RESUMO
The effects of electron beam irradiation (EBI) pretreatment on the alkaline extraction of pectic polysaccharides from Diaphragma juglandis fructus (DJF) are highly dependent on the irradiation dosage. Comprehensive characterizations encompassing physicochemical, structural, and functional properties were conducted on crude pectic polysaccharide extract from DJF subjected to various EBI doses. EBI pretreatment significantly increased the yields of crude pectic polysaccharides extract (increasing by 41.89 %), also facilitating the extraction of uronic acid, RG-I structure, and protein content, despite causing a decrease in total sugar content. EBI pretreatment induced the degradation of pectin, resulting in decreased molecular weight, particle size, crystallinity, viscosity, thermal stability, and water holding capacity, while enhancing solubility and oil holding capacity. Variations in physicochemical and structural properties induced by different EBI doses influenced the functional activities of DJF pectic polysaccharides. Low-dose EBI (at 5 kGy) pretreatment markedly improved the emulsifying activity/stability (increasing by 20.82/74.10 %) and ABTS/DPPH radical scavenging activity (increasing by 27.91/12.40 %), whereas high-dose EBI pretreatment (50 kGy) greatly enhanced foaming capacity/stability (increasing by 259.99/175.56 %). These findings provide a novel regulatory strategy for the functional activity of pectic polysaccharides.
RESUMO
Kiwifruit ripening and senescence after harvesting are closely related to its economic value. Transcriptome analysis and biochemical parameters were used to investigate the differences in gene expression levels and the potential regulation of cell wall metabolism in kiwifruit treated with ozone, thereby regulating fruit softening and prolonging postharvest life. Compared to the control group, the activities of the cell wall modification enzyme were lower under ozone treatment, the content of polysaccharide in the cell wall of primary pectin and cellulose was higher, and the content of soluble pectin was lower. Meanwhile, ozone treatment delayed the degradation of the cell wall mesosphere during storage. A total of 20 pectinesterase (PE)-related genes were identified by sequencing analysis. The data analysis and quantitative polymerase chain reaction results confirmed that cell wall modifying enzyme genes played an important role in softening and senescence after harvesting, which may reduce or induce the expression of certain genes affecting cell wall metabolism. Ozone treatment not only regulates active genes such as xyloglucan endo glycosyltransferase/hydrolase, cellulose synthase, polygalacturonase, and PE to maintain the quality of fruit after harvest but also acts synergically with cell wall modifying enzymes to inhibit the degradation of cell wall, resulting in changes in the ultrastructure of cell wall, thereby reducing the hardness of kiwifruit. In addition, according to the results of cis-acting elements, cell wall degradation is also related to downstream hormone signaling, especially PE-related genes. These results provide a theoretical basis for studying the mechanism of firmness and cell wall metabolism difference of kiwifruit and also lay a good foundation for further research.
Assuntos
Actinidia , Ozônio , Humanos , Ozônio/farmacologia , Atraso no Tratamento , Perfilação da Expressão Gênica , Pectinas/metabolismo , Actinidia/química , Parede Celular , Frutas/químicaRESUMO
This study aimed to optimize the temperature adaptive conditions of pulsed vacuum drying (PVD) for green walnut husk (GWH) to tackle the issues of severe environmental pollution and limited utilization of GWH. The results of the single-factor experiment revealed that the optimal drying temperature for PVD of GWH was 65°C, with a pulsed ratio of 9 min: 3 min. The drying time decreased from 10.87 to 6.32 h with increasing drying temperature and from 8.83 to 6.23 kW·h/kg with increasing pulsed ratio. Energy consumption also decreased with shorter drying time and shorter vacuum time. Under this optimal variable temperature drying condition, GWH exhibited the highest total active substance content, with respective values of 9.43 mg/g for total triterpenes, 35.68 mg/g for flavonoids, 9.51 mg/g for polyphenols, and 9.55 mg/g for quinones. The experimental drying data of GWH were best fitted by a logarithmic model, with R2 values ranging from 0.9927 to 0.9943. Furthermore, the observed microstructure of GWH corresponded to the variations in total active substance content. This study provided valuable theoretical guidance for addressing environmental pollution associated with GWH and facilitating the industrialization and refinement of GWH drying processes. PRACTICAL APPLICATION: There is a growing interest in harnessing the potential value of agricultural waste to transform low-cost raw materials into high-value products while mitigating environmental pollution. In this study, for the first time, the effects of variable temperature pulsed vacuum drying on the content of active substances, drying time, and energy consumption of green walnut husk (GWH) were investigated. The findings serve as a theoretical foundation for addressing environmental pollution issues associated with GWH and enabling the industrialization and precision drying of GWH.
