Emerging technologies for preservation and quality evaluation of postharvest edible mushrooms: A review.

Edible mushrooms are the highly demanded foods of which production and consumption have been steadily increasing globally. Owing to the quality loss and short shelf-life in harvested mushrooms, it is necessary for the implementation of effective preservation and intelligent evaluation technologies to alleviate this issue. The aim of this review was to analyze the development and innovation thematic lines, topics, and trends by bibliometric analysis and review of the literature methods. The challenges faced in researching these topics were proposed and the mechanisms of quality loss in mushrooms during storage were updated. This review summarized the effects of chemical processing (antioxidants, ozone, and coatings), physical treatments (non-thermal plasma, packaging and latent thermal storage) and other emerging application on the quality of fresh mushrooms while discussing the efficiency in extending the shelf-life. It also discussed the emerging evaluation techniques based on the various chemometric methods and computer vision system in monitoring the freshness and predicting the shelf-life of mushrooms which have been developed. Preservation technology optimization and dynamic quality evaluation are vital for achieving mushroom quality control. This review can provide a comprehensive research reference for reducing mushroom quality loss and extending shelf-life, along with optimizing efficiency of storage and transportation operations.

Ultralow-Loading and High-Performing Ionic Liquid-Immobilizing Rhodium Single-Atom Catalysts for Hydroformylation.

We have developed a Keggin polyoxometalate (POM)-based ionic-liquid (IL)-immobilizing rhodium single-atom Rh catalyst (MTOA)5 [SiW11 O39 Rh] (MOTA=methyltrioctylammonium cation) that can afford exceptionally high catalytic activity for the hydroformylation of alkenes to produce aldehydes at an ultralow loading of Rh (ca. 3 ppm). For styrene hydroformylation, both the conversion and the yield of the aldehyde can reach almost 99 %, and a TOF as high as 9000 h-1 was obtained without using any phosphine ligand in the reaction process. Further characterization by FTIR, ICP and ESI-MS analysis revealed that the single Rh atom was incorporated in the lacunary POM anions. In particular, the bulky IL cation can play an additional role in stabilizing Rh species and thus prevent aggregation and leaching of Rh species. The IL catalyst was miscible with n-hexane at temperatures; this contributed to exceptionally high activity for hydroformylation even at ultra-low loading of IL catalyst.

Role of Organic Fluoride Salts in Stabilizing Niobium Oxo-Clusters Catalyzing Epoxidation.

We present here that easily available organic salts can stabilize/modify niobium (Nb) oxo-clusters. The as-synthesized Nb oxo-clusters have been characterized by various methods. These Nb oxo-clusters were catalytically active for the epoxidation of allylic alcohols and olefins with H2O2 as an oxidant. Notably, Nb-OC@TBAF-0.5 appeared as highly dispersed nanosized particles and showed the highest catalytic activity, which can be attributed to the following reasons on the basis of characterization. First, the strong coordination of fluorine ions with Nb sites and the steric protection with bulky organic cations led to high stabilization and dispersion of the oxo-clusters in the course of the reaction. Second, a hydrogen-bond interaction between the coordinated fluorine atom and the -OH group of allylic alcohol favored the epoxidation reaction. Third, the electron density of Nb sites decreased due to the strong electron-withdrawing ability of F- adjacent to Nb sites, thus promoting the electrophilic oxygen transfer to the C═C bond.

Thermoregulated Ionic Liquid-Stabilizing Ru/CoO Nanocomposites for Catalytic Hydrogenation.

