Utilization of Yacon Damaged Roots as a Source of FOS-Enriched Sweet-Tasting Syrup

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This paper is well presented, and the design is propriate, it could be accepted after minor revision.

2.1 please give more informaition about the material, such as size, initial water content.

2.4.3 give more information about protein analysis, such as the equipment parameters..

line 349 ’ is 2.7 g/kg’

Line 445, Lower temperatures, how low?

conclusion should  be improved.line 462 . This results in sweeter and more fluid syrups.?

 

 

 

Author Response

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Reviewer 2 Report

Comments and Suggestions for Authors

• Section 2.1: please describe what is the category of damaged root. If possible also with pictures. What is the damage level which is still acceptable for this study?

• So, in this study, which one is used, the skin or the pulp or both? If I read in line 93, only pulp is used, so why the information about skin is provided in line 79.

• Line 84: up to a final concentration of the samples or the ethanol concentration? Is it possible just to mention how much ethanol is added to the mixture (10 g + 100 mL water)? 

• Why is ethanol extraction needed if at the end, water is added for syrup production? Would it be possible just to make juice from fresh after peeling without drying? What is the reason for ethanol extraction?

• the discussion seems too difficult to read. too much repetition of number from table. I would suggest to simplify them, not to repeat the numbers from table of figure into the text. just describe the important messages from the results obtained, and explain why does it occur.

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

The main goal of the reviewed paper is extraction of sugars in presence of lemon juice or citric acid in order to obtain clean labelled yacon syrup for different purposes. The holistic approach is mentioned but no clear explanation what it means in general. The question arises if the extraction of plant residues is worthy and environmentally friendly, since it is not known what is the process efficiency at the final step. The material contained in the publication is very interesting cognitively, but  results presentation and novelty of the research is not satisfactory and the biggest drawback of the reviewed work.

Title is too general and does not present a material included in the paper, when only roots were examined, also the sweetening potential was not compared with sucrose, which is standard procedure.

Detailed queries:

line 54: all inulin kinds are recognized as sweet? What is the structure of this oligosaccharide that makes it sweet? Is it simple linear or “tree” structure sweet? Needs explanation. What is the sweetness in comparison to sucrose?

Material and methods:

line 74-80: how long were roots stored and how was it protected from browning?

line 82-91: samples with 80% ethanol solution were boiled? How the authors assured the samples from evaporation at this stage? What were the losses?

line 93-107: what was the temp. of syrup processing? What was the source of lemon juice, was it standardized for any active component? What was the equation for citric acid proportion and why it was used instead of ascorbic acid?

line 105: polyphenol oxidase was inhibited by the combination of AA and CA, but no polyphenolic compounds were measured. How could it be concluded that there are any polyphenols in the syrup or enzymes left when it was boiled few times?

line 106-107: juice was concentrated – what was the physical characteristic, what was the yield or was it powdered?

line 115: what was the initial moisture of plants, was it similar in all or no considered as important? What was the loss during processing?

line 162-165: protein content evaluation is not properly explained – what was the purpose of its evaluation if the thermal processing and ethanolic extraction were used, what was the ratio of precipitation?  The protein content was explained as a result of solubility but other process needs to be addressed as well (line 374-380).

line 168-180: TA.XT analysis were conducted as liquid or powdered sample of juice? Should it be named as texture analysis? If that is a liquid the viscosity should be measured not the texture. What does it mean for the processing when samples are sticky and stringy.

line 183-205: what was the sweetness of the syrup in comparison to sucrose? Why there was no sensory evaluation planned, especially when it is aimed to be used as a sweetener? Why energy value did not consider protein content, when there was 12-23% in the syrup? (Table 3). Does the “uptake” mean content or consumption amount?

Results:

The section is too long and poorly organized. There is a lack of informative discussion, too many irrelevant results, when it should be pointed out what were the results and its significance for food industry, not to mention the environment cost. It is very hard to focus on the merit of research.

Tables and figures: abbreviations are needed within all.

 

Section 3.3 and 3.2.2. needs correction within the number and title, which is the same.

Conclusion

line 454-455: “The potential of yacon damaged roots as a resource for the development of syrups

aimed at decreasing sugar in foods has been demonstrated” – there was nothing in the paper demonstrating the conclusion. Authors need to be precise with their results not the common knowledge or general conclusions.

line 459: how many juices were evaluated? In material and method section only limited amount of samples were presented, mainly CA.

