissue were enhanced. The contents of major substrates such as trans-cinnamic, p-coumaric, caffeic, and ferulic acids also increased. The presented results suggested that the combination treatment of chlorogenic acid and sodium alginate coating stimulated wound healing in pears by elevating the phenylpropanoid metabolism pathway, so that maintain high postharvest fruit quality.

Application of Plant-Based Edible Coatings and Extracts Influences the Postharvest Quality and Shelf Life Potential of "Surahi" Guava Fruits

Guava fruits have a short shelf life due to climacteric nature. The current work was conducted to extend the shelf life of guavas with garlic extract (GRE), ginger extract (GNE), gum arabic (GA), and Aloe vera (AV) gel coatings. After coating, fruits of guava were stored at 25 ± 3 °C and RH 85 ± 2% for 15 days. Results showed that guavas treated with plant-based edible coatings and extracts had lower weight loss than that of the control. GRE-treated guavas had the maximum shelf life in contrast to all other treatments including the control. GNE-treated guavas showed the lowest nonreducing sugar content, whereas they had higher antioxidant activity, vitamin C content, and total phenolics compared with all other coating treatments. After the control, antioxidant capacity was the highest in GNE- and GRE-treated fruits. On the other hand, GA-treated guavas had reduced total soluble solids and juice pH (more acidic) and exhibited higher total flavonoids compared with the control, while both GA- and GNE-treated guavas had the highest flavonoid content. GRE-treated fruits exhibited the highest total sugar content and taste and aroma scores. In conclusion, GRE treatment was more effective in conserving the quality and extending the shelf life of guava fruits.

Exploring the Potential of Pomegranate Peel Extract as a Natural Food Additive: A Review

PURPOSE OF THE REVIEW

Pomegranate is one of the super fruit and a storehouse of several antioxidants and health-promoting compounds which can act as a natural food additive. The pomegranate processing industry generates huge quantities of by-products, particularly peels (50% of fresh fruit weight), that cause environmental pollution due to improper disposal. In this perspective, the present review article focuses on the chemical composition of pomegranate peel and its application as a natural food additive in different food products such as bakery, dairy, meat/meat products, fish/fish products, edible oils, and packaging materials.

RECENT FINDINGS

There is a continuous demand for processed foods exhibiting natural food additives over foods containing synthetic additives/colorants, which can cause serious health implications such as cancer with regular consumption. The food industry is looking for an alternative to synthetic/artificial food additives. To overcome these problems, pomegranate peel or its extract can be used as a natural biopreservative in food products that are prone to fat oxidation and microbial growth. Pomegranate peel contains bioactive compounds, especially tannins, phenolic acids, and flavonoids, which have nutraceutical value and possess higher antioxidant activity and antimicrobial properties. Due to these properties, pomegranate peel prevents lipid oxidation in fatty foods and can also retard the microbial growth.

Chitosan oligosaccharide as a plant immune inducer on the Passiflora spp. (passion fruit) CMV disease

Cucumber mosaic virus (CMV), one of the main viruses, is responsible for Passiflora spp. (passion fruit) virus diseases, which negatively affect its planting, cultivation, and commercial quality. In this study, a laboratory anti-CMV activity screening model for Passiflora spp. CMV disease was first established. Then, the effects of different antiviral agents of chitosan oligosaccharide (COS), dufulin (DFL), and ningnanmycin (Ning) on CMV virulence rate in Passiflora spp. were determined. The virulence rate and anti-CMV activity in Passiflora spp. treated with COS were 50% and 45.48%, respectively, which were even better than those of DFL (66.67% and 27.30%, respectively) and Ning (83.30% and 9.17%, respectively). Field trials test results showed COS revealed better average control efficiency (47.35%) against Passiflora spp. CMV disease than those of DFL (40.93%) and Ning (33.82%), indicating that COS is effective in the control of the Passiflora spp. CMV disease. Meanwhile, the nutritional quality test results showed that COS could increase the contents of soluble solids, titratable acids, vitamin C, and soluble proteins in Passiflora spp. fruits as well as enhance the polyphenol oxidase (PPO), superoxide dismutase (SOD), and peroxidase (POD) activity in the leaves of Passiflora spp. seedlings. In addition, the combined transcriptome and proteome analysis results showed that COS mainly acted on the Brassinosteroids (BRs) cell signaling pathway, one of plant hormone signal transduction pathway, in Passiflora spp., thus activating the up-regulated expression of TCH4 and CYCD3 genes to improve the resistance to CMV disease. Therefore, our study results demonstrated that COS could be used as a potential plant immune inducer to control the Passiflora spp. CMV disease in the future.