Catalytic hydrogenations represent fundamental processes and allow for atom-efficient and clean functional group transformations for the production of chemical intermediates and fine chemicals in chemical industry. Herein, the Ru/CoO nanocomposites have been constructed and applied as nanocatalysts for the hydrogenation of phenols and furfurals into the corresponding cyclohexanols and tetrahydrofurfuryl alcohols, respectively. The functionalized ionic liquid acted not only as a ligand for stabilizing the Ru/CoO nanocatalyst but also as a thermoregulated agent. The as-obtained nanocatalyst showed superior activity, and it could be conveniently recovered via the thermoregulating phase separation. In six recycle experiments, the catalysts maintained excellent performance. It was observed that the catalytic performance highly hinged on the molar ratio of Ru to Co in the nanocatalyst. The catalyst characterization was carried out by high-resolution transmission electron microscopy (HRTEM), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray photoelectron spectroscopy, X-ray diffraction, high-resolution mass spectrometry, Fourier transform infrared, nuclear magnetic resonance, and UV-vis. Especially, the characterization by HRTEM and HAADF-STEM images of the nanocatalyst demonstrated that Ru(0) and Co(II) species were distributed uniformly and the Ru and Co(II) species were close to each other. However, Co(0) was generated and an electronic transfer from Co to Ru species could occur under the hydrogenation conditions. The 13C NMR characterization indicated further that Co(II) sites were mainly responsible for phenol adsorption. Meanwhile, the adjacent electron-rich Ru(0) sites can promote H2 dissociation and favor for the sequential hydrogenation.

Ionic Liquid Stabilized Niobium Oxoclusters Catalyzing Oxidation of Sulfides with Exceptional Activity.

We present here a new class of niobium oxoclusters that are stabilized effectively by carboxylate ionic liquids. These functionalized ILs are designated as [TBA][LA], [TBA][PA], and [TBA][HPA] in this work, in which TBA represents tetrabutylammonium and LA, PA, and HPA refer to lactate, propionate, 3-hydroxypropionate anions, respectively. The as-synthesized Nb oxoclusters have been characterized by use of elemental analysis, NMR, IR, XRD, TGA, HRTEM. It was found that [TBA][LA]-stabilized Nb oxoclusters (Nb-OC@[TBA][LA]) are uniformly dispersed with an average particle size of 2-3 nm and afforded exceptionally high catalytic activity for the selective oxidation of various thioethers. The turnover number with Nb-OC@[TBA][LA] catalyst was over 56 000 at catalyst loading as low as 0.0033 mol % (1 ppm). Meantime, the catalyst also showed the high activity for the epoxidation of olefins and allylic alcohols by using only 0.065 mol % of catalyst (50 ppm). The characterization of 93 Nb NMR spectra revealed that the Nb oxoclusters underwent structural transformation in the presence of H2 O2 but regenerated to their initial state at the end of the reaction. In particular, the highly dispersed Nb oxoclusters can absorb a large amount of polar organic solvents and thus were swollen greatly, which exhibited "pseudo" liquid phase behavior, and enabled the substrate molecules to be highly accessible to the catalytic center of Nb oxocluster units.

Temperature-Responsive Ionic Liquids: Fundamental Behaviors and Catalytic Applications.

Temperature-responsive ionic liquids (ILs), their fundanmental behaviors, and catalytic applications were introduced, especially the concepts of upper critical solution temperature (UCST) and lower critical solution temperature (LCST). It is described that, during a catalytic reaction, they form a homogeneous mixture with the reactants and products at reaction temperature but separate from them afterward at ambient conditions. It is shown that this behavior offers an effective alternative approach to overcome gas/liquid-solid interface mass transfer limitations in many catalytic transformations. It should be noted that IL-based thermomorphic systems are rarely elaborated until now, especially in the field of catalytic applications. The aim of this article is to provide a comprehensive review about thermomorphic mixtures of an IL with H2O and/or organic compounds. Special focus is laid on their temperature dependence concerning UCST and LCST behavior, including systems with conventional ILs, metal-containing ILs, polymerized ILs, as well as the thermomorphic behavior induced via host-guest complexation. A wide range of applications using thermoregulated IL systems in chemical catalytic reactions as well as enzymatic catalysis were also demonstrated in detail. The conclusion is drawn that, due to their highly attractive behavior, thermoregulated ILs have already and will find more applications, not only in catalysis but also in other areas.

Peroxotantalate-Based Ionic Liquid Catalyzed Epoxidation of Allylic Alcohols with Hydrogen Peroxide.

