Umami taste and its association with energy status in harvested Pleurotus geesteranus stored at different temperatures

Changes in quality, endogenous enzyme activities, and their relationships during post-harvest storage of Phlebopus portentosus- an edible fungus

The postharvest quality of Phlebopus portentosus, a valuable edible fungus, is highly susceptible to spoilage due to endogenous enzymes during storage. This study investigated changes in firmness, weight loss, color, browning degree, malondialdehyde concentration, oxidation level, enzyme activities, and volatile compounds in P. portentosus during storage at 4 °C and 25 °C, alongside their interrelationships. Both storage conditions exhibited similar trends in quality deterioration, with slower changes at 4 °C and a critical turning point observed on the 4th day. The activities of polyphenol oxidase (PPO), peroxidase (POD), lipoxygenase (LOX), and phenylalanine ammonia-lyase (PAL) increased during storage, significantly impacting browning, oxidation, and volatile compounds, as confirmed by Pearson correlation analysis. These enzymes might be key factors affecting the postharvest quality of P. portentosus. This study would provide a theoretical basis for the development of post-harvest preservation techniques for P. portentosus.

Comparative analyses of Pleurotus pulmonarius mitochondrial genomes reveal two major lineages of mini oyster mushroom cultivars

Pleurotus pulmonarius, commonly known as the mini oyster mushroom, is highly esteemed for its crisp texture and umami flavor. Limited genetic diversity among P. pulmonarius cultivars raises concerns regarding its sustainable industrial production. To delve into the maternal genetic diversity of the principal P. pulmonarius cultivars, 36 cultivars and five wild isolates were subjected to de novo sequencing and assembly to generate high-quality mitogenome sequences. The P. pulmonarius mitogenomes had lengths ranging from 69,096 to 72,905 base pairs. The mitogenome sizes of P. pulmonarius and those of other mushroom species in the Pleurotus genus showed a significant positive correlation with the counts of LAGLIDAG and GIY-YIG homing endonucleases encoded by intronic open reading frames. A comparison of gene arrangements revealed an inversion of a fragment containing atp9-nad3-nad2 between P. pulmonarius and P. ostreatus. The mitogenomes of P. pulmonarius were clustered into three distinct clades, two of which were crowded with commercial cultivars. Clade I, all of which possess an inserted dpo gene, shared a maternal origin linked to an ancestral cultivar from Taiwan. Primers were designed to target the dpo gene, potentially safeguarding intellectual property rights. The wild isolates in Clade III exhibited more divergent mitogenomes, rendering them valuable for breeding.

The Role of Camellia Shell Substrates in Modulating the Nutritional Characteristics of Pleurotus pulmonarius

Camellia shells are the main by-product of camellia seed processing and are usually incinerated or disposed of as agricultural waste. In this study, camellia shells were employed in the Pleurotus pulmonarius cultivation process using five distinct formulae substituting for cottonseed shells. Our results show that as the substitution rate of camellia shells increased from 0% to 35%, the protein content in P. pulmonarius significantly increased from 34.05% to 53.35%. The polysaccharide content reached a peak value of 5.62% at 30% substitution of camellia shells. The DPPH free radical scavenging rate reached its maximum of 82.70% at 20% substitution of camellia shells. Furthermore, increases in the total amino acid contents in P. pulmonarius were positively correlated with the substitution rate of camellia shells. Considering the yield characteristics, the formula of 20% camellia shell substitution tested in this study appears to be optimal for P. pulmonarius cultivation. These findings not only provide a substrate to enhance the nutritional quality of P. pulmonarius but also demonstrate a novel approach for the ecological utilization of camellia shells.

Investigating the Respiratory and Energy Metabolism Mechanisms behind ε-Poly-L-lysine Chitosan Coating's Improved Preservation Effectiveness on Tremella fuciformis

Freshly harvested Tremella fuciformis contains high water content with an unprotected outer surface and exhibits high respiration rates, which renders it prone to moisture and nutrient loss, leading to decay during storage. Our research utilized ε-poly-L-lysine (ε-PL) and chitosan as a composite coating preservative on fresh T. fuciformis. The findings revealed that the ε-PL + chitosan composite coating preservative effectively delayed the development of diseases and reduced weight loss during storage compared to the control group. Furthermore, this treatment significantly decreased the respiration rate of T. fuciformis and the activity of respiratory metabolism-related enzymes, such as alternative oxidase (AOX), cytochrome c oxidase (CCO), succinic dehydrogenase (SDH), 6-phosphogluconate dehydrogenase, and glucose-6-phosphate dehydrogenase (6-PGDH and G-6-PDH). Additionally, the composite coating preservative also delayed the depletion of ATP and ADP and maintained higher levels of the energy charge while preserving low levels of AMP. It also sustained heightened activities of Mg2+-ATPase, Ca2+-ATPase, and H+-ATPase enzymes. These results demonstrate that utilizing the ε-PL + chitosan composite coating preservative can serve as a sufficiently safe and efficient method for prolonging the shelf life of post-harvest fresh T. fuciformis.

