Assessment of Bioactive Compounds and Physiological Activities of Ethanolic and Aqueous Extracts from Black Rice, Black Rice Bran, and Milled Black Rice
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThe manuscript of Fu et al. investigates the antioxidative properties of ethanolic and water extracts from black rice, black rice bran and milled black rice. Subsequently the authors investigated the anti-obesity, anti-obesogenic and anti-muscle atrophy effects. The extraction of bioactive compounds from biomass feedstocks is extensively researched in the literature. Therefore, the authors should emphasize the key novelty of this work more explicitly. Thus, the introduction section should be revised while also elaborating on what has already been done in the literature. Overall, the approach of the authors is well executed, the article is well written and the applied methodology merits publication in Applied Sciences. However, after reading the manuscript I have some major and minor comments which ought to be addressed before publication:
- Italicize species names.
- The introduction section is very limited. The authors mention that there is already extensive research regarding the antioxidant activity of black rice. What were the findings of these studies? Please elaborate on key results and how the current study distinguishes itself from these studies.
- The introduction section does not mention how these extracts are obtained? It only states very briefly that water and 80% ethanol are used? How is the extraction performed?
- The authors mention that BR, BRB, and MBR are pulverized prior to extraction. What was the particle size (range) used in the extraction experiments? This influences the extraction efficiency greatly, and therefore, is important information.
- The authors mention that reflux extraction is performed at 60 °C with water. How is this effectively done with water under atmospheric pressure?
- Please add additional information on the HPLC method? For instance, which column was used, the mobile phase composition, etc.
- Which standard was used for the determination of β-glucan? Did the authors run the hydrolysis procedure with a β-glucan standard in order to verify the hydrolysis efficiency?
- Please be consistent with the use of numbers and units in the manuscript. Sometimes a space is used between number and unit, sometimes not (for the same parameter, for example for “nm”).
- There are chemicals mentioned in the text that are not mentioned in Section 2.1. “Chemicals and reagents”. Please go through the text and add them to this section.
- Line 132: “2” should be in subscript.
- Figure 1B,C,D,E,F and G are difficult to read. Please scale them appropriately so that the smaller peaks after > 10 min retention time become more pronounced.
- Did the authors consider any (bio-)chemical test to determine the feedstock’s composition? That way the extraction yield can also be determined.
- What is the overall extraction yield (not considering the feedstock’s composition)?
- Please add some quantitative key results in the abstract and conclusion section.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsThe methods of analyzing biological activities of black rice (BR), bran black rice (BRB) and milled black rice (MBR) such as anti-obesity, anti-obesogenic, and anti-muscle atrophy effects are nice, but the rice materials used in this experiment are unclear. We do not know the name of variety, how they are purchased, how they were cultivated. If the authors can verify these information, and compare the variation among different varieties of black rice and their by products, the paper will be more valuable. We know already that many compounds in rice bran such as gama oryzanols are higher than milled rice grain, as well as their relevant medicinal and pharmaceutical activities. Thus, they are the limitations of this paper.
At this point, this paper can not be considered for publication of the mentioned above reason, as the data are at a very early stage.
Comments on the Quality of English LanguageMinor revisions in English are needed.
Author Response
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Reviewer 3 Report
Comments and Suggestions for AuthorsWhat is the reason for the formation of water and ethanolic extract of rice? It seems to be obvious that rice can be eaten without the formation of extract.
Line 58. Can you indicate the “application prospects” of the obtained extracts?
A justification is needed as to why 60oC is enough to obtain water extract using reflux extraction. (lines 72-73)
Sentence “The total phenolic and flavonoid contents in the DW and 80% EtOH extracts of BR,
BRB, and MBR were measured in Table 1” (lines 204-205) has to be corrected
Figure 3 is unreadable.
The subject of the submitted manuscript is interesting; however, additional studies that can indicate the composition of the obtained extract have to be performed, in particular, indicating the composition of phenolic and flavonoid compounds that are responsible for the antioxidative properties.
Author Response
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Reviewer 4 Report
Comments and Suggestions for AuthorsThe paper, "Assessment of bioactive compounds and physiological activities of ethanolic and aqueous extracts from black rice, black rice bran, and milled black rice," evaluates the bioactive compounds present in black rice and its derivatives, particularly focusing on their antioxidant, anti-obesity, and anti-muscle atrophy properties. Through comparative analysis of distilled water and 80% ethanol extracts, the study highlights the potential health benefits of black rice and its bran, emphasizing their use in functional foods and therapeutic applications.
Please find below my critical comments:
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Lack of novelty: The extraction and analysis of bioactive compounds in black rice and its bran have been extensively studied. However, the manuscript lacks a clear explanation of how the current findings contribute novel insights beyond existing literature. The authors should clarify their study's unique contributions.
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Methodological rationale: The paper does not provide a comprehensive rationale for selecting specific solvent concentrations (e.g., 80% ethanol) for extraction. Including a justification for selecting these parameters based on preliminary studies or literature would enhance the scientific rigor of the methodology.
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Limited discussion on practical applications: Although the study mentions the potential of black rice and its derivatives in functional foods, it lacks detail on how these findings could be translated into real-world applications, such as product development or clinical use.
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Inadequate focus on mechanistic pathways: The paper presents data on the physiological effects of black rice extracts. However, it lacks a detailed discussion of the molecular or biochemical pathways through which these effects are mediated. A deeper exploration of the mechanisms would provide a stronger foundation for the reported health benefits.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors addressed most of the comments of the reviewer, and therefore, the reviewer accepts this manuscript for publication in Applied Sciences.
Author Response
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Author Response File: Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsAs I commented in the first review, this paper did experiment on a single rice cultivar but they can not make it clear here, and reason why they chose that cultivar. Actually, there are hundred rice cultivars are black rice in South Korea as well as many countries.
To be acceptable in Applied Science, I think they must clear the above point, as well as do further experiments to make comparison among different rice cultivars to show their novel findings. At this point, the results are not novel enough for readers. The compounds they are analyzed are too common in rice including black rice.
Comments on the Quality of English LanguageMinor revision
Author Response
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Reviewer 3 Report
Comments and Suggestions for AuthorsI have to admit that the Authors have improved the manuscript. However, I have one more question: How was extraction yield calculated? Please add appropriate information in the methodology section.
Author Response
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