Preparation of hydroxypropyl methylcellulose/pueraria-based modified atmosphere film and its influence on delaying the senescent process of postharvest Agaricus bisporus.

Based on the key factor of spontaneous modified atmosphere packaging (MAP)-gas permeability, a spontaneous MAP film was created for the preservation of Agaricus bisporus by delaying the senescence of white mushrooms. Compared with other mixed films, hydroxypropyl methylcellulose (HPMC)/pueraria (P)-2 showed better mechanical properties, barrier properties and thermal stability energy. Applying the HPMC/P-2 film for preserving white mushrooms can spontaneously adjust the internal gas environment. Moreover, the O2 concentration in the package remained stable at 1-2 %, and the CO2 concentration was between 8 % and 14 %. The film can effectively reduce the respiration rate of white mushrooms, inhibit enzymatic browning, maintain their good color and texture, and delay their aging. In conclusion, the HPMC/P-2 film can be used not only for fruit and vegetables preservation but also provide theoretical basis for sustainable food packaging.

The development of a highly sensitive and quantitative SARS-CoV-2 rapid antigen test applying newly developed monoclonal antibodies to an automated chemiluminescent flow-through membrane immunoassay device.

BACKGROUND: Rapid and accurate diagnosis of individuals with SARS-CoV-2 infection is an effective way to prevent and control the spread of COVID-19. Although the detection of SARS-CoV-2 viral RNA by RT-qPCR is the gold standard for COVID-19 testing, the use of antigen-detecting rapid diagnostic tests (Ag-RDTs) is emerging as a complementary surveillance tool as Omicron case numbers skyrocket worldwide. However, the results from Ag-RDTs are less accurate in individuals with low viral loads. RESULTS: To develop a highly sensitive and accurate Ag-RDT, 90 monoclonal antibodies were raised from guinea pigs immunized with SARS CoV-2 nucleocapsid protein (CoV-2-NP). By applying a capture antibody recognizing the structural epitope of the N-terminal domain of CoV-2-NP and a detection antibody recognizing the C-terminal tail of CoV-2-NP to an automated chemiluminescence flow-through membrane immunoassay device, we developed a novel Ag-RDT, CoV-2-POCube. The CoV-2-POCube exclusively recognizes CoV-2-NP variants but not the nucleocapsid proteins of other human coronaviruses. The CoV-2-POCube achieved a limit of detection sensitivity of 0.20 ~ 0.66 pg/mL of CoV-2-NPs, demonstrating more than 100 times greater sensitivity than commercially available SARS-CoV-2 Ag-RDTs. CONCLUSIONS: CoV-2-POCube has high analytical sensitivity and can detect SARS-CoV-2 variants in 15 min without observing the high-dose hook effect, thus meeting the need for early SARS-CoV-2 diagnosis with lower viral load. CoV-2-POCube is a promising alternative to currently available diagnostic devices for faster clinical decision making in individuals with suspected COVID-19 in resource-limited settings.

Properties of an active film based on glutenin/tamarind gum and loaded with binary microemulsion of melatonin/pummelo essential oil and its preservation for Agaricus bisporus.

In order to improve the effectiveness of the active packaging, we aimed to develop an active packaging film with unidirectional sustained release, high barrier protection, and seamless attachment between the layers. An active film based on glutenin/tamarind gum loaded with the binary microemulsion of melatonin/pummelo essential oil (G/T-M-E) with sustained release and combination effects of internal and external layers was prepared. The outer barrier layer exerted an excellent protective barrier effect after adding (3-chloropropyl) triethoxysilane, which effectively reduced external interference and the ineffective diffusion of active substances in the inner layer. The effective attachment of melatonin and essential oil layer in the G/T-M-E film enhanced antioxidation, microorganism inhibition, and free-radical-scavenging properties, which effectively delayed the senescence of post-harvest white mushrooms. Furthermore, the G/T-M-E exhibited excellent tensile strength, barrier capacity, and load-bearing strength, which had a potential, positive effect on food preservation. Therefore, this film is highly recommended for packaging purposes.

Lipid Oxidation Changes of Arabica Green Coffee Beans during Accelerated Storage with Different Packaging Types.