Postharvest of fresh white shimeji mushroom subjected to UV-C radiation

This study aimed to evaluate the postharvest characteristics of edible fresh white shimeji mushrooms under different UV-C radiation doses. The experimental design used was fully randomized, in a 5 × 8 factorial scheme (UV-C radiation dose: 0 (control), 1, 2, 3, and 4 kJ m-2 x day of analysis), with 3 replications of 70 ± 1 g mushrooms each. After exposure to different doses, they were stored at 2 ± 0.5 °C and 60 ± 3.8 % RH. Data were subjected to permutational multivariate analysis (PERMANOVA) (p ≤ 0.05). There was no significance for interaction, nor the factor day, only for the UV-C radiation doses factor. Regarding PCA, among the doses applied, the dose of 2 kJ m-2 was effective in maintaining the quality of mushrooms with greater lightness, greater whiteness index, a greater amount of total extractable polyphenols, and total antioxidant activity. In conclusion, the dose of 2 kJ m-2 was effective in maintaining the postharvest quality of white shimeji mushrooms.

Effect of sugar reduction on sensory characteristics of dried fish mince product

BACKGROUND

Excessive sugar consumption has been linked to type 2 diabetes, obesity and other diseases. Therefore, it is indispensable to reduce sugar of food. However, the sensory characteristics of food are affected after sugar reduction (SR). Currently, SR has been reported in drinks, jams, candies, and other fruit related or sweet foods; but salty or protein related foods have not been explored, therefore there is a big gap that needs to be filled.

RESULTS

Sensory scores of initial sweetness and sweetness reduced by 0.26 and 0.12 in 10% SR dried fish mince product compared with control, and there was a small difference between 25% SR (3.33) and 40% SR (3.09) samples. It also showed that 10% SR sample had a small reduction in sweetness value and free sugar content by 3.5% (0.42/11.9) and 7.8% (2.12/27.06) compared with control; while values in 25% SR sample decreased sharply but were not much different from 40% SR sample. Electronic nose results showed that SR had a small effect on odor. Texture analysis showed that texture properties of 25% SR sample were significantly different from control.

CONCLUSIONS

Dried fish mince product with below 10% SR had a small difference on the sensory characteristics and there was a big change when SR was more than 20%. Dried fish mince product with 25% SR and 40% SR had no significant difference. SR had a small effect on odor, but had a great effect on texture properties, especially over 20% SR. © 2023 Society of Chemical Industry.

Influence of Storage Temperature on Levels of Bioactive Compounds in Shiitake Mushrooms (Lentinula edodes)

Shiitake mushroom (Lentinula edodes) hold high nutritional and medicinal value as they contain an abundance of health-promoting compounds. However, the effect of long-term postharvest storage on the variation in the levels of health-promoting compounds has not been extensively studied. In this study, we investigated the changes in the levels of phenolic compounds, antioxidants, eritadenine, and ergothioneine in shiitake mushrooms stored at three different temperatures (1, 3, and 5 °C) for 4 weeks. Compared to mushrooms stored at lower temperatures, those stored at 5 °C exhibited a higher level of total phenolics in their pileus after 2 weeks of storage; however, storage at 5 °C also increased the deterioration of the fruiting body of these mushrooms. In mushrooms stored at all temperatures, the eritadenine content in the pilei tended to increase up to 2 weeks of storage. In contrast, the ergothioneine content in the pileus decreased during storage, with a significantly lower level detected in mushrooms stored at 5 °C for 4 weeks. Together, these results suggest that the mechanisms underlying the accumulation of phenolics and eritadenine may be related to mushroom deterioration during storage. Our findings indicate that the levels of health-promoting compounds in shiitake mushrooms are influenced by storage temperature, suggesting the potential to control adjustments of specific bioactive compounds by regulating storage conditions.

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

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

Effects of continuous enzymolysis on the umami characteristics of Lentinula edodes and the flavor formation mechanism of umami peptides

The purpose of this study was to explore the effect of continuous enzymolysis on the umami characteristics of Lentinula edodes and illuminate the umami mechanism of peptides. The results indicated that the continuous enzymolysis extracts (LFTE) of L.edodes had higher umami intensity and palatability than the water extracts (LWE). ¹H NMR and LC-MS/MS were used to evaluate taste metabolites and peptide profiles. Among the identified peptides, LPGVAE, LDELEK, DVELSK, LPDEAR, and TTLPDK with high umami scores which threshold in the range of 0.091-0.371 mmol/L were screened by iUmami-SCM and BIOPEP-UWM, and further verified by sensory evaluation. The results of molecular docking suggested that Ser148, Asn150, Ser276, Ser278 of T1R1 and Asn68, Val277, Ala302, Ser306 of T1R3 played a key role in the umami peptides docking. The study revealed continuous enzymolysis of L.edodes could obtain more umami substances and umami peptides, which laid a foundation for researching flavor substances and developing flavor products from L.edodes.

