Submerged Culture of Edible and Medicinal Mushroom Mycelia and Their Applications in Food Products: A Review.

Edible mushrooms have rich nutrition (e.g., proteins, dietary fibers, polysaccharides) and they can be potential sources of important ingredients in food processing. However, the cultivation of mushroom fruiting bodies needs a relatively long time, and they can be easily polluted during the growth process. At the same time, a lot of labor and larger planting areas are also required. As we all know, submerged fermentation is a good way to produce edible mushroom mycelia with less environmental pollution and small footprint, which are also rich in nutrition and bioactive components that are used as dietary supplements or health care products in the food industry. Therefore, it can be considered that the replacement of edible mushroom fruiting bodies with edible mushroom mycelia produced through submerged fermentation has great application potential in food production. At present, most of the research about edible mushroom mycelia focuses on the production of bioactive metabolites in fermentation liquid, but there are few reports that concentrate on their applications in food. This paper reviews the research progress of submerged culture of edible mushroom mycelia and their applications in food products.

The beneficial potential of protein hydrolysates as prebiotic for probiotics and its biological activity: a review.

Probiotics are not only a food supplement, but they have shown great potential in their nutritional, health and therapeutic effects. To maximize the beneficial effects of probiotics, it is commonly achieved by adding prebiotics. Prebiotics primarily comprise indigestible carbohydrates, specific peptides, proteins, and lipids, with oligosaccharides being the most extensively studied prebiotics. However, these rapidly fermenting oligosaccharides have many drawbacks and can cause diarrhea and flatulence in the body. Hence, the exploration of new prebiotic is of great interest. Besides oligosaccharides, protein hydrolysates have been demonstrated to enhance the expression of beneficial properties of probiotics. Consequently, this paper outlines the mechanism underlying the action of protein hydrolysates on probiotics, as well as the advantageous impacts of proteins hydrolysates derived from various food sources on probiotics. In addition, this paper also reviews the currently reported biological activities of protein hydrolysates. The aim is a theoretical basis for the development and implementation of novel prebiotics.

Examining the Cultivation, Degradation Characteristics and Health Effects of the Golden Oyster Mushroom Pleurotus citrinopileatus (Agaricomycetes): A Review.

Pleurotus citrinopileatus, also known as golden oyster mushroom, is a newly industrialized edible mushroom mainly distributed in East Asia. It is a kind of saprophytic edible fungus with strong degradation characteristics, commonly found on fallen trees and stumps of broad-leaf tree species. So far, abundant kinds of bioactive compounds such as polysaccharides, ergothioneine, sesquiterpenes, and glycoprotein have been isolated from P. citrinopileatus and studied. Studies have confirmed that these compounds are beneficial to human health. In this paper, the recent studies on the cultivation, degradation characteristics application, and health effects of P. citrinopileatus are reviewed, and their development trends are discussed.

A review on recent advances in LED-based non-thermal technique for food safety: current applications and future trends.

Light-emitting diodes (LEDs) is an eco-friendly light source with broad-spectrum antimicrobial activity. Recent studies have extensively been conducted to evaluate its efficacy in microbiological safety and the potential as a preservation method to extend the shelf-life of foods. This review aims to present the latest update of recent studies on the basics (physical, biochemical and mechanical basics) and antimicrobial activity of LEDs, as well as its application in the food industry. The highlight will be focused on the effects of LEDs on different types (bacteria, yeast/molds, viruses) and forms (planktonic cells, biofilms, endospores, fungal toxin) of microorganisms. The antimicrobial activity of LEDs on various food matrices was also evaluated, together with further analysis on the food-related factors that lead to the differences in LEDs efficiency. Besides, the applications of LEDs on the food-related conditions, packaged food, and equipment that could enhance LEDs efficiency were discussed to explore the future trends of LEDs technology in the food industry. Overall, the present review provides important insights for future research and the application of LEDs in the food industry.

Surfactant-free oleogel-based emulsion stabilized by co-assembled ceramide/lecithin crystals with controlled digestibility.

