Effect of nano-silica coating combined with pressurized Ar treatment on postharvest quality and reactive oxygen species metabolism in sweet cherry fruit

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.

A New Strategy for Enhancing Postharvest Quality of Sweet Cherry: High-Voltage Electrostatic Field Improves the Physicochemical Properties and Fungal Community

Sweet cherry has a short shelf life due to the occurrence of senescence and fungal infection after harvest. This study aimed to study the effects of high-voltage electrostatic field (HVEF) on the physicochemical properties and fungal composition of sweet cherry during cold storage. The experiments were conducted at 4 °C for 28 days and the quality indicators were determined every 7 days during the period of storage. The fungal composition on sweet cherry was determined using high-throughput sequencing. The results showed that HVEF could better maintain the total soluble solids and inhibit the respiration of cherries. The decay incidence in sweet cherries was decreased by HVEF during cold storage. High-throughput sequencing revealed that HVEF could alter the fungal community and increase the fungal diversity on sweet cherries. Compared with the control group, HVEF decreased the abundance of Alternaria and Cladosporium on sweet cherries, while Aureobasidium, as a nonpathogenic fungus, increased and became the dominant strain at the end of the storage period. In summary, HVEF can improve the physicochemical properties of sweet cherry by inhibiting respiration and can reduce decay incidence by inhibiting specific pathogenic fungi. HVEF is expected to become an efficient and promising technology for the preservation of fruit.

Improving physicomechanical properties of arrowroot starch films incorporated with kappa-carrageenan: Sweet cherry coating application

Arrowroot starch (AS)-based films potential is influenced by its low-cost processing and high transparency packaging material but low tensile strength; hence, AS was blended with kappa-carrageenan (KC) to improve mechanical properties of AS-based films and enhance its potential use in food packaging or coating applications. AS-KC-based films were characterized based on structural, physicomechanical, thermal, pasting properties, and coating application in sweet cherry. The films demonstrated high tensile strength from 3.2 to 29.4 MPa and low elongation properties from 160.3 % to 1.9 %. Moreover, AS/KC films exhibited peak viscosities of 18.7 to 34.8 RVU, and thermal analysis depicted lower weight losses (59-45 %) compared to AS-based films (62 %). In addition, sweet cherry samples coated with AS/KC films and stored at 20 °C for 15 days depicted lower weight losses (26.6 %) compared to non-coated samples (>41 %), which indicated the potential use of the film's coating application in extending the shelf life and quality of fresh fruits.

Processing and preservation technologies to enhance indigenous food sovereignty, nutrition security and health equity in North America

Indigenous foods are carriers of traditional native North American food culture and living philosophy. They are featured by the wide varieties in fresh and processed forms, richness in nutrition, flavor, health benefits and diversity in origins, but are usually misunderstood or underrepresented in the modern food systems. Conventional processing and cooking methods are sometimes labor-intensive, less efficient and lack science-based guidelines to prevent unseen safety risks and food loss. Global and regional climate change have caused additional challenges to conventional cooking/processing, and increased native communities' reliance on externally produced foods, which have resulted in increasing nutritional unbalance and prevalence of diet-related health issues. Current and emerging technologies, such as storage and packaging, drying, safety processing, canning, pickling, and fermentation, which treat foods under optimized conditions to improve the safety and extend the shelf-life, are increasingly used in current food systems. Therefore, exploring these technologies for indigenous foods offers opportunities to better preserve their nutrition, safety, and accessibility, and is critical for the sovereignty and independence of indigenous food systems, and sustainability of indigenous food culture. This mini-review focuses on identifying adoptable processing and preservation technologies for selected traditional indigenous foods in North America, summarizing education, extension, and outreach resources and discussing the current challenges and future needs critical to expanding knowledge about indigenous foods and improving food sovereignty, nutrition security, and health equity.

