Interactions between Beer Compounds and Human Salivary Proteins: Insights toward Astringency and Bitterness Perception
, Victor de Freitas 1,2,* and Susana Soares 1,2,*Round 1
Reviewer 1 Report
The work is devoted to the study of interactions between human saliva proteins (SP) and beer phenolic compounds (PC). The influence of these interactions on the perception of astringency and bitterness in drinks.
The study is aimed at obtaining new data in the field of the interaction of beer polyphenols and saliva proteins, as well as the impact of these interactions on the sensory perception of drinks.
The studies presented in the article are interesting, but at the same time, there are a number of comments. Studies on the interaction of polyphenols and salivary proteins are certainly presented in the literature. This work is aimed at developing knowledge in this area.
The most valuable material in the article is the search for correlations between instrumental and sensory indicators. However, a large number of evaluated indicators makes the perception of the article difficult.
Separating a separate section on correlations and structuring it would improve the perception of the article and its value to readers.
The authors are advised to highlight the "conclusions" section, since it is absent in this version of the article.
In the explanation to Figure 3, it is desirable to reduce information about well-known data and strengthen the analysis of the found correlations.
The overall structure of the article requires more consistency.
Section Objects and Methods is advisable to do 2, then the results and discussions. There is a lack of a general section "conclusions" and summarizing the achievement of the goal of the work.
Author Response
# Reviewer 1
Thank you for your comments. Please find below the revisions made for each point.
Comment 1.1. Separating a separate section on correlations and structuring it would improve the perception of the article and its value to readers.
Answer 1.1.: We would like to thank the reviewer comment. A separate section of statistical analysis (correlations) has now been amended. It appears in the results section (section 2.5), as it displays a better view of the results, and it becomes easier to readers. The discussion of these results is displayed in the discussion section (section 3).
Comment 1.2. The authors are advised to highlight the “conclusions” section, since it is absent in this version of the article.
Answer1.2.: We acknowledge the reviewer suggestion to add and highlight the “conclusions” section. Although this section is not mandatory for this Journal, we agreed with the reviewer’s opinion. So, a conclusion section was added in the article (section 5).
Comment 1.3.: In the explanation to Figure 3, it is desirable to reduce information about well-known data and strengthen the analysis of the found correlations.
Answer 1.3.: Regarding to this suggestion, alterations in the manuscript were made (line 401-415) to improve the analysis of the found correlations.
Comment 1.4.: The overall structure of the article requires more consistency.
Answer 1.4.: We appreciate the comment, and with all the changes performed according to the reviewers’ suggestions in the manuscript we think that now the article presents more consistency.
Comment 1.5: Section Objects and Methods is advisable to do 2, then the results and discussions. There is a lack of a general section “conclusions” and summarizing the achievement of the goal of the work.
Answer 1.5.: For instance, in this Journal the “Material and Methods” section in the manuscript must appear after the discussion and conclusion section. Therefore, a “conclusion” section was added after the “Discussion” section to present a general and brief conclusion of the goals of this work (section 4).
Reviewer 2 Report
This research aimed to relate bitterness and astringency perceptions of beers to the products' phenolic compounds and panelists' salivary proteins. Overall, the investigation seems to have provided meaningful data, but some points should be addressed for the sake of repeatability and validity of interpretation.
Abstract: Abbreviations AAL, IPA, HL, and SBO are undefined, and so their meaning in the abstract is unclear.
L45-47: Here or in the discussion it should be mentioned that marked bitterness is a desirable characteristic in the taste profiles of certain beers but not others.
L110-111: This sentence is confusing. It first states that relationships between sensory and instrumental data have not often been found, but then states that several correlations have been reported between the two.
L123, L156, and elsewhere: For accuracy and consistency, astringency should be described as a tactile sensation (or mouthfeel) rather than a taste throughout the manuscript.
Table 1: Why did the authors choose to express descriptive sensory data in this way, rather than numerically? Means and standard deviation (or some measure of spread) should be provided.
Lines 171-173 and Figure 1(B): "Each panelist had statistically equal behavior and SP fold regardless of the studied beer..."
The data in Figure 1(B) indicate statistical differences. Please clarify.
Can the observed increase or decrease in soluble SP be isolated to their interaction with PC as claimed in the caption of Figure 1? How would SP levels be different in response to other (non-phenolic) compounds?
L316-318: Can the authors explain why some panelists would exhibit an increase in SP and others a decrease?
L360-361: "the interaction with a specific PC-rich mixture occurred always in a similar way and was not affected by individual variability."
This statement seems in conflict with the results presented in Figure 2.
Figure 3: Should this be in the results section?
Section 4.1.1: How much of each beer sample was evaluated, and at what temperature? Please describe the sample presentation order.
Section 4.2: How was saliva collected? How much?
Author Response
Dear Reviewer 2,
thank you for your comments. Please find attached the revisions provided to each point.
Author Response File: 
Author Response.pdf
