Box-Behnken Design for Optimizing Ultrasonic-Assisted Enzymatic Extraction of Soluble Dietary Fiber from Pleurotus citrinopilestus

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Comments to the Authors

The manuscript “Optimization of an ultrasound-assisted process to enzymatically extract soluble dietary fiber from Pleurotus citrinopilestus” is quite well written, and the results provided are scientifically sound. However, the aim of the manuscript and its novelty should be better highlighted, the results comprehensively discussed and the language improved.

Here are my detailed comments:

Abstract

-        Line 16: ultrasonic-assisted extraction, uniform this attribute, in the title for example it has been reported as ultrasound-assisted.

-        Line 20: The RSM results revealed that the optimal parameters were: 45 mL/g as solid‒liquid ratio, 1.5% of α-amylase, 1.2% of complex protease, and 35 min as ultrasonication time.

-        Solid-to-liquid ratio, the unit measurements were not coherent (mL/g), it should be g/mL.

-        Line 22: Uniform the tenses, use always the past tense, as previously reported in the abstract. Do the same also throughout all the manuscript.

Introduction

-        Line 41: are the main active ingredients

-        Line 43: According to previous studies. Add which studies, by reporting the references related to that statement.

-        Lines 46-47: there is a lack of studies focusing on the recovery of dietary fiber and other active compounds from this matrix.

-        Line 58: Soluble dietary fiber (SDF) and insoluble dietary fiber (IDF). Then, report always the acronyms instead of the whole word throughout all the manuscript (example line 60).

-        Line 65: “Additionally, it is beneficial in that it protects the intestines.” This sentence can be eliminated, since not clear.

-        Line 67: SDS content should be more than 10%, but where? Please clarify.

-        Line 82: Better explain why RSM has been used and what are the deriving advantages?

-        Why an ultrasonic-assisted enzyme extraction technology has been selected to be used in this investigation? This is not clear, it is only introduced UMAE which is another extraction process. Report the advantages of using this technology instead of other technologies by discussing the main results found in the literature.

-        Line 85: replace the first person pronouns with impersonal constructions.

-        Lines 88-91: this paragraph should be moved before line 86.

-        Overall, I suggest to clearly state the reasons why this study was conducted, the main shortcomings emerging from the literature and how the authors want to fill these lacks or contribute to their advancement.

-        Figure 1 and Figure 2 are not cited in the text.

 

Materials and Methods

-        Line 110: what does it mean: with various amounts of water?

-        Line 115: explain how the extract was collected and precipitated to obtain SDF.

-        Line 121: Solid to liquid ratio.

-        What about the ultrasonic power and frequency?

-        Line 123: the other three remained unchanged. What does it mean, which values have been fixed? Please clarify.

-        Line 130: please explain why this approach has been used.

-        Line 135: Yield (%) was considered as the response to the design test.

-        Line 138, Table 1: name the variables in the same way, argument or independent.

-        Table 2: does the column related to the yield of soluble dietary fiber (%) report the values predicted by the model?

-        Line 144: is reported in the Equation (2).

-        Line 146: Please better explain the meaning of Y.

-        Line 154: were assessed.

-        Line 156: p value < 0.05.

 

Results and discussion

-        As general comment:  This section is confusing and should be deeply improved.

Since this section is the “Results and discussion” section you should not only describe the content of the Figures and Tables, but add a critical discussion of the results supported by the main findings reported in previous literature studies, analyzing the effect of each variable investigated on the SDF yield as well as their interactions and how they impact the response variable.

-        Line 164: the trends were comparable with each other.

-        Line 166: as the conditions become more severe.

-        Line 173: which outcomes? This is not clear from Figure 3. There is not a control sample, such as a SDF extract obtained by using a conventional extraction process, to be compared with the ultrasonic-assisted enzymatic extraction process in order to assess the effectiveness of this technology in improving the extraction yield of SDF from the fungus matrix investigated.

-        Line 183: which configurations?

-        Line 191: Auriculus auriculatus?

-        Line 192: ultrasonic-aided extraction technique, please name it as done in the rest of the manuscript.

-        Line 196: which process?

-        Line 229: remove “analysis”

-        Replace “interplay” with “interactions”

-        Line 231: Which is the conventional approach? There is no mention of it, and no results related to it.

-        Line 239: Equation (3)

-        Figure 5: The axes are not clearly visible and readable.

Per each graph, the effect of only two variables on SDF yield was reported, while how the other two variables were fixed? If they were fixed to 0, please explain why.

What is the meaning of the letters (a) – (f), since not reported and described in the figure caption?

-        Figure 6: What is the meaning of reporting 2D graphs? This figure gives the same, and even less, information of Figure 5 without adding a surplus to the discussion of the results.

 

 

Conclusions

Conclusions should be focused on summarizing the main conclusions from the findings achieved in this study and possible future perspectives, rather than reporting the aim of the manuscript and the conducted analyses which, instead, should be discussed in the Introduction and Materials and Methods sections. In this sense, please rewrite the Conclusions section.

Comments on the Quality of English Language

Several sentences and concepts reported in the text of the manuscript are not clearly stated. Please revise their English language throughout the manuscript by reading the comments and suggestions for authors.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

Dear,

I carefully read the manuscript entitled: "Optimization of an ultrasound-assisted process to enzymatically extract soluble dietary fiber from Pleurotus citrinopilestus". It is a well-organized manuscript, however, some minor corrections are needed before further consideration. My comments are shown in a pdf file. 

Kind regards.

Comments for author File: Comments.pdf

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 3 Report

Comments and Suggestions for Authors

Dear Authors! The manuscript sent for evaluation contains some deficiencies that need to be corrected (see comments below).

TITLE

The title of the article should be changed as it does not correctly represent the content of the research performed. My proposal is: ‘Box-Behnken design for optimizing ultrasound- and enzyme-assisted extraction of soluble dietary fiber from Pleurotus citrinopilestus’

INTRODUCTION

The introduction should be thoroughly revised as it does not refer to the relevant scientific work published in recent years that dealt with the problems described below.

1)      Current research on the phytochemical profile of P. citrinopilestus (e.g. Gogoi P. et al. DOI: 10.1111/jfpe.13172) -  the text in lines 39-40 should be completed and more fully described

2)      The text in lines 48-59 should be deleted as it refers to obvious information on insoluble dietary fiber which has not been studied in P. citrinopilestus.

3)      The information on extraction methods (lines 70-82) should be removed and revised. There are a number of currently published papers that describe extraction methods used to isolate polysaccharides (including UAE) from various Pleurotus species (P. ostreatus, P. eryngii, P. djamor) or other fungi of therapeutic interest that should be described and cited instead. Several important review articles on modern polysaccharide extraction methods in combination with response surface methodology have also been published in the last decade. Authors should include this information in the introductory section.

4)      In the final part of the introduction, the authors should present the novelty of their study, against the achievements of other authors, as the RSM method has been previously used to support the extraction of polysaccharides from other Pleurotus species.

MATERIALS & METHODS

I wonder if the overall structural identification of the monosaccharide composition in the SDF of P. citrinopilestus has been processed by FT-IR. If YES, the relevant information should be included in the experimental section, and comments provided in the Results & Discussion section.

RESULTS & DISCUSSION

There are no appropriate references in this paragraph to current published literature data on similar extraction methods used to isolate polysaccharides from other fungi (including other Pleurotus species) and the RSM methods used.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf