Biorefinery Development Based on Brewers’ Spent Grain (BSG) Conversion: A Forecasting Technology Study in the Brazilian Scenario

Round 1

Reviewer 1 Report

In the present work, the authors reviewed in detail the possibilities of producing high value-added products from Brewer's Grain (BSG) in Brazil and conducted a detailed analysis of numbers of articles and patents. BSG is an important waste produced in beer companies, which can be transformed into commercial by-products.

I can recommend this article for publication after considering some comments:

* Abstract can be expanded

* It is desirable to more clearly formulate the goals and objectives of the study.

* What was the data selection based on? Why do the authors not take into account the data of the inventor "Oleg Ivanovich Kvasenkov"?

* It is desirable to make more comparisons with similar studies.

* In the conclusions, it is desirable to indicate the novelty and originality of this work.

* The format of the article is more suitable for a review. Perhaps structure of the article can be more detailed with contain more additional sections, for example:

1. Formulate a goal, highlight the problem

2. Provide an overview of existing solutions for the processing of source based on literature data and patents (include additional subsections: industries where BSG are used, economic analysis)

3. Suggest a solution to the problem. Possible path

* In Figure 8, you can add more information (indicate temperature values, sign processes). You can also select this section separately.

Author Response

We thank the Reviewer for the careful reading of the manuscript and the suggestions to improve the quality of our work. The work became clear and well-organized with the suggested modifications. We have tried to follow the reviewer’s remarks in the revised version of the paper.

All the specific answers can be seen in the attachment document.

Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript of Evaristo et al., investigated the utility case of brewer spent grain (BSG) from a Brazilian perspective. The use of BSG is an important feedstock (both in quantity and quality) that is highly relevant in (potential) biorefineries. Therefore this paper deserves recognition in this field of research. The approach of the authors is well performed, the article is very well written and the applied methodology merits publication in Biomass. However, after reading the manuscript I have some minor comments which ought to be addressed before publication:

-     -   Mighty be interesting to also add anaerobic digestion to table 1. It is not a high value valorization route but also fits in Table 1. A lot of research is currently being done on the anaerobic digestion for the production of biogas (and/or VFA) from BSG with/without pretreatment.

-    -    Besides arabinoxylans - which the authors correctly mention as a potential high value product to be extracted-, β-glucan is another high value product that could be valorized. This should also be added in the introduction section.

-  -      Improve the quality of Figure 3.

-   -     Add reference(s) in Lines 278-279.

-    -    Figure 3 is redundant as the same information is depicted in Figure 5.

-   -     Figure 7 is not sufficiently clear on its own. The reader needs the information in the text to understand what the figure is about (abbreviations/legend is not given). It is advisable to already introduce some information in the Figure rather than the text. This would facilitate reading.

-    -    Lines 386-389: wastewater generation is also an important issue/challenge regarding (cascaded) biorefinery processes. Especially when chemicals are applied to extract a certain compound this often leads to excessive washing steps/wastewater generation.

-    -    The authors opted for more “classic” treatment/conversion technologies (cfr. Figure 8) such as (bio-, thermos- )chemical conversion. In recent years also many novel – green- technologies emerges as a (pre-)treatment step to convert BSG or to make BSG compounds more accessible (such as ultrasound/microwave processes). These technologies can easily be coupled with the technologies mentioned by the authors. Therefore, the reviewer suggests to also mention these emerging technologies in the manuscript.

Author Response

We thank the Reviewer for the careful reading of the manuscript and the suggestions to improve the quality of our work. The work became clear and well-organized with the suggested modifications. We have tried to follow the reviewer’s remarks in the revised version of the paper.

All the modifications can be seen in the attachment document.

Author Response File: Author Response.docx

Reviewer 3 Report

-Page 2 Line 56-57  BSG is well known as the major lignocellulosic biomass “it will be more beneficial information if authors add some information about the amounts of BSG annually”

-Page 2 Line 60  acid lactic production, “recheck”

-Page 3 Line 96 l for its applications “which one? please be specific”

-Page 4  Line 152 A total of 7 keyword combinations “please explain criteria to select these keywords”

-Page 6 Line 189 Figure 2 “please indicate which database authors used to retrieve this data and please indicate keyword for searching. What's the red dash line?

-Page 8 Line 241-242 The technological forecasting study through the Brazilian “please indicate the link/source/reference?”

-Page 11 Line 328 Figure 7. “authors need to add the description of each letter”

-Page 13 Line 413-414 Two main business models were employed “what are they”

-Page 13 Line 417-420 Biorefineries face along, with any other renewable energy system “the main product of biorefinery now is bioenergy which is high value and high volume, authors should carefully revise this paragraph”

-Page 15 Line 442-447  Reactors 2, 3, and 5 refer to the thermochemical process in different “please add references that authors mentioned for the condition here. and are these reference are for BSG or general lignocellulose?, please be specific”

-Page 15 Line 473-475 Several studies demonstrated successful growth of both funga “please add references”

-Page 15 Line 479-482 Saba et al. (2019) showed the suitability of BSG “please recheck again if this study fit to the scope of this paper?”

-Page 16 Line 496-499 The key proposed by Cherubini (2010) “what authors extract information from this study is too general, please revise to add specific finding of this study”

-Page 16 Line 512  Open innovation models “please explain”

-Page 18 Line 573 5. Conclusions “conclusion should be short and tense. reference should not be add here. authors should move some contents to discussion. also, authors should provide the future direction of biorefinery of BSG in the real market sector”

it will be beneficial to have English correction

Author Response

We thank the Reviewer for the careful reading of the manuscript and the suggestions to improve the quality of our work. The work became clear and well-organized with the suggested modifications. We have tried to follow the reviewer’s remarks in the revised version of the paper.

All the modifications can be seen in the attachment document.

Author Response File: Author Response.docx