Cereal Grain Arabinoxylans: Processing Effects and Structural Changes during Food and Beverage Fermentations^†

Round 1

Reviewer 1 Report

Comments for author File: Comments.pdf

Author Response

Thank you for performing this review; our manuscript has been strengthened by it. We have copied and pasted your original comments below. Our responses are in bolded text, where we describe all changes that were made in the manuscript.

Reviewer 1 comments:

Arabian xylan plays an important role in food processing and fermentation, and its structure has a significant impact on process efficiency and food quality. This paper focuses on structure to discuss how AX affects the processing of cereal foods, and will describe how the natural AX structure is altered during the production of common fermented foods. However, there are still some parts that need to be further modified.

1. In Chapter “Native Arabinoxylan Structure in Cereal Grains”, the author mentioned that the main chain of xylan backbone is substituted with various branching elements, whose quantity and pattern of distribution differ between grain species. What are the branching elements in wheat, barley and rye, and what are the differences in their quantity and branching pattern compared with maize and sorghum?

• Arabinose is the most common branching element in all of these grains, and the arabinose/xylose (A/X) ratio provides an approximation of this. Differences in the A/X ratio between these grains were discussed on lines 72-90.
• Feruloylated arabinose or feruloylated oligosaccharide side chains and dehydrodiferulates are other ubiquitous substituent. We have discussed differences in these components between corn and barley/rye/wheat on lines 95-99.
• Finally, there are non-arabinose (and also non-feruloylated) branches, such as acetyl groups, glucuronic acid and 4-O-methyl-glucuronic acid. We have discussed differences in these components between corn and barley/rye/wheat on lines 85-89.
• We have added some additional phrases to this text to better compare and explain the substitution patterns between these grains.

2. Endo-1,4-β-D-xylanase can significantly reduce the average polymerization degree of AX, resulting in partial dissolution of AX, i.e., an increase in WE-AX fraction. What effect does this have in the malting step?

Increased WE-AX does not directly affect the malting step itself. However, increased WE-AX means that there is more WE-AX available to be extracted during the mashing stage.

WE-AX are a contributing factor to beer viscosity, filtration challenges, foam stability, etc, but they do not singlehandedly change any aspect of beer brewing. Because beer is a mostly aqueous solution, WE-AX are especially relevant, so increasing WE-AX in the malting stage will result in a greater content of soluble AX in beer brewed with that malt.

3. In Chapter “Filtration”, the author mentioned that the need to delve deeper into the side-chain branching patterns that lead to reduced membrane permeability, as fewer branches lead to more AX aggregation. Is there any relevant literature report at present?

Model studies have shown that decreased AX branching is related to increased aggregation, and we have cited a model study for this (Reference 72, Shrestha, U.R.; Smith, S.; Pingali, S.V.; Yang, H.; Zahran, M.; Breunig, L.; Wilson, L.A.; Kowali, M.; Kubicki, J.D.; Cosgrove, D.J.; et al. Arabinose substitution effect on xylan rigidity and self-aggregation. Cellulose 2019, 26, 2267–2278. https://doi.org/10.1007/s10570-018-2202-8). However, we have not found published studies specifically focused on beer with this level of structure-function exploration (i.e. branching patterns-wort filterability). Studies investigating the relationship between AX and filterability have evaluated the effect of overall AX content or AX molecular weight on filterability.

4. In addition to the sensory characteristics of beer, what other aspects of AX content and structure affect the beer?

Beer is an elective item consumed for pleasure, so discussions of sensory characteristics should be emphasized in this section. Discussing AX’s effects on the sensory/organoleptic characteristics of beer (viscosity, mouthfeel, foam stability, and flavor) is a consumer-focused angle to discussing beer’s physiochemical characteristics.  We have discussed these items in Sections 3.6- 3.7.

5. In addition to the sensory properties of the beer, what other aspects of the beer are affected by the content and structure of AX?

Duplicate question; see answer to Question 4.

6. Excessive degradation of WE-AX has a negative effect on dough viscosity and loaf volume, so what is the optimal type and dosage of xylanase?

Specific recommendations of type and dosage of xylanase are outside the scope of this paper, since this review article is not intended to be a practical guide to bread production.

Generally, an ideal xylanase choice for breadbaking will maximize WE-AX content without reducing their molecular weight. This means that an enzyme should primarily target WU-AX. We summarized this for readers in lines 279-282.

Reviewer 2 Report

In this manuscript “Cereal Grain Arabinoxylans: Processing Effects and Structural Changes During Food and Beverage Fermentations”, the authors focus specifically on two structure-function relationships between AX 4

and fermented food production The research is meaningful, but there are some problems with your manuscript. The comments and problems are as follows:

 

1.I think the language of the abstract should be modified to make the article more logical and to highlight the research purpose and significance of the review.

2.“AX’s relationships with water, gluten, and starch are most impactful for bread quality”, it says. Are there any references? If yes, please mark.

3.The language of this manuscript needs further improvement and improvement.

4.I think the key words of this manuscript need to be reconsidered, and the key words can be more concise.

5.I think in the end of the article in addition to future research prospects can also add conclusions for the field of the current research status and other content.

 

The language of this manuscript needs further improvement and improvement.

Author Response

Thank you for performing this review; our manuscript has been strengthened by it. We have copied and pasted your original comments below. Our responses are in bolded text, where we describe all changes that were made in the manuscript.

Reviewer 2 comments:

In this manuscript “Cereal Grain Arabinoxylans: Processing Effects and Structural Changes During Food and Beverage Fermentations”, the authors focus specifically on two structure-function relationships between AX and fermented food production The research is meaningful, but there are some problems with your manuscript. The comments and problems are as follows:

1.I think the language of the abstract should be modified to make the article more logical and to highlight the research purpose and significance of the review.

We have modified the abstract to clarify the purpose and significance of the review by adding the following sentence:

Results from recently-published papers have provided new insights into the connection between AX's structure at the molecular level and their effects on fermented food production. The purpose of this article is to review the historical progress in this area and introduce updates from recent years. Current knowledge gaps in the area are highlighted.

2.“AX’s relationships with water, gluten, and starch are most impactful for bread quality”, it says. Are there any references? If yes, please mark.

Gluten, water, and starch are the major quality-influencing constituents of bread, so it is natural to emphasize any interactions between these components and AX.  We have updated this sentence to provide a good citation for this statement.

For more details on the roles of gluten, water, and starch in bread quality, we recommend the following books:

• Delcour, Jan, and R. Carl Hoseney. "Principles of Cereal Science and Technology." (2010).
• Hutkins, Robert W. Microbiology and Technology of Fermented Foods. John Wiley & Sons, 2008.

3.The language of this manuscript needs further improvement and improvement.

The manuscript has been closely read by a native English speaker for grammatical, spelling, and typographical errors.

4.I think the key words of this manuscript need to be reconsidered, and the key words can be more concise.

We have removed the keyword “beer,” since it was redundant with “brewing.” We have replaced “structural polysaccharide” with “carbohydrate polymer.”

5.I think in the end of the article in addition to future research prospects can also add conclusions for the field of the current research status and other content.

In the main body of the article, we have highlighted numerous research and knowledge gaps in this field. However, because this research area (the relationship between AX’s molecular structure and its processing effects) is still actively evolving, we feel that it would be misleading to readers to present firm research conclusions in the Conclusion section.

Round 2

Reviewer 2 Report

Accepted