Extraction of chitin-glucan complex from shiitake (Lentinula edodes) fruiting bodies using natural deep eutectic solvents and its prebiotic potential.

Chitin-glucan complex (CGC) is an emerging novel prebiotic with numerous physiological activities in amelioration of clinical manifestations. In the present work, natural deep eutectic solvent (NADES), ultrasonication, and submerged fermentation using probiotic microorganisms were deployed for the extraction of CGC from Shiitake fruiting bodies. CGC obtained through non-ultrasonication assisted fermentation employing Lactiplantibacillus plantarum exhibited maximum polysaccharide yield (27.86 ± 0.82 % w/w). However, based on antioxidant potential, NADES combination of urea: glycerol (1:1 M ratio) was selected for further characterization. The rheological behavior of CGC under optimized conditions showed shear thinning property in both 0.1 M NaCl and salt-free solution. FTIR, 1H-(1D), and 2D 1H1H Homonuclear NMR spectra displayed distinctive patterns associated with ß-glycosidic linkage and ß-d-glucopyranose sugar moiety. XRD profiles of CGC exhibited characteristic peaks at 2θ = 23°, 25°, and 28° with corresponding hkl values of (220), (101), and (130) lattice planes, respectively. Enhanced radical scavenging activities were noticed due to the triple helical structure and anionic nature of CGC. CGC exhibited potential prebiotic activity (prebiotic score 118-134 %) and short chain fatty acids liberation (maximum 9.99 ± 0.41 mM by Lactobacillus delbrueckii). Simulated static in-vitro digestion demonstrated that CGC withstands acidic environment of gastric phase, which indicated its suitability for use as a prebiotic in nutraceutical-enriched food products.

Metabolomic differences between non-hydrothermal treated water-soluble (WSPs) and hydrothermally treated water-insoluble (WIPs) Maitake polysaccharides fermented by Lactobacillus acidophilus and L. plantarum.

Bacterial Metabolite through a fermentation process is a growing trend and a promising alternative for use as functional components. Non-hydrothermal water-soluble (WSPs) and hydrothermally treated water-insoluble (WIPs) Maitake polysaccharides were fermented with Lactobacillus acidophilus (LA) and Lactobacillus plantarum (LP). Chemical composition analysis indicated that Maitake polysaccharides contained 58.22 ± 1.35 % total sugar and 31.46 % ß-glucan, essential for metabolites production. 6-glucanase was used to degrade the WIPs, and hydrothermally treated WIP fibers exhibited smooth microstructure. Hence, the LA and LP bacteria investigated the potential fermented metabolic activities and differences between WSPs(Sp1)and WIP(Sp3) Maitake polysaccharides using LC-MS, and 887 metabolites were identified. Using Venn, Partial least squares discriminant analysis (PLS-DA), VIP Metabolites, and other multivariate statistical analysis methods, metabolites were expressed differently in all samples. Due to hydrothermal processing, WIP induced the highest growth of LA and LP, with an abundance of isocitrate metabolites. Furthermore, 50 metabolite correlations were identified, leading to the classification of 6 distinct metabolic groups. Thus, the study offers the initial comprehensive analysis of metabolites in Lactobacillus-fermented Maitake polysaccharides, aiding in understanding its metabolic interactions and facilitating progress in food engineering research.

Formation and non-covalent interactions of binary and ternary complexes based on ß-casein, Lentinus edodes mycelia polysaccharide, and taxifolin.