Carbon dioxide sensitization delays the postharvest ripening and fatty acids composition of Capsicum fruit by regulating ethylene biosynthesis, malic acid and reactive oxygen species metabolism

Present study would be significant in the sustenance of quality characters for postharvest storage of Capsicum fruit with CO2-sensitization in biocompatible manner. The present experiment describes effects of CO2 sensitization on delaying postharvest ripening through physiological attributes in Capsicum fruit. The experiment was conducted with acidified bicarbonate-derived CO2 exposure for 2 h on Capsicum fruit, kept under white light at 25 °C through 7 days postharvest storage. Initially, fruits responded well to CO2 as recorded sustenance of greenness and integrity of fruit coat resolved through scanning electron micrograph. Loss of water and accumulation of total soluble solids were marginally increased on CO2-sensitized fruit as compared to non-sensitized (control) fruit. The ethylene metabolism biosynthetic genes like CaACC synthase, CaACC oxidase were downregulated on CO2-sensitization. Accompanying ethylene metabolism cellular respiration was downregulated on CO2 induction as compared to control through 7 days of storage. Fruit coat photosynthesis decarboxylating reaction by NADP malic enzyme was upregulated to maintain the reduced carbon accumulation as recorded on 7 days of storage under the same condition. CO2-sensitization effectively reduced the lipid peroxides as oxidative stress products on ripening throughout the storage. Anti-oxidation reaction essentially downregulates the ROS-induced damages of biomolecules that otherwise are highly required for food preservation during postharvest storage. Thus, the major finding is that CO2-sensitization maintains a higher ratio of unsaturated to saturated fatty acids in fruit coat during storage. Tissue-specific downregulation of ROS also maintained the nuclear stability under CO2 exposure. These findings provide basic as well as applied insights for sustaining Capsicum fruit quality with CO2 exposure under postharvest storage.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-024-01471-4.

Development of starch-based films reinforced with curcumin-loaded nanocomplexes: Characterization and application in the preservation of blueberries

In current study, curcumin-loaded bioactive nanocomplexes (Cur NCs) (2 %, 5 %, 8 %, and 11 %) were used to prepare corn starch (CS)-based composite films (CS-Cur NCs). Fourier-transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy revealed that Cur NCs were uniformly dispersed in the polymer matrix via physical interaction. Moreover, the mechanical, gas barrier, hydrophobicity, optical, and thermal properties and the antioxidant activity of composite films were potentially improved with the addition of Cur NCs. Subsequently, CS-based film with 11 % Cur NCs exhibited high antioxidant activity (the scavenging rates of DPPH and ABTS are 50.07 % ± 0.82 % and 65.26 % ± 1.60 %, respectively) and was used for packaging blueberries. Compared with the control, the CS-Cur NCs packaging treatment effectively improved the appearance and nutrition of blueberries, and maintained the high activity of several antioxidant enzymes. Furthermore, CS-Cur NCs packaging treatment significantly improved the ascorbic acid (AsA) and glutathione (GSH) levels, thus regulating the AsA-GSH cycle system and suppressing the accumulation of reactive oxygen species (ROS). In summary, the CS-Cur NCs packaging could effectively conserve the postharvest quality of blueberries by improving antioxidant enzyme activity and suppressing excessive accumulation of ROS, which contributes to the development of bioactive packaging and provides novel insights into the preservation of blueberries. This work demonstrates that the development of active packaging is promising to absorb the oxidative radicals from food, and protect the food from inherent and external factors, thus enhancing the quality, security, and shelf-life of the food during storage.

Antioxidant Systems and Quality in Sweet Cherries Are Improved by Preharvest GABA Treatments Leading to Delay Postharvest Senescence

γ-Aminobutyric acid (GABA) plays important roles in plant development, including the maintenance of fruit quality when applied as postharvest treatment. However, little information is available about the effects of preharvest GABA treatments. Thus, GABA (10, 50 and 100 mM) was applied as foliar spray at key points of fruit development in three sweet cherry cultivars and over two years. The results show that quality parameters, such as total soluble solid content, titratable acidity and firmness were higher in the fruit from GABA-treated trees than in the controls, either at harvest or during four weeks of cold storage. In addition, the total phenolic and total and individual anthocyanin concentrations were also enhanced by GABA treatments and the fruit color was improved. The activities of the antioxidant enzymes catalase, ascorbate peroxidase and peroxidase were also enhanced by the GABA treatments. The most effective concentration was 50 mM, which led to extending the storage period of sweet cherries with high quality traits to up to four weeks, while for the controls this was two weeks. Thus, GABA treatment had a clear effect on delaying the postharvest ripening and senescence processes in sweet cherries, with an additional effect on enhancing the content of bioactive compounds, such as phenolics and anthocyanins, with antioxidant properties and health benefits.

