Mushroom Agaricus Bisporus Research Articles

Natural Strain Observation of Button Mushroom (Agaricus bisporus) from South Africa Using 18S rDNA

Natural Strain Observation of Button Mushroom (Agaricus bisporus) from South Africa Using 18S rDNA

Green facile synthesis of cajuput (Melaleuca cajuputi Powell.) essential oil loaded chitosan film and evaluation of its effectiveness on shelf-life extension of white button mushroom

This study reports first time investigation on efficacy of cajuput essential oil loaded chitosan nanoparticle (CjEO-CSNP) on shelf-life of white button mushroom (Agaricus bisporus) stored at 4±1 °C for 7-days. CjEO-CSNP was characterized through scanning electron microscopy, X-ray diffraction, and dynamic light scattering. The nanoparticles exhibited spherical shapes with average particle size 43.17–97.03 nm. The nanoencapsulation efficiency and loading capacity were ranged between 45.86 and 92.26% and 0.69–8.87%, respectively. The release study confirmed that CjEO-CSNP showed biphasic release patterns at different pH. Positive results were unveiled when the effect of CjEO-CSNP on shelf-life of mushroom was validated by analyzing the visual appearance and firmness. Further, CjEO-CSNP prevented weight loss and respiration rate, and improved the antioxidant activity of mushrooms. CjEO-CSNP also exhibited high safety profile (LD50= > 1200 mg/Kg body weight) without altering the sensory quality of coated mushrooms. Overall, CjEO-CSNP might be used as promising candidate to lengthen the shelf-life of button mushroom.

The impact of roasting and steaming on savory flavors contributed by amino acids, 5′-nucleotides, and volatiles in Agaricus bisporus mushrooms

Mushrooms have been used to enhance meat flavor, although studies regarding cooking approach and mushroom type impact on savory flavors are limited. This study aimed to compare taste-related compounds (free amino acids and 5′-nucleotides) and volatile aromas in raw, steamed, and roasted white and crimini Agaricus bisporus mushrooms. Using gas chromatography–mass spectrometry (GC–MS) and high-performance liquid chromatography–ultraviolet detection (HPLC–UV), 22 free amino acids were quantified. Glu (umami taste) was the most dominant amino acid in both raw and cooked white and crimini, while Asp (umami taste) content was much lower. These mushrooms also contained all essential amino acids and other sweet- and bitter-related amino acids. Five 5′-nucleotides were quantified using HPLC–UV, with 5′-GMP (umami taste) being the most dominant, followed by 5′-CMP and 5′-UMP (tasteless). Cooking significantly decreased free amino acids by 7-14 times and 5′-nucleotides by 3-8 times. GC–MS identified 125 volatiles in total, with only around 45 of those presenting in raw mushrooms. Cooking increased almost all volatiles by number and quantity (20–68 times). Variety difference was minimal for free amino acids and 5′-nucleotides, whereas it was more obvious for volatiles. These results demonstrated how cooking impacted mushroom free amino acids, 5′-nucleotides, and volatiles, providing evidence for mushroom savory flavor changes due to cooking.

Transcriptomic analysis reveals the mechanism of bacterial disease resistance of postharvest button mushroom (Agaricus bisporus)

Brown blotch disease caused by Pseudomonas tolaasii infection is one of the major problems affecting the storage quality of postharvest button mushrooms (Agaricus bisporus). In this study, P. tolaasii treatment accelerated the accumulation of pathogen resistance-related substances/proteins, induced disease resistance-related enzyme activities, and promoted the increase of jasmonic acid (JA) during the whole storage. To gain full insight into the defense mechanisms of button mushrooms against P. tolaasii, a transcriptomics analysis of mushroom samples at 12 h was conducted. A total of 2861 differentially expressed genes (DEGs) were identified, among which there were 1557 up-regulated and 1304 down-regulated genes. Further bioinformatic analysis showed that P. tolaasii inoculation mainly activated shikimate pathway, phenylpropanoid metabolism, sulfur metabolism, methane metabolism, arginine and proline metabolism, cysteine and methionine metabolism, JA biosynthesis and signaling pathways, as well as oxidative phosphorylation pathways. Transcriptomics data combined with qPCR verification indicated that 10 DEGs including PIP1, MET3, AGX, PAL1, GCL, LOX 1/3, PR-like, MYB3R, UCR, and SDHB are the most potential genes involved in the early defense of A. bisporus against P. tolaasii. Additionally, taking the physiological and transcriptomics results together, the existence and important participation of JA biosynthesis and signaling pathways were demonstrated in the disease resistance of A. bisporus, although this organism probably possesses different catalyzing enzymes and transduction pathways with plants. In a word, our findings revealed the mechanism of the button mushroom's early defense response against pathogens, providing a reference for the development of rational approaches to control of mushroom diseases.

