Preharvest Application of Chitosan Improves the Postharvest Life of 'Garmrok' Kiwifruit through the Modulation of Genes Related to Ethylene Biosynthesis, Cell Wall Modification, and Lignin Metabolism

Pre- and postharvest chitosan coatings extend the physicochemical and bioactive qualities of minimally processed 'Crimson Seedless' grapes during cold storage

BACKGROUND

Food marketers desire residue-free fresh grapes although grapes have a short postharvest life. This study was performed to determine the influences of pre- and/or postharvest chitosan (Ch) coatings on postharvest quality of minimally processed (stem-detached) organic 'Crimson Seedless' berries. Berries were sorted as: (a) control (untreated berries); (b) preharvest Ch (dipping the clusters on the vine into 1% Ch 10 days before harvest at 20% soluble solid content (SSC)); (c) postharvest Ch (dipping the stem-detached berries into 1% Ch); and (d) pre + postharvest Ch. Berries were stored in 12 × 15 cm rigid polypropylene cups for up to 42 days at 1.0 ± 0.5 °C.

RESULTS

Pre- and/or postharvest Ch coating reduced weight loss during storage. Pre- + postharvest Ch was the best treatment for restricting polygalacturonase (PG) activity, extending the visual quality, color features (L*, C and h°), skin rupture force, biochemical (SSC, titratable acidity, maturity index and pH) and bioactive (total phenol content, antioxidant activity) features. Pre- or postharvest Ch was also significantly effective in maintaining many quality features.

CONCLUSION

Pre- and/or postharvest 1% Ch coatings effectively maintained the quality of minimally processed grape berries of organically produced 'Crimson Seedless' grapes by delaying weight loss and PG activity and keeping the postharvest physical, biochemical and bioactive features for 42-day cold storage at 1.0 ± 0.5 °C. The combined use of pre- and postharvest Ch found to be more effective than single treatment. Thus, pre- + postharvest 1% Ch coating could be recommended as an ecofriendly sustainable methodology for extending the postharvest quality of minimally processed fresh grapes. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Advancements in coating technologies: Unveiling the potential of chitosan for the preservation of fruits and vegetables

Post-harvest losses of fruits and vegetables pose a significant challenge to the agriculture industry worldwide. To address this issue, researchers have turned to natural and eco-friendly solutions such as chitosan coatings. Chitosan, a biopolymer derived from chitin, has gained considerable attention due to its unique properties such as non-toxicity, biodegradability, biocompatibility and potential applications in post-harvest preservation. This review article provides an in-depth analysis of the current state of research on chitosan coatings for the preservation of fruits and vegetables. Moreover, it highlights the advantages of using chitosan coatings, including its antimicrobial, antifungal, and antioxidant properties, as well as its ability to enhance shelf-life and maintain the quality attributes of fresh product. Furthermore, the review discusses the mechanisms by which chitosan interacts with fruits and vegetables, elucidating its antimicrobial activity, modified gas permeability, enhanced physical barrier and induction of host defense responses. It also examines the factors influencing the effectiveness of chitosan coatings, such as concentration, molecular weight, deacetylation degree, pH, temperature, and application methods.

Shotgun Metagenomic Sequencing Revealed the Prebiotic Potential of a Fruit Juice Drink with Fermentable Fibres in Healthy Humans

Fibre-based dietary interventions are at the forefront of gut microbiome modulation research, with a wealth of 16S rRNA information to demonstrate the prebiotic effects of isolated fibres. However, there is a distinct lack of data relating to the effect of a combination of soluble and insoluble fibres in a convenient-to-consume fruit juice food matrix on gut microbiota structure, diversity, and function. Here, we aimed to determine the impact of the MOJU Prebiotic Shot, an apple, lemon, ginger, and raspberry fruit juice drink blend containing chicory inulin, baobab, golden kiwi, and green banana powders, on gut microbiota structure and function. Healthy adults (n = 20) were included in a randomised, double-blind, placebo-controlled, cross-over study, receiving 60 mL MOJU Prebiotic Shot or placebo (without the fibre mix) for 3 weeks with a 3-week washout period between interventions. Shotgun metagenomics revealed significant between-group differences in alpha and beta diversity. In addition, the relative abundance of the phyla Actinobacteria and Desulfobacteria was significantly increased as a result of the prebiotic intervention. Nine species were observed to be differentially abundant (uncorrected p-value of <0.05) as a result of the prebiotic treatment. Of these, Bifidobacterium adolescentis and CAG-81 sp900066785 (Lachnospiraceae) were present at increased abundance relative to baseline. Additionally, KEGG analysis showed an increased abundance in pathways associated with arginine biosynthesis and phenylacetate degradation during the prebiotic treatment. Our results show the effects of the daily consumption of 60 mL MOJU Prebiotic Shot for 3 weeks and provide insight into the functional potential of B. adolescentis.

