Structure and composition changes in the cell wall in relation to texture of shiitake mushrooms (Lentinula edodes) stored in modified atmosphere packaging

Semisolid medium internal phase emulsions stabilized by dendritic-like mushroom cellulose nanofibrils: Concentration effect and stabilization mechanism

Emulsions with reduced fat and natural stabilizers are currently prevalent. Herein, semisolid emulsions with an oil phase of 50 % were successfully prepared using cellulose nanofibrils from mushroom stipes as stabilizers. Cellulose nanofibrils obtained by high-pressure homogenization were dendritic-like and possessed a contact angle of 70.50 ± 0.41°. The rheological properties and stability of emulsions increased significantly as nanocellulose concentrations increased from 5 to 20 mg/mL, while nanocellulose at 25-30 mg/mL significantly reduced the storage stability and anti-lipid oxidation ability of emulsions. The microstructure of semisolid emulsions demonstrated that nanocellulose fibers at 20 mg/mL could stabilize emulsions by forming compact interfacial films around droplets and creating intensive bridging networks between neighboring droplets, while nanofibers at concentrations over 20 mg/mL easily clustered in the aqueous phase, making the droplets more susceptible to aggregation and demulsification. The results demonstrate that cellulose nanofibrils from mushroom byproducts have the potential to stabilize semisolid food-grade emulsions.

Deep-Learning-Based Wireless Visual Sensor System for Shiitake Mushroom Sorting

The shiitake mushroom is the second-largest edible mushroom in the world, with a high nutritional and medicinal value. The surface texture of shiitake mushrooms can be quite different due to different growing environments, consequently leading to fluctuating market prices. To maximize the economic profit of the mushroom industry, it is necessary to sort the harvested mushrooms according to their qualities. This paper aimed to develop a deep-learning-based wireless visual sensor system for shiitake mushroom sorting, in which the visual detection was realized by the collection of images and cooperative transmission with the help of visual sensors and Wi-Fi modules, respectively. The model training process was achieved using Vision Transformer, then three data-augmentation methods, which were Random Erasing, RandAugment, and Label Smoothing, were applied under the premise of a small sample dataset. The training result of the final model turned out nearly perfect, with an accuracy rate reaching 99.2%. Meanwhile, the actual mushroom-sorting work using the developed system obtained an accuracy of 98.53%, with an 8.7 ms processing time for every single image. The results showed that the system could efficiently complete the sorting of shiitake mushrooms with a stable and high accuracy. In addition, the system could be extended for other sorting tasks based on visual features. It is also possible to combine binocular vision and multisensor technology with the current system to deal with sorting work that requires a higher accuracy and minor feature identification.

Development of Active Packaging to Extend the Shelf Life of Agaricus bisporus by Using Plasma Technology

In this study, a preservation package that can extend the shelf life of Agaricus bisporus was developed using plasma modification combined with low-density polyethylene (LDPE), collagen (COL), and carboxymethyl cellulose (CMC). Out results showed that the selectivity of LDPE to gas can be controlled by plasma modification combined with coating of different concentrations of CMC and COL. Packaging test results applied to A. bisporus showed that 3% and 5% of CMC and COL did not significantly inhibit polyphenol oxidase and β-1,3-glucanase, indicating no significant effect on structural integrity and oxidative browning. The use of 0.5% and 1.0% CMC and COL can effectively inhibit the polyphenol oxidase and β-1,3-glucanase activity of A. bisporus, leading to improved effects in browning inhibition and structural integrity maintenance. P-1.0COL can effectively maintain gas composition in the package (carbon dioxide: 10–15% and oxygen: 8–15%) and catalase activity during storage, thereby reducing the oxidative damage caused by respiration of A. bisporus. The current study confirmed that the use of plasma modification technology combined with 1.0% COL can be used in preservation packaging by regulating the respiration of A. bisporus, thus extending its shelf life from 7 to 21 days.

