The Glucans Mushrooms: Molecules of Significant Biological and Medicinal Value
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis study shows a significant correlation between the structure, biological activity, and extraction techniques of fungal polysaccharides. To ensure that they covered a sufficient amount of the available bibliography, the authors must clarify the process by which they chose the literature for the paper. Furthermore, because this is only a general overview, there are still some unanswered questions about the benefits and mechanisms of action of these polysaccharides in humans.
Author Response
This study shows a significant correlation between the structure, biological activity, and extraction techniques of fungal polysaccharides. To ensure that they covered a sufficient amount of the available bibliography, the authors must clarify the process by which they chose the literature for the paper.
Response to Reviewer: Thanks to your suggestion, the authors, in order to clarify the process by which they chose the literature for the paper, have decided to include the following section in the manuscript: "2. Methodology" (page 2).
Furthermore, because this is only a general overview, there are still some unanswered questions about the benefits and mechanisms of action of these polysaccharides in humans.
Response to Reviewer: We would like to express our gratitude to the Reviewer for the valuable comments, which have significantly enhanced the quality of our manuscript. Accordingly, the benefits and mechanisms of action of β-glucans in humans have been addressed in Sections 4 and 5.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsFlores et al., have written a review regarding the use of mushroom polysaccharides for nutraceutical applications. This field of research certainly is an interesting and widely investigated relevant topic and therefore this manuscript *could* merit publication in polysaccharides. However, there are multiple issues in the current version of this manuscript that do not allow publication at this stage. First of all, the title states mushroom polysaccharides but it is clear from the manuscript that the authors primarily discuss the glucan part of the polysaccharides present in the mushrooms. Therefore the title is not really accurate with the content of the manuscript. Secondly, the review reads like a textbook. The authors state that the novelty is in the most recent literature, but throughout the text almost no quantitative statements are given of the recent literature. Thirdly, a lot of statements that are made in the text are sometimes contradictory or not correct. Overall this manuscript requires an extensive revision and needs to be extended to allow publication in Polysaccharides. Herewith are my comments:
- Please capitalize all keywords (since polysaccharides is capitalized).
- Line 50-51: “Fungi can be sustainably cultivated to produce polysaccharides, which offers a significant advantage”. This statement is rather vague. A lot of products can be grown sustainably if wanted/needed.
- Why do the authors not zoom in on chitin in section 2: “Structure and function of polysaccharides”? Chitin is one of the most important polysaccharides in the fungal cell wall that make mushroom/fungi unique offering a vegan alternative to chitin derived from insects/crustaceans. Therefore, why is this not addressed in section 2 (since it is mentioned in the introduction section briefly).
- Lines 113-114: “Since polysaccharides are easily soluble in hot water but insoluble in organic solvents and cold water, hot water extraction is required for polysaccharides.” This statement is not entirely correct. This depends on the type of polysaccharide you want to extract. Native glucans and chitin can easily withstand these temperatures without solubilization. Chitin for example is “easily” separated from glucans by performing a deacetylation step to chitosan at high temperature and extremely high NaOH conc. Both polymers (chitosan and glucan) remain in solid form here. Depending on the pretreatment smaller MW’s can be obtained that are indeed more soluble than the natives ones. But this highly depends on the type of polysaccharides and the degree of pretreatment (and/or the addition of chemicals).
- Lines 154-156: “When compared to hot water extraction, alkaline aqueous extraction is more effective at dissolving cell walls and removing polysaccharides from edible mushrooms”. Is alkaline extraction not intended to remove proteins from the fungi/mushrooms? Normally the solubilization of polysaccharides is very limited in mild alkaline extraction (see also comment above regarding deacetylation).
- Lines 172-174 are a repetition of Lines 163-166.
- The authors mostly mention advantages of the extraction of mentioned compounds. There are certainly also disadvantages using these methods. For instance for enzymes, relatively long processing times, when using chemicals corrosion issues, waste water generation when chemicals are added, low extraction yields only applying hot water extraction, etc.
