5-Azacytidine accelerates mandarin fruit post-ripening and enhances lignin-based pathogen defense through remarkable gene expression activation.

5-Azacytidine (AZ) is a DNA methylation inhibitor that has recently demonstrated potential in regulating fruit quality through exogenous application. In this study, we treated mandarin fruits for 4-day storage. Noteworthy were the induced degreening and the enhanced citrus aroma of fruits under AZ treatment, involving the promotion of chlorophyll degradation, carotenoid biosynthesis, and limonene biosynthesis. Key genes associated with these processes exhibited expression level increases of up to 123.8 times. Additionally, AZ treatment activated defense-related enzymes and altered phenylpropanoid carbon allocation towards lignin biosynthesis instead of flavonoid biosynthesis. The expression levels of lignin biosynthesis-related genes increased by nearly 100 times, leading to fortified lignin that is crucial for citrus defense against Penicillium italicum. Currently, the underlying mechanisms of such intense AZ-induced changes in gene expressions remain unclear and further research could help establish AZ treatment as a viable strategy for citrus preservation.

Light-responsive transcription factors VvHYH and VvGATA24 mediate wax terpenoid biosynthesis in Vitis vinifera.

The cuticular wax that covers the surfaces of plants is the first barrier against environmental stresses and increasingly accumulates with light exposure. However, the molecular basis of light-responsive wax biosynthesis remains elusive. In grape (Vitis vinifera), light exposure resulted in higher wax terpenoid content and lower decay and abscission rates than controls kept in darkness. Assay for transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) and RNA-seq data were integrated to draw the chromatin accessibility and cis-elements regulatory map to identify the potential action sites. Terpenoid synthase 12 (VvTPS12) and 3-Hydroxy-3-methylglutaryl-CoA reductase 2 (VvHMGR2) were identified as grape wax biosynthesis targets, while VvHYH and VvGATA24 were identified as terpenoid biosynthesis activators, as more abundant wax crystals and higher wax terpenoid content were observed in transiently overexpressed grape berries and Nicotiana benthamiana leaves. The interaction between VvHYH and the open chromatin of VvTPS12 was confirmed qualitatively using a dual luciferase assay and quantitatively using surface plasma resonance, with an equilibrium dissociation constant of 2.81 nM identified via the latter approach. Molecular docking simulation implied the structural nature of this interaction, indicating that 24 amino acid residues of VvHYH, including Arg106A, could bind to the VvTPS12 G-box cis-element. VvGATA24 directly bound to the open chromatin of VvHMGR2, with an equilibrium dissociation constant of 8.59 nM. 12 amino acid residues of VvGATA24, including Pro218B, interacted with the VvHMGR2 GATA-box cis-element. Our work characterizes the mechanism underlying light-mediated wax terpenoid biosynthesis and provides gene targets for future molecular breeding.

The regulation of postharvest strawberry quality mediated by abscisic acid under elevated CO2 stress.

Elevated CO2 was a potential strategy for strawberry preservation. However, the regulatory mechanism remained unclear. In current study, transcriptome analysis showed that elevated CO2 played important roles in regulating strawberry fruit quality at the transcriptional level, and plant hormones metabolism at least partially involved in the regulatory process. Further, ABA was demonstrated to play important roles in the response to elevated CO2. Elevated CO2 inhibited the accumulation of ABA, which was 61% lower than that in control. Elevated CO2 repressed ABA synthesis by inhibiting NCED activity and the expression of FaNCED1/2, leading to the reduction of ABA accumulation as a result. Meanwhile, elevated CO2 also decreased ABA sensitivity by down-regulating FaSnRK2.4/2.6 and FaABI5 expression. The dual down-regulation of ABA signaling accounted for the regulation of fruit quality under elevated CO2 treatment. These results provide new insights into the mechanism of strawberry fruit response to elevated CO2.

The combination of metabolome and transcriptome clarifies the inhibition of the Alternaria toxin accumulation by methyl ferulate.

As one of the most typical pathogens in fruit postharvest diseases, Alternaria alternata (A. alternata) can produce Alternaria toxins (ATs) aggravating fruit decay and harming human health. In this study, ATs (tenuazonic acid, alternariol monomethyl ether, and alternariol) production was inhibited effectively by 200 and 8000 mg/L MF (methyl ferulate) in vitro and in vivo. 1-Octen-3-ol and 3-octanol were the potential iconic volatile organic compounds of ATs (R2 > 0.99). MF induced oxidative stress, resulting in physiological and metabolic disorders, membrane lipid oxidation and cell damage. It decreased precursors and energy supply by disturbing amino acid metabolism, ABC transporters, citrate cycle, pentose and glucuronate interconversions to regulate ATs synthesis. MF down-regulated the genes related to ATs synthesis (PksJ, AaTAS1, and OmtI), transport (AaMFS1 and MFS), and pathogenicity to affect ATs production and virulence. This study provided a theoretical basis for the control of ATs production.