The efficient and environmentally benign epoxidation of allylic alcohols has been attained by using new kinds of monomeric peroxotantalate anion-functionalized ionic liquids (ILs=[P4,4,4,n ]3 [Ta(O)3 (η-O2 )], P4,4,4,n =quaternary phosphonium cation, n=4, 8, and 14), which have been developed and their structures determined accordingly. This work revealed the parent anions of the ILs underwent structural transformation in the presence of H2 O2 . The formed active species exhibited excellent catalytic activity, with a turnover frequency for [P4,4,4,4 ]3 [Ta(O)3 (η-O2 )] of up to 285 h-1 , and satisfactory recyclability in the epoxidation of various allylic alcohols under very mild conditions by using only one equivalent of hydrogen peroxide as an oxidant. NMR studies showed the reaction was facilitated through a hydrogen-bonding mechanism, in which the peroxo group (O-O) of the peroxotantalate anion served as the hydrogen-bond acceptor and hydroxyl group in the allylic alcohols served as the hydrogen-bond donor. This work demonstrates that simple monomeric peroxotantalates can catalyze epoxidation of allylic alcohols efficiently.

Phase Transfer of Nanoparticles Using an Amphiphilic Ionic Liquid.

The phase transfer of nanoparticles (NPs) from water to organic solvents by an amphiphilic room-temperature ionic liquid (IL) was reported. The geminal IL modified with Pluronic P123 stabilizes a variety of NPs of different size and nature, such as Pd, Au, Ag, and SiO2 NPs. Their phase transfer into a hydrophobic environment was realized by raising the temperature and adding salts (such as NaCl and KBr), both of which have a common effect of breaking the hydrogen bonds of the IL with H2O. A more straightforward method of using an organic solvent working as a hydrogen bond donor (such as butyl alcohol) was then proposed. In this case, NaCl was no longer required. To further apply this strategy to the organic solvents that are generally incapable of forming hydrogen bonds (e.g., toluene), a small quantity of benzoic acid was added to the organic phase. By forming hydrogen bonds from benzoic acid to the IL, an even more facile approach was provided. FT-IR confirmed the hydrogen bonding between them. The phase-transfer protocol does not rely on coordination bonding of ligands with a specific metal and is capable of the phase transfer of objects with large sizes and different natures. Thus, it has the potential for wide application.

Gold nanoparticles embedded in silica hollow nanospheres induced by compressed CO2 as an efficient catalyst for selective oxidation.

Metal nanoparticles embedded in hollow materials are important due to their wide applications in catalysis. In this work, we disclosed a nontraditional synthetic pathway to prepare silica hollow nanospheres by hydrothermal treatment in the presence of compressed CO2. Especially, the silica hollow nanospheres with an outer diameter of about 16 nm and an inner pore size of 7 nm were obtained using 1.0 MPa CO2. The formation mechanism of silica hollow nanospheres induced by CO2 was investigated by high-pressured UV/Vis spectroscopy. Moreover, gold nanoparticles (2.5 nm) embedded in the silica hollow nanospheres were prepared by a one-pot synthesis using HAuCl4 as a precursor. The current synthetic route of nano-catalysts was simple and facile, in which no etching agent was needed in the process of the hollow material preparation. Besides, this nano-catalyst showed an excellent catalytic performance in epoxidation of styrene with high conversion (82.2%) and selectivity (90.2%) toward styrene oxide, as well as in the selective oxidation of ethylbenzene with good conversion (26.6%) and selectivity (87.8%) toward acetophenone. Moreover, the Au nanoparticles (AuNPs) embedded in silica hollow nanospheres exhibited an excellent recyclability in both the oxidation reactions.

Key components, formation pathways, affecting factors, and emerging analytical strategies for edible mushrooms aroma: A review.

Aroma is one of the decisive factors affecting the quality and consumer acceptance of edible mushrooms. This review summarized the key components and formation pathways of edible mushroom aroma. It also elaborated on the affecting factors and emerging analytical strategies of edible mushroom aroma. A total of 1308 volatile organic compounds identified in edible mushrooms, 61 were key components. The formation of these compounds is closely related to fatty acid metabolism, amino acid metabolism, lentinic acid metabolism, and terpenoid metabolism. The aroma profiles of edible mushrooms were affected by genetic background, preharvest factors, and preservation methods. Molecular sensory science and omics techniques are emerging analytical strategies to reveal aroma information of edible mushrooms. This review would provide valuable data and insights for future research on edible mushroom aroma.