BACKGROUND: There is increasing interest in the development of oleogel-based emulsions. However, they usually contained surfactants for stabilization, especially small-molecular weight surfactants, which may have adverse health impacts. RESULTS: Herein, a surfactant-free oleogel-based emulsion stabilized by co-assembled ceramide/lecithin (CER/LEC) crystals was developed. The formation and stabilization mechanisms were explored. The different molar ratios of gelator (LEC and CER) in emulsions resulted in different crystal morphology, crystallinity as well as different emulsion properties. This suggested that appropriate crystallinity, crystal size, and interfacial distribution of these crystals provided higher surface coverage against droplets coalescence, thus better emulsion stabilization. Both X-ray diffractograms and contact angle results confirmed that the crystals which were primarily responsible for emulsion stabilization, are co-assembled crystals consisted of both gelators (CER and LEC). Furthermore, the percentage of free fatty acids (FFAs%) results revealed a negative relationship between lipid digestibility and crystal concentration. CONCLUSIONS: This strategy greatly enriched surfactant-free oleogel-based emulsion formulations, as well as their potential applications in healthy lipid-based products and novel food delivery systems with controlled lipid digestibility. © 2022 Society of Chemical Industry.

Cordyceps militaris polysaccharides modulate gut microbiota and improve metabolic disorders in mice with diet-induced obesity.

BACKGROUND: Cordyceps militaris is an edible and medicinal fungus, and its polysaccharides are among its main pharmacological components. They can display immunomodulation, anti-oxidation, anti-inflammation, anti-hypolipidemic, and other functions. The anti-obesity effect of C. militaris polysaccharides (CMP) is not yet fully understood, however. RESULTS: In this study, a CMP diet intervention was applied over a 4 week period to mice with obesity induced by a high-fat diet (HFD), followed by profiling of obesity-induced dyslipidemia, low-grade inflammation, and gut dysbiosis. The results suggested that CMP could significantly reduce HFD-induced obesity, alleviate obesity-induced hyperlipidemia and insulin resistance, and ameliorate systemic inflammation, showing a promising ability to protect mice from obesity. Further analyses revealed that CMP could regulate obesity-induced gut dysbiosis by restoring the phylogenetic diversity of gut microbiota. It could also increase the relative abundance of short-chain fatty acid (SCFA)-producing bacteria, while down-regulating the level of bacteria that were positively related to the development of obesity. A correlation analysis showed that Helicobacter, Allobaculum, Clostridium XVIII, Parabacteroides, Ligilactobacillus, Faecalibaculum, Adlercreutzia, and Mediterraneibacter were positively related to obese phenotypes. CONCLUSION: This study highlights the potential of CMP as a prebiotic agent to protect obese individuals from metabolic disorders and gut dysbiosis. © 2022 Society of Chemical Industry.

Rheological and microstructural properties of polysaccharide obtained from the gelatinous Tremella fuciformis fungus.

The gelatinous feature of Tremella fuciformis polysaccharide (TFP) has attracted growing interest in its application as a thickening agent in the food industry. This study aims to reveal the microstructure and rheological properties of TFP. Results showed that TFP randomly distributed in aqueous solutions in an irregular worm-like morphology and formed a more extensive entangled network and stiffer chains at higher concentration solutions. The further rheological study indicated that the TFP solutions exhibited a shear-thinning behavior. Multiple results of dynamic oscillation tests confirmed the viscoelastic properties of TFP. Frequency sweep data display that TFP solutions exhibit solid-like behavior at high frequencies, showing the oscillatory behavior of entangled polymers. The temperature sweep demonstrated that the rheological behavior of TFP is thermally reversible. These results enriched the understanding of the rheology-microstructure relationship of TFP solution and were beneficial to expanding the application of TFP in food processing.

Physicochemical and functional properties of Pleurotus geesteranus proteins.