- Lines 189-191: “Lower extraction temperatures are beneficial for maintaining the biological activity of polysaccharides in addition to lowering energy consumption and increasing yield.” It is highly unlikely that ultrasound-assisted extraction has a lower energy consumption compared to traditional heating system. Indeed, the temperature can be reduced. But as ultrasound itself generates heat, there needs to be constant cooling to avoid temperature increases. Also the ultrasound itself uses quite a lot of power (if used to disrupt cellular material, especially in the case of fungi/mushrooms).
- Line 195: “%” is missing.
- Line 197: “-“ is missing.
- In Lines 189-191 the authors mention that lower extraction temperatures is beneficial for the biological activity of polysaccharides, later on (Lines 207-209) the authors mention that the microwave-assisted extraction preserves the biological activity. This is quite contradictory, since by definition microwaves-assisted extraction is associated with high(er) temperatures.
- The focus of the manuscript is clearly on mushrooms, therefore it is not advisable to describing yeasts (Lines 301 -311) that have a different polysaccharide structure compared to mushrooms.
- Please italicize Agaricus and Pleurotus in Line 322, 332, 352
- The manuscript does not have a conclusion (/future outlook) section.
Author Response
Flores et al., have written a review regarding the use of mushroom polysaccharides for nutraceutical applications. This field of research certainly is an interesting and widely investigated relevant topic and therefore this manuscript *could* merit publication in polysaccharides. However, there are multiple issues in the current version of this manuscript that do not allow publication at this stage.
First of all, the title states mushroom polysaccharides but it is clear from the manuscript that the authors primarily discuss the glucan part of the polysaccharides present in the mushrooms. Therefore the title is not really accurate with the content of the manuscript.
Response to Reviewer: We concur with the Reviewer’s suggestion and have accordingly revised the title of the manuscript to "The Glucans Mushrooms: Molecules of Significant Biological and Medicinal Value."
Secondly, the review reads like a textbook. The authors state that the novelty is in the most recent literature, but throughout the text almost no quantitative statements are given of the recent literature.
Response to Reviewer: We agree with the Reviewer. In the revised text, we have incorporated several recent articles and added a section titled "2. Methodology" to clearly outline the strategy used to cover a wide range of relevant literature.
Thirdly, a lot of statements that are made in the text are sometimes contradictory or not correct. Overall this manuscript requires an extensive revision and needs to be extended to allow publication in Polysaccharides. Herewith are my comments:
Please capitalize all keywords (since polysaccharides is capitalized).
Response to Reviewer: All keywords have been written with capital letters
Line 50-51: “Fungi can be sustainably cultivated to produce polysaccharides, which offers a significant advantage”. This statement is rather vague. A lot of products can be grown sustainably if wanted/needed.
Response to Reviewer: We agree with the reviewer and have therefore deleted lines 50-51.
Why do the authors not zoom in on chitin in section 2: “Structure and function of polysaccharides”? Chitin is one of the most important polysaccharides in the fungal cell wall that make mushroom/fungi unique offering a vegan alternative to chitin derived from insects/crustaceans. Therefore, why is this not addressed in section 2 (since it is mentioned in the introduction section briefly).
Response to Reviewer: We would like to thank the reviewer for the very useful comment. In response, we have changed the title of section 2 to "Structure and Function of Polysaccharides: Focus on Chitin, Glycogen, and β-Glucans."
Lines 113-114: “Since polysaccharides are easily soluble in hot water but insoluble in organic solvents and cold water, hot water extraction is required for polysaccharides.” This statement is not entirely correct. This depends on the type of polysaccharide you want to extract. Native glucans and chitin can easily withstand these temperatures without solubilization. Chitin for example is “easily” separated from glucans by performing a deacetylation step to chitosan at high temperature and extremely high NaOH conc. Both polymers (chitosan and glucan) remain in solid form here. Depending on the pretreatment smaller MW’s can be obtained that are indeed more soluble than the natives ones. But this highly depends on the type of polysaccharides and the degree of pretreatment (and/or the addition of chemicals).