Impact of post-harvest processing or thermal dehydration on physiochemical, nutritional and sensory quality of shiitake mushrooms

Shiitake mushrooms are one of the most popular and highly consumed mushrooms worldwide both in fresh and dry forms. However, it rapidly starts losing its quality immediately after harvest which necessitates processing and/or proper storage before being distributed. However, the processes used for preserving other mushrooms (e.g., Agaricus) become unviable for shiitake due to its uniqueness (higher respiration rate, varied biochemicals, growth, etc.) which demands individual studies on shiitake. This review starts by listing the factors and their interdependence leading to a quality decline in shiitake after harvest. Understanding well about these factors, numerous post-harvest operations preserve shiitake as fresh form for a shorter period and as dried forms for a longer shelf-life. These processes also affect the intrinsic quality and nutrients of shiitake. This review comprehensively summarizes and discusses the effects of chemical processing (washing, fumigation, coating, and ozone), modified atmosphere packaging (including irradiation) on the quality of fresh shiitake while discussing their efficiency in extending their shelf-life by inhibiting microbial spoilage and deterioration in quality including texture, appearance, nutrients, and favor. It also reviews the impact of thermal dehydration on the quality of dried shiitake mushrooms, especially the acquired unique textural, nutritional, and aromatic properties along with their merits and limitations. Since shiitake are preferred to be low-cost consumer products, the applicability of freeze-drying and sophisticated novel methodologies, which prove to be expensive and/or complex, are discussed. The review also outlines the challenges and proposes the subsequent future directives, which either retains/enhances the desirable quality in shiitake mushrooms.

Coating shiitake mushrooms (Lentinus edodes) with a polysaccharide from Oudemansiella radicata improves product quality and flavor during postharvest storage

In this work, we investigated whether coating fresh shiitake mushrooms with a polysaccharide isolated from Oudemansiella radicata (ORWP) would impact key quality characteristics after 18 d of storage at 4 °C. We found that ORWP-coated mushrooms had significant improvements in many qualities during storage, including reduced weight loss, improved firmness, reduced browning, decreased malondialdehyde content, and an improved physical microstructure. Further, ORWP-coated mushrooms had higher contents of nutritional and cell wall compounds compared to control samples. ORWP-coated mushrooms had reduced activities of the following enzymes: protease, polyphenol oxidase, peroxidase, phenylalanine ammonia lyase, cellulase, and chitinase, relative to control samples. However, mushrooms coated with ORWP had higher concentrations of superoxide dismutase and catalase, as well as higher contents of certain key monosodium glutamate-resembling amino acids, umami 5'-nucleotides and 1-octen-3-ol. These findings suggest that ORWP coatings have potential value as a method to improve the postharvest quality of shiitake mushrooms.

Molecular identification of Shiitake [Lentinula edodes Berk (Pegler)] and production of secondary metabolites with biotechnological potential

The Shitake mushroom (Lentinula edodes) is the second most-consumed mushroom in the world; in Colombia, it is cultivated and commercialized on a small scale in some supermarkets. Little is known about the precedence, nutritional and medicinal properties of Shiitake produced in Colombia. In this study, four shiitake isolates were grown in Colombia (LEUCO1, LEUCO2, LEUCO3, and LEUCO4) were sequenced in their ITS genes and evaluated for the production of three medicinal metabolites, eritadenine, ergotioneine and β-glucans (1,3-1, 6), using submerged culture. Genetic analysis revealed that all the isolates were close and related to the Japanese strain Cr62. LEUCO1 and LEUCO2 showed a distance of 0.000, as well as LEUCO3 and LEUCO4. All four isolates produced erythadenin in a range of 26.3-8.6 mg / L, with the best performance of LEUCO1 at 26.3 mg / L (p <0.05). Ergotioneine was produced with similar statistical yields in all the isolates with an average of 0.7 mg / g of dry weight biomass (DW). Β-glucans (1.3-1.6) were produced with yields of 5.6 - 3.8% of DW biomass, with the best values ​​for LEUCO2 and the lowest for LEUCO4 (p <0.05). In conclusion, we identified low genetic diversity in the four isolates, corresponding to two haplotypes with minimal genetic difference between them, related to the Japanese strain Cr62, indicating that Colombian farmers cultivate almost the same strains of shitake. Secondary metabolites, eritadenine, β-glucans and ergotioneine were found in promising yields useful for the pharmaceutical and food industries. More studies should be conducted to improve the yield of shitake metabolites through new growing conditions for industrial production and to find metabolic pathways and related genes.