Effects of chitosan and nano-SiO2 concentrations on the quality of postharvest guavas (Psidium guajava L.)

Guava (Psidium guajava L.) is a perishable fruit susceptible to postharvest losses at tropical ambient temperature. Therefore, the development of green storage solution such as biodegradable film could be an alternative to increase guavas’ shelf life. The primary objective of the present work was to explore the effects of combining chitosan and nano-SiO2 coating at different concentrations on the external and internal quality parameters of guavas during 12-d storage at 15°C, and 8-d storage at 30°C. Weight loss, skin colour, firmness, ascorbic acid content, total soluble solids (TSS), decay incidence, and sensory taste score during storage were also analysed. Guavas coated with 2% chitosan and 0.02% nano-SiO2 film were economically optimum to maintain the tested postharvest quality parameters, including better skin colour, higher TSS, fruit firmness, ascorbic acid content, and good taste scores, while keeping lower weight loss and decay incidence when compared with those of other treatments at both tested temperatures. Therefore, chitosan and nano-SiO2 as a coating is a promising strategy for improving the postharvest quality of guavas.

Effect of Composite Chitosan/Sodium Alginate Gel Coatings on the Quality of Fresh-Cut Purple-Flesh Sweet Potato

In this study, single-layer coating using chitosan (Ch) and sodium alginate (SA) solutions and their gel coating (ChCSA) formed by layer-by-layer (LbL) electrostatic deposition using calcium chloride (C) as a cross linking agent were prepared to improve storage qualities and shelf-life of fresh-cut purple-flesh sweet potatoes (PFSP). The preservative effects of single-layer coating in comparison with LbL on the quality parameters of fresh-cut PFSP, including color change, weight loss, firmness, microbial analysis, CO2 production, pH, solid content, total anthocyanin content (TAC), and total phenolic content (TPC) were evaluated during 16 days of storage at 5 °C. Uncoated samples were applicable as a control. The result established the effectiveness of coating in reducing microbial proliferation (~2 times), color changes (~3 times), and weight loss (~4 times) with negligible firmness losses after the storage period. In addition, TAC and TPC were better retained in the coated samples than in the uncoated samples. In contrast, quality deterioration was observed in the uncoated fresh cuts, which progressed with storage time. Relatively, gel-coating ChCSA showed superior effects in preserving the quality of fresh-cut PFSP and could be suggested as a commercial method for preserving fresh-cut purple-flesh sweet potato and other similar roots.

Essential oils and plant extracts for tropical fruits protection: From farm to table

The tropical fruit industry in Malaysia makes up a large proportion of the agriculture sector, contributing to the local economy. Due to their high sugar and water content, tropical fruits are prone to pathogenic infections, providing optimal microorganism growth conditions. As one of the largest exporters of these fruits globally, following other Southeast Asian countries such as Thailand, Indonesia and the Philippines, the quality control of exported goods is of great interest to farmers and entrepreneurs. Traditional methods of managing diseases in fruits depend on chemical pesticides, which have attracted much negative perception due to their questionable safety. Therefore, the use of natural products as organic pesticides has been considered a generally safer alternative. The extracts of aromatic plants, known as essential oils or plant extracts, have garnered much interest, especially in Asian regions, due to their historical use in traditional medicine. In addition, the presence of antimicrobial compounds further advocates the assessment of these extracts for use in crop disease prevention and control. Herein, we reviewed the current developments and understanding of the use of essential oils and plant extracts in crop disease management, mainly focusing on tropical fruits. Studies reviewed suggest that essential oils and plant extracts can be effective at preventing fungal and bacterial infections, as well as controlling crop disease progression at the pre and postharvest stages of the tropical fruit supply chain. Positive results from edible coatings and as juice preservatives formulated with essential oils and plant extracts also point towards the potential for commercial use in the industry as more chemically safe and environmentally friendly biopesticides.