Assuntos
Juglans , Vácuo , Temperatura , Dessecação/métodos , Polifenóis/análiseRESUMO
Owing to its easy decomposition and residue-free properties, ozone has been used as an effective and environmentally friendly physical preservation method for maintaining the post-harvest quality of fruits. This study aimed to investigate the effects of ozone treatment on the levels of oxidative stress markers and the status of the antioxidant defense system in refrigerated kiwifruit. Additionally, the study aimed to identify the differences in gene expression levels and potential regulatory effects from the transcriptional level. The results showed that ozone treatment reduced the respiration rate, maintained the fruit hardness and storage quality, and inhibited the ripening and senescence of kiwifruit. Ozone treatment activated antioxidant enzymes (superoxide dismutase, peroxidase, and catalase) and ascorbate-glutathione cycle to prevent the increase of reactive oxygen species levels (H2O2, O2-â¢) and malonaldehyde content, maintaining lower membrane lipid peroxidation and reactive oxygen species (ROS) accumulation than the control treatment. Further analysis showed that the regulatory ability of ROS in kiwifruit treated with ozone was not only related to the synergistic effect of enzyme activity and gene expression related to the antioxidant oxidase system and the ascorbate-glutathione (ASA-GSH) cycle but also related to downstream hormone signaling. This study provides a foundation for understanding the potential effects of ozone treatment on the antioxidant cycle of kiwifruit and provides valuable insights into the molecular basis and related key genes involved in regulating ROS to delay aging in kiwifruit.
Assuntos
Antioxidantes , Ozônio , Antioxidantes/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Ozônio/farmacologia , Ozônio/metabolismo , Frutas/metabolismo , Peróxido de Hidrogênio/metabolismo , Transcriptoma , Catalase/metabolismo , Superóxido Dismutase/metabolismo , Glutationa/metabolismoRESUMO
Walnut green husk (WGH) is rich in natural compounds and is valued as a potential source of antioxidant and antimicrobial properties. In this study, the antioxidant and antimicrobial activities of petroleum ether polar fraction, dichloromethane polar fraction, ethyl acetate polar fraction (EAPF), and n-butanol polar fraction from WGH were analyzed. The results showed that EAPF exhibited the highest total flavonoid content (65.74 ± 1.01 mg rutin equivalents [RE]/g dry weight [DW]) and total phenol content (48.73 ± 1.09 mg gallic acid equivalent [GAE]/g DW), with the highest 2,2-diphenyl-1-picrylhydrazyl, hydroxyl radical (â¢OH), and 2,2-azino-bis-3-ethylbenzothiazoline-6-sulfonate scavenging activity compared with other fractions. EAPF also showed good antibacterial activity against Escherichia coli and Bacillus cereus vegetative cells, with a diameter of inhibition zones of 33.5 and 37.6 mm, respectively, a minimum inhibitory concentration of 31.25 mg/ml and a minimum bactericidal concentration of 62.5 mg/ml, which inhibited the growth of both bacteria. Analysis of the antibacterial mechanism demonstrated that EAPF damaged the integrity of the cell membrane, increased the membrane permeability, and triggered the leakage of intracellular material. In addition, ultrahigh performance liquid chromatography-tandem with mass spectrometry analysis revealed that 8 polyphenols and 14 flavonoids were mainly present in EAPF, such as chlorogenic acid (C16 H18 O9 ), gallic acid (C7 H6 O5 ), vanillic acid (C8 H8 O4 ), ferulic acid (C10 H10 O4 ), epicatechin (C15 H14 O6 ), catechin (C15 H14 O6 ), hesperetin (C16 H14 O6 ), naringenin (C15 H12 O5 ), hyperin (C21 H20 O12 ), luteolin (C15 H10 O6 ), and so on. Therefore, WGH had the potential to be developed as a natural antioxidant and antibacterial material. PRACTICAL APPLICATION: Our work indicates that WGH contains abundant flavonoids and polyphenols compounds. Therefore, the plant byproducts like WGH may have a promising application as a source of antimicrobial and antioxidant additives.