Comparison of physicochemical and rheology properties of Shiitake stipes-derived chitin nanocrystals and nanofibers

Chitin production from fungal sources has gained increased attention in recent years in terms of continuous supply and safety. In this study, we produced chitin from Shiitake stipes through deproteinization, depigmentation, demineralization and removal of glucans, and then prepared chitin nanocrystal (ChNC) and chitin nanofibers (ChNF) by acid hydrolysis or high-pressure homogenizers. Such obtained ChNFs have higher length than the ChNCs with a length of 142.4 ± 40.4 nm, with the similar diameter (9 nm). In addition, the purity of ChNC and ChNF were over 98 % measured by HPAEC. The zeta potential analysis showed that ChNC is stable in acid form, while ChNF is in the opposite. Finally, we evaluated the rheology properties of samples to find the impact of salt concentrations on nanoparticles interactions. Overall, the fungi-derived chitin nanomaterials with diversity of characters exhibit immense potential for applications in nutraceutical and food industry.

Effects of mixed agro-residues (corn crop waste) on lignin-degrading enzyme activities, growth, and quality of Lentinula edodes

Using agro-residues in bioreactors to produce mushrooms is an important component of eco-agriculture. Here, we tested the cultivation of Lentinula edodes with corn cob (CC) and corn straw (CS), and then evaluated the resulting enzyme activities, agronomic traits, textures and nutrient compositions of mushrooms. Laccase (T1 formula, 3.26 g U⁻¹) and carboxymethyl cellulase (T3 formula, 1.01 g U⁻¹) activities were the highest at the time for a complete substrate colonization stage (TCSC), while acidic xylanase activity was the highest (CK formula, 4.05 g U⁻¹) in the mushroom block to color-turned (TMBCT) stage. The biological efficiency of growth on the T6 formula was 8.82% higher than growth on the CK formula, wherein the low C/N ratio of the substrate had an obvious negative effect on yield while the mass ratio of pileus (MRP) of fruiting bodies did not change with mixed substrates. No significant differences were observed in mineral composition for CK formulas, but corn crop waste (CCW) formulas exhibited more optimal nutritional contents. A formula containing more corn cob and sawdust (SD) (sum of at least 70%) as the substrate can produce fruiting bodies with good hardness. These results indicate that the use of corn cobs as the main ingredient, mixed with sawdust and corn straw to grow L. edodes provides a more efficient use of agro-residues for growth. Thus, mixed agro-residue formulas have exceptional advantages in texture, nutrition of fruiting bodies, and yields.

Using agro-residues in bioreactors to produce mushrooms is an important component of eco-agriculture.

Postharvest biochemical characteristics and ultrastructure of Coprinus comatus

BACKGROUND

Coprinus comatus is a novel cultivated edible fungus, hailed as a new preeminent breed of mushroom. However, C. comatus is difficult to keep fresh at room temperature after harvest due to high respiration, browning, self-dissolve and lack of physical protection.

METHODS

In order to extend the shelf life of C. comatus and reduce its loss in storage, changes in quality, biochemical content, cell wall metabolism and ultrastructure of C. comatus (C.c77) under 4 °C and 90% RH storage regimes were investigated in this study.