Effect of Sterility Values and Retort Temperatures on the Antioxidant Activities, Soluble Protein, and PH of Canned Mushroom

This research aimed to study the effect of sterility values on antioxidant activity, soluble protein, and pH of canned Agaricus bisporus mushrooms processed at various retort temperatures (115, 121, and 130 °C) and processing times (2-97 minutes). The canning process was carried out by following commercial production procedures in one of the mushroom canning industries. Measurement of heat penetration into the product was carried out using a standard protocol. The sterility values (F0-value) were calculated using the General Method. Our results indicate that antioxidant activity, soluble protein contents, and pH of canned mushrooms are not only affected by sterility value but also by the combination of temperature and time used to process the product. At the same F0-value of 10 minutes, retorting of A. bisporus mushroom at a higher retort temperature (130 °C) resulted in higher antioxidant activity (RSA 73.73%) and soluble protein contents (24.1 mg/g), but resulted in lower pH-value as of (5.5±0.04 in drained liquid and 6.52±0.21 in drained solid) than other retort temperature of 115 and 121 °C. Since retort temperature is crucial parameters of chemical quality of product attributes in the canning industry, the selection of higher temperatures and shorter time of retorting will have a positive impact on quality parameter such as antioxidant activity and total soluble protein.

Environmental and economic assessment of food additive production from mushroom bio-residues

This work analysed the environmental and economic impacts of extracts enriched in ergosterol and vitamin D 2 production from bio-residues of Agaricus Bisporus mushrooms. The main hotspots of the extractive processes in environmental terms were identified through the standardized methodology Life Cycle Assessment. In respect to the economic analysis, the Material Flow Cost Accounting approach was applied to identify production costs, distinguishing between valued and wasted costs. The LCA results showed that electricity consumption is a key factor in environmental aspects, having the highest contribution to the process's environmental impact. In general, the most electricity-consuming unit processes analysed were lyophilization, extraction and evaporation. Despite evaporation being a process with great energy consumption, it also mitigates environmental impacts, since it allows solvent recovery through the extraction and reutilization phases in new iterations. The production costs for the identified extracts were determined: extract enriched in ergosterol (2.43€/1 g of extract) and extract enriched in vitamin D 2 (8.28€/1 g of extract). Recovered solvent incorporation in posterior iterations resulted in a total cost decrease of about 47% for ergosterol-extract and about 39% for vitamin D 2 extract. Solvent's recovery and reutilization allowed to not only reduce the environmental impacts but also the production costs.

Optimization of Osmotic Dehydration of White Mushrooms by Response Surface Methodology for Shelf-Life Extension and Quality Improvement of Frozen End-Products.

Button mushrooms (Agaricus bisporus), one of the most common edible mushroom species, are sensitive to damages because of the absence of a protective skin layer and have a limited shelf life. Osmotic dehydration (OD), mainly used as a pre-processing step of conventional preservation methods, has been proposed as an efficient, mild treatment to preserve mushroom superior quality. In this study, response surface methodology, coupled with a Box–Behnken design, was used to investigate the effect of glycerol concentration (30–50%), temperature (30–50 °C), and duration of osmosis (0–180 min) in order to optimize the process prior to a subsequent freezing step. For each response, including mass transfer and selected quality indices, a second-order polynomial model was developed, and all process factors were found to have a significant impact. Based on the desirability approach and pre-set criteria, optimum operating conditions were estimated, namely osmosis at 50 °C, for 120 min, with a 42% glycerol solution, and the corresponding validation experiments were performed. Based on the error estimated between experimental and predicted values, polynomial equations were found to adequately predict parameter values. Based on a shelf-life test under frozen storage, OD-treated samples retained better quality attributes compared to their untreated counterparts.