Polyphenols, polysaccharides, and proteins are essential nutrients and functional substances present in food, and when present together these components often interact with each other to influence their structure and function. Proteins and polysaccharides are also excellent carrier materials for polyphenols. In this context, this study investigated the non-covalent interactions between taxifolin (TAX), Lentinus edodes mycelia polysaccharide (LMP), and ß-casein (ß-CN). ß-CN and LMP spontaneously formed nanocomplexes by hydrogen bonds and van der Waals forces. The quenching constant and binding constant were (1.94 ± 0.02) × 1013 L mol-1 s-1 and (3.22 ± 0.17) × 105 L mol-1 at 298 K, respectively. The altered conformation of ß-CN, resulting from the binding to LMP, affected the interaction with TAX. LMP significantly enhanced the binding affinity of TAX and ß-CN, but did not change the static quenching binding mode. The binding constant for ß-CN-TAX was (3.96 ± 0.09) × 1013 L mol-1, and that for the interaction between TAX and ß-CN-LMP was (32.06 ± 0.05) × 1013 L mol-1. In summary, ß-CN-LMP nanocomplexes have great potential as a nanocarrier for polyphenols, and this study provides a theoretical foundation for the rational design of non-covalent complexes involving LMP and ß-CN, both in binary and ternary configurations.

Novel Catechol O-methyltransferases from Lentinula edodes Catalyze the Generation of Taste-Active Flavonoids.

Due to the increasing demand for natural food ingredients, including taste-active compounds, enzyme-catalyzed conversions of natural substrates, such as flavonoids, are promising tools to align with the principles of Green Chemistry. In this study, a novel O-methyltransferase activity was identified in the mycelium of Lentinula edodes, which was successfully applied to generate the taste-active flavonoids hesperetin, hesperetin dihydrochalcone, homoeriodictyol, and homoeriodictyol dihydrochalcone. Furthermore, the mycelium-mediated OMT activity allowed for the conversion of various catecholic substrates, yielding their respective (iso-)vanilloids, while monohydroxylated compounds were not converted. By means of a bottom-up proteomics approach, three putative O-methyltransferases were identified, and subsequently, synthetic, codon-optimized genes were heterologously expressed in Escherichia coli. The purified enzymes confirmed the biocatalytic O-methylation activity against targeted flavonoids containing catechol motifs.

Preparation and characterization of water vapor-responsive methylcellulose-polyethylene glycol-400 composite membranes and an indication of freshness of shiitake mushrooms.

Intelligent packaging with freshness indication capability can help consumers purchase fresh food. However, current research primarily focuses on carbon dioxide-sensitive intelligent packaging, with limited research on water vapor-sensitive indication packaging. In this study, the water vapor-sensitive indicator membrane was prepared and used to determine the freshness of mushrooms. The results of this study showed that the water permeability of the indicator membrane decreased from 33.17 % to 21.59 % with the increase of Polyethylene glycol-400(PEG-400) content in methylcellulose(MC) membrane, and the contact angle of the indicator membrane increased from 87 % to 98 % with the addition of PEG-400. The addition of plasticizer PEG-400 increased the hydrophobicity of the indicator film, which could be attributed to the improvement of the molecular arrangement and crystallinity of the indicator film by the addition of PEG-400. After encountering water, the transparency of the indicator membrane changes from completely opaque (white) to transparent. Addition of PEG-400 reduces the rate of change in the transparency of the indicator membrane. The indicator membrane was successfully used to indicate the freshness of mushrooms and effectively reflected the freshness of mushrooms during storage. This technology could be applied to measure the freshness of other foods.

Edodin: A New Type of Toxin from Shiitake Mushroom (Lentinula edodes) That Inactivates Mammalian Ribosomes.

Ribosome-inactivating proteins (RIPs) are a group of proteins with rRNA N-glycosylase activity that irreversibly inhibit protein synthesis and consequently cause cell death. Recently, an RIP called ledodin has been found in shiitake; it is cytotoxic, strongly inhibits protein synthesis, and shows rRNA N-glycosylase activity. In this work, we isolated and characterized a 50 kDa cytotoxic protein from shiitake that we named edodin. Edodin inhibits protein synthesis in a mammalian cell-free system, but not in insect-, yeast-, and bacteria-derived systems. It exhibits rRNA N-glycosylase and DNA-nicking activities, which relate it to plant RIPs. It was also shown to be toxic to HeLa and COLO 320 cells. Its structure is not related to other RIPs found in plants, bacteria, or fungi, but, instead, it presents the characteristic structure of the fold type I of pyridoxal phosphate-dependent enzymes. Homologous sequences have been found in other fungi of the class Agaricomycetes; thus, edodin could be a new type of toxin present in many fungi, some of them edible, which makes them of great interest in health, both for their involvement in food safety and for their potential biomedical and biotechnological applications.