Effect of pH on the emulsifying performance of protein-polysaccharide complexes.

BACKGROUND: Protein-polysaccharide complexes have been successfully used for emulsion stabilization. However, it is unclear how the complex's surface charge influences aggregation stability and coalescence stability of emulsions, and whether a low charged interfacial film can still maintain the coalescence stability of oil droplets. In the present study, the effects of pH (around the pI of protein) on the aggregation and coalescence stability of emulsions were investigated. RESULTS: Whey protein isolate (WPI) and peach gum polysaccharides (PGP) complexes (WPI-PGP complexes) were synthesized at pH 3, 4 and 5. Their sizes were 598, 274 and 183 nm, respectively, and their ζ-potentials were +2.9, -8.6 and -22.8 mV, respectively. Interface rheological experiments showed that WPI-PGP complex at pH 3 had the lowest interfacial tension, and formed the softest film compared to the complexes at pH 4 and 5. Microfluidic experiments showed that all WPI-PGP complexes were able to stabilize droplets against coalescence within short timescales (milliseconds). At pH 3, no coalescence was observed even under conditions where the continuous phase flow influenced the shape of oil droplets (from spheres to ellipsoids). At pH 4 and 5, the model emulsions were stable over 16 days of storage, extensive aggregation and creaming occurred at pH 3 after 8 days. Importantly, no coalescence took place. CONCLUSION: The present study confirmed that the aggregation stability of the emulsions was mainly determined by the surface charge of the complex, whereas the coalescence stability of emulsions is expectedly determined by steric repulsion, providing new insights into how to prepare stable food emulsions. © 2024 Society of Chemical Industry.

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.

Transient autophagy inhibition strengthened postharvest tomato (Solanum lycopersicum) resistance against Botrytis cinerea through curtailing ROS-induced programmed cell death.

Autophagy (AU) and programmed cell death (PCD) are dynamically regulated during tomato fruit defense against Botrytis cinerea, which are also manipulated by pathogenic effectors to promote colonization. Present study demonstrated that the enhanced defense induced by transient inhibition on AU by hydroxychloroquine (HCQ) facilitated the restriction of B. cinerea lesion on postharvest tomato. Pre-treatment of 2 mM (16.08 ± 3.42 cm at 7 d) and 6 mM (7.80 ± 2.39 cm at 7 d) HCQ inhibited the lesion development of B. cinerea compared with Mock treatment (50.02 ± 7.69 cm at 7 d). Transient inhibition of AU induced expression of fungal defense and transcriptional regulation related genes, but attenuated reactive oxygen species (ROS) burst gene expression. The ROS-induced PCD was compromised by HCQ with promoted ROS scavenging. The transient pre-treatment of HCQ slightly inhibited AU which triggered the feedback loop that enhanced the autophagic activity defensing against B. cinerea infection.

Camellia Oleifera shells derived nano cellulose crystals conjugated with gallic acid as a sustainable Pickering emulsion stabilizer.

Lately, emulsions with low-fat and natural stabilizers are predominant. This study extracted the nano cellulose crystals (NCs) from Camellia Oleifera shells, and their gallic acid (GA) conjugates were synthesized by free-radical grafting. Pickering emulsions were prepared using NCs 1 %, 1.5 %, 2.5 %, and gallic acid conjugates NC-GA1, NC-GA2, and NC-GA3 as stabilizers. The obtained nano cellulose crystals exhibited 18-25 nm, -40.01 ±â€¯2.45 size, and zeta potential, respectively. The contact angle of 83.4° was exhibited by NC-GA3 conjugates. The rheological, interfacial, and microstructural properties and stability of the Pickering emulsion were explored. NC-GA3 displayed the highest absorption content of 79.12 %. Interfacial tension was drastically reduced with increasing GA concentration in NC-GA conjugates. Rheological properties suggested that the low-fat NC-GA emulsions showed a viscoelastic behavior, increased viscosity, gel-like structure, and increased antioxidant properties. Moreover, NC-GA3 displayed reduced droplet size and improved emulsion temperature and storage stability (28 days) against phase separation. POV and TBARS values were reduced with the NC-GA3 (P < 0.05). This work confirmed that grafting phenolic compounds on NCs could enhance bioactive properties, which can be used in developing low-fat functional foods. NC-GA conjugates can potentially fulfill the increasing demand for sustainable, healthy, and low-fat foods.