Pomegranate (Punica granatum L.) Peel Extracts as Antimicrobial and Antioxidant Additives Used in Alfalfa Sprouts

Aqueous and ethanolic pomegranate peel extracts (PPE) were studied as a source of phenolic compounds with antimicrobial, anti-quorum sensing, and antioxidant properties. The aqueous extract showed higher total phenolic and flavonoid content (153.43 mg GAE/g and 45.74, respectively) and antioxidant capacity (DPPH radical inhibition: 86.12%, ABTS radical scavenging capacity: 958.21 mg TE/dw) compared to the ethanolic extract. The main phenolic compounds identified by UPLC-DAD were chlorogenic and gallic acids. The aqueous PPE extract showed antimicrobial activity against Listeria monocytogenes, Salmonella Typhimurium, Candida tropicalis (MICs 19–30 mg/mL), and anti-quorum sensing activity expressed as inhibition of Chromobacterium violaceum violacein production (%). The aqueous PPE extracts at 25 mg/mL applied on alfalfa sprouts reduced psychrophilic bacteria (1.12 Log CFU/100 g) and total coliforms (1.23 Log CFU/100 g) and increased the antioxidant capacity of the treated sprouts (55.13 µmol TE/100 g (DPPH) and 126.56 µmol TE/100 g (ABTS)) compared to untreated alfalfa. This study emphasizes PPE’s antioxidant and antimicrobial activities in alfalfa sprouts preservation.

From Pomegranate Byproducts Waste to Worth: A Review of Extraction Techniques and Potential Applications for Their Revalorization

The food industry is quite interested in the use of (techno)-functional bioactive compounds from byproducts to develop ‘clean label’ foods in a circular economy. The aim of this review is to evaluate the state of the knowledge and scientific evidence on the use of green extraction technologies (ultrasound-, microwave-, and enzymatic-assisted) of bioactive compounds from pomegranate peel byproducts, and their potential application via the supplementation/fortification of vegetal matrixes to improve their quality, functional properties, and safety. Most studies are mainly focused on ultrasound extraction, which has been widely developed compared to microwave or enzymatic extractions, which should be studied in depth, including their combinations. After extraction, pomegranate peel byproducts (in the form of powders, liquid extracts, and/or encapsulated, among others) have been incorporated into several food matrixes, as a good tool to preserve ‘clean label’ foods without altering their composition and improving their functional properties. Future studies must clearly evaluate the energy efficiency/consumption, the cost, and the environmental impact leading to the sustainable extraction of the key bio-compounds. Moreover, predictive models are needed to optimize the phytochemical extraction and to help in decision-making along the supply chain.

Determination of Phenolic Compounds and Bioactive Potential of Plum (Prunus salicina) Peel Extract Obtained by Ultrasound-Assisted Extraction