Cooperative effects in catalytic hydrogenation regulated by both the cation and anion of an ionic liquid.

The use of transition-metal nanoparticles/ionic liquid (IL) as a thermoregulated and recyclable catalytic system for hydrogenation has been investigated under mild conditions. The functionalized ionic liquid was composed of poly(ethylene glycol)-functionalized alkylimidazolium as the cation and tris(meta-sulfonatophenyl)phosphine ([P(C(6)H(4)-m-SO(3))(3)](3-)) as the anion. Ethyl acetate was chosen as the thermomorphic solvent to avoid the use of toxic organic solvents. Due to a cooperative effect regulated by both the cation and anion of the ionic liquid, the nanocatalysts displayed distinguished temperature-dependent phase behavior and excellent catalytic activity and selectivity, coupled with high stability. In the hydrogenation of α,ß-unsaturated aldehydes, the ionic-liquid-stabilized palladium and rhodium nanoparticles exhibited higher selectivity for the hydrogenation of the C=C bonds than commercially available catalysts (Pd/C and Rh/C). We believe that the anion of the ionic liquid, [P(C(6)H(4)-m-SO(3))(3)](3-), plays a role in changing the surrounding electronic characteristics of the nanoparticles through its coordination capacity, whereas the poly(ethylene glycol)-functionalized alkylimidazolium cation is responsible for the thermomorphic properties of the nanocatalyst in ethyl acetate. The present catalytic systems can be employed for the hydrogenation of a wide range of substrates bearing different functional groups. The catalysts could be easily separated from the products by thermoregulated phase separation and efficiently recycled ten times without significant changes in their catalytic activity.

[Study on HPLC fingerprint of Ganershu intermediate and determination of three active components].

OBJECTIVE: To establish the fingerprint analysis method of Ganershu intermediate by HPLC. METHODS: An analysis was performed on a sunFire C18 (4. 6 mm x 250 mm, 5 microm) column with acetonitrile-0.1% phosphate aqueous as the mobile phase by gradient elution. The flow rate was 1.0 mL/min, the detection wavelength was 320 nm and detection time was 80 min. The column temperature was 35 degrees C. In the recorded chromatogram of Ganershu intermediate, neohesperidin was used as reference substance, and RSD of the relative retention time and the relative peak areas of all peaks compared with its peak were measured. The similarity of 10 batches of Ganershu intermediate was appraised by the similarity evaluation system. Using the external standard method, the contents of chlorogenic acid, neohesperidin and naringin were determined in 10 batches of intermediate. RESULTS: Tweenty-three peaks were separated on HPLC fingerprint in Ganershu intermediate, degree of similarity of fingerprint for ten batches of Ganershu intermediate were greater than 0.90. Three compounds' contents were almost the same in each batch of intermediate sample. CONCLUSION: The method is stable, accurate, reliable and can be used as a quality control for Ganershu intermediate and sustained-release capsules.

Effects of different monochromatic lights on umami and aroma of dried Suillus granulatus.

Dried edible mushrooms have a unique flavor which is worth exploring to preserve and improve their flavor.Light can improve flavor for dried edible mushrooms, but there are few reports about monochromatic light. In this study, effects of red-light, yellow-light, green-light, blue-light and white-light on the umami taste and aroma of dried Suillus granulatus were investigated. The results showed that contents of umami amino acids and 5-nucleotides, equivalent umami concentration (EUC) and electronic tongue umami scores were higher under blue-light treatment. Principal component analysis (PCA) of volatiles showed that comprehensive scores under blue-light treatment were higher. The flavor was better under five light treatments at 6 and 9 days. Partial least squares-discrimination analysis (PLS-DA) further revealed the detailed differences between various light treatments, which were mainly caused by umami amino acids, alcohols, ketones and pyrazines. Collectively,blue-light treatment can be used as a processing technology to improve the flavor quality of dried edible mushrooms.