Edible mushroom protein has been regarded as a promising protein source due to its nutritional value and sustainability. In the present study, Pleurotus geesteranus proteins were extracted with alkaline solution and then precipitated with salting out (PPS) and isoelectric point precipitation (PPI), respectively. The influences of precipitation method on the physicochemical and functional properties of these two kinds of proteins were studied. The results showed that both PPS and PPI had a good balance of essential amino acids. These two proteins were mainly consisted of polypeptides with a molecular weight lower than 70 kDa. Using proteome analysis, a number of 772 and 459 protein compositions were identified in PPS and PPI, respectively. Compared to PPS, PPI showed a higher zeta potential, higher surface hydrophobicity, lower content of ß-sheet and ß-turn secondary structure, as well as lower denaturation temperature (Td) and enthalpy change of the denaturation (ΔH). These differences in the physicochemical properties between PPS and PPI resulted in the occurrence of differences in their functional and digestive properties. For example, PPS showed obviously higher protein solubility in water than PPI, especially at natural pH, PPS solution was clear, while PPI showed precipitates. PPI had higher foam capability (FC), lower foaming stability (FS), and lower emulsion stability index (ESI) as compared to PPS. PPI was easier to digest in the pepsin digestion period, while PPS showed a higher nitrogen release after trypsin digestion. These findings on the physicochemical and functional properties of P. geesteranus proteins will help to broaden their applications as protein ingredient in food industry.

Amelioration effect of water extract from Ganoderma resinaceum FQ23 solid-state fermentation fungal substance with high-yield ergothioneine on anxiety-like insomnia mice.

Herein, a solid-state fermentation (SSF) system of Ganoderma resinaceum FQ23 with high-yield ergothioneine (EGT) was established, and the amelioration effect of the water extract from its fungal substance on anxiety-like insomnia mice was studied. The content of EGT in the G. resinaceum FQ23 SSF fungal substance increased to 1.146 ± 0.066 mg g-1 DW in the optimization tests. Besides EGT, the common functional components of the water extract from the G. resinaceum FQ23 SSF fungal substance (GSW) were determined, including triterpenoids, polysaccharides, phenols, proteins and amino acids. The animal experiments showed that GSW could alleviate the anxiety-like behavior, improve the antioxidant capacity and protect the organ structure of the anxiety-like insomnia mice. With an increase in the dose of GSW given to the anxiety-like insomnia mice, their serum 5-HT and GABA levels increased, HPA axis hormone levels significantly decreased, BDNF level notably increased, and the response level of the BDNF/CREB signaling pathway was significantly enhanced, indicating that GSW may improve neuroendocrine regulation and neuroprotection in anxiety-like insomnia mice. A 30-times dose of GSW had no acute toxicity in the normal mice. Therefore, the SSF fungal substance of G. resinaceum FQ23 is a potential dietary source for improving sleep. It can be used as a solid drink to help people who are poor sleepers and as a substitute for tea or coffee to help people who are like to drink tea or coffee and cannot sleep.

The in Vitro Fermentation of Cordyceps militaris Polysaccharides Changed the Simulated Gut Condition and Influenced Gut Bacterial Motility and Translocation.

The motility ability of intestinal lipopolysaccharide (LPS)-producing bacteria determines their translocation to the enterohepatic circulation and works as an infectious complication. In this study, the health effects of Cordyceps militaris polysaccharides (CMPs) were re-evaluated based on whether these polysaccharides could affect the motility of gut commensal LPS-producing bacteria and impede their translocation. The results showed that CMP-m fermentation in the gut could change the chemical environment, leading to a decrease in velocity and a shift in the motility pattern. Further study suggested that detachment/fragmentation of flagella, decreased motor forces, and changed chemical conditions might account for this weakened motility. The adhesion and invasion abilities of gut bacteria were also reduced, with lower expression of virulence-related genes. These results indicated that the health regulation effects of CMP-m might be through decreasing the motility of LPS-producing bacteria, hindering their translocation and therefore reducing the LPS level in the enterohepatic circulation.

Fabrication of gel-like emulsions with γ-zein particles using microfluidization: Structure formation and rheological properties.

In this work, γ-zein, which is a type of cysteine rich prolamine in corn, was prepared into particles for fabricating stable gel-like emulsions. The effects of homogenization pressure (0.1-120 MPa) on structure formation and rheological properties of emulsions were systematically studied. Microscopy showed that γ-zein particles provided stabilization at droplet interfaces, and that excess protein particles provided a particle network in continuous phase, and microfluidization significantly decreased droplet size and induced to form droplet clusters and gel-like network. With an increase of homogenization pressure, protein content adsorbed at droplet interfaces and entrapped within gel-like structure of emulsions increased, and more hydrophobic interactions and disulfide bonds between protein particles were formed. As a result, stronger gel strength of emulsions were observed, for example, apparent viscosity, storage modulus (G'), loss modulus (G''), and G'/ G'' crossover strain (γco) increased, the frequency dependency of G' (n, G' ∼ ωn) decreased. Also, Lissajous curves were used to further understand the non-linear viscoelastic behavior of these emulsions. Emulsions prepared without microfluidization (control, 0.1 MPa) showed a weak gel structure with viscous-dominating behavior at high strain, while emulsions prepared with microfluidization showed predominantly elastic behavior at low strain, and plastic-dominating behavior at high strain. These findings showed that cysteine rich protein based- emulsion gels with tunable microstructure and rheological properties can be easily produced by controlling the homogenization pressure.