Assuntos
Anti-Infecciosos , Juglans , Antioxidantes/química , Extratos Vegetais/farmacologia , Extratos Vegetais/química , Anti-Infecciosos/farmacologia , Flavonoides/análise , Antibacterianos/farmacologia , Antibacterianos/análise , Polifenóis , Ácido Gálico/farmacologiaRESUMO
Inhibiting the activity of α-amylase has been considered an effective strategy to manage hyperglycemia. Hyperoside and quercetin are the main natural flavonoids in various plants, and the inhibition mechanism on α-amylase remains unclear. In this study, the structure-activity relationships between hyperoside/quercetin and α-amylase were evaluated by enzyme kinetic analysis, multi-spectroscopic techniques, and molecular docking analysis. Results showed that hyperoside and quercetin exhibited significant α-amylase inhibitory activities with IC50 values of 0.491 and 0.325 mg/mL, respectively. The α-amylase activity decreased in the presence of hyperoside and quercetin in a competitive and noncompetitive manner, respectively. UV-vis spectra suggested that the aromatic amino acid residues (Trp and Tyr) microenvironment of α-amylase changed in the presence of these two flavonoids. FTIR and CD spectra showed the vibrations of the amide bands and the secondary structure content changes. The fluorescence quenching mechanism of α-amylase by hyperoside and quercetin belonged to the static quenching type. Finally, molecular docking intuitively showed that hyperoside/quercetin formed hydrogen bonds with the key active site residues (Asp197, Glu233, and Asp300) in α-amylase. MD simulation indicated hyperoside/quercetin-α-amylase docked complexes had good stability. Taken together, this research provides new sights to developing potent drugs or functional foods with hyperoside and quercetin, offering new avenues for hyperglycemia treatment.
Assuntos
Hiperglicemia , alfa-Amilases , Humanos , alfa-Amilases/metabolismo , Simulação de Acoplamento Molecular , Quercetina/química , Cinética , Flavonoides/química , Relação Estrutura-Atividade , Análise EspectralRESUMO
Antibacterial hand sanitizers could play a prominent role in slowing down the spread and infection of hand bacterial pathogens; luteolin (LUT) is potentially useful as an antibacterial component. Therefore, this study elucidated the antibacterial mechanism of LUT against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) and developed an antibacterial hand sanitizer. The results showed that LUT had excellent antibacterial activity against both E. coli (minimum inhibitory concentration (MIC) = 312.5 µg/mL, minimal bactericidal concentration (MBC) = 625 µg/mL), and S. aureus (MIC = 312.5 µg/mL, MBC = 625 µg/mL). Furthermore, LUT induced cell dysfunction in E. coli and S. aureus, changed membrane permeability, and promoted the leakage of cellular contents. Confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM) analysis showed that LUT treatment affected cell structure and disrupted cell membrane integrity. The Fourier transform infrared analysis (FTIR) also confirmed that the LUT acted on the cell membranes of both E. coli and S. aureus. Overall, the application of LUT in hand sanitizer had better inhibition effects. Therefore, this study could provide insight into expanding the application of LUT in the hand sanitizer markets.