The storage conditions of green coffee beans (GCBs) are indispensable in preserving their commercial value. In Thailand, coffee farmers and roasters typically store GCBs for six months to a year before roasting. However, the beans undergo oxidation during storage, influencing both quality and taste. This study investigated changes in GCB lipid oxidation under different accelerated storage conditions (30 °C, 40 °C and 50 °C with 50% RH) and packaging, i.e., plastic woven (PW), low-density polyethylene (LDPE) and hermetic/GrainPro® (GP) bags. Samples were collected every five days (0, 5, 10, 15 and 20 days) and analyzed for lipid oxidation parameters including acid value (AV), free fatty acids (FFA), peroxide value (PV), ρ-anisidine value (PAV), total oxidation value (TOTOX), thiobarbituric acid reactive substances (TBARS), moisture content (MC), water activity (aw) and color. Primary oxidation was observed, with AV, FFA and PAV gradually changing during storage from 1.49 ± 0.32 to 3.7 ± 0.83 mg KOH/g oil, 3.82 ± 0.83 to 9.51 ± 1.09 mg KOH/g oil and 0.99 ± 0.03 to 1.79 ± 0.14, respectively. Secondary oxidation changes as PV and TBARS were reported at 0.86 ± 0.12 to 3.63 ± 0.10 meq/kg oil and 6.76 ± 2.27 to 35.26 ± 0.37 MDA/kg oil, respectively, affecting the flavor and odor of GCBs. Higher storage temperature significantly influenced a lower GCB quality. GP bags maintained higher GCB quality than LDPE and PW bags. Results provided scientific evidence of the packaging impact on oxidation for GCB under accelerated storage.

Melatonin retards senescence via regulation of the electron leakage of postharvest white mushroom (Agaricus bisporus).

Currently, melatonin (N-acetyl-5-methoxytrytamine) is recognized as a potential scavenger of free radicals. In this study, the effect of exogenous melatonin at various concentrations (0.05, 0.1, and 0.2 mM) on the texture, sensory qualities, and electron leakage in white mushrooms was evaluated at 3 ± 1 °C. It was observed that mushrooms treated with 0.1 mM melatonin were of good quality and their electron leakage was dramatically dampened. The results showed that 0.1 mM melatonin retained a higher adenosine triphosphate level and also prevented the release of cytochrome c into the cytoplasm. More significantly, it prominently inhibited electron leakage by increasing the activities of complexes I and III by the upregulation of AbNdufB9 and AbRIP1. It also regulated respiratory states in mushrooms; delayed the decline of respiratory state 3; enhanced respiratory state 4; boosted the oxidative phosphorylation and efficiency of mitochondria; and ultimately retarded the senescence of the white mushrooms.

Effects of a high O2 dynamic-controlled atmosphere technology on the browning of postharvest white mushroom ( Agaricus bisporus) in relation to energy metabolism.

Browning is one of the main problems in senescence of mushrooms, and it is also one of the most important attributes accounting for the loss of the quality and reduction in market value. In order to study the relationship between the energy metabolism and the browning of white mushroom under high O2 dynamic-controlled atmosphere (HO-DCA), mushrooms were stored in 100% O2 (SCA1), 80% O2 + 20% CO2 (SCA2), 100% O2 for three days and then transferred into the treatment of 80% O2 + 20% CO2 (HO-DCA) at 2 ± 1 ℃ and air as control. In this study, adenosine triphosphate (ATP) content, energy charge level, sensory evaluation, browning of surface and flesh, cell membrane integrity, exogenous ATP, polyphenol oxidase (PPO) and peroxidase (POD) activity and genes encoding PPO of the white mushroom were investigated. These were all closely related to the browning of products. The optimal storage condition of the HO-DCA treatment could delay the browning of pericarp and flesh tissues of the mushrooms, inhibit PPO activity and reduce the relative expression levels of the three genes encoding PPO. Meanwhile, it maintained moderate POD activity, good sensory properties and cell membrane integrity in a certain extent and thus slowed down the senescence of mushrooms. Results indicated that there was a positive correlation between the ATP content and whitening index ( r = 0.901). In addition, HO-DCA maintained a higher ATP level, prolonged the storage time to 28 days and it might be an ideal strategy for preserving the quality of mushroom during storage.

Regulation of Respiratory Pathway and Electron Transport Chain in Relation to Senescence of Postharvest White Mushroom (Agaricus bisporus) under High O2/CO2 Controlled Atmospheres.