Non-isothermal crystallization kinetics study of multi-component oleogels.

In this study, the influence of non-isothermal conditions on multi-component oleogel (lecithin, LEC and ceramide, CER) was systematically investigated by rheological characterization, polarized light microscopy, and differential scanning calorimetry. Jeziorny and Mo models were applied to reveal the crystallization behavior. When the cooling rate increased, the LEC/CER oleogel exhibited lower G' and larger crystal size. The crystallization kinetics showed that at lower cooling rate, the LEC/CER co-assembled crystals grew at 2-3 dimensions by one step crystallization process. While at high cooling rate, the crystals first grew at 1-2 dimensions through self-assembly of CER. Then, the primary CER crystals served as nuclei for further co-assembly of CER/LEC growing in 2-3 dimensions. Our findings indicated that the cooling rate not only modulated the crystal structure and physical properties, but also the assembly mechanism of multi-component oleogels. Such information is useful for engineering the functional properties of oleogel-based lipidic materials.

Gelation and foaming properties of fatty acid mixtures in sunflower oil.

BACKGROUND: The development of lipid-lowering products has become the focus of the food industry due to increasing consumer awareness of the relationship between diet and health. Recently, edible oleofoams have drawn attention due to their enormous potential in reformulating food products with reduced fat content and unique mouth feel. RESULTS: We have developed an edible oleofoam system by whipping oleogel composed of fatty acid mixtures in sunflower oil. The crystal morphology, gelation properties, and foaming properties of these oleogels could be tailored by changing the ratio of stearic acid (SA) and myristic acid (MA). Specifically, SA/MA = 2:8 (2S8M) was demonstrated to have superior foaming capability and foam stability, likely due to the densely packed and uniformly distributed crystals formed at this fatty acid ratio. Small lipid crystals in 2S8M absorbed to the air-oil interface more efficiently, and together with the strengthened network established in the bulk phase, helped stabilize the foam structure. As a result, the 2S8M oleofoam showed excellent foaming properties: strong plasticity, significantly increased overrun (up to 63.56 ± 2.58%), and significantly improved foam stability. The X-ray diffraction (XRD) results indicated that the diffraction pattern observed for 2S8M samples at d-spacing of 4.20 and 3.79 Å was related to the characteristic peak of ß' type crystals, which were responsible for the enhanced foaming capability of 2S8M oleogels. Oleophobic property of 2S8M increased, as indicated by wettability in oil phase, which could possibly drive crystals to the air-oil interface. CONCLUSIONS: These results highlighted the importance of lipid crystal morphology in determining the whippability of oleogels. © 2021 Society of Chemical Industry.

Ergothioneine exhibits longevity-extension effect in Drosophila melanogaster via regulation of cholinergic neurotransmission, tyrosine metabolism, and fatty acid oxidation.

Many studies have demonstrated the protective effect of ergothioneine (EGT), the unique sulfur-containing antioxidant found in mushrooms, on several aging-related diseases. Nevertheless, to date, no single study has explored the potential role of EGT in the lifespan of animal models. We show here that EGT consistently extends fly lifespan in diverse genetic backgrounds and both sexes, as well as in a dose and gender-dependent manner. Additionally, EGT is shown to increases the climbing activity of flies, enhance acetylcholinesterase (AchE) activity, and maintain the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG)of aged flies. The increase in lifespan by EGT is gut microorganism dependent. We proposed potential mechanisms of lifespan extension in Drosophila by EGT through RNA-seq analysis: preservation of the normal status of the central nervous system via the coordination of cholinergic neurotransmission, tyrosine metabolism, and peroxisomal proteins, regulation of autophagic activity by altering the lysosomal protein CTSD, and the preservation of normal mitochondrial function through controlled substrate feeding into the tricarboxylic acid (TCA) cycle, the major energy-yielding metabolic process in cells.

