Yeast Fermentation for Production of Neutral Distilled Spirits
Round 1
Reviewer 1 Report
Dear editor and authors,
The presented review “Yeast fermentation for production of neutral distilled spirits” gives an overview of the topic and presents both the background and current interests for development. It is concisely structured and written. However, although covering the main tuning points for neutral spirit production, the review is not very extensive. For many points it appears that the review is content in stating that neutral spirit production is just the opposite as flavorful spirit production. Repeatedly, information is not presented but the reader is directed to other publications. Information on recent advances is quite shallow. Yeast strain improvement opportunities are most extensively presented (not explained though), however, a big part of the information seems to come from existing reviews. If there are few published novelties more recent than 5 years, this kind of contradicts the need for publishing a review. In addition, the presented review is poorly backed up by references, while of the given references ~50% are self-citations. This could seem ridiculous, as if the authors didn’t want to cite anybody else but themselves.
Minor remarks:
- Consider restructuring the Introduction to bundle what the paper will describe in one paragraph instead of several places throughout the introduction.
- After the introduction, header II does not exist.
- Page 2, line 49: “… will be also be described” - Repetition of “be”.
- Page 2, Table 1: “Higher alcohols” instead of “High alcohols”.
Author Response
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Author Response File: 
Author Response.docx
Reviewer 2 Report
The review article brings a simple but very informative review on the production of the so-called neutral ethanol. This is a term used for the production of ethanol without the presence of other fermentation products such as polyalcohols, organic acids and esters. This type of ethanol, devoid of aromas, is required for the production of some flavored beverages and for the manufacture of perfumes. This is indeed an industrially important subject, although little explored, and seems to fall within the scope of this Special Issue "Yeast Fermentation and Biotechnology".
The text is well organized and the tables and figures are informative. The more in-depth aspects of the biochemistry and physiology of fermentation are not brought, but the text explores well the main points of the production of this type of biotechnological product.
Author Response
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Author Response File: Author Response.docx
Reviewer 3 Report
In general, this review summarised information about neutral and congener distilled spirits which gives an overview of the topic but do not provide any new information and the perspectives section is reduced. Moreover, the main focus of this article, as is presented in the title, is the yeast utilised during the production of these beverages although any further data is provided apart from the well-known metabolic pathways and aroma production which is continuously compared to congener distilled spirits. Additionally, I notice a lack of bibliography further from the previous studies carried out by the authors. Regarding the different sections, I would consider to improve the introduction since its only gives a summary of the review. It would be more interesting if the authors explain which studies has been done so far in this field, improvement strategies used in this industry and why this review is necessary.
Specific comments:
Line 54 – There is no section 2 after introduction.
Figure 1. I do not understand in which part of this workflow of alcoholic beverages production is explained the role of yeast. I think that a renaming of the figure legend needs to be considered.
Lines 184/185 – If Saccharomyces cerevisiae has been written with the full name in the introduction, the abbreviation should be used afterwards in the rest of the article.
Author Response
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Author Response File: Author Response.docx
Reviewer 4 Report
Dear Authors,
I would like to appreciate your efferots. The article seems well prepared and thoughtful. It can be a significant contribution for the field. Still, there is one chapter missing in the review. The article describes the fermentation technology of neutral distilled sporit focusing mainly on yeast species involved in the microbial synthesis of ethanol and other congeners. In my opinion, the last chapter on the achievements of genetic engineering in the context of improving yeast strains is missing. It should be expanded. There is a necessity to write whether GM yeast can be used in distilled spirits production and are there nowadays used. What are the achievements of science in this field. The Figure 6 should be discussed in the text.
Still, some minor mistakes need to be improved:
- table 1 - please change the title, remove the word "example", add "according to EU regulation. Than the firs line of the table is not necessary;
- add missing parentheses in table 1;
- check propriety of chemical compounds names e.g. table 1 - there is 2 propanol and should be 2-propanol; table 7 - iso-amyl or isoamyl?
- Fig. 3 - explain what are component 1 and 2;
- Fig 3, 4 - what is the source of data, shouldn't it be written in references;
- Put the description of legend in the table title;
- Fig 5 - add some information above arrow on the process or enzyme involved in the synthesis reaction
Author Response
Please see the attachment.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Dear editor and authors,
the authors have adequately addressed my remarks and I recommend the review "Yeast fermentation for production of neutral distilled spirits" for publication in MDPI Applied Sciences.
Reviewer 3 Report
I appreciate the hard work performed by the authors as well as all the substantial changes that have done along the manuscript. As a consequence, I consider this manuscript adequate for its publication.
Reviewer 4 Report
I would like tothank the authors for reviewing the manuscript according to my suggestions.