Chitosan treatment reduces softening and chilling injury in cold-stored Hami melon by regulating starch and sucrose metabolism

Cold-stored Hami melon is susceptible to chilling injury, resulting in quality deterioration and reduced sales. Pre-storage treatment with chitosan reduces fruit softening and chilling injury in melon; however, the underlying mechanism remains unclear. In this study, Gold Queen Hami melons were treated with 1.5% chitosan solution for 10 min before cold storage at 3°C and then the effect of chitosan was examined on fruit firmness, weight loss, chilling injury, soluble solid content (SSC), pectin, and soluble sugar contents of melon fruit. Also, the enzyme activities and gene expressions related to fruit softening and starch and sucrose metabolism were investigated. Chitosan treatment reduced the fruit softening and chilling injury, maintained the high levels of starch and sucrose contents, and regulated the enzyme activities and gene expressions related to starch and sucrose metabolism. Fruit firmness was significantly positively correlated with sucrose and starch contents. Altogether, we uncovered the potential mechanism of chitosan coating mitigating melon softening and chilling injury through the regulation of starch and sucrose metabolism.

Antifungal Activities of Bacillus mojavensis BQ-33 towards the Kiwifruit Black Spot Disease Caused by the Fungal Pathogen Didymella glomerata

‘Hongyang’ kiwifruit (Actinidia chinensis, cultivar ‘Hongyang’) black spot disease is caused by the fungal pathogen Didymella glomerata, and is a serious disease, causing considerable losses to the kiwifruit industry during growth of the fruit. Hence, we aimed to identify a potential biocontrol agent against D. glomerata. In this study, bacterial isolates from the rhizosphere soil of kiwifruit were tested for their potential antifungal activity against selected fungal pathogens. Based on a phylogenetic tree constructed using sequences of 16S rDNA and the gyrA gene, BQ-33 with the best antifungal activity was identified as Bacillus mojavensis. We evaluated the antagonistic activity and inhibitory mechanism of BQ-33 against D. glomerata. Confrontation experiments showed that both BQ-33 suspension and the sterile supernatant (SS) produced by BQ-33 possessed excellent broad-spectrum antifungal activity. Furthermore, the SS damaged the cell membrane and cell wall of the mycelia, resulting in the leakage of a large quantity of small ions (Na⁺, K⁺), soluble proteins and nucleic acids. Chitinase and β-1,3-glucanase activities in SS increased in correlation with incubation time and remained at a high level for several days. An in vivo control efficacy assay indicated that 400 mL L⁻¹ of SS completely inhibited kiwifruit black spot disease caused by D. glomerata. Therefore, BQ-33 is a potential biocontrol agent against kiwifruit black spot and plant diseases caused by other fungal pathogens. To our knowledge, this is the first report of the use of a rhizosphere microorganism as a biocontrol agent against kiwifruit black spot disease caused by D. glomerata.

A comprehensive review of food gels: formation mechanisms, functions, applications, and challenges

Gels refer to the soft and flexible macromolecular polymeric materials retaining a large amount of water or biofluids in their three-dimensional network structure. Gels have attracted increasing interest in the food discipline, especially proteins and polysaccharides, due to their good biocompatibility, biodegradability, nutritional properties, and edibility. With the advancement of living standards, people's demand for nutritious, safe, reliable, and functionally diverse food and even personalized food has increased. As a result, gels exhibiting unique advantages in food application will be of great significance. However, a comprehensive review of functional hydrogels as food gels is still lacking. Here, we comprehensively review the gel-forming mechanisms of food gels and systematically classify them. Moreover, the potential of hydrogels as functional foods in different types of food areas is summarized, with a special focus on their applications in food packaging, satiating gels, nutrient delivery systems, food coloring adsorption, and food safety monitoring. Additionally, the key scientific issues for future food gel research, with specific reference to future novel food designs, mechanisms between food components and matrices, food gel-human interactions, and food gel safety, are discussed. Finally, the future directions of hydrogels for food science and technology are summarized.

