Coffee Roasting and Extraction as a Factor in Cold Brew Coffee Quality

Round 1

Reviewer 1 Report

The manuscript is well organized, the novel information is satisfactory, the literature references are  reasonable (with 77 references) and the conclusions are very interesting (particularly the analyte-focused discussions in paragraphs 3.2), at least as related to cold brew coffee. They employed also two available standards for basic research, the run model matrix matching samples, therefore I can recommend acceptance of it. However, I would be happy if the authors proceed to remedy the following minor issues and improve the clarity of their paper.

Supplementary material: The footnotes of table in the supplement are falsely numbered. By the way, I could suggest that this table is useful and can be incorporated in the main text. Usually we provide more tables, lengthy tables, many figures etc. as supplementary. If supplementary online material contains just one Table is meaningless. Anyway, this is also editorial decision.

Line 16. Instead of “Using solid-phase” correct to “Using headspace solid-phase”.

Line 20. The authors write “

 In terms of quantitative composition, the study showed that cold 20 brew coffees are an exceptional source of chlorogenic acid as well as caffeine.” OK for chlorogenic, but for caffeine what is new or unexpected?

Line 25. It is written “or in similar level of 400-500 mg/L, which is an important aspect of innovative research.” Please specify the expected innovation. On composition, on quantities?

Line 64: Not “The aim of the publication…” but rather “The aim of the research…”

Line 77: “experiment was prepared in similar condition what green beans processing” Syntax error? clarify.

Line 81. “A model matrix consisting of sand grains c.a. 1.5 mm in diameter was used in the experiment to determine the effect of temperature on the content of bioactive compounds.” Provide a reference for this procedure.

Line 83. “Coarse grind coffee” Since the author claim in the text for lack of standardization in cold brew coffee, it is necessary that they have to provide here and in other places in the manuscript exact conditions, i.e., here a defined grinding level for their experiments.

Line 114. One of the employed methods for identification of the analyzed compounds was “retention times were compared to retention times of authentic standards. ” However, how many such standards were available? If I do not miss them, I have just seen 2 standards (chlorogenic and caffeine) which were truly employed for the antioxidant compounds time/temperature experiments, but not for all the 39 analytes. The paragraph must be more precise.

Figure 6. Correct Pyrolisis to Pyrolysis.

Author Response

Respect Editor,

we are very grateful for Your valuable comments. On behalf of my co-authors, i would like to submit a manuscript after corrections. We hope that we have made all the efforts for a positive consideration of our research paper and improve the clarity of the paper follow by:

1. Supplementary material was incorporated at the end of text,
2. Line 16 - was corrected to "using headspace solid-phase",
3. Line 20 - we agree with Your atention about exceptional source of chlorogenic acid but for caffeine it isn't innovative so we chnged the text,
4. Line 25 - was corrected like „The analyses confirm the possibility of producing a beverage with increased chlorogenic acid content above 900 mg/L or at a similar level of 400-500 mg/L with caffeine, which may be important on an industrial scale due to the possibility of diversifying beverage production”.

We want to draw attention to helping of diversifying production. We think that now it is more clearly.

5. Line 64 - of course „the aim of research” is correct.
6. Line 77 - we understand our error, which was factual and resulted mainly from the English translation. Now is more clearly: ”pure compounds of caffeine and chlorogenic acid (Sigma Aldrich) were roasted with green beans at the same time and it was the author's experiment”.
7. Line 81 – this was the author's experiment. We wanted to reflect similar conditions as the weight of green beans, so we didn't think this reference are necessary, because we only determine the effect of temperature of bioactive compounds (chlorogenic acid and caffeine). Sand was neutral filler.
8. Line 83 – We provide now that coarse grand is c.a. 1.6 mm
9. Line 114 – the attached new table from the supplemental text to the main text should clarify the Editor's concern. Moreover, retention time were compared to retention times of authentic standards from database.
10. In figure 6 all mistakes were checked

Please reconsider our work for inclusion in the Special Issue. We look forward to hearing from you in the near future.

Kind regards,

Damia Maksimowski

Reviewer 2 Report

The study presented in this manuscript is aimed to elucidate the best combination of beans roasting for cold brewing coffee.

A significant effort has been put into the study of different conditions and a good amount of data is provided. However, the authors says that “a limited amount of information is available on cold brew coffee” and I disagree. Some examples can be found in:

https://doi.org/10.1016/j.lwt.2021.112231

https://doi.org/10.1016/j.foodchem.2021.129806

 https://doi.org/10.1002/jsfa.11125

https://doi.org/10.1111/jfpe.13748

https://doi.org/10.3390/foods10061347

And these are only for 2021. The most important part to bring up these references are that they bring into the study some other variables such as pressure or vacuum during preparation, which are missing in the presented manuscript.

Although cold brew is attracting interest in the coffee consumption, I´m sure that hot brewing is still present and important, and therefore a comparison with this method for the same grains could be interesting. An example of this can be found in https://doi.org/10.1016/j.lwt.2021.111363

In my opinion the science behind the paper is good and the study is well design, but I found that the novelty is very limited. Therefore I cannot recommend its publication in this journal unless a much deeper discussion and comparison with the aforementioned references and others are included.

In addition, English requires a major revision as well as format (some spaces seem to be missing but this could be a formatting error). A major flaw is detected in figure 6 where grammar error marks are still present underlining some words.

Author Response

Respected Editor,

Since we also wanted the content to reach the producers of the popular beverage through the Special Issue thank You for your comment - "the best combination of beans roasting for cold brewing coffee". We can see the goal being achieved at this early stage.

We also agree with the view that more and more scientific and popular science content is about the topic drink, including in the context of unconventional production methods. We apologize for not including this earlier like references. Now we can see how we were able to improve the article.

Nevertheless, we did not focus i.e. on sonification, as we have industrial experience where we mainly encounter doubts and problems with the traditional method of cold brew coffee production. Thus, we thank you for the idea, which has provided us with further opportunities for laboratory work that we would like to optimize in the future so that industry can benefit from it. We thus emphasize that we have cited exemplary references and enriched the discussion. All elements are clearly highlighted.

In response to our Special Issue application, You certainly mention that „hot brewing is still present and important”. Of course, we agree in all percentages, but we only focused on cold brew research because it is also done in a company that only produces cold brew coffee at scale and would like to expand the quality control sector and learn more about the causal relationships that arise from the technology and our publication. Nevertheless, we have addressed the opinions and made changes based on the exploration of the literature on the subject (e.g. authors Wang and Lim or Cordoba et al). As a result, we believe that the text is definitely better than the original version. Furthermore, we apologize for figure 6, which we did not revise at the very beginning to avoid formatting error.

Please reconsider our work for inclusion in the Special Issue. We hope that now it pass positive opinion. We look forward to hearing from you in the near future.

Kind regards,

Damia Maksimowski

Round 2

Reviewer 2 Report

The manuscript in this version has been thoroughly enhanced through the modifications submitted by the authors. However, some minor English correction can still be done. My only remaining concern with the article is that not all the references have the doi link, maybe is a format issue.