Assuntos
Higienizadores de Mão , Staphylococcus aureus , Escherichia coli , Higienizadores de Mão/farmacologia , Luteolina/farmacologia , Testes de Sensibilidade Microbiana , Antibacterianos/farmacologia , Antibacterianos/químicaRESUMO
Foodborne disease caused by Listeria monocytogenes is a major global food safety problem. A potential solution is the antimicrobial development of the highly bioactive natural product juglone, yet few studies exist on its antibacterial mechanism against L. monocytogenes. Thus, we aimed to elucidate the antibacterial mechanism of action of juglone against L. monocytogenes by determining the resultant cell morphology, membrane permeability, membrane integrity, and proteome changes. The minimum inhibitory concentration of juglone against L. monocytogenes was 50 µg/mL, and L. monocytogenes treated with juglone had longer lag phases compared to controls. Juglone induced L. monocytogenes cell dysfunction, leakage of potassium ions, and membrane potential hyperpolarization. Confocal laser scanning microscopy and field-emission-gun scanning electron microscope assays revealed clear membrane damage due to juglone treatment. Fourier transform infrared analyses showed that L. monocytogenes responded to juglone by some conformational and compositional changes in the molecular makeup of the cell membrane. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis showed that juglone either destroyed proteins or inhibited proteins synthesis in L. monocytogenes. Therefore, our findings established juglone as a natural antibacterial agent with potential to control foodborne L. monocytogenes infections.
RESUMO
Green walnut husk (GWH) contains abundant active compounds and is valued as a potential source of natural antioxidants. This study aimed at assessing the impact of electron beam irradiation (EBI) pretreatment on the extraction yield and antioxidant activity of active compounds in GWH. The ultrasonic extraction of active substances was optimized by response surface method (RSM). Scanning electron microscopy, Fourier-transform infrared spectroscopy, and X-ray diffraction revealed physical structure changes in GWH powder. After EBI pretreatment, the content of polyphenols, flavonoids, and triterpenes in GWH increased by 18.88%, 43.00%, and 11.08%, respectively. Irradiation doses up to 30 kGy, DPPH, OH, and ABTS radical scavenging activity and reducing power of the crude extract were enhanced by 9.56%, 15.62%, 15.60%, and 36.98%, respectively. This was significantly different (P < 0.05) than the non-irradiated GWH. Therefore, EBI is a new pretreatment technology with potential application in the extraction and utilization of GWH.
Assuntos
Antioxidantes , Juglans , Elétrons , Flavonoides , Extratos Vegetais , PolifenóisRESUMO
This study aimed to assess the effects of Penicillium expansum (P. expansum) infection on the quality and flavor of Jinmi (JM) and Jinyan (JY) kiwifruit. Kiwifruit were inoculated with P. expansum and stored at 0 ± 1°C, and the changes in quality indicators and volatile substances (VCs) at different stages of disease were determined. Results showed that in wound-inoculated kiwifruit, the soluble solid content (SSC) increased. Conversely, their titratable acidity and vitamin C (VC) content, firmness, lightness, and saturation decreased. The taste-related parameters and nutritional value of kiwifruit declined after infection. VCs such as ethanol, 3-methyl-1-butanol, and 2-methylisoborneol were detected only in the diseased fruit and gradually increased as the disease aggravated, suggesting that they may be the main sources of odor during P. expansum infection. Therefore, VCs detection can be used to determine possible P. expansum infection, as well as the degree of infection in kiwifruit. PRACTICAL APPLICATIONS: In practical application, we can use the results of this study to determine possible Penicillium expansum infection, as well as the degree of infection in kiwifruit according to the indicators such as volatile substances. Kiwifruit enterprises can use the nondestructive detection model established in this study to screen out the kiwifruit infected with P. expansum more efficiently, quickly, and accurately, in order to prevent harm to the health of consumers.
Assuntos
Actinidia , Penicillium , Frutas , PaladarRESUMO
This study aimed to reveal the physiological mechanism of resistance to postharvest blue mold of kiwifruit. Hongyang and Qihong kiwifruits were inoculated with Penicillium expansum (P. expansum) and stored at low temperature (0⯱â¯1⯰C). The disease incidence and lesion diameter, activities of defense-related enzymes, and contents of defense-related substance of Hongyang and Qihong kiwifruits were also compared, combined with the observation of fruit pericarp structure by scanning electron microscopy. Results showed that the disease resistance of Hongyang was stronger than that of Qihong with late onset, low incidence, and small lesion diameter. And Hongyang kiwifruit showed a high biochemical resistance after inoculation with P. expansum. The epidermis structure of Hongyang kiwifruit had typical disease resistance characteristics with a dense epidermis structure, orderly cell arrangement, and less obvious microcracks. The strong biochemical resistance, dense, and complete epidermis structure of Hongyang fundamentally guarantee its strong resistance to diseases.