Effects of postharvest coating using chitosan combined with natamycin on physicochemical and microbial properties of sweet cherry during cold storage

Sweet cherry is prone to senesce and decay due to high postharvest respiration rate and fungal infection. The effects of natamycin-chitosan coating on physicochemical and microbial properties of sweet cherries stored at 4 °C were investigated. Scanning electron microscopy results revealed that natamycin was more uniformly distributed on sweet cherry pericarps with the help of chitosan coating. Respiration rate of sweet cherries was suppressed by chitosan coating during the storage and as a result, total soluble solids (13.53 %-13.80 %) and titratable acidity (0.91 %-0.93 %) were remained higher values and weight loss (2.54 %-2.85 %) was decreased in chitosan and natamycin-chitosan groups. Although both natamycin and chitosan were effective in inhibiting yeast and mold, sweet cherries treated with the combination of natamycin and chitosan showed significantly lower yeast and mold count (3.31 log CFU/g) and decay rate (1.67 %) compared with control. Natamycin combined chitosan inhibited the pathogenic fungi of sweet cherries, such as Alternaria, Cladosporium and Penicillium. These results indicated that postharvest natamycin-chitosan coating has great advantages in maintaining fruit quality, inhibiting fungi, and reducing decay rate of sweet cherry.

Effects of preharvest applications of chemicals and storage conditions on the physico-chemical characteristics and shelf life of tomato (Solanum lycopersicum L.) fruit

The aim of this study was to investigate the influence of preharvest sprays of chemicals and evaporative cooling (ZECC) on the postharvest physico-chemical quality and shelf life of tomatoes. The experiment was conducted using a combination of ten preharvest sprays of chemicals (chitosan (0.1%), chitosan (0.3%), chitosan (0.5%), salicylic acid (SA) (0.015%), SA (0.03%), SA (0.045%), calcium chloride (CaCl₂) (1%), CaCl₂ (3%), CaCl₂ (5%) and control) and two storage conditions (ambient environment storage and ZECC). The design of the experiment was completely randomized design with three replications. Data were collected from tomato samples (Solanum lycopersicum L. cv. ARP tomato D2) on four days interval. The result showed that all physico-chemical quality indicators were significantly (p ≤ 0.05) affected by both preharvest sprays and storage conditions. CaCl₂ (5%) sprays extended the shelf life of tomato by 6 days in ZECC and 11 days in ambient storage compared to the control. The highest concentration of CaCl₂ and SA sprays minimized PLW and maintained fruit marketability compared to the control. The firmness of tomatoes was better retained with the sprays of SA (0.045%) in both storage conditions. CaCl₂ (5%), SA (0.045%) and chitosan (0.5%) sprays retained the titratable acidity by 42.86%, 47.62% and 33.33%, respectively compared to the control inside ZECC storage. At the end of storage period, the highest TSS was observed on tomatoes sprayed with SA (0.03%) followed by chitosan (0.1%) and chitosan (0.3%). The lycopene contents were lower with sprays of SA (0.045%), SA (0.03%), CaCl₂ (3%), CaCl₂ (5%) and chitosan (0.1%) stored inside ZECC indicating the effectiveness of preharvest sprays in delaying lycopene accumulation. Moreover, the AA contents of tomatoes sprayed with CaCl₂ (5%), SA (0.045%) and chitosan (0.1%) were higher by 34.10%, 38.19% and 23.84%, respectively compared to the control. The result indicated that combining preharvest chemical sprays and ZECC storage is important to maintain the physico-chemical quality and shelf life of tomatoes.

Genome-Wide Identification of MYB Transcription Factors and Screening of Members Involved in Stress Response in Actinidia

MYB transcription factors (TFs) play an active role in plant responses to abiotic stresses, but they have not been systematically studied in kiwifruit (Actinidia chinensis). In this study, 181 AcMYB TFs were identified from the kiwifruit genome, unevenly distributed on 29 chromosomes. The high proportion (97.53%) of segmental duplication events (Ka/Ks values less than 1) indicated that AcMYB TFs underwent strong purification selection during evolution. According to the conservative structure, 91 AcR2R3-MYB TFs could be divided into 34 subgroups. A combination of transcriptomic data under drought and high temperature from four AcMYB TFs (AcMYB2, AcMYB60, AcMYB61 and AcMYB102) was screened out in response to stress and involvement in the phenylpropanoid pathway. They were highly correlated with the expression of genes related to lignin biosynthesis. qRT-PCR analysis showed that they were highly correlated with the expression of genes related to lignin biosynthesis in different tissues or under stress, which was consistent with the results of lignin fluorescence detection. The above results laid a foundation for further clarifying the role of MYB in stress.