RESULTS

The results showed that: (1) After 10 days of storage, mushrooms appeared acutely browning, cap opening and flowing black juice, rendering the mushrooms commercially unacceptable. (2) The activity of SOD, CAT, POD gradually increased, peaked at the day 10, up to 31.62 U g-1 FW, 16.51 U g-1 FW, 0.33 U g-1 FW, respectively. High SOD, CAT, POD activity could be beneficial in protecting cells from ROS-induced injuries, alleviating lipid peroxidation and stabilizing membrane integrity. (3) The activities of chitinase, β-1,3-glucanase were significantly increased. Higher degrees of cell wall degradation observed during storage might be due to those enzymes' high activities. (4) The fresh C. comatus had dense tissue and every single cell had the number of intracellular organelles which structure can be observed clearly. After 10 d storage, the number of intracellular organelles was declined and the structure was fuzzy, the nucleus disappeared. After 20 d storage, C. comatus's organization was completely lost, many cells were stacked together and the cell wall was badly damaged.

Enhancement of quality retention of Grifola frondosa fruiting bodies by erythorbic acid treatment

In this paper, the effects of erythorbic acid (EA) treatment with different concentrations on the quality of Grifola frondosa fruiting bodies stored at 4 °C for 27 days were studied by determining the changes in moisture content, weight loss, browning, electrolyte leakage, malondialdehyde (MDA), and nutritional compounds. The activities of polyphenoloxidase (PPO), cellulase and other antioxidant enzymes including superoxide dismutase (SOD), catalase, and peroxidase (POD) were also measured. Results showed that 0.1% EA-treated G. frondosa fruiting body maintained lower weight loss (< 6.0%, w/w), electrolyte leakage (< 45.8%), MDA (< 4.17 µmol kg-1), and higher moisture content (> 90.7%, w/w). Lower activities of PPO (< 72.64 × 103 U kg-1) and cellulase (< 189.86 × 103 U kg-1) in 0.1% EA-treated samples were observed compared with the other treatments. As a stereoisomer of ascorbic acid (AA), EA also could enhance SOD and POD activities of G. frondosa fruiting bodies. Our findings were the first time to evaluate the effect of EA on maintaining quality in G. frondosa fruiting bodies, and proved that low concentrations of EA (especially 0.1% EA, w/v) treatments were beneficial to preserve G. frondosa fruiting body with even higher efficiency than AA treatment. This study paved a foundation for the enhancement of quality retention of G. frondosa fruiting bodies.

Suppression of Cell Wall Degrading Enzymes and their Encoding Genes in Button Mushrooms (Agaricus bisporus) by CaCl2 and Citric Acid

Fresh button mushrooms (Agaricus bisporus) were harvested and treated with a solution of 1.5% CaCl₂ + 0.5% citric acid and stored for 16 days at 12 °C. The effects of this treatment on firmness, weight, color, cell wall compositions (cellulose and chitin) and cell wall degrading enzymes (cel1ulase, beta-1, 3 glucanase, chitinase and phenylalanine ammonialyase) were investigated during post-harvest storage. The expressions of major genes (Cel1, Glu1, Chi1 and PAL1) involved in cell wall degradation during post-harvest storage were also monitored. The results revealed that the post-harvest chemical treatment maintained better firmness, weight, color and inhibited cellulase, beta-1, 3 glucanase, chitinase and phenylalanine ammonialyase activities. These findings showed that the down-regulation of cell wall degrading enzymes is a possible mechanism that delays the softening of button mushrooms by the application of combined chemical treatment.

Selection of strains for shiitake production in axenic substrate

Shiitake mushroom consumption is increasing in Brazil. In addition to the implementation of new production methods, it is also important to increase productivity, quality and reduce production costs. In this study, six commercial Lentinula edodes strains were characterized for genetic diversity (rep-PCR analysis) and mushroom production (yield, number and weight of individual mushrooms) using different substrates and cultural conditions. All strains showed genetic differences by repetitive element palindromic based-polymerase chain reaction (rep-PCR). The richest substrate resulted in the greatest production under both environmental conditions. Strains LE4 and LE6 produced the majority of their mushrooms earlier than the other strains. The highest number of mushrooms was observed in the LE6 strain while the highest weights of individual mushrooms were observed in the LE4 strain. Controlled environmental conditions resulted in superior production for all strains, except for LE4, which had empirically greater yield in the semi-controlled environmental condition.