Lentinus edodes mycelium polysaccharide inhibits AGEs-induced HUVECs pyroptosis by regulating LncRNA MALAT1/miR-199b/mTOR axis and NLRP3/Caspase-1/GSDMD pathway.

A novel Lentinus edodes mycelia polysaccharide (LMP) prepared in our laboratory has been identified to be effective in inhibiting the damage of islet ß cells induced by glucose toxicity. However, whether it can effectively alleviate the pyroptosis of human umbilical vein endothelial cells (HUVECs) induced by advanced glycation end products (AGEs) remains unclear. Bioinformatics and cell biology techniques were used to explore the mechanism of LMP inhibiting AGEs-induced HUVECs damage. The results indicated that AGEs significantly increased the expression of LncRNA MALAT1, decreased cell viability to 79.67 %, increased intracellular ROS level to 248.19 % compared with the control group, which further led to cell membrane rupture. The release of LDH in cellular supernatant was increased to 149.42 %, and the rate of propidium iodide staining positive cells increased to 277.19 %, indicating the cell pyroptosis occurred. However, the above trend was effectively retrieved after the treatment with LMP. LMP effectively decreased the expression of LncRNA MALAT1 and mTOR, promoted the expression of miR-199b, inhibited AGEs-induced HUVECs pyroptosis by regulating the NLRP3/Caspase-1/GSDMD pathway. LncRNA MALAT1 might be a new target for LMP to inhibit AGEs-induced HUVECs pyroptosis. This study manifested the role of LMP in improving diabetes angiopathy and broadens the application of polysaccharide.

Effects of combined drying techniques and cellulase hydrolysis on the nutritional value and sensory properties of shiitake mushrooms (Lentinus edodes).

Dried shiitake mushrooms offer rich nutritional value and unique sensory properties, prompting further investigation. The effects of different drying techniques (hot air drying (HAD), infrared hot air drying (IRHAD), pulsed vacuum drying (PVD), vacuum freeze drying (VFD), and natural drying (ND)) combined with enzymatic hydrolysis on the release of flavor compounds and nutrients from shiitake mushrooms were explored. The combination of HAD with cellulase hydrolysis yielded notably high levels of umami amino acids (5.4723 ± 0.1501 mg/g) and 5'-nucleotides (4.0536 ± 0.0062 mg/g), and superior volatile flavors. Combined with cellulase hydrolysis, IRHAD achieved the highest level of total sugars (6.57 ± 0.34 mg/mL), VFD resulted in the greatest soluble protein content (153.21 ± 0.23 µg/mL), PVD yielded the highest total phenolics content (93.20 ± 0.41 µg GAE/mL), and ND produced the maximum reducing sugar content (5.79 ± 0.13 mg/mL). This study addresses crucial gap in the post-drying processing of shiitake mushrooms, offering valuable insights for further product development of shiitake mushrooms.

Extraction of Lentinus Edodes Polysaccharides with Ultrasound Enhanced with Deep Eutectic Solvent and Their Structural Characterization and Antioxidant Activity.

Ultrasound extraction (UE) enhanced with deep eutectic solvent (DES) was used to extract Lentinus edodes polysaccharides. Box-Behnken design (BBD) was applied to investigate the influences of water content (10-90 %), solid-liquid solvent (1 : 10-1 : 50 g/mL), time (4-12 min), temperature (40-80 °C) and ultrasonic power (100-500 W) on the yield of Lentinus edodes polysaccharides. The optimal extraction conditions were ultrasonic power of 300 W, extraction time of 8 min, water content of 80 %, a solid-liquid ratio of 1 : 30 g/mL and a temperature of 60 °C, respectively. The highest extraction yield of Lentinus edodes polysaccharide was 10.17 % under optimal conditions. The results of FT-IR, SEM, and monosaccharide composition confirmed that the extracts possessed the characteristics of polysaccharides. In addition, the polysaccharides obtained with the UE enhanced with DES method exhibited higher antioxidant activities than the polysaccharides extracted with the UE method and HWE method. This extraction method can further expand the production efficiency and structural diversity of Lentinus edodes polysaccharides and meet the supply and demand relationship. It can be foreseen that this method can be applied to the extraction of more active substances.