Ultrasound-assisted extraction (UAE) of bioactive compounds from black plum peels was optimized by response surface methodology (RSM). Temperature (35-55°C), time (15-45 min), and ethanol concentration (50-90%) were selected as independent extraction parameters, whereas total anthocyanin content (TAC), total phenolic content (TPC), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) inhibition were kept as response variables. The optimized extraction conditions were determined by RSM as extraction at 49°C for 37 min with 68% ethanol, which corresponded to TAC, TPC, and DPPH inhibition values of 5.42 ± 0.61 mg/g, 6.217 ± 0.76 mg GAE/g, and 89 ± 2.13%, respectively. Fourier-transform infrared spectrometer (FTIR), high-performance liquid chromatography (HPLC), and gas chromatography mass spectrometer (GCMS) were used for chemical characterization of optimized plum peel extract (PPE). Optimized PPE was further evaluated for antibacterial, antioxidant, anticancer, and food preservation potential. PPE showed 92.31% DPPH inhibition with IC₅₀ value of 360.6 μg/ml. Optimized PPE extract was effective in the inhibition of cancer cell proliferation and migration, and IC₅₀ values were in the range 1.85-3.96 mg/ml for different human cancer cell lines. Major phenolics identified in PPE were ferulic acid (47.87 mg/kg), sinapic acid (9.15 mg/kg), quercetin (7.44 mg/kg), gallic acid (3.24 mg/kg), m-coumaric acid (2.59 mg/kg), and vanillic acid (1.12 mg/kg). PPE extract inhibited the growth of various foodborne bacterial pathogens and increased the shelf life of PPE coated fresh grapes. PPE due to antibacterial, anticancer, antioxidant, and food preservation potential can be used in developing functional food and pharmaceutical products.

Chitosan-Cinnamon Oil Coating Maintains Quality and Extends Shelf Life of Ready-to-Use Pomegranate Arils under Low-Temperature Storage

Different formulations of chitosan (1%, 2%, or 3%) with the incorporation of cinnamon oil (0.25% or 0.50%) were prepared for the preservation of pomegranate aril cv. Bhagwa. Six combinations of chitosan-cinnamon oil formulations along with one control (untreated) were applied to the freshly extracted arils using the dipping application method. All treatments were found to be effective in enhancing the shelf life, improving the postharvest characteristics, and reducing microbial populations on pomegranate arils during a 15-day storage period at 4 ± 1°C. The treated pomegranate arils exhibited excellent resistance to microbial decay, moisture loss, respiration rate, preservation of phenolics, flavonoids, and antioxidants activity, among other characteristics. Chitosan 2% + cinnamon oil 0.25% edible coating has a high potential to enhance the storage life and biochemical properties and reduce the microbial population of arils. This treatment recorded a higher total phenolic content (18%) and antioxidant activity (16%) than the control sample, respectively, at the end of storage. In addition, the treatment also helped to decrease the microbial activity by 45% compared to the control sample. The present investigation proposed an alternative method to prolong the shelf life of pomegranate arils during the 15 days of storage.

Amelioration of chilling injury and enhancement of quality maintenance in cold-stored guava fruit by melatonin treatment

The influence of melatonin treatment on the quality and chilling injury of guavas during storage at 4 ± 1 °C were evaluated. Compared with control group, fruit of guava cv. Xiguahong exposed to various concentrations (50, 100, 150, and 200 μmol/L) of melatonin showed a significantly lower fruit respiration rate, weight loss, cell membrane permeability, and chilling injury index, but a higher commercially acceptable fruit rate, higher peel L*, h° value, and chlorophyll content. Melatonin treatment also delayed the decreases of fruit firmness, sucrose, total soluble sugar, vitamin C, titratable acidity, and total soluble solids. These data indicate that melatonin treatment could increase chilling tolerance and retain quality of cold-stored guavas. Among various concentrations of melatonin treatment, 100 μmol/L melatonin-treated guavas showed the preferable quality properties and lowest chilling injury index. Thus, melatonin may be a novel method of postharvest handling to enhance cold resistance and extend storage-life of cold-stored guava fruit.

Combination of chitosan coating and heat shock treatments to maintain postharvest quality and alleviate cracking of Akebia trifoliate fruit during cold storage

Akebia trifoliata fruit cracks easily, which shortens the shelf life and declines commercial value. This work aimed to evaluate the effects of heat shock and coating treatments on postharvest quality of A. trifoliata fruit and to elucidate the mechanism underlying retarding cracking by cell wall metabolism. Coating could decline cracking incidence (from 16.05% to 3.61%), decay incidence (from 31.21% to 18.06%), total soluble solids (TSS), and malondialdehyde (MDA) content compared to uncoated treatment during 35 days of storage. Heat shock could further decrease decay incidence but did not influence TSS, pH, firmness, and starch. Heat shock at 40 °C combined with coating treatment had the best preservation performance with the highest synthetic score (4.41). Furthermore, coated fruit displayed lower β-glucosidase and polygalacturonase activities which resulted in higher cellulose and Na₂CO₃-soluble pectin. These modifications together with lower weight loss, MDA, and ion leakage contributed to the lower cracking incidence.