Response to Reviewer: We agree with the reviewer and have therefore deleted the statement: "Since polysaccharides are easily soluble in hot water but insoluble in organic solvents and cold water, hot water extraction is required for polysaccharides."
Lines 154-156: “When compared to hot water extraction, alkaline aqueous extraction is more effective at dissolving cell walls and removing polysaccharides from edible mushrooms”. Is alkaline extraction not intended to remove proteins from the fungi/mushrooms? Normally the solubilization of polysaccharides is very limited in mild alkaline extraction (see also comment above regarding deacetylation).
Response to Reviewer: In the section “3.2 Alkaline- or acid-extraction”, the authors have included the following text:” In alkaline extraction, strong bases like NaOH or KOH are used, which can efficiently extract polysaccharides such as chitosan, β-glucans, and mannans by breaking down the cell wall components and enhancing solubility. Acid extraction, using acids like HCl or ammonium oxalate, is particularly effective for extracting acid-soluble polysaccharides like galactomannans and xylans. In comparison, hot water extraction is a milder method that involves using hot water to solubilize polysaccharides like glucans and mannans. While it is effective for extracting water-soluble polysaccharides, it may not be as efficient in breaking down the cell walls as the alkaline or acid methods. Hot water extraction is often used as a preliminary step before subsequent acid or alkaline extraction to maximize polysaccharide recovery. Acid and alkaline extraction methods are more effective for breaking down cell walls and extracting a broader range of polysaccharides, although they may compromise the biological activity of the polysaccharides”
Lines 172-174 are a repetition of Lines 163-166.
Response to Reviewer: Corrected
Lines 189-191: “Lower extraction temperatures are beneficial for maintaining the biological activity of polysaccharides in addition to lowering energy consumption and increasing yield.” It is highly unlikely that ultrasound-assisted extraction has a lower energy consumption compared to traditional heating system. Indeed, the temperature can be reduced. But as ultrasound itself generates heat, there needs to be constant cooling to avoid temperature increases. Also the ultrasound itself uses quite a lot of power (if used to disrupt cellular material, especially in the case of fungi/mushrooms).
Response to Reviewer: The phrase "Lower extraction temperatures are beneficial for maintaining the biological activity of polysaccharides in addition to lowering energy consumption and increasing yield" was intended to highlight the benefits of using lower temperatures in general and was not specifically referring to the technique in question. Therefore, we have decided to remove the phrase to avoid any misunderstandings.
Line 195: “%” is missing.
Response to Reviewer: Corrected
Line 197: “-“ is missing
Response to Reviewer: Corrected
In Lines 189-191 the authors mention that lower extraction temperatures is beneficial for the biological activity of polysaccharides, later on (Lines 207-209) the authors mention that the microwave-assisted extraction preserves the biological activity. This is quite contradictory, since by definition microwaves-assisted extraction is associated with high(er) temperatures
Response to Reviewer: We acknowledge the potential for higher temperatures associated with MAE. However, the preservation of polysaccharides' biological activity is achieved by carefully optimizing key parameters such as extraction time, temperature, and microwave power. Lower extraction temperatures are beneficial for maintaining the biological activity of polysaccharides in general, while MAE's efficiency lies in its rapid processing time, which minimizes thermal degradation despite the higher temperatures.
The focus of the manuscript is clearly on mushrooms, therefore it is not advisable to describing yeasts (Lines 301 -311) that have a different polysaccharide structure compared to mushrooms.
Response to Reviewer: In agreement with the reviewer, given that the focus of the manuscript is primarily on mushrooms, the authors have removed all references to yeasts during the revision process.
Please italicize Agaricus and Pleurotus in Line 322, 332, 352
Response to Reviewer: Corrected
The manuscript does not have a conclusion (/future outlook) section."
Response to Reviewer: The “Conclusion section” has been included in the manuscript. The authors apologize for the oversight.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe authors addressed most of the comments raised by the reviewer and therefore, the reviewer accepts this manuscript for publication in Polysaccharides.