Ohmic heating blanching of Agaricus bisporus mushroom: Effects on polyphenoloxidase inactivation kinetics, color, and texture

The effect of ohmic heating blanching (OHB) on the inactivation kinetics of polyphenol oxidase (PPO), color, and texture from Agaricus bisporus mushroom treated at different temperatures (67–90 °C) for 1 to 5 min was investigated in the present work. OHB and conventional blanching (CB) treatments were able to inactivate mushroom PPO. However, the inactivation kinetics results showed a lower energy activation (Ea) value during OHB (16.03 ± 1.34 KJmol-1) compared to conventional blanching (20.07 ± 1.85 KJmol-1). Significant differences were observed in color (L*, h° and ΔE) and mushroom texture between the blanching treatments. Nevertheless, both treatments caused minimal physicochemical changes. Therefore, OHB is a promising technology for mushroom blanching because it promotes PPO inactivation in less time and reduces the impact on the color and texture of mushrooms compared to CB.

Morphological and molecular characterization of some popular cultivated mushrooms of India

Morphological and molecular characterization of some popular cultivated mushrooms of IndiaSanjeev Kumar1*, Anand Sagar2, Shwet Kamal3 and Jagriti Rana41. Associate professor, Govt. College Bilaspur.2. Dean of Life Sciences, H.P. Univ.. Shimla. 3. Principal Scientist, DMR Solan.4. PhD research Scholar, Department of Biosciences, H.P. Univ.Shimla.* Corresponding author, E-mail: sanjeev5112@gmail.com +919418045021 AbstractThe mushroom cultivation is a highly lucrative agribusiness to produce nutritious food and earn money in short space and time. The present studies were conducted to analyze morphological and molecular characteristics of five cultivated strains of mushrooms Agaricus bisporus (NBS-5), Calocybe indica (DMRO-302), Flammulina velutipes (DMRO-253), Pleurotus florida (DMRP-136) and Volvariella volvacea (DMRO-484). The fruiting bodies were procured from ICAR-Directorate of Mushroom Research, Solan, HP (India) and screened for morphological and molecular details. Macroscopic features like shape, size and colour of stipe and pileus were recorded. Microscopic details were worked out by cutting free hand sections of material and observed under research microscope and scanning electron microscope. Molecular identification was done through internal transcribed spacer (ITS) regions of ribosomal DNA sequencing. The nucleotide sequences of each sample were analyzed for Basic local Alignment Search Tool (BLAST) search program in US National Centre for Biotechnology Information (NCBI) for identification. The DNA sequences obtained in this study were submitted in the Gen Bank database at NCBI with accession numbers MW718994.1 (A. bisporus), MW714627.1 (C. indica), MW719474.1 (F. velutipes), MW719254.1 (P. florida) and MW720603.1 (V. volvacea).Keywords: Mushroom, Molecular identification, ITS, rRNA, Nucleotide sequencing, Gen Bank database

Utilisation of waste Agaricus bisporus and Torreya grandis as potential natural additive coating in Agaricus bisporus preservation

Natural additives obtained from vegetable and fruit wastes can potentially be used as coatings to enhance the shelf life of button mushrooms (Agaricus bisporus). The present study was therefore conducted to assess the effects of natural additive coatings A. bisporus polysaccharides (ABP) and Torreya grandis essential oils (TEO) on the post-harvest quality of button mushrooms up to 16 days under cold storage (4 °C). Different concentrations for coatings were used including control (no additives), 500, 1 000, 5 000 ppm or a combination of ABP and TEO. Changes in weight loss, firmness, polyphenol oxidase (PPO) activity and microbial biomass were investigated as well as the sensory evaluation was carried out. Results show a significant decrease in the weight loss rate (decreased up to 2.34%), down regulated the PPO activities (reduced up to 30.15%) and maintained tissue firmness in ABP/TEO treatments compared to the control, whereas TEO inhibited especially the growth of microorganisms. Natural additive coatings can better protect the inner mushroom colour and flavour compared to the control.

Safety of vitamin D2 mushroom powder as a Novel food pursuant to Regulation (EU) 2015/2283 (NF 2019/1471).