Chitin Nanofiber Elucidates the Elicitor Activity of Polymeric Chitin in Plants

Chitin, an N-acetyl-D-glucosamine polymer, is a component of fungal cell walls and a microbe/pathogen-associated molecular pattern that elicits plant defense responses. As polymeric chitin is difficult to handle due to its insolubility in water, many studies on chitin-induced immune responses have used water-soluble low-molecular weight chitin instead. Thus, it is unclear if polymeric chitin can induce resistance. Here, we examined the elicitor activity of chitin nanofiber (CNF) of submicron thickness prepared from polymeric chitin. CNF showed a high dispersing ability in water and induced both reactive oxygen species (ROS) production and chitin-induced defense-related gene expression in Arabidopsis thaliana seedlings. The Arabidopsis chitin elicitor receptor kinase 1 (Atcerk1) mutant, which is impaired in chitin perception, also failed to respond to CNF. CNF exposure triggered ROS generation in suspension-cultured cells from Oryza sativa. Furthermore, pre-treatment of Arabidopsis leaves with CNF effectively reduced pathogen infection by both the fungus Alternaria brassicicola and the bacterium Pseudomonas syringae pv. tomato DC3000. These results demonstrate that CNF has elicitor activity and will help define the role of polymeric chitin in plant immune responses.

Effects of ultrasound and chemical treatments on white mushroom (Agaricus bisporus) prior to modified atmosphere packaging in extending shelf-life

Effects of pre-treatments of white mushrooms prior to modified atmosphere packaging on their physico-chemical and microbiological properties were studied during 12 days of storage at 4 °C. Physico-chemical and microbiological properties of differently treated mushrooms stored at 4 °C were significantly different (P < 0.05) from untreated ones. Washed samples exhibited the smallest respiration rate compared to all other samples. Hydrogen peroxide washing was effective in retaining mushrooms colour change. Furthermore, the diminishments in weight of ultrasound treated samples during storage were significantly (P < 0.05) low in comparison with the other four treatments. The weight loss for ultrasound treated samples were 3.52 %, 4.07 % and 4.59 % for Uca, UH2O2 and UH2O respectively. The lowest PPO activity was observed in Uca, UH2O2 followed by Wca, WH2O2, UH2O and WH2O treatments respectfully. Combined treatments showed lower polyphenol oxidase activity, retained antioxidants, delayed pseudomonas growth and did not cause any decline in tissue firmness during storage time implying that it could extend shelf life of white mushrooms up to 12 days at 4 °C.

Differential effects of shiitake- and white button mushroom-supplemented diets on hepatic steatosis in C57BL/6 mice

Shiitake mushrooms (SMs) have been used in Asia for treatment and/or prevention of chronic diseases and hypercholesterolemia. Previously, we observed a diet supplemented with 5% SM resulted in a twofold increase in plasma IL-6 levels in DBA arthritic mice. An elevation in plasma IL-6 has also been implicated in the pathogenesis fatty liver disease. Thus, the aim of this study was to investigate the effect of SM supplemented-diet on hepatic steatosis. In study 1, eight-week old female C57BL/6 mice were randomly assigned to the following groups for 6 weeks: the AIN-93 diet; 5% SM, and 5% white button mushroom (WBM) supplemented diets (12/group). In study 2, mice were fed either the AIN-93 diet or SM (20/group). After 6 weeks, 13 mice fed SM diet were given the AIN93 diet for 8 or 15 days. Unlike other groups, all mice fed the SM diet developed fatty liver (mean histopathology score 4.5 vs <1 in the other groups; p<0.001) without fibrosis and inflammation. Fifteen days post withdrawal of SM completely normalized liver histology. To the best of our knowledge, this is the first report that chronic consumption of SM is associated with the development of fatty liver. The mechanism by which SM causes hepatic steatosis warrants further investigation.