Photoactivated TiO2 Nanocomposite Delays the Postharvest Ripening Phenomenon through Ethylene Metabolism and Related Physiological Changes in Capsicum Fruit

Capsicum is one of the most perishable fruit which undergo rapid loss of commercial value during postharvest storage. In this experiment our aim is to evaluate the effect of photoactivated TiO₂ nano-particle complexed with chitosan or TiO₂-nanocomposite (TiO₂-NC) on extension self-life of Capsicum fruit and its effect on related morphological, physiological and molecular attributes at room temperature (25 °C). Initially, TiO₂-NC coated fruits recorded superior maintenance of total soluble solids accumulation along with retention of firmness, cellular integrity, hydration, color etc. On the extended period of storage, fruit recorded a lower bioaccumulation of TiO₂ in comparison to metallic silver over the control. On the level of gene expression for ethylene biosynthetic and signaling the TiO₂-NC had more regulation, however, discretely to moderate the ripening. Thus, ACC synthase and oxidase recorded a significantly better downregulation as studied from fruit pulp under TiO₂-NC than silver. On the signaling path, the transcripts for CaETR1 and CaETR2 were less abundant in fruit under both the treatment when studied against control for 7 d. The reactive oxygen species (ROS) was also correlated to retard the oxidative lysis of polyamine oxidation by diamine and polyamine oxidase activity. The gene expression for hydrolytic activity as non-specific esterase had corroborated the development of essential oil constituents with few of those recorded in significant abundance. Therefore, TiO₂-NC would be reliable to induce those metabolites modulating ripening behavior in favor of delayed ripening. From gas chromatography-mass spectrometry (GC-MS) analysis profile of all tested essential oil constituents suggesting positive impact of TiO₂-NC on shelf-life extension of Capsicum fruit. Our results indicated the potentiality of TiO₂-NC in postharvest storage those may connect ethylene signaling and ROS metabolism in suppression of specific ripening attributes.

The Efficacies of 1-Methylcyclopropene and Chitosan Nanoparticles in Preserving the Postharvest Quality of Damask Rose and Their Underlying Biochemical and Physiological Mechanisms

Simple Summary

Damask rose is one of the most important aromatic plants that is being used in the perfume, cosmetic and pharmaceutical industries. However, the short blooming period leads to a reduced oil quantity and quality; therefore, preserving the flower shelf life is a crucial step in maintaining the economic viability of this crop. This research aimed to study the effect of 400 mg m⁻³ of 1-methylcyclopropene (1-MCP) and either the pre- or postharvest application of 1% chitosan nanoparticles (CSNPs) on maintaining the quality of damask rose flowers during storage at 4 or 20 °C. The results showed that both treatments were shown to help preserve the quality and extend the shelf life of damask rose. CSNPs were more effective than 1-MCP. Collectively, 1-MCP or CSNPs as eco-friendly applications are recommended as novel and promising approaches for the commercial industry for retaining the quality of damask rose during storage.

Abstract

Preserving the flower shelf life of damask rose is a crucial matter in promoting its economic viability. Chitosan nanoparticles (CSNPs) and 1-methylcyclopropene (1-MCP) may potentially decrease the postharvest loss of several horticultural commodities, but no findings on damask rose have been published. Therefore, the aim of this research was to study the effect of 1-MCP (400 mg m⁻³) and either the pre- or postharvest application of CSNPs (1%) on maintaining the quality of damask rose flowers during storage at 4 or 20 °C. The shelf life of damask rose has been significantly extended, along with a reduction in weight loss due to 1-MCP, CSNPs and pre-CSNP treatments. 1-MCP or CSNP applications have resulted in a higher relative water content, volatile oil, total anthocyanins, total carotenoids, total phenolics and antioxidant activity. Ethylene evolution, H₂O₂ generation and malondialdehyde content were significantly decreased due to 1-MCP or CSNPs treatment, and hence, the cell membrane functions have been maintained. The 1-MCP or CSNP-treated flowers have shown higher activities of catalase and ascorbate peroxidase and lower activities of polyphenol oxidase and lipoxygenase in comparison to untreated flowers. Our results showed that the postharvest application of 1-MCP or CSNPs is a very promising method to maintain the postharvest quality of damask rose during storage.