Comparison of the umami taste and aroma of dried Suillus granulatus packed using four different packaging methods.

Umami and aroma are important flavor qualities of edible mushrooms, and packaging can maintain or improve the flavor during storage. This study explored the effects of light-proof packaging (LPP), light-transparent packaging (LTP), vacuum light-proof packaging (VLPP), and vacuum light-transparent packaging (VLTP) on umami taste and aroma of dried Suillus granulatus. Monosodium glutamate-like amino acid content, equivalent umami concentration, and electronic tongue umami sensory scores in VLTP were higher at 2, 4, and 6 months and higher in LTP at 8 and 10 months. Principal component analysis of aroma components showed that the comprehensive scores were higher for the transparent packaging. Ketones and pyrazines were more abundant in transparent packaging. Flavor quality was better at 4-6 months, based on the equivalent umami concentration and the concentration of eight-carbon compounds that contribute to aroma. Transparent packaging is a promising way to optimize the flavor of dried Suillus granulatus.

Effects of drying temperature on umami taste and aroma profiles of mushrooms (Suillus granulatus).

Temperature is one of the most important factors for drying edible mushrooms. To evaluate the effects of different hot-air drying (HAD) temperatures on the umami taste and aroma profile of Suillus granulatus (S. granulatus) mushrooms, we measured umami substances and volatile compounds of S. granulatus dried at 40°C, 50°C, 60°C, 70°C, and 80°C. Results showed that when dried at 60°C, S. granulatus exhibited significantly higher (p < 0.05) equivalent umami concentration, taste activity values of glutamic acid (Glu) and 5'-guanosine monophosphate (5'-GMP), and electronic tongue umami sensory scores. The results identified a total of 71 volatile components of which geranylacetone, benzaldehyde, phenylethyl alcohol, and 3-methylbutanoic acid were the dominant compounds. Sensory evaluation and relative odor activity values (ROAVs) revealed that 16 volatile compounds were the key volatile organic compounds contributing mushroom-like and sweet odor to the overall aroma of S. granulatus; these included 1-octen-3-ol (ROAV: 15.11-62.06) and ethyl phenylacetate (ROAV: 13.62-79.11). The drying temperature changed the aroma profile of S. granulatus. Furthermore, the mushroom dried at 60°C had a more desirable mushroom-like and almond odor. It was, therefore, proposed that HAD at 60°C was optimal for retaining a pleasant flavor in S. granulatus. This study provides a theoretical basis for the optimal drying condition selection for the mushroom processing industry. PRACTICAL APPLICATION: Hot-air drying at 60°C can significantly retain the flavor of S. granulatus and is an optimal temperature for mushroom drying.

Amphiphilic ionic liquid stabilizing palladium nanoparticles for highly efficient catalytic hydrogenation.

The highly water-soluble palladium nanoparticles (NPs) were synthesized by using the amphiphilic poly(ethylene glycol)-functionalized dicationic imidazolium-based ionic liquid (C(12)Im-PEG IL) as a stabilizing agent. The aqueous dispersed palladium NPs in the range of 1.9 ± 0.3 nm were observed by transmission electron microscopy (TEM). The physicochemical properties of C(12)Im-PEG IL in aqueous phase have been characterized by electrical conductivity, surface tension and dynamic light scattering (DLS) measurements. It was demonstrated that the amphiphilic ionic liquid can form micelles above its critical micelle concentration (CMC) in aqueous solution and the micelles played a crucial role in stabilizing the palladium NPs and thus promoted catalytic hydrogenation. Furthermore, the dicationic ionic liquid can also act as a gemini surfactant and generated emulsion between hydrophobic substrates and the catalytic aqueous phase during the reaction. The aqueous dispersed palladium NPs showed efficient activity for the catalytic hydrogenation of various substrates under very mild conditions and the stabilizing Pd(0) nanoparticles (NPs) can be reused at least eight times with complete conservation of activity.

Biosynthetic Mechanism of Key Volatile Biomarkers of Harvested Lentinula edodes Triggered by Spore Release.