Analysis of Volatile Aroma Components in Different Parts of Shiitake Mushroom (Lentinus edodes) Treated with Ultraviolet C Light-Emitting Diodes Based on Gas Chromatography-Ion Mobility Spectroscopy.

Further assessment of ultraviolet C light-emitting diode (UVC-LED) irradiation for influencing shiitake mushrooms' (Lentinus edodes) volatile and sensory properties is needed. In this study, a comparison of UVC-LED irradiation treatment on the flavor profiles in various parts of shiitake mushrooms was conducted using gas chromatography-ion mobility spectrometry (GC-IMS) and sensory analysis. Sixty-three volatile compounds were identified in shiitake mushrooms. The fresh shiitake mushrooms were characterized by the highest values of raw mushroom odors. After UVC-LED treatment, the content of C8 alcohols decreased, especially that of 1-octen-3-ol, while the content of aldehydes increased, especially the content of nonanal and decanal. The score of fatty and green odors was enhanced. For fresh samples, the mushroom odors decreased and the mushroom-like odors weakened more sharply when treated in ethanol suspension than when treated with direct irradiation. The fruit odors were enhanced using direct UVC-LED irradiation for fresh mushroom samples and the onion flavor decreased. As for shiitake mushroom powder in ethanol suspension treated with UVC-LED, the sweaty and almond odor scores decreased and the vitamin D2 content in mushroom caps and stems reached 668.79 µg/g (dw) and 399.45 µg/g (dw), respectively. The results obtained from this study demonstrate that UVC-LED treatment produced rich-flavored, quality mushroom products.

Anti-inflammatory and immunomodulatory properties of polysaccharides in mushrooms.

Mushrooms are distinguished as important food-containing polysaccharides possessing potent anti-inflammatory and immunomodulating properties. These compounds belong mostly to polysaccharides that are mostly ß-D-glucans. Among them, ß-1,3-glucan with ß-1,6 side chains of glucose residues, has more important roles in their properties. In this review, we have introduced polysaccharides mainly from Lentinula edodes and Pleurotus citrinopileatus with anti-inflammatory and immunomodulating properties. In addition, the mechanisms of activation of their physiological properties and signal cascade are also reviewed.

Effect of postharvest storage time on quality characteristics of explosion puffing dried whole shiitake mushroom (Lentinula edodes) crisps.

BACKGROUND: Non-fried shiitake mushroom (Lentinula edodes) crisps fabricated by explosion puffing drying (EPD) are receiving worldwide attention because of their crispness, convenience, nutrition and health functions. The quality of mushroom crisps varies with storage time of fresh L. edodes. Therefore, the effect of postharvest storage time (ranging from 0 to 14 days) of fresh L. edodes on quality characteristics of EPD- processed mushroom crisps was evaluated. RESULTS: The weight loss and total color difference of fresh L. edodes were increased to 2.95% and 24.66, but moisture content, firmness and lightness were reduced by 6.14%, 40.70% and 43.57%, respectively, after 14 days storage. The puffing degree of mushroom crisps was initially increased to its highest value (55.95%) on the 4th day storage and thereafter decreased. The highest rehydration ratio (2.36) and crispness (63.67), and lowest hardness (102.95 N) of mushroom crisps were fabricated with L. edodes on the 4th day of storage. Free water was predominant in fresh L. edodes, which was decreased for fresh L. edodes, whereas it increased initially to the maximum value and decreased thereafter for osmotic dehydrated and heat pump pre-dried L. edodes with increasing storage time. Principal component analysis and hierarchical cluster analysis confirmed that fresh L. edodes stored at different times had a remarkable effect on quality characteristics of mushroom crisps. CONCLUSION: Fresh L. edodes stored at 4 ± 1 °C for 4 days is recommended for fabrication of mushroom crisps with superior quality. This study provides a theoretical basis for selection of a suitable storage time for fresh L. edodes before EPD of crisps. © 2023 Society of Chemical Industry.