A novel edible packaging film based on chitosan incorporated with persimmon peel extract for the postharvest preservation of banana

This study aimed to develop a novel edible packaging film for the postharvest preservation of banana based on chitosan (CS) and persimmon peel extract (PPE). Scanning electron microscopy (SEM) analysis showed PPE was evenly distributed in the CS matrix and Fourier transform infrared (FT-IR) spectroscopy analysis showed CS and PPE interacted to form hydrogen bonds, demonstrating good compatibility. Simultaneously, the addition of PPE also significantly improved CS film's physical properties and antioxidant activity. Among them, the CS film containing 10% PPE (CS-PPE 10) showed the optimal mechanical properties, water vapor barrier properties and oxygen barrier properties. The CS film containing 15% PPE (CS-PPE 15) exhibited the best thermal stability, UV-Vis barrier properties and antioxidant activity. In the experiment of banana preservation, CS-PPE 10 film obtained optimal performance on decreasing senescence spots, weight loss, fruit softening, cell wall degradation, inhibiting the activities of polyphenol oxidase and cell wall degrading enzymes and maintaining the content of total soluble sugar and ascorbic acid during the storage period. Consequently, CS-PPE 10 film was expected to be a novel edible packaging material to maintain banana quality and prolong shelf life.

Effects of chitosan coatings fused with medicinal plant extracts on postharvest quality and storage stability of purple passion fruit (Passiflora edulis var. Ester)

Chitosan edible coating (Ch; 2% w/v) enriched with 2% of 0.1 mg/L Bidens pilosa (Ch+B), Lippia javanica (Ch+L), Syzygium cordatum (Ch+S), or Ximenia caffra (Ch+X) was applied as a composite edible coating in alleviating shrivel and maintaining the quality of purple passion fruit (Passiflora edulis var. Ester). Treated fruit were dipped for 3 min in the coating solution, and control fruit were dipped in distilled water. The fruit were stored at 8±2 °C and 90±5% relative humidity (RH) for 32 d. Sampling was done every 8 d plus 3 d (20±2 °C and 50±5% RH) to simulate retail conditions. Efficacy of medicinal plant extracts in the chitosan matrix varied; lower ethylene production (82.42 µL C2H4/kg h) was seen in fruit coated with Ch+S, and the lowest respiration rate (75 mL CO2/kg h) was observed in fruit coated with Ch+B. The control fruit showed the highest ethylene production (84.90 µL C2H4/kg h) and respiration rate (117.98 mL CO2/kg h). Fruit coated with Ch+B had the lowest weight loss (41.67%), higher juice content (60.13%) and BrimA (3.31), while the control fruit had the highest weight loss (88.03%), lowest juice content (21.90%), and BrimA (2.49). Shrivel incidence was lowest (23.70%) on fruit coated with Ch+L and highest (83.30%) on the control fruit. Fruit coated with Ch+X had the lowest electrolyte leakage (71.40%), while the control fruit had the highest (91.97%). Fruit coated with chitosan alone performed better than the control fruit but did not exceed the quality of composite chitosan coated fruit. Based on the principal component analysis, it can be concluded that passion fruit coated with Ch+B was more effective in alleviating shrivel incidence, better maintained the quality of passion fruit during storage, and shows potential for commercial applications.