In this study, headspace solid-phase microextraction-gas chromatography-mass spectrometry, multivariate analyses, and transcriptomics were used to explore the biosynthesis of key volatiles and the formation of spores in Lentinula (L.) edodes. Among the 50 volatiles identified, 1-octen-3-ol, phenethyl alcohol, and several esters were considered key aromas because of their higher odor activity values. Eleven volatiles were screened as biomarkers by orthogonal partial least squares discriminant analysis, and hierarchical cluster analysis showed that these biomarkers could represent all volatiles to distinguish the spore release stage. The activities of lipoxygenase (LOX), hydroperoxide lyase, alcohol dehydrogenase, and alcohol acyltransferase were higher in L. edodes with spore release. Moreover, linolenic acid and phenylalanine metabolism were involved in aroma biosynthesis. One LOX-related gene and five aryl alcohol dehydrogenase-related genes could regulate the biosynthesis of 1-octen-3-ol, phenethyl alcohol, and phenylacetaldehyde. In addition, several key genes were involved in meiosis to regulate sporulation.

Functionalized poly(ethylene glycol)-stabilized water-soluble palladium nanoparticles: property/activity relationship for the aerobic alcohol oxidation in water.

The preparation, characterization, and catalytic properties of water-soluble palladium nanoparticles stabilized by the functionalized-poly(ethylene glycol) as a protective ligand were demonstrated for aerobic oxidation of alcohols in aqueous phase. UV/vis spectra and X-ray photoelectron spectroscopy (XPS) proved that there was an electronic interaction between the bidentate nitrogen ligand and palladium atoms. Transmission electron microscopy and XPS analysis showed that the particle size and surface properties of the generated palladium nanoparticles can be controlled by varying the amount of protective ligand and the kinds of reducing agents. It was found that both the size and surface properties of palladium nanoparticles played very important roles in affecting catalytic performance. The stabilized metallic palladium nanoparticles were proven to be the active centers for benzyl alcohol oxidation in the present system, and the water-soluble Pd nanocatalysts can also be extended to the selective oxidation of various alcohols.

Direct Transformation of Glycerol to Propanal using Zirconium Phosphate-Supported Bimetallic Catalysts.

Selective transformation of glycerol to propanal (PA) provides a feasible route towards the sustainable synthesis of high value-added chemicals. In this work, zirconium phosphate (ZrP) was studied as support and Ru and Co as metal sites for glycerol hydrogenolysis in a continuous-flow reactor. It was found that ZrP-supported Co-O species had a moderate selectivity to PA (49.5 %) in glycerol hydrogenolysis. Notably, once Ru species were doped into CoO/ZrP, the resulting catalyst exhibited not only an outstanding catalytic performance for glycerol hydrogenolysis to PA (a selectivity of 80.2 % at full conversion), but also a high stability at least a 50 h long-term performance. The spent catalyst could be regenerated by calcining in air to remove carbonaceous deposits. Characterization indicated that the acid sites on ZrP played a very critical role in the dehydration of glycerol into acrolein (AE), that the distribution of Co was uniform, basically consistent with that of Zr, P and Ru, and that an especially close contact between Co-O and Ru species was formed on Ru/CoO/ZrP catalyst. The further activity tests and characterizations confirmed that there was a strong interaction between the dispersed Co-O species and Ru0 nanoparticles, which endowed Ru sites with high electronic density. This effect could play a role in facilitating the dissociation of H2 , and thus in promoting the hydrogenation reaction. Besides, DFT calculations suggested that the Co-O species can adsorb more strongly the C=C bond of the intermediate AE on a highly coordinatively unsaturated Co (Cocus ) site and thus lead to preferential hydrogenation at the C=C bond of AE to PA.

Molecular level dispersed Pd clusters in the carbon walls of ordered mesoporous carbon as a highly selective alcohol oxidation catalyst.

Ordered mesoporous carbon containing molecular-level dispersed Pd clusters in the carbon walls can be synthesized by the nanocasting pathway, which shows high selectivity for the oxidation of alcohols to aldehydes.