Influence of biopolymer coatings on the storage stability of osmotically dehydrated mushrooms

The main aim of this research was to apply biopolymer coatings on osmotically dehydrated mushrooms and monitor their quality during storage. Mushrooms were osmotically dehydrated in sugar beet molasses (80% dry matter) under optimized conditions (45 °C for 5 hours), as previously reported elsewhere. Two different biopolymers were chosen: chitosan, a polysaccharide polymer, and zein, a protein polymer. A non-treated mushroom sample was chosen as a control sample. The mushroom samples were analysed for sugar and protein content, as well as water loss and microbiological profile. An increase in sugar content was the most noticeable in the osmotically dehydrated mushrooms compared to the control sample due to the use of molasses as a hypertonic solution. The contribution of used biopolymer coatings to the sugar and protein content of the coated and osmotically treated mushrooms was negligible. Chitosan coating contributed to better storage stability of treated mushrooms by lowering the moisture loss and microbial count. For this reason, chitosan treated sample was chosen for further examination related to the evaluation of its baking potential as a filling in a traditional stuffed pie-like layered bakery product - burek. Burek was stuffed with fresh mushrooms, osmotically treated mushrooms or osmotically treated mushrooms coated with chitosan. The sensorial assessment proved that control burek and burek samples with osmotically dehydrated mushrooms coated with chitosan were the most preferred groups based on odour and overall impression.

Influence of biopolymer coatings on the storage stability of osmotically dehydrated mushrooms

The main aim of this research was to apply biopolymer coatings on osmotically dehydrated mushrooms and monitor their quality during storage. Mushrooms were osmotically dehydrated in sugar beet molasses (80% dry matter) under optimized conditions (45 °C for 5 hours), as previously reported elsewhere. Two different biopolymers were chosen: chitosan, a polysaccharide polymer, and zein, a protein polymer. A non-treated mushroom sample was chosen as a control sample. The mushroom samples were analysed for sugar and protein content, as well as water loss and microbiological profile. An increase in sugar content was the most noticeable in the osmotically dehydrated mushrooms compared to the control sample due to the use of molasses as a hypertonic solution. The contribution of used biopolymer coatings to the sugar and protein content of the coated and osmotically treated mushrooms was negligible. Chitosan coating contributed to better storage stability of treated mushrooms by lowering the moisture loss and microbial count. For this reason, chitosan treated sample was chosen for further examination related to the evaluation of its baking potential as a filling in a traditional stuffed pie-like layered bakery product-burek. Burek was stuffed with fresh mushrooms, osmotically treated mushrooms or osmotically treated mushrooms coated with chitosan. The sensorial assessment proved that control burek and burek samples with osmotically dehydrated mushrooms coated with chitosan were the most preferred groups based on odour and overall impression.

Efficiency of chitosan application against Phytophthora infestans and the activation of defence mechanisms in potato

Late blight, caused by the oomycete Phytophthora infestans, is one of the most devastating diseases that results in huge losses of potato crops worldwide. Chitosan as a defence elicitor can induce plant innate immunity against pathogen infection, but the efficiency and specific defence mechanism of chitosan against late blight in potato have not been elaborated. In this study, we demonstrated that the application of chitosan significantly enhanced potato resistance and reduced P. infestans infection in potted potato and in the field. Large-scale transcriptomic analysis suggested that chitosan preferentially activated several important pathways related to the plant defence response. Notably, we revealed that chitosan triggered pattern-triggered immunity responses in potato. Chitosan could trigger pattern recognition receptors to initiate intracellular signalling, and gradually amplify the immune signal. qRT-PCR verification showed that chitosan induced the expression of defence-related genes in potato. Moreover, treatment with chitosan result in Induced Systemic Resistance (ISR) in potato, including an accumulation of plant hormone salicylic acid, increase in the level of phenylalanine ammonia lyase activity and a content decrease of malondialdehyde. These findings help elucidate chitosan-mediated activation of the immune system in potato and provide a potential ecofriendly strategy to control potato late blight in the field.