Bioconversion of rice straw by Lentinula edodes under different spawn formulations.

To attend to the growing world demand for mushrooms, it is interesting to increase the system's productivity, improve quality and reduce production costs. This study aimed to optimize the production and quality of fruiting bodies of the edible and medicinal mushroom Lentinula edodes (shiitake), in agroresidues substrate using appropriate strain and spawn formulation. The evaluation was conducted using two strains under seven different spawn formulations (Control [C]: Sorghum grain + 2.5% CaCO3; (2) C + 2.5% sawdust; (T3) C + 5% sawdust; (T4) C + 2.5% peat; (T5) C + 5% peat; (T6) C + 1.25% sawdust + 1.25% peat; (T7) C + 2.5% sawdust + 2.5% peat) that were inoculated into the blocks at a proportion of 2% (w/w). The substrate was formulated with 63% rice straw, 20% sawdust, 15% wheat bran, and 2% CaCO3 and sterilized. The incubation period was 87 days. Two flushes were obtained. Adding small aliquots of peat and sawdust to the inoculum gave significantly higher morphological results than the control in all variables analyzed. The days required for the first harvest ranged from 87 to 94 days. The average weight of basidiomes ranged from 6.38 to 28.75 g. The productivity data show superior results for the treatments in which the spawn was supplemented with sawdust and peat. Enhanced bioconversion with supplemented spawn shows promises for yield and composition improvement, crucial for commercial viability. It can be concluded that shiitake production using agroresidues such as straw can be increased using a suitable strain/spawn for optimal production.

Dynamic changes and formation of key contributing odorants with amino acids and reducing sugars as precursors in shiitake mushrooms during hot air drying.

The dynamic variations in key contributing odorants, amino acids and reducing sugars in shiitake mushrooms during hot-air drying were determined by gas chromatography-mass spectrometry (GC-MS), high performance liquid chromatography-tandem mass (HPLC-MS/MS) and ion chromatography (IC). The potential precursors were explored by the partial least squares-discriminant analysis and Pearson correlation analysis, and Met, Cys, and ribose were considered as the possible precursors of dimethyl trisulfide and lenthionine. The verification experiments in the absence and presence of shiitake mushroom matrix further confirmed that Met and its interaction with ribose both contributed to generating dimethyl trisulfide. The polynomial nonlinear fitting curve could better represent the dose-effect relationships of Met and Met-ribose to produce dimethyl trisulfide with R2 of 0.9579 and 0.9957. Conversely, ribose, Cys or Cys-ribose were verified to be unable to form the key contributing odorants. Collectively, the results provided a method to reveal precursors and generation pathway of odorants.

ß-Glucan produced by Lentinus edodes suppresses breast cancer progression via the inhibition of macrophage M2 polarization by integrating autophagy and inflammatory signals.