The grading quality markers identification of Panax notoginseng under the guidance of traditional experience using untargeted metabolomics and anti-myocardial ischemia evaluation of zebrafish

BACKGROUND

Panax notoginseng (PN) was an edible Chinese herbal medicine. PN's current quality control standard cannot precisely match the traditional grading experience.

PURPOSE

In this study, under the guidance of the traditional grading experience, the combined metabolomics and biological effect evaluation were used to reveal the distinct chemical quality of PN.

METHODS

The quality of PN was evaluated by traditional experience and characterized by the electronic tongue. A zebrafish myocardial ischemia model was developed to verify the grading experience. The untargeted metabolomics method was used to identify and validate the grading markers of PN.

RESULTS

The taste was the critical indicator for classifying the quality. Based on the experience sensory scores (ranged from 47.0 to 87.8), PNs could be divided into two grades. The experience scores were significantly associated with umami and richness of the electronic tongue(p<0.01). Besides, superior PN showed substantially stronger anti-myocardial ischemia activity(p<0.001). Thirty-nine differential components were found using UHPLC-LTQ-Orbitrap MS, of which 22 were identified. A new kind of grading quality markers alkynols in PN-associated efficacy was identified, which revealed stronger anti-myocardial ischemia activities than saponin.

CONCLUSION

This study evaluated PN through untargeted metabolomics and anti-myocardial ischemia evaluation of zebrafish and proposed the critical role of alkynols in PN's quality classification.

Variations of nonvolatile taste components of mushrooms with different operating conditions and parameters from farm to fork

Mushroom is a sustainable food option and a meat substitute which yet needs some strategies to enhance sensory attributes. Especially, their taste characteristics (nonvolatile taste components: soluble sugars, organic acids, free amino acids, and 5'-nucleotides) can vary significantly due to operating conditions and parameters during different stages from farm to fork. This review is aimed to provide an overall view of the determined effects of operating conditions and parameters for mushroom taste attributes, suggestions for future research from lacking variables, and some recommendations for improving the taste perception of mushrooms. Taste compounds of mushrooms alter differently based on cultivation (species, cultivation or maturity stage, substrate composition, part, grade, mycelium strain), cooking (cooking method, time, temperature), preservation, and post-harvest storage conditions (drying parameters, pretreatment, preservation method, gamma irradiation, packaging, storage time and temperature). The dominant tastes of mushrooms given by sweet and umami taste active substances can be enhanced significantly with proper control of parameters during cultivation, cooking, drying, or post-harvest storage. The parameters and variations organized in this review can be used to develop a mathematical model for obtaining optimum taste attributes of mushrooms and mushroom-based meat alternatives and to discover the variables of mushroom species not studied yet.

Determination of umami compounds in edible fungi and evaluation of salty enhancement effect of Antler fungus enzymatic hydrolysate

The demand for low-salt foods is increasing due to their health benefits. Umami is known to enhance salty, and a large amount of umami components have been identified in edible fungi. 5'-nucleotides and umami amino acids from nine species of edible fungi were quantified. The equal umami concentration (EUC) in nine edible fungi was within the range of 37.7-1317.72 g MSG/100 g, and umami intensity as determined by electronic tongue and sensory evaluation was within the range of 11.22-13.53 and 2.85-5.55, respectively. Antler fungus had the highest umami intensity. Umami amino acids and nucleotides could increase salty intensity of NaCl at medium and high concentrations. The enzymatic hydrolysate of Antler fungus at higher concentrations could more effectively enhance salty taste of NaCl at lower concentration. This synergistic effect between umami and salty indicates that Antler fungus can potentially be used as an ingredient in low-salt foods.

Improved Foods Using Enzymes from Basidiomycetes

Within the kingdom of fungi, the division Basidiomycota represents more than 30,000 species, some with huge genomes indicating great metabolic potential. The fruiting bodies of many basidiomycetes are appreciated as food (“mushrooms”). Solid-state and submerged cultivation processes have been established for many species. Specifically, xylophilic fungi secrete numerous enzymes but also form smaller metabolites along unique pathways; both groups of compounds may be of interest to the food processing industry. To stimulate further research and not aim at comprehensiveness in the broad field, this review describes some recent progress in fermentation processes and the knowledge of fungal genetics. Processes with potential for food applications based on lipases, esterases, glycosidases, peptidases and oxidoreductases are presented. The formation and degradation of colourants, the degradation of harmful food components, the formation of food ingredients and particularly of volatile and non-volatile flavours serve as examples. In summary, edible basidiomycetes are foods—and catalysts—for food applications and rich donors of genes to construct heterologous cell factories for fermentation processes. Options arise to support the worldwide trend toward greener, more eco-friendly and sustainable processes.