Recent Advances in Novel Packaging Technologies for Shelf-Life Extension of Guava Fruits for Retaining Health Benefits for Longer Duration

Guava (Psidium guajava L.) fruit is also known as the apple of tropics, belongs to the family of genus Psidium, and is widely cultivated in tropical zones of the world. Recently, the importance of guava fruit has increased due to its inherent nutritional content, pleasant aroma, excellent flavor, and delicious taste. It is considered an excellent source of nutrients and phytochemicals. Guava is a climacteric fruit that continues to mature or ripen even after harvest, showing an increase in the rate of respiration and metabolic activities within a short period, leading to rapid senescence or spoilage of fruit. It has limitations in terms of commercialization due to short storage life after harvest and sensitivity to diseases and chilling injury during the storage period. Many postharvest technologies such as edible packaging, modified atmosphere packaging (MAP), composite packaging, controlled atmosphere packaging (CAP), antimicrobial/antifungal packaging, and nano packaging have been used to retard the chilling injury and enhance the keeping quality of guava fruits during the storage period to control respiration rate, reduce weight loss, minimize lipid oxidation, and maintain organoleptic properties. However, these packaging technologies have varied effects on the internal and external quality attributes of guava fruits. This review, therefore, discusses the physiology, mechanism of ripening, oxidation, and ethylene production of guava fruits. The review also discusses the packaging technologies and their effect on the postharvest characteristics of guava fruits during the storage period.

Effects of Gum Arabic Coatings Enriched with Lemongrass Essential Oil and Pomegranate Peel Extract on Quality Maintenance of Pomegranate Whole Fruit and Arils

The effects of gum arabic coatings combined with lemongrass oil and/or pomegranate peel extract on freshly harvested mature 'Wonderful' pomegranate fruit were studied. Fruit were coated with gum arabic (GA) (1.5% w/v) alone or enriched with lemongrass oil (LM) (0.1% v/v) and/or pomegranate peel extract (PP) (1% w/v). Fruit were packed into standard open top ventilated cartons (dimensions: 0.40 m long, 0.30 m wide and 0.12 m high), and stored for 6 weeks at 5 ± 1 °C (90% RH). Evaluations were made every 2 weeks of cold storage and after 5 d of shelf life (20 °C and 65% RH). Fruit coated with GA + PP (4.09%) and GA + PP + LM (4.21%) coatings recorded the least cumulative weight loss compared to the uncoated control (9.87%). After 6 weeks, uncoated control and GA + PP + LM recorded the highest (24.55 mg CO2Kg-1h-1) and lowest (10.76 mg CO2Kg-1h-1) respiration rate, respectively. Coating treatments reduced the incidence of decay and treatments GA + LM + PP and GA + PP recorded the highest total flavonoid content between 2 and 6 weeks of storage. The findings suggest that GA coatings with/without LM and PP can be a beneficial postharvest treatment for 'Wonderful' pomegranates to reduce weight loss and decay development during cold storage.

The Effects of a Gum Arabic-Based Edible Coating on Guava Fruit Characteristics during Storage

Guava is a nutritious fruit that has perishable behavior during storage. We aimed to determine the influences of some edible coatings (namely, cactus pear stem (10%), moringa (10%), and henna leaf (3%) extracts incorporated with gum Arabic (10%)), on the guava fruits’ properties when stored under ambient and refrigeration temperatures for 7, 14, and 21 days. The results revealed that the coating with gum Arabic (10%) only, or combined with the natural plant extracts, exhibited a significant reduction in weight loss, decay, and rot ratio. Meanwhile, there were notable increases in marketability. Moreover, among all tested treatments, the application of gum Arabic (10%) + moringa extract (10%) was the superior treatment for most studied parameters, and exhibited for the highest values for maintaining firmness, total soluble solids, total sugars, and total antioxidant activity. Overall, it was suggested that coating guava with 10% gum Arabic combined with other plant extracts could maintain the postharvest storage quality of the cold-storage guava.