BACKGROUND: ß-Glucan from Lentinus edodes (LNT), an edible mushroom, possesses strong anticancer activity. However, the therapeutic effects of LNT during the occurrence and progression of breast cancer and their underlying molecular mechanisms have not been elucidated. METHODS: Mouse mammary tumor virus-polyoma middle tumor-antigen (MMTV-PyMT) transgenic mice were used as a breast cancer mouse model. Hematoxylin and eosin, immunohistochemical, and immunofluorescence staining were performed for histopathological analysis. Moreover, we developed an inflammatory cell model using tumor necrosis factor-α (TNF-α). Macrophage polarization was assessed using western blot analysis and immunofluorescence. RESULTS: Orphan nuclear receptor 77 (Nur77) and sequestosome-1 (p62) were highly expressed and positively correlated with each other in breast cancer tissues. LNT significantly inhibited tumor growth, ameliorated inflammatory cell infiltration, and induced tumor cell apoptosis in PyMT transgenic mice. Moreover, LNT attenuated the ability of tumors to metastasize to lung tissue. Mechanistically, LNT treatment restrained macrophage polarization from M1 to M2 phenotype and promoted autophagic cell death by inhibiting Nur77 expression, AKT/mTOR signaling, and inflammatory signals in breast tumor cells. However, LNT did not exhibit a direct pro-autophagic effect on tumor cell death, except for its inhibitory effect on Nur77 expression. LNT-mediated autophagic tumor cell death depends on M1 macrophage polarization. In in vitro experiments, LNT inhibited the upregulation of p62, autophagy activation, and inflammatory signaling pathways in Nur77 cells. CONCLUSION: LNT inhibited macrophage M2 polarization and subsequently blocked the AKT/mTOR and inflammatory signaling axes in breast cancer cells, thereby promoting autophagic tumor cell death. Thus, LNT may be a promising therapeutic strategy for breast cancer.

Structural and functional characterization of the cytotoxic protein ledodin, an atypical ribosome-inactivating protein from shiitake mushroom (Lentinula edodes).

We have purified ledodin, a cytotoxic 22-kDa protein from shiitake mushroom (Lentinula edodes) consisting of a 197 amino acid chain. Ledodin possessed N-glycosylase activity on the sarcin-ricin loop of mammalian 28S rRNA and inhibited protein synthesis. However, it was not active against insect, fungal, and bacterial ribosomes. In vitro and in silico studies suggested that ledodin exhibits a catalytic mechanism like that of DNA glycosylases and plant ribosome-inactivating proteins. Moreover, the sequence and structure of ledodin was not related to any protein of known function, although ledodin-homologous sequences were found in the genome of several species of fungi, some edible, belonging to different orders of the class Agaricomycetes. Therefore, ledodin could be the first of a new family of enzymes widely distributed among this class of basidiomycetes. The interest of these proteins lies both, in the fact that they can be a toxic agent of some edible mushrooms and in their application in medicine and biotechnology.

Efficient isolation of immunostimulatory polysaccharides from Lentinula edodes by autoclaving-ultrasonication extraction and fractional precipitation.

A hyphenated process, autoclaving followed by ultrasonication (AU), was evaluated for efficient extraction of polysaccharides (PS) from Lentinula edodes (Shiitake) mushroom. The PS yield (w/w) was 8.44 % from hot-water extraction (HWE), 11.01 % by autoclaving extraction (AE), and 16.3 % by AUE. The AUE water extract was subject to fractional precipitation in four-steps with increasing ethanol concentration of 40 %, 50 %, 70 % and 80 % (v/v), yielding four PS fractions in descending molecular weight (MW), PS40 > PS50 > PS70 > PS80. All the four PS fractions were composed of four monosaccharide residues, mannose (Man), glucose (Glc) and galactose (Gal) but in different mole ratios. The PS40 fraction with the highest average MW (4.98 × 106) was the most abundant fraction, accounting for 64.4 % of the total PS mass and also had the highest glucose molar ratio (~80 %). PS40 also most significantly enhanced the NO, and ROS generation and phagocytic activity in RAW 264.7 cells. The results proved that AUE followed by fractional ethanol precipitation is an efficient strategy with reduced solvent expenditure for isolation of the major immunostimulatory PS from L. edodes mushroom.

A Standardized Extract of Cultured Lentinula edodes mycelia Up-regulates COX-2 in Inflammation-related Malignant Progressive Fibrosarcoma Cell Clone QRsP-11.