Cordyceps militaris Immunomodulatory Protein Promotes the Phagocytic Ability of Macrophages through the TLR4-NF-κB Pathway.

Enhancing the phagocytosis of immune cells with medicines provides benefits to the physiological balance by removing foreign pathogens and apoptotic cells. The fungal immunomodulatory protein (FIP) possessing various immunopotentiation functions may be a good candidate for such drugs. However, the effect and mechanism of FIP on the phagocytic activity is limitedly investigated. Therefore, the present study determined effects of Cordyceps militaris immunomodulatory protein (CMIMP), a novel FIP reported to induce cytokines secretion, on the phagocytosis using three different types of models, including microsphere, Escherichia Coli and Candida albicans. CMIMP not only significantly improved the phagocytic ability (p < 0.05), but also enhanced the bactericidal activity (p < 0.05). Meanwhile, the cell size, especially the cytoplasm size, was markedly increased by CMIMP (p < 0.01), accompanied by an increase in the F-actin expression (p < 0.001). Further experiments displayed that CMIMP-induced phagocytosis, cell size and F-actin expression were alleviated by the specific inhibitor of TLR4 (p < 0.05). Similar results were observed in the treatment with the inhibitor of the NF-κB pathway (p < 0.05). In conclusion, it could be speculated that CMIMP promoted the phagocytic ability of macrophages through increasing F-actin expression and cell size in a TLR4-NF-κB pathway dependent way.

A review on the bioavailability, bio-efficacies and novel delivery systems for piperine.

As the major naturally occurring alkaloid in pepper with a pungent taste, piperine is known for its beneficial biological functions and therapeutic effects. In this work, the bioavailability and biological activities of piperine were presented and discussed. Novel delivery systems for enhancing the bioavailability of piperine were also reviewed. This study could provide a better understanding of the physiological and biochemical aspects of piperine to be further developed in the food and nutraceutical industries.

Comparative transcriptome and proteome provide new insights into the regulatory mechanisms of the postharvest deterioration of Pleurotus tuoliensis fruitbodies during storage.

The Pleurotus tuoliensis (Pt), a precious edible mushroom with high economic value, is widely popular for its rich nutrition and meaty texture. However, rapid postharvest deterioration depreciates the commercial value of Pt and severely restricts its marketing. By RNA-Seq transcriptomic and TMT-MS MS proteomic, we study the regulatory mechanisms of the postharvest storage of Pt fruitbodies at 25 ℃ for 0, 38, and 76 h (these three-time points recorded as groups A, B, and C, respectively). 2,008 DEGs (Differentially expressed genes) were identified, and all DEGs shared 265 factors with all DEPs (Differentially expressed proteins). Jointly, the DEGs and DEPs of two-omics showed that the category of the metabolic process contained the most DEGs and DEPs in the biological process by GO (Gene Ontology) classification. The top 17 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways with the highest sum of DEG and DEP numbers in groups B/A (38 h vs. 0 h) and C/A (76 h vs. 0 h) and pathways closely related to energy metabolism were selected for analysis and discussion. Actively expression of CAZymes (Carbohydrate active enzymes), represented by laccase, chitinase, and ß-glucanase, directly leads to the softening of fruitbodies. The transcription factor Rlm1 of 1,3-ß-glucan synthase attracted attention with a significant down-regulation of gene levels in the C/A group. Laccase also contributes, together with phenylalanine ammonia-lyase (PAL), to the discoloration reaction in the first 76 h of the fruitbodies. Significant expression of several crucial enzymes for EMP (Glycolysis), Fatty acid degradation, and Valine, leucine and isoleucine degradation at the gene or protein level supply substantial amounts of acetyl-CoA to the TCA cycle. Citrate synthase (CS), isocitrate dehydrogenase (ICDH), and three mitochondrial respiratory complexes intensify respiration and produce high levels of ROS (Reactive oxygen species) by significant up-regulation. In the ROS scavenging system, only Mn-SOD was significantly up-regulated at the gene level and was probably interacted with Hsp60 (Heat shock protein 60), which was significantly up-regulated at the protein level, to play a dominant role in antioxidation. Three types of stresses - cell wall stress, starvation, and oxidative stress - were suffered by Pt fruitbodies postharvest, resulting in cell cycle arrest and gene expression disorder.