Following a request from the European Commission, the EFSA Panel on Nutrition, Novel Foods and Food Allergens (NDA) was asked to deliver an opinion on vitamin D2 mushroom powder as a novel food (NF) pursuant to Regulation (EU) 2015/2283. The NF is produced from Agaricus bisporus mushroom that has been exposed to ultraviolet (UV) irradiation to induce the conversion of provitamin D2 (ergosterol) to vitamin D2 (ergocalciferol). The NF contains levels of vitamin D in the form of vitamin D2 in the range of 125–375 µg/g. The information provided on the production process, composition and specifications of the NF does not raise safety concerns. The applicant intends to add the NF as an ingredient in a variety of foods and beverages in amounts that result in either 1.125 or 2.25 µg vitamin D2 per 100 g or 100 mL of the food as consumed. The applicant also intends to add the NF in food supplements, for infants from 7 to 11 months at a maximum of 10 µg vitamin D2/day and of 15 µg vitamin D2/day for individuals aged 1 year or older, as well as in foods for special medical purposes (FSMPs) and total and meal diet replacement for weight control. For the adult population, the maximum intended use level in FSMPs is 15 µg vitamin D2/day and 5 µg vitamin D2/meal in total and meal diet replacement for weight control. The Panel concludes that the NF is safe under the proposed conditions of use. The Panel notes uncertainty regarding the calculated combined exposures to vitamin D for the general population, given the fact that the range of foods fortified with vitamin D has increased over the years, as well as the marketing of high‐dose vitamin D supplements.

Dynamics of Changes in pH and the Contents of Free Sugars, Organic Acids and LAB in Button Mushrooms during Controlled Lactic Fermentation.

The aim of the study was to assess changes in the basic quality parameters induced by controlled lactic fermentation of fruiting bodies of the button mushroom (Agaricus bisporus). Lactiplantibacillus plantarum 299v with documented probiotic properties and L. plantarum EK3, i.e., an isolate obtained from spontaneously fermented button mushrooms, were used as starter strains. The fruiting bodies of fresh, blanched, and fermented mushrooms were analyzed at different stages of the lactic fermentation process. The content of free sugars (high-performance liquid chromatography with charged aerosol detector method; HPLC-CAD) and organic acids (high-performance liquid chromatography with diode array detector method; HPLC-DAD) was determined both in the mushroom fruiting bodies and in the brine. Five free sugars (ribose, trehalose, sucrose, glucose, and fructose), mannitol, and six organic acids (lactic, malic, succinic, citric, acetic, and fumaric acids) were detected in the samples. Lactic acid dominated in the final products. The starter cultures exhibited varying degrees of utilization of available mushroom sugars and sucrose used as an additional substrate. Sucrose was utilized at a higher rate and in greater amounts by the L. plantarum EK3 isolate. This starter culture was characterized by a significantly higher final amount of produced lactic acid, a lower pH value, and higher numbers of LAB (lactic acid bacteria). These important quality parameters largely determine the stability of fermented products. Based on the analysis results and the high scores in the organoleptic evaluation of the fermented mushrooms, the L. plantarum EK3 isolate can be recommended as an appropriate starter culture for lactic fermentation of mushroom fruiting bodies.

Management of Green Mold Disease in White Button Mushroom (Agaricus bisporus) and Its Yield Improvement.

Mycoparasites cause serious losses in profitable mushroom farms worldwide. The negative impact of green mold (Trichoderma harzianum) reduces cropping surface and damages basidiomes, limiting production and harvest quality. The goal of the current study was to evaluate new generation fungicides, to devise suitable management strategies against the green mold disease under prevailing agro-climatic conditions. Six non-systemic and five systemic fungitoxicants were evaluated for their efficacy against pathogen, T. harzianum, and host, Agaricus bisporus, under in vitro conditions. Among non-systemic fungicides, chlorothalonil and prochloraz manganese with mean mycelium inhibition of 76.87 and 93.40 percent, respectively, were highly inhibitory against the pathogen. The least inhibition percentage of 7.16 of A. bisporus was exhibited by chlorothalonil. Under in vivo conditions, use of captan 50 WP resulted in a maximum yield of button mushroom of 14.96 kg/qt. So far, systemic fungicides were concerned, carbendazim proved extremely inhibitory to the pathogen (89.22%), with least inhibitory effect on host mycelium (1.56%). However, application of non-systemic fungitoxicants further revealed that fungicide prochloraz manganese 50 WP at 0.1–0.2 percent or chlorothalonil 50 WP at 0.2 percent, exhibited maximum disease control of 89.06–96.30 percent. Moreover, the results of systemic fungitoxicants showed that carbendazim 50 WP or thiophanate methyl 70 WP at 0.1 percent reduced disease to 2.29–3.69 percent, hence exhibiting the disease control of 80.11–87.66 percent. Under in vivo conditions, fungicide myclobutanil at 0.1 percent concentration produced the maximum button mushroom production of 12.87 kg/q.