The Effects of Combined 1-Methylcyclopropene and Melatonin Treatment on the Quality Characteristics and Active Oxygen Metabolism of Mango Fruit during Storage

In this study, mango fruit (Tainong No. 1) was treated with either 0.1 mg/L 1-methylcyclopropene (1-MCP) alone or with a combination of 0.1 mg/L 1-MCP and 0.2 mM melatonin (MT). The mango fruit was then stored for 10 days at 25 °C and 85-90% relative humidity. Quality characteristics and the active oxygen metabolism of postharvest mangoes were evaluated every 2 days. Compared to untreated mango fruit, those with the treatments of 1-MCP alone or 1-MCP + MT had a better appearance and higher levels of soluble sugar, ascorbic acid, and titratable acidity. Moreover, these treatments prevented the loss of fruit firmness, successfully delayed the escalation of a* and b* values, and reduced malondialdehyde content and superoxide anion generation rate. After 10 days of storage, mango fruit treated by 1-MCP alone or 1-MCP + MT exhibited increased activities of antioxidant enzymes such as ascorbate peroxidase, catalase, superoxide dismutase, and other peroxidases; nevertheless, the two treatment protocols maintained higher mango total phenolic content only at the later stage of storage. These findings suggest that mango fruit treated with 1-MCP alone or with 1-MCP + MT improves the quality characteristics and antioxidant activities. Moreover, compared to 1-MCP treatment alone, 1-MCP + MT-treated mangoes exhibited higher quality and a stronger regulation of active metabolism during storage.

6-Benzyladenine Treatment Maintains Storage Quality of Chinese Flowering Cabbage by Inhibiting Chlorophyll Degradation and Enhancing Antioxidant Capacity

The cytokinin 6-benzyladenine (6-BA) is widely used to regulate the growth of horticultural crops. However, it is not clear how postharvest treatment with 6-BA at various concentrations affects the quality of Chinese flowering cabbage. In this study, harvested Chinese flowering cabbage was foliar sprayed with 6-BA solution at concentrations of 5, 10, 20, 40, and 80 mg·L^-1. All 6-BA treatments protected the quality of Chinese flowering cabbage during storage, and the treatment with 20 and 40 mg·L^-1 6-BA showed the most obvious effect. Treatment with 6-BA reduced leaf yellowing degree and weight loss rate; maintained high chlorophyll a and chlorophyll b contents; suppressed the declines in ascorbic acid and soluble protein; enhanced antioxidant capacity; and reduced oxidative damage in cabbage leaves. Furthermore, 6-BA treatment upregulated the expression of antioxidant genes and the activities of SOD, POD, and CAT, while inhibiting the expression of senescence-related gene (BrSAG12) and chlorophyll catabolic genes (BrPAO, BrPPH, BrSGR1, BrNYC1, BrRCCR). These results suggest that postharvest 6-BA treatment enhances antioxidant capacity, delays leaf senescence, and inhibits chlorophyll degradation, thereby maintaining the quality of Chinese flowering cabbage during storage. The findings of this study provide a candidate method for preserving Chinese flowering cabbage after harvest.