BACKGROUND/AIM: Cyclooxygenase is an enzyme that transforms arachidonic acid to prostaglandins. Cyclooxygenase-2 (COX-2) is an isoform of cyclooxygenase. There exist many reports on the expression levels of COX-2 in cancer tissues, and prognosis of cancer patients has been reported to be related to COX-2 up-regulation. In the present study we assessed the suppressive effect of AHCC® on the expression of COX-2 in QRsP-11cells. MATERIALS AND METHODS: QR-32 is a clone which was derived from murine fibrosarcoma BMT-11 cells by treatment with quercetin. These clone cells regress spontaneously after injection into C57BL/6 mice. QRsP-11 is a clone derived from QR-32, showing very aggressive tumorigenicity. AHCC® is a standardized extract of cultured Lentinula edodes mycelia and has been reported to exert suppressive effects on various tumor-associated proteins including HSP27. The protein levels of COX-2 in QR-32 and QRsP-11 cells were compared by using western blotting. Furthermore, the expression levels of COX-2 were assessed in QRsP-11 cells after AHCC®-treatment. RESULTS: Western blot analysis showed a significant up-regulation of COX-2 in QRsP-11 cells compared to QR-32 cells. In vitro AHCC®-treatment increased COX-2 expression levels in QRsP-11 cells contrary to expectations. CONCLUSION: When using AHCC® in cancer treatment, it might be important to decrease COX-2 expression by means of non-steroidal anti-inflammatory drugs (NSAIDs), such as aspirin. Further studies are required to clarify the mechanism of up-regulation of COX-2 through AHCC®-treatment.

Evaluation of Polysaccharide Content in Shiitake Culinary-Medicinal Mushroom, Lentinula edodes (Agaricomycetes), via Near-Infrared Spectroscopy Integrated with Deep Learning.

Polysaccharide is one of the bioactive ingredients extracted from the fruiting body of Lentinula edodes (=L. edodes), which has many medicinal functions. While the content of polysaccharide can be measured by near-infrared (NIR) spectroscopy, the NIR analytical models established previously only covered L. edodes from very limited sources, and thus could not achieve high accuracy for large samples from more varied sources. Strictly, there is a nonlinear relationship between NIR spectral data and chemical label values, and traditional modeling methods for NIR data analysis have problems such as insufficient feature learning ability and difficulty in training. The deep learning model has excellent nonlinear modeling ability and generalization capacity, which is very suitable for analyzing larger samples. In this study, we constructed a novel framework with deep learning techniques on the NIR analysis of the content of polysaccharide in L. edodes. The siPLS model was established based on the combination of the bands 4797-3995 cm-1 and 6401-5600 cm-1, while the one-dimensional convolutional neural network (1D-CNN) model was established with improved feature in the treatment of the spectral data. The comparative experimental results showed that the 1D-CNN model (R2pre = 95.50%; RMSEP =0.1875) outperformed the siPLS model (R2pre = 87.89%, RMSEP = 0.6221). As such, this work has demonstrated that NIR spectroscopy with the integration of deep learning can provide more accurate quantification of polysaccharide in L. edodes. Such method can be very useful for nutritional grading and quality control of diverse L. edodes in the market.

Compositional differences of ß-glucan-rich extracts from three relevant mushrooms obtained through a sequential extraction protocol.

In this work, a sequential fractionation protocol (cold and hot aqueous and alkaline extractions) and detailed compositional analysis (gross composition, monosaccharide analysis, FTIR, TGA) was applied to three relevant mushrooms in terms of global production (Grifola frondosa, Lentinula edodes and Pleurotus ostreatus) aiming to understand what is preferentially extracted during fractionation and how ß-glucan extraction is affected by mushroom source. Room temperature aqueous extracts showed highest overall yields (56.3-82%) consisting of proteins, sugars and polyphenols. ß-glucan content was highest in P. ostreatus and was concentrated in the more soluble fractions. On the contrary, a recalcitrant ß-glucan in G. frondosa was mainly present in the residue (7.38%). L. edodes showed ß-glucan populations distributed along aqueous and alkaline extracts, higher abundance of non-glucan polysaccharides and higher chitin purity (47.78%) in the residue. This work sets the basis for the rational design of extraction processes aiming to valorise mushroom biomass.