Characterization of a Novel Protease Inhibitor from the Edible Mushroom Agaricus bisporus.

Protease inhibitors inhibit the activity of protease enzymes; hence, they are essentially involved in the regulation of the metabolic processes involving protease enzymes and the protection of the host organism against external damage due to proteases. These inhibitors are abundantly present in all living organisms but have not been much reported in mushrooms. Mushrooms are one of the major food components of humans, with delicious taste and high nutritional value. Mushrooms also have therapeutic and economic significance. The edible mushrooms with medicinal properties are much in commercial demand. To date, the presence of protease inhibitors has not been reported much in edible mushrooms. The present study reports the characterization of a protease inhibitor isolated from the common white button mushroom Agaricus bisporus. The objective of the present study is to characterize the novel protease inhibitor from Agaricus bisporus in order to determine its nature and activity under varying environmental conditions. The protease inhibitor was characterized through SDS PAGE, gel filtration chromatography, and de novo sequencing in order to determine its molecular mass and sequence, respectively. The optimum pH, temperature, and thermal stability were studied to determine the optimum working range of the protease inhibitor. The protease inhibitory activity (%) was determined in the presence of metal ions, surfactants, oxidizing agents, and reducing agents. The kinetic parameters and the type of inhibition exhibited by the protease inhibitor were determined using casein and trypsin protease enzyme. The protease inhibitor was found to be a low molecular mass compound of 25 kDa. The de novo sequencing matched the inhibitor against a 227 amino acid containing peptide molecular mass of 24.6 kDa molecular mass. The protease inhibitory activity (%) was found highest at pH 7.0 and temperature 50 °C, and the inhibitor was stable from pH 4.0-9.0 and temperature 30-80 °C. In the presence of metal ions, the residual protease inhibitory activity (%) enhanced in the presence of Na+, Mg2+, and Fe3+. The residual activity increased in the presence of the surfactant SDS slightly in comparison to control, while it decreased in the case of Triton-X and Tween 20. The presence of oxidizing agents, hydrogen peroxide and dimethyl sulfoxide decreased the residual inhibitory activity. The protease inhibitor's activity was unaffected by the reducing agents, dithiothreitol and β-mercaptoethanol, at up to 2mM concentration, but it decreased at higher concentrations. The inhibitor exhibited uncompetitive inhibition against trypsin with an inhibitory constant of 166 nM, indicating a strong affinity towards the protease, with a half-life of 93.90 minutes at 37 °C. Protease inhibitors isolated from mushrooms are generally small in size, more stable, and tolerant towards varying external conditions. The protease inhibitor isolated from Agaricus bisporus also exhibited similar characteristics.

RNA-Seq, Bioinformatic Identification of Potential MicroRNA-like Small RNAs in the Edible Mushroom Agaricus bisporus and Experimental Approach for Their Validation.

Although genomes from many edible mushrooms are sequenced, studies on fungal micro RNAs (miRNAs) are scarce. Most of the bioinformatic tools are designed for plants or animals, but the processing and expression of fungal miRNAs share similarities and differences with both kingdoms. Moreover, since mushroom species such as Agaricus bisporus (A. bisporus, white button mushroom) are frequently consumed as food, controversial discussions are still evaluating whether their miRNAs might or might not be assimilated, perhaps within extracellular vesicles (i.e., exosomes). Therefore, the A. bisporus RNA-seq was studied in order to identify potential de novo miRNA-like small RNAs (milRNAs) that might allow their later detection in diet. Results pointed to 1 already known and 37 de novo milRNAs. Three milRNAs were selected for RT-qPCR experiments. Precursors and mature milRNAs were found in the edible parts (caps and stipes), validating the predictions carried out in silico. When their potential gene targets were investigated, results pointed that most were involved in primary and secondary metabolic regulation. However, when the human transcriptome is used as the target, the results suggest that they might interfere with important biological processes related with cancer, infection and neurodegenerative diseases.

Spatial Assessment of Potentially Toxic Elements (PTE) Concentration in Agaricus bisporus Mushroom Collected from Local Vegetable Markets of Uttarakhand State, India.