Integrative transcriptomic and TMT-based proteomic analysis reveals the mechanism by which AtENO2 affects seed germination under salt stress

Seed germination is critical for plant survival and agricultural production and is affected by many cues, including internal factors and external environmental conditions. As a key enzyme in glycolysis, enolase 2 (ENO2) also plays a vital role in plant growth and abiotic stress responses. In our research, we found that the seed germination rate was lower in the AtENO2 mutation (eno2^- ) than in the wild type (WT) under salt stress in Arabidopsis thaliana, while there was no significant difference under normal conditions. However, the mechanisms by which AtENO2 regulates seed germination under salt stress remain limited. In the current study, transcriptome and proteome analyses were used to compare eno2^- and the WT under normal and salt stress conditions at the germination stage. There were 417 and 4442 differentially expressed genes (DEGs) identified by transcriptome, and 302 and 1929 differentially expressed proteins (DEPs) qualified by proteome under normal and salt stress conditions, respectively. The combined analysis found abundant DEGs and DEPs related to stresses and hydrogen peroxide removal were highly down-regulated in eno2^- . In addition, several DEGs and DEPs encoding phytohormone transduction pathways were identified, and the DEGs and DEPs related to ABA signaling were relatively greatly up-regulated in eno2^- . Moreover, we constructed an interactive network and further identified GAPA1 and GAPB that could interact with AtENO2, which may explain the function of AtENO2 under salt stress during seed germination. Together, our results reveal that under salt stress, AtENO2 mainly affects the expression of genes and proteins related to the phytohormone signal transduction pathways, stress response factors, and reactive oxygen species (ROS), and then affects seed germination. Our study lays the foundation for further exploration of the molecular function of AtENO2 under salt stress at the seed germination stage in Arabidopsis thaliana.

Preparation of a biodegradable chitosan packaging film based on zinc oxide, calcium chloride, nano clay and poly ethylene glycol incorporated with thyme oil for shelf-life prolongation of sweet cherry

This study includes development of chitosan-based films with incorporated essential thyme oil and different combinations of cross-linkers viz., ZnO, CaCl₂, NC, and PEG for the safe storage of sweet cherries. The resulting films stored with sweet cherries were analyzed for different physicochemical and antimicrobial properties. Incorporation of ZnO, CaCl₂, NC, and PEG in chitosan-based films maintained fruit quality by conserving higher total soluble solids, titratable acidity, and reduced weight loss. The combined ZnO + CaCl₂ + NC + PEG in chitosan-based films also suppressed microbial activity. The sensorial quality of fruits stored with CH + ZnO + CaCl₂ + NC + PEG treatment was also stable during storage. In conclusion, the combined CH + ZnO + CaCl₂ + NC + PEG with added thyme oil application is an effective approach to maintain the postharvest quality and could be an alternative to increase the shelf life of sweet cherries, besides decreasing environmental impacts of non-biodegradable packages.

Melatonin Pre-harvest Treatments Leads to Maintenance of Sweet Cherry Quality During Storage by Increasing Antioxidant Systems

Melatonin has been reported to have an important role in fruit ripening, although the effect of pre-harvest melatonin treatment on sweet cherry quality properties during storage is still unknown. In the present experiments, the effects of melatonin (0.1, 0.3, and 0.5 Mm) by foliar spray treatments of 'Prime Giant' and 'Sweet Heart' sweet cherry trees on fruit quality traits and antioxidants systems during storage was evaluated. Results showed that these treatments reduced weight losses during storage, as well as losses in firmness and titratable acidity. In addition, changes in fruit colour and total soluble solid content were also delayed in fruit from melatonin treated trees with respect to controls. Moreover, in general, total phenolic and anthocyanin concentrations were higher in fruit from treated trees than in those from control ones, either at harvest or during the whole storage period. Finally, the activity of the antioxidant enzymes catalase, ascorbate peroxidase and peroxidase was also enhanced as a consequence of melatonin treatment. Overall results show that pre-harvest melatonin treatment delayed the post-harvest ripening process of sweet cherry fruit, leading to maintenance of their quality properties in optimum levels for consumption 2 weeks more with respect to fruit from control trees. Antioxidant systems, both enzymatic and non-enzymatic ones, were also enhanced by melatonin treatments, which would account for the delay on fruit post-harvest ripening process and fruit quality maintenance during storage.