Nucleic Acid Plate Culture: Label-Free and Naked-Eye-Based Digital Loop-Mediated Isothermal Amplification in Hydrogel with Machine Learning.

Digital nucleic acid amplification enables the absolute quantification of single molecules. However, due to the ultrasmall reaction volume in the digital system (i.e., short light path), most digital systems are limited to fluorescence signals, while label-free and naked-eye readout remain challenging. In this work, we report a digital nucleic acid plate culture method for label-free, ultrasimple, and naked-eye nucleic acid analysis. As simple as the bacteria culture, the nanoconfined digital loop-mediated isothermal amplification was performed by using polyacrylamide (PAM) hydrogel as the amplification matrix. The nanoconfinement of PAM hydrogel with an ionic polymer chain can remarkably accelerate the amplification of target nucleic acids and the growth of inorganic byproducts, namely, magnesium pyrophosphate particles (MPPs). Compared to that in aqueous solutions, MPPs trapped in the hydrogel with enhanced light scattering characteristics are clearly visible to the naked eye, forming white "colony" spots that can be simply counted in a label-free and instrument-free manner. The MPPs can also be photographed by a smartphone and automatically counted by a machine-learning algorithm to realize the absolute quantification of antibiotic-resistant pathogens in diverse real samples.

Valorization and protection of anthocyanins from strawberries (Fragaria×ananassa Duch.) by acidified natural deep eutectic solvent based on intermolecular interaction.

This study introduces an innovative approach for the valorization and protection of anthocyanins from 'Benihoppe' strawberry (Fragaria × ananassa Duch.) based on acidified natural deep eutectic solvent (NADES). Choline chloride-citric acid (ChCl-CA, 1:1) was selected and acidified to enhance the valorization and protection of anthocyanins through hydrogen bond. The optimal conditions (ultrasonic power of 318 W, extraction temperature of 61 °C, liquid-to-solid ratio of 33 mL/g, ultrasonic time of 19 min), yielded the highest anthocyanins of 1428.34 µg CGE/g DW. UPLC-Triple-TOF/MS identified six anthocyanins in acidified ChCl-CA extract. Stability tests indicated that acidified ChCl-CA significantly increased storage stability of anthocyanins in high temperature and light treatments. Molecular dynamics results showed that acidified ChCl-CA system possessed a larger diffusion coefficient (0.05 m2/s), hydrogen bond number (145) and hydrogen bond lifetime (4.38 ps) with a reduced intermolecular interaction energy (-1329.74 kcal/mol), thereby efficiently valorizing and protecting anthocyanins from strawberries.

The uncharted territory of NAD+-capped RNA.

The critical redox cofactor NAD+ was recently reported to serve as an RNA cap in both eukaryotes and prokaryotes. However, its reversible regulation and biological functions remain unclear. Here, we provide insights into its discovery, capping and decapping mechanisms, for further discovery of their potential functional implications.

Changes in properties of human milk under different conditions of frozen storage.

Human milk is the best source of nutrition for infants. Lower freezing temperatures and faster freezing rates allow for better preservation of human milk. However, research on the freezing conditions of human milk is limited. This study investigated the effectiveness of quick freezing and suitable freezing conditions for home preservation. Human milk was stored under different freezing conditions (-18 °C, -18 °C quick freezing, -30 °C, -40 °C, -60 °C, and - 80 °C) for 30, 60, and 90 days and then evaluated for changes in the microbial counts, bioactive protein, and lipid. The results showed that the total aerobic bacterial and Bifidobacteria counts in human milk after storage at freezing temperatures of - 30 °C and lower were closer to those of fresh human milk compared to - 18 °C. Furthermore, the lysozyme loss, lipid hydrolysis degree, and volatile organic compound production were lower. However, -18 °C quick freezing storage was not markedly different from -18 °C in maintaining human milk quality. Based on the results, for household and environmental reasons, the recommended temperature for storing human milk is suggested as -30 °C.

Construction of self-assembled nano cellulose crystals/chitosan nanobubbles composite hydrogel with improved gallic acid release property.