In order to study the respiration metabolism mechanism based on the generation of adenosine triphosphate (ATP) and reactive oxygen species (ROS) and nitric oxide (NO) by the electron transport chain (ETC) of the white mushroom under high O2/CO2 controlled atmospheres, the treatments of 100% O2, 80% O2 + 20% CO2, 60% O2 + 40% CO2, and 40% O2 + 60% CO2 at 2 ± 1 °C were employed and natural air was used as the control. ATP and energy charge can maintain the membrane integrity and function, life activities, and physicochemical reactions of higher plants. The results showed that the 80% O2 + 20% CO2 treatment inhibited the respiration rate, embden-meyerhof-parnas or glycolysis pathway, and ROS and NO contents. It significantly delayed the reduction of the ATP content and energy charge level, tricarboxyfic-acid-cycle and cytochrome pathway proportion, and their key enzymes activity and gene expression. It also maintained a high phosphopentose pathway and moderate alternative pathway. Results indicated that the 80% O2 + 20% CO2 prolonged the storage time of mushrooms to 24 days and retarded the senescence through retaining the higher energy, suppressing the ROS contents, enhancing the endurance capability in adversity, and regulating the respiration pathways and ETC metabolism.

Effects of various asparagus production methods on rutin and protodioscin contents in spears and cladophylls.

The purpose of this study was to clarify the relationship between various cultivation conditions and the amounts of the rutin (RT) and protodioscin (PD) in asparagus spears. Green and white spears were grown in open culture and under two different blanching conditions. Although RT was detected only in the green spears, PD was detected mainly in white spears produced by covering with soil. The RT and PD contents of cladophylls grown in an open field and in a closed cultivation system were also investigated, and the closed system resulted in cladophylls with low RT and high PD, unlike the open field.

Screening and analysis of genes expressed upon infection of broad bean with Clover yellow vein virus causing lethal necrosis.

Clover yellow vein virus (ClYVV) causes lethal systemic necrosis in legumes, including broad bean (Vicia faba) and pea (Pisum sativum). To identify host genes involved in necrotic symptom expression after ClYVV infection, we screened cDNA fragments in which expression was changed in advance of necrotic symptom expression in broad bean (V. faba cv. Wase) using the differential display technique and secondarily with Northern blot analysis. Expression changes were confirmed in 20 genes, and the six that exhibited the most change were analyzed further. These six genes included a gene that encodes a putative nitrate-induced NOI protein (VfNOI), and another was homologous to an Arabidopsis gene that encodes a glycine- and proline-rich protein GPRP (VfGPRP). We recently reported that necrotic symptom development in ClYVV-infected pea is associated with expression of salicylic acid (SA)-dependent pathogenesis-related (PR) proteins and requires SA-dependent host responses. Interestingly, VfNOI and VfGPRP expression was correlated with that of the putative SA-dependent PR proteins in ClYVV-infected broad bean. However, broad bean infected with a recombinant ClYVV expressing the VfGPRP protein showed weaker symptoms and less viral multiplication than that infected with ClYVV expressing the GFP protein. These results imply that VfGPRP plays a role in defense against ClYVV rather than in necrotic symptom expression.

Activation of the salicylic acid signaling pathway enhances Clover yellow vein virus virulence in susceptible pea cultivars.

The wild-type strain (Cl-WT) of Clover yellow vein virus (ClYVV) systemically induces cell death in pea cv. Plant introduction (PI) 118501 but not in PI 226564. A single incompletely dominant gene, Cyn1, controls systemic cell death in PI 118501. Here, we show that activation of the salicylic acid (SA) signaling pathway enhances ClYVV virulence in susceptible pea cultivars. The kinetics of virus accumulation was not significantly different between PI 118501 (Cyn1) and PI 226564 (cyn1); however, the SA-responsive chitinase gene (SA-CHI) and the hypersensitive response (HR)-related gene homologous to tobacco HSR203J were induced only in PI 118501 (Cyn1). Two mutant viruses with mutations in P1/HCPro, which is an RNA-silencing suppressor, reduced the ability to induce cell death and SA-CHI expression. The application of SA and of its analog benzo (1,2,3) thiadiazole-7-carbothioic acid S-methyl ester (BTH) partially complemented the reduced virulence of mutant viruses. These results suggest that high activation of the SA signaling pathway is required for ClYVV virulence. Interestingly, BTH could enhance Cl-WT symptoms in PI 226564 (cyn1). However, it could not enhance symptoms induced by White clover mosaic virus and Bean yellow mosaic virus. Our report suggests that the SA signaling pathway has opposing functions in compatible interactions, depending on the virus-host combination.