Enhancement of carotenoid production and its regulation in edible mushroom Cordyceps militaris by abiotic stresses.

Cordyceps militaris carotenoids are widely used as food additives, animal feed supplements, and so on. However, the biosynthetic pathway of carotenoids in C. militaris is still obscure. In this paper, changes of mycelial morphology and carotenoid accumulation of C. militaris were investigated under oxidative (KMnO4) and osmotic stress (NaCl). Subsequently, qRT-PCR was employed to detect the expression levels of genes related to carotenogenesis to explore the mechanism of adaptation to abiotic stress. When the concentrations of KMnO4 and NaCl were respectively 0.4 g/L and 2 g/L, carotenoid accumulation reached a maximum of 6616.82 ±â€¯666.43 µg/g and 6416.77 ±â€¯537.02 µg/g. Under the oxidative stress condition of KMnO4, the expressions of psy and hsp70 increased significantly compared with control. Besides, the genes fus3 and hog1 were significantly enriched in the MAPK signal pathway. Compared with the control group, there was no significant difference in expression of psy in the NaCl group. Moreover, the accumulation of triacylglycerols may contribute significantly to the increase in carotenoid accumulation. The increased accumulation of antioxidant carotenoids induced under environmental stress is to resist oxidative conditions. Fus3 and Hog1 signaling in the MAPK pathway was activated and subsequently take effects on the resistance of oxidative condition by regulating related metabolic processes. C. militaris resist the stress of high oxygen by producing a large amount of glycerol and carotenoids when this fungus is cultured in a saline environment for a long time.

Antimicrobial activity of 405 nm light-emitting diode (LED) in the presence of riboflavin against Listeria monocytogenes on the surface of smoked salmon.

This study investigated the antimicrobial activity of 405 nm light-emitting diode (LED) with and without riboflavin against Listeria monocytogenes in phosphate buffered saline (PBS) and on smoked salmon at different storage temperatures and evaluated its impact on food quality. The results show that riboflavin-mediated LED illumination in PBS 25 °C significantly inactivated L. monocytogenes cells by 6.2 log CFU/mL at 19.2 J/cm2, while illumination alone reduced 1.9 log CFU/mL of L. monocytogenes populations at 57.6 J/cm2. L. monocytogenes populations on illuminated smoked salmon decreased by 1.0-2.2 log CFU/cm2 at 1.27-2.76 kJ/cm2 at 4, 12, and 25 °C, regardless of the presence of riboflavin. Although illumination with and without riboflavin caused the lipid peroxidation and color change in smoked salmon, this study demonstrates the potential of a 405 nm LED to preserve the smoked salmon products, reducing the risk of listeriosis.

Physicochemical, functional and structural properties of the major protein fractions extracted from Cordyceps militaris fruit body.

The physicochemical and functional as well as structural properties of major protein fractions (albumin, globulin, glutelin) sequentially extracted in water, salt, alkaline solution respectively from Cordyceps militaris Minfu20 fruit body were investigated. The glutelin (43.11%, w/w) was the predominant protein component of C. militaris fruit body followed by albumin (36.47%) and globulin (17.94%). The three proteins extracted from different solvents showed different characteristics, which were related to the alternation of amino acid composition, surface hydrophobicity, and structural feature. Sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) showed that the albumin and globulin mainly consisted of polypeptides with size < 20 kDa. The glutelin showed serious staining on the lane which may have a relatively bigger molecular weight. Intrinsic fluorescence intensity (FI) suggested glutelin contained more unfolding conformations (highest FI) which were probably resulted in a better foaming capacity of 151% and emulsion formation with the smallest size oil droplets (10.410 µm). The protein fractions showed great nutritional quality since they satisfied all recommended essential amino acid allowances for adults of Food & Agriculture Organization (FAO)/World Health Organization (WHO). Therefore, Cordyceps militaris Minfu20 fruit body proteins have potential alternative renewable edible fungi (mushroom) protein and could be used effectively as a food ingredient to improve food nutrition and product diversification compared with plant proteins.