Effects of konjac glucomannan/pomegranate peel extract composite coating on the quality and nutritional properties of fresh-cut kiwifruit and green bell pepper

The effects of an edible coating, based on konjac glucomannan (KG) incorporated with pomegranate peel extracts (PE), on the physicochemical and nutritional properties of fresh-cut kiwifruit and green bell pepper during storage were investigated. The optimal extract time (40.6 min), temperature (54.5 °C), and ultrasound power (255.5 W) with response surface method, provided a high total antioxidant activity (TAA) of (92.31 ± 1.43)%. Fresh-cut kiwifruit and green bell pepper were coated by dipping using five treatments (distilled water, ascorbic acid, KG, PE, KG + PE), packed into polymeric film and stored for 8 days at 10 °C. Distilled water treatment was used as control. KG + PE treatment resulted in the highest total soluble solid and titratable acidity in fresh-cut kiwifruit, while the maximum firmness in fresh-cut green bell pepper. The weight loss was both effectively decreased in samples treated with KG or KG + PE. All samples treated with KG + PE had significantly higher contents of chlorophyll, ascorbic acid, total phenolic and TAA than others. Moreover, the KG + PE group had the lowest counts of microorganisms in all samples. KG coating incorporated with PE was proved to be efficient in maintaining the physico-chemical and nutritional properties of fresh-cut kiwifruit and green bell pepper during low temperature storage compared with control.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13197-021-05006-7.

Polysaccharide-Based Active Coatings Incorporated with Bioactive Compounds for Reducing Postharvest Losses of Fresh Fruits

This review reports recently published research related to the application of polysaccharide-based biodegradable and edible coatings (BECs) fortified with bioactive compounds obtained from plant essential oils (EOs) and phenolic compounds of plant extracts. Combinations of polysaccharides such as starches, pectin, alginate, cellulose derivatives, and chitosan with active compounds obtained from clove, lemon, cinnamon, lavender, oregano, and peppermint have been documented as potential candidates for biologically active coating materials for retardation of quality changes in fresh fruits. Additionally, polysaccharide-based active coatings supplemented with plant extracts such as cashew leaves, pomegranate peel, red roselle, apple fiber, and green tea extracts rich in phenolic compounds and their derivatives have been reported to be excellent substituents to replace chemically formulated wax coatings. Moreover, EOs and plant polyphenolics including alcohols, aldehydes, ketones phenols, organic acids, terpenes, and esters contain hydroxyl functional groups that contribute bioactivity to BECs against oxidation and reduction of microbial load in fresh fruits. Therefore, BECs enriched with active compounds from EOs and plant extracts minimize physiological and microbial deterioration by reducing moisture loss, softening of flesh, ripening, and decay caused by pathogenic bacterial strains, mold, or yeast rots, respectively. As a result, shelf life of fresh fruits can be extended by employing active polysaccharide coatings supplemented with EOs and plant extracts prior to postharvest storage.

Application of Potentially Probiotic Fruit-Derived Lactic Acid Bacteria Loaded into Sodium Alginate Coatings to Control Anthracnose Development in Guava and Mango During Storage

This study evaluated the efficacy of potentially probiotic fruit-derived lactic acid bacteria (LAB) strains loaded into sodium alginate (SA) coatings to control the anthracnose development in guava cv. Paluma and mango cv. Palmer caused by distinct pathogenic Colletotrichum species (C. asianum, C. fructicola, C. tropicale, C. siamense, C. karstii, and C. gloeosporioides) during 15 days of room temperature storage (25 ± 0.5 °C). The effects of the formulated coatings on physicochemical parameters indicative of overall postharvest quality of guava and mango were evaluated. The eight examined LAB strains caused strong inhibition on the mycelial growth of all target Colletotrichum species in vitro. LAB strains with the highest inhibitory effects (Levilactobacillus brevis 59, Lactiplantibacillus pentosus 129, and Limosilactobacillus fermentum 263) on the target Colletotrichum species were incorporated into SA coatings. These strains had viable counts of > 6 log CFU/mL in SA coatings during 15 days of room temperature storage. Application of coatings with SA + L. brevis 59, SA + L. pentosus 129, and SA + L. fermentum 263 delayed the development and decreased the severity of anthracnose lesions in guava and mango artificially contaminated with either of the tested Colletotrichum species. These coatings impacted positively on some physicochemical parameters indicative of postharvest quality and more prolonged storability of guava and mango. The formulated SA coatings loaded with tested fruit-derived potentially probiotic LAB strains could be innovative and effective strategies to control postharvest anthracnose and extend the storability of guava and mango.