This study presents a spatial assessment of eight potentially toxic elements (PTE: Cd, Cr, Cu, Fe, Pb, Ni, Mn, and Zn) in white button (Agaricus bisporus J.E. Lange) mushroom samples collected from the local vegetable markets of Uttarakhand State, India. Fresh A. bisporus samples were collected from thirteen districts and fifteen sampling locations (M1-M15) and analyzed for the concentration of these PTE using atomic absorption spectroscopy (AAS). The results revealed that A. bisporus contained all eight selected PTE in all sampling locations. Based on the inverse distance weighted (IDW) interpolation, principal component (PC), and hierarchical cluster (HC) analyses, the areas with a plane geographical distribution showed the highest PTE concentrations in the A. bisporus samples as compared to those in hilly areas. Overall, the decreasing order of PTE concentration in A. bisporus was recognized as Fe > Zn > Mn > Cr > Cu > Ni > Cd > Pb. The Kruskal–Wallis ANOVA tests displayed a highly significant (p < 0.05) difference among the sampling locations. However, the concentration of PTE was below permissible limits, indicating no potential hazard in consuming the A. bisporus. Similarly, the health risk assessment studies using the target hazard quotient (THQ) also showed no significant health risk associated with the consumption of A. bisporus being sold in the local mushroom markets of Uttarakhand, India. This study is the first report on state-level monitoring of PTE in A. bisporus mushrooms, which provides crucial information regarding the monitoring and occurrence of potentially toxic metallic elements.

Effect of micro‐perforated film packing on physicochemical quality and volatile profile of button mushroom ( Agaricus bisporus ) during postharvest shelf‐life

The perishable characteristics of button mushrooms (Agaricus bisporus) decrease the physicochemical and change the flavor profile, affecting consumer purchase. In this study, button mushrooms were separately stored in the package with 0, 2, 4, 8, and 16 perforations for 8 days at 10°C, and whether the micro-perforated film packing delayed button mushrooms the changes in physicochemical quality and volatile profile was investigated. The results showed that 0 perforation packages could maintain the weight and firmness of button mushrooms. Micro-perforated film packing was found effective to decrease the browning index of button mushrooms during shelf-life. In addition, mushrooms in micro-perforation film packing had a lower concentration of 3 off-flavor compounds (2-methylbutanal, 3-methylbutanal, and ethanol) and a higher concentration of 13 mushroom characteristic flavor compounds than that in 0 perforation film when stored for 8 days. The 8 perforations groups had the most varieties of aroma impact compounds (odor active values, OAV ≥ 1), which contributed to the flavor profile of button mushrooms. It is concluded that film with 8 perforations could create an atmosphere condition to maintain the physiology quality and volatile profile of button mushrooms during shelf-life. Novelty impact statement The firmness of the mushroom was maintained due to the ethanol and low oxygen. 2-Methylbutanal, 3-methylbutanal, and ethanol were the main off-flavor compounds.

Survival of Listeria monocytogenes, Bacillus cereus and Salmonella Typhimurium on sliced mushrooms during drying in a household food dehydrator

The historic view on low-moisture foods (LMFs) as safe due to the lack of microbial growth in these foods is challenged by an increasing number of reports of outbreaks and recalls caused by LMFs contaminated with foodborne pathogens. The objective of this study was to determine the survival of Salmonella Typhimurium , Bacillus cereus and Listeria monocytogenes on sliced Portobello mushrooms ( Agaricus bisporus variant Portobello) during hot-air drying (mushroom internal temperature below 45 °C) for 8 h (h) in a small household food dehydrator (250 W) and subsequent storage of the vacuum-packed dried product for 2 months at room temperature. Hot-air drying reduced the water activity (a w ) of the mushrooms to 0.17 ± 0.03 well below the limit for microbial growth. S. Typhimurium and L. monocytogenes displayed total log CFU reductions of 2.5 ± 0.4 and 2.6 ± 0.8, respectively, while B. cereus exhibited significantly ( p < 0.05) lower log reductions of 1.2 ± 0.1. Storage of vacuum-packed dried mushrooms further reduced L. monocytogenes by 2 log CFU, while numbers of viable S. Typhimurium and B. cereus were not further reduced. The higher stability of S. Typhimurium and B. cereus were reflected in the number of reports in the European Rapid Alert System for Food and Feed system of the presence of these organisms in dried mushrooms. All three organisms regrew to high concentrations when dried mushrooms were soaked overnight at room temperature, simulating a scenario where mushrooms are improperly rehydrated. Combining results from hot-air drying and subsequent storage underlines that hot-air drying and prolonged storage at low a w cannot be relied on alone to reduce the microbial and pathogen load on Portobello mushroom. • Hot-air drying reduced the water activity well below microbial growth limits. • Observed inactivation during drying could not reduce reported mushroom pathogen loads. • B. cereus and S. Typhimurium were stable in stored vacuum packed dried mushrooms. • Foodborne pathogens were able to regrow when dried mushrooms were rehydrated. • Hot-air drying and storage at low a w are not sufficient to ensure safety for dried mushrooms.