Hydrogels are of great significance in the field of bioactive delivery. This study designed the self-assembly of gallic acid-loaded nano cellulose crystals/chitosan (NC/CS) hydrogels via Nano bubbles (NBs). NC/CS NBs 4:2 hydrogels improved the mechanical properties compared to those without NBs. The hardness of NC/CS (4:2) NBs hydrogels was greatly enhanced by 1.15 ± 0.05. The water-holding and swelling behavior can be tuned at different ratios. NC/CS NBs (4:2) showed the electrostatic interaction analyzed by FTIR, XRD, and XPS. SEM results displayed smoother and smaller pores along dense networks promoted by NBs. The antioxidant activity of hydrogels was increased by adding NBs (P < 0.05). In vitro and vivo release activity of gallic acid was higher in simulated intestinal fluid (SIF) at 4:2, depicting the controlled release mechanism. Thus, current work revealed that NBs and low concentrations of NC can be self-assembled with chitosan chains, producing a highly compact hydrogel structure.

Development of a chitosan/pectin-based multi-active food packaging with both UV and microbial defense functions for effectively preserving of strawberry.

Multi-active food packaging was prepared for strawberry fruit preservation where epigallocatechin gallate (EGCG)-containing pectin matrix and natamycin (NATA)-containing chitosan (CS) matrix were utilized to complete LBL electrostatic self-assembly. The results showed that the physicochemical properties of the multi-active packaging were closely related to the addition of NATA and EGCG. It was found that NATA and EGCG were embedded in the CS/pectin matrix through intermolecular hydrogen bonding interactions. The CN/PE 15 % multi-active films prepared based on the spectral stacking theory formed a barrier to UV light in the outer layer, exhibited excellent NATA protection under UV light exposure conditions at different times, and provided long-lasting and sustained bacterial inhibition in the inner layer. In addition, the CN/PE 15 % multi-active packaging extended the shelf life of strawberry at room temperature compared with the control samples. In conclusion, the developed CN/PE 15 % packaging provided potential applications for multi-active food packaging materials.

Hydrogel Digital LAMP with Suppressed Nonspecific Amplification for Rapid Diagnostics of Fungal Disease in Fresh Fruits.

Fungal disease, mainly caused by Alternaria alternata infection, can generate severe economic losses and health hazards. However, rapid nucleic acid test without nonspecific reaction still remains challenging. Here, we reported the hydrogel digital loop-mediated isothermal amplification (HdLAMP) with suppressed nonspecific amplification for rapid diagnosis of fungi in fresh fruits. The introduction of hydrogel offered a simple platform to achieve absolute quantification. By breaking the 3'end G-C anchor, the nonspecific amplification of primers could be suppressed, while the specific positive reaction in HdLAMP was not affected. This method could be applied for A. alternata detection in 9 min with excellent performances in speed, specificity, reproducibility, sensitivity, and detection limit down to a single copy. Finally, the real diseased jujubes during postharvest storage were successfully diagnosed as an A. alternata infection. HdLAMP promotes the molecular diagnosis of fungal diseases and broadens the application of hydrogels in the agricultural and food industry.

Bioactive Components and Biological Activities of Crocus sativus L. Byproducts: A Comprehensive Review.

The production of saffron spice results in numerous byproducts, as only 15 g of spice can be produced from 1 kg of flowers, indicating that over 90% of the saffron flower material is eventually discarded as waste. In view of this, the paper reviews current knowledge on the natural active components in saffron byproducts and their biological activities, aiming to lay a theoretical and scientific foundation for the further utilization. Saffron byproducts contain a variety of phytochemical components, such as flavonoids, anthocyanins, carotenoids, phenolic acids, monoterpenoids, alkaloids, glycosides, and saponins. The activities of saffron byproducts and their mechanisms are also discussed in detail here.

How to effectively and greenly prepare multi-scale structural starch nanoparticles for strengthening gelatin film (ultrasound-Fenton system).