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

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

Relationship between flavor and energy status in shiitake mushroom (Lentinula edodes) harvested at different developmental stages

To understand the relationship between flavor and energy, the flavor, energy, and enzyme activity related to energy metabolism in shiitake mushrooms harvested at different developmental stages were investigated. The results indicated that the adenosine triphosphate level increased significantly in developing mushrooms and was strongly correlated with the fresh weight. The levels of equivalent umami concentration (EUC), total aroma compounds, energy charge, adenosine triphosphatase, cytochrome c oxidase, and succinic dehydrogenase varied with maturity. In addition, a strong correlation was observed between aroma compounds, EUC, and energy status (p < 0.05). Our results suggest that the unique flavor of developing shiitake mushroom is closely related to energy. The findings may provide a new strategy to improve the flavor of mushrooms by regulating their energy levels. PRACTICAL APPLICATION: The unique flavor of shiitake mushroom, which has a significant impact on consumer preferences, is one of its key characteristics. This research paper provides a theoretical foundation for determining the optimal harvest period for shiitake mushrooms with high quality and a new strategy to improve the flavor of mushrooms by regulating their energy levels.

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

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

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

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

Effects of fermentation with Lactiplantibacillus plantarum GDM1.191 on the umami compounds in shiitake mushrooms (Lentinus edodes)

Shiitake mushroom (Lentinus edodes) is the second most-widely-consumed edible fungi with strong flavor and unique taste. To study the effects of Lactiplantibacillus plantarum fermentation on umami compounds in shiitake mushrooms, the levels of taste-imparting compounds were analyzed, including organic acids, free amino acids, and 5'-nucleotides during fermentation. The contents of all umami compounds except for succinic acid and fumaric acid were improved with increasing fermentation time; broths obtained at each fermentation stage formed clear clusters upon subjecting the electronic tongue data to principal component and discriminant function analyses. Compounds that predominantly contributed to important umami were identified. Among the 30 umami compounds investigated, 11 compounds were considered to be predominantly responsible for the different taste characteristics of shiitake mushroom broths at various stages of fermentation. Taken together, L. plantarum fermentation improved the contents of umami taste compounds in shiitake mushroom.

Microflora and umami alterations of different packaging material preserved mushroom (Flammulina filiformis) during cold storage

In order to clarify the effect of nanocomposite-based packaging (NP) on umami and microflora characteristics of F. filiformis during cold storage, the contents of umami amino acids and 5'-nucleotides, equivalent umami concentration (EUC), and microflora succession were investigated. Results showed that NP could delay the degradation of umami components and inhibit bacterial growth in F. filiformis. At the initial stage, the dominant bacteria were Lactobacillus, Thermus and Acinetobacter. After 15 days of storage, the bacteria count in NP reached 7.63 lg cfu/g, which was significantly (P < 0.05) lower than that in control, and the major bacterial communities of packaged F. filiformis were Ewingella, Serratia and Pseudomonas. Moreover, the correlation analysis showed that Lactobacillus, Brevibacillus and Okibacterium were negatively correlated with AMP and IMP 5-nucleotides. Present work suggested that NP could enhance the umami flavor formation and improve the microbial community structure of F. filiformis, resulting in a better commercial quality. The results provided theoretical basis for large-scale applications of NP.

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.

Analysis on the Fatty Acids and Volatile Components in Pleurotus geesteranus by HS-SPME-GC-MS

The volatile constituents and fatty acids in Pleurotus geesteranus were assayed by headspace solid-phase microextraction coupled with GC-MS. There were 5 volatile compounds in P. geesteranus that accounted for 43.43% of the total ion current peak area, and its main compounds were 2-undecanone (13.99%), 3-ethyl-2,5-dimethyl pyrazine (12.67%), and l-β-bisabolene (6.79%). Fourteen compounds were identified in the ethanol extract of P. geesteranus and 6 fatty acids were identified from the petroleum ether extract, which accounted for 93.72% and 98.48% of the total ion current peak area, the main compounds in the ethanol extract were ethyl linoleate (67.36%) and ethyl palmitate (21.83%), and the main fatty acids in the petroleum ether extract were linoleic acid (78.22%), palmitic acid (10.74%), and oleic acid (8.13%).