Isolation and Molecular Characterization of The Pathogens Trichoderma harzianum and Pseudomonas tolaasii on the Edible Mushroom Agaricus bisporus and Evaluation of Some Desert Plant Extracts for Control Them

Seven isolates of Pseudomonas bacteria were isolated from the casing soil and 11 fungal isolates from mushroom farm residues in the mushroom production farm - College of Agriculture , Tikrit University. According to the pathogenicity test, the highest infection rate was recorded by the bacterial isolate 1077, It was diagnosed to the species level as Pseudomonas tolaasii according to the nucleotide sequence of the 16S rRNA gene. It was registered globally in the NCBI website within the accession number MW085029.1, this record is the first for this bacteria in Iraq, while the fungal isolate 1076 showed the highest pathogenicity and this isolate was diagnosed phenotypically to the level of the genus Trichoderma and diagnosed to the level of species T. harzianum according to the nucleotide sequences of the 5.8S rRNA gene and registered globally in the NCBI website within the accession number MW147763.1. In studying the effect of treatments of alcoholic extracts of Atriplex tatarica and Haloxylon salicornicum and their powder in the presence of the pathogenic fungus T. harzianum (Th) and the pathogenic bacteria P. tolaasii (P.t) on the morphological characteristics, infection rate, productivity and quality of mushroom Agaricus bisporus, the results showed that the pathogens had no effect on the most of the morphological characteristics, while the treatment (A. tatarica and H.salicornicum extracts 4 mg/ml + P. tolaasii + T. harzianum) was the best treatment that increased the productivity of the A. bisporus, reduced the severity and rate of infection, and improved of some qualitative characteristics.

Enhancement of vitamin D2 in edible mushroom using ultraviolet irradiation and assessing its storage and cooking stability

Purpose The purpose of this study was to optimize the parameters for enhancing the vitamin D2 formation in three edible mushroom varieties, namely, shiitake mushroom (Lentinula edodes), white button mushroom (Agaricus bisporus) and oyster mushroom (Pleurotus ostreatus) using ultraviolet (UV) irradiation. Design/methodology/approach Freshly harvested mushrooms were irradiated with UV-B and UV-C lamps. Further, mushrooms were treated with UV-B at a distance ranging between 10 and 50 cm from the UV light source, for 15–150 min, to maximize the conversion of ergosterol to vitamin D2. Analysis of vitamin D2 content in mushrooms before and after UV exposure was done by high pressure liquid chromatography (HPLC). Findings HPLC results showed a significant (p &lt; 0.001) increase in vitamin D2 levels of shiitake (17.3 ± 0.35 µg/g), button (24.9 ± 0.71 µg/g) and oyster (19.1 ± 0.35 µg/g) mushrooms, irradiated with UV-B at a distance of 20–30 cm for 120 min. Further, stability studies revealed that vitamin D2 levels in UV-B-irradiated mushrooms gradually increased for 48 and 72 h of storage at room and refrigeration temperatures, respectively. During cooking operations, 62%–93% of vitamin D2 was retained in UV-B-irradiated mushrooms. Originality/value This study describes the most effective parameters such as ideal wavelength, mushrooms size, duration of exposure and distance from UV sources for maximum vitamin D2 formation in edible mushrooms using UV irradiation. Further, assessment of vitamin D2 stability in UV exposed mushrooms during storage period and cooking operations has been carried out. In addition, this study also provides a comparison of the vitamin D2 levels of the three widely cultivated and consumed mushroom varieties treated simultaneously under similar UV exposure conditions.