Ultrasound (US) assisted with Fenton (US-Fenton) reaction was developed to efficiently and greenly prepare starch nanoparticles (SNPs) that were employed as nanofillers to enhance gelatin (G) film properties. Compared to Fenton reaction alone, US-Fenton reaction significantly improved preparation efficiency and dispersion of SNPs (p < 0.05). An optimal US-Fenton reaction parameter (300 mM H2O2, ascorbic acid 55 mM, US 45 min) was found to prepare SNPs with uniform sizes (50-90 nm) and low molecular weight (Mn 7.91 × 105 Da). The XRD, FT-IR, and SAXS analysis revealed that the US-Fenton reaction degraded the amorphous and crystalline zones of starch from top to down, leading to the collapse of the original layered structure starch and the progressive formation of SNPs. The different sizes of SNPs were selected to prepare the composite films. The G-SNP3 film (with 50-90 nm SNPs) showed the most outstanding UV blocking, tensile, and barrier properties. Especially, the tensile strength of G-5%SNP3 film (containing 5 % SNPs) increased by 156 % and 6 % over that of G film and G-5%SNP2 film (containing 5%SNPs with 100-180 nm), respectively. Therefore, the nanomaterial was promisingly prepared by the US-Fenton system and provided a strategy for designing and producing nanocomposite films.

An efficient approach for extraction of polysaccharide from abalone (Haliotis Discus Hannai Ino) viscera by natural deep eutectic solvent.

In this study, a natural deep eutectic solvent (NADES) was proposed for the ultrasonic-assisted extraction of polysaccharides from abalone (Haliotis Discus Hannai Ino) viscera. Eleven NADESs were employed for abalone viscera polysaccharide (AVP) extraction. NADES, composed of choline chloride and ethylene glycol in a molar ratio 1: 3 had the highest extraction efficiency. The optimal extraction conditions were obtained using a four-factor, three-level Box-Behnken design and specific response surface methodology. The maximum predicted polysaccharide yield was 17.32 %. Fick's second law was fitted to the extraction process of AVP by ultrasonic-assisted NADES based on a high linear correlation (R2 ≥ 0.9). The extraction rate constants (k), diffusion coefficients (Du) and half-lives (t1/2) were calculated. Compared to the polysaccharides prepared by the conventional method, the polysaccharides extracted by NADES had a higher sugar content, lower molecular weight, more glucuronic acid, and stronger antioxidant capacity. Overall, the NADES extraction method established in this research can become a strategy for the preparation of high-purity and highly bioactive abalone viscera polysaccharides, which has implications for the exploitation and application of marine food byproduct resources.

Novel insight into the role of sulfur dioxide in fruits and vegetables: Chemical interactions, biological activity, metabolism, applications, and safety.

Sulfur dioxide (SO2) are a category of chemical compounds widely used as additives in food industry. So far, the use of SO2 in fruit and vegetable industry has been indispensable although its safety concerns have been controversial. This article comprehensively reviews the chemical interactions of SO2 with the components of fruit and vegetable products, elaborates its mechanism of antimicrobial, anti-browning, and antioxidation, discusses its roles in regulation of sulfur metabolism, reactive oxygen species (ROS)/redox, resistance induction, and quality maintenance in fruits and vegetables, summarizes the application technology of SO2 and its safety in human (absorption, metabolism, toxicity, regulation), and emphasizes the intrinsic metabolism of SO2 and its consequences for the postharvest physiology and safety of fresh fruits and vegetables. In order to fully understand the benefits and risks of SO2, more research is needed to evaluate the molecular mechanisms of SO2 metabolism in the cells and tissues of fruits and vegetables, and to uncover the interaction mechanisms between SO2 and the components of fruits and vegetables as well as the efficacy and safety of bound SO2. This review has important guiding significance for adjusting an applicable definition of maximum residue limit of SO2 in food.

Synthesis and characterization of fucoidan/chitosan-coated nanoliposomes for enhanced stability and oral bioavailability of hydrophilic catechin and hydrophobic juglone.

This study aimed to improve the thermodynamic performance of nanoliposomes (NLs) using fucoidan (F) as the second-layer coating biopolymer along with chitosan (CS), to control the delivery and bioavailability of catechin (C) and juglone (J). The stabilized liposomal carrier of F/CS-conjugated JC-NL (F-CS-JC-NL) was developed with optimum concentrations of CS (0.09 wt%) and F (0.10 wt%), with the highest encapsulation efficiency of juglone (95.47%) and catechin (90.88%). Physicochemical characterization revealed that F-CS-JC-NL disclosed improved stability under different pH and ionic strengths, with the maximum juglone/catechin retention under thermal, oxidative and storage conditions. In vitro digestion revealed that NL double-coating (F-CS-JC-NL) significantly reduced compound leakage in the gastrointestinal tract, providing a controlled release and better bioavailability of juglone/catechin compared to CS-JC-NL and JC-NL. Conclusively, this study provides a novel NL-based delivery carrier with enhanced physicochemical stability and controlled release that might have promising use in delivering functional ingredients.