What is the stability of syrups, especially its sweeteness – line 460-462 conclude further changes, therefore how to standarize its quality?

line 470-472: “The cost-to-health benefit ratio is also a significant consideration in making yacon syrups a competitive sweetener and expanding the availability of low-sugar foods.” What is the environmental cost of syrup processing instead of roots recycling or natural deterioration?

Summarizing the work is not synthetic, it has many lengthy passages from which nothing essential emerges. It is hard to follow, therefore the paper is not suitable for publication in Applied Sciences in its present format. Significant revisions of the results and discussion are required in the manuscript to warrant further consideration for publication of this manuscript, therefore I do not recommend it for further processing.

Author Response

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Reviewer 4 Report

Comments and Suggestions for Authors

The article entitled «Valuation of yacon agri-food by-products as sweetening agents» by Fernandes et al. is of great interest. The idea regarding the valorization of yacon waste into sweetening agents is quite novel and interesting. The methodology and results are both well presented. The article should be considered for publication after addressing the following minor comments and corrections.

Abstract

1)     Line 17: please provide the whole name of ‘’Fru’’, as fructose, before introducing the respective abbreviation.

2)     Line 19: fructooligosaccharides

3)     Please rephrase the sentence in lines 24-26 to make more sense.

Introduction

Overall, the introduction is well-written and provides an overview of the key literature points.

1)     Line 48: have focused

2)     Line 57: such as

3)     Lines 65-71: Please rephrase the paragraph to highlight the main focus areas of the study. There are some grammatical errors that need to be addressed (e.g., same tense in all sentences)

Materials and methods

The materials and methods section is very well and clearly presented.

1)     Line 76: Not sure of the address link for the company is needed

2)     Line 79: Info on particle size?

Results

The results are presented in detail, backed up by the respective literature

1)     Please check the numbering and format of subsections

2)     Line 214: are exhibit

Conclusions

1)     Please rephrase the first sentence (lines 454 – 455) to make more sense.

2)     Lines 462 – 466: Since the addition of citric acid affects the syrup color, the researchers could also test this parameter in their work, i.e., comparison of syrup color upon various citric acid addition. Color is an important parameter in food products that may affect consumers’ choices.

Comments on the Quality of English Language

The manuscipt is well written

Author Response

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Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

The authors have made sufficient revision to meet the scientific soundness of the manuscript to be published. Congratulations.

Author Response

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Reviewer 3 Report

Comments and Suggestions for Authors

Although the Authors revised the paper it still lacks a novelty and many detailed information were not provided. The title is misleading, and not informing about the real goal of the work. There are many questions which were not addressed.

Inulin from Yacon is linear? On what basis it was concluded, what is the influence of the processing and boiling temp. on this fructooligosaccharides? It is well proven that such high temp. influences the sweetness of all known sugars.

Freeze-drying process enhances the oxidation process as well as browning process, when not protected accordingly (no Authors comments on that).

The theoretical “Relative sweetness” (line 236) have no scientific basis, and the works cited are reviews of knowledge about sweeteners. The authors do not take into account the interactions between "sweet" ingredients (eg. partial hydrolysis of inulin or the other components), which is unacceptable and a very superficial approach to science. How the fructooligosaccharides were evaluated, what is the sweetness, Gi, etc. Were there any of theoretical evaluations validated? There is a need of sensory evaluation of each syrup’s sweetness.

The glycemic index (line 244). How the Authors evaluate Gi when in table 2 (cited paper no 22 Chattopadhyay et al. 2014) there are value ranges, which do not allowed to provide an adequate and reliable value. The same question considers caloric value (line 249). All cited papers are reviews, not providing the results of source research, but a compilation of selected results, which is not an appropriate approach.

As Authors responded: “To inhibit these reactions, citric acid, ascorbic acid, and their combination were used for syrup production, allowing to conclude that the phenolic compounds are likely present in their native form in the syrups.” This statement raises even more scientific doubts about the authors' research and knowledge of the content and activity of polyphenols in the material studied. The polyphenols content needs to be evaluated.

The “Results” section is still too long and poorly organized. As it was stated in previous review, there is a lack of informative discussion, too many irrelevant results, not allowing to concentrate on the subject matter.

Query: “line 459: how many juices were evaluated? In material and method section only limited amount of samples were presented, mainly CA.” – was about the lemon juice not yacon, as it was stated in the cited line.

The Authors did not respond to the environmental cost of syrup processing instead of roots recycling or natural deterioration, there is no information about its significance.

Taking under the consideration the above mentioned queries I do not recommend it for further processing in Applied Sciences.

Comments on the Quality of English Language

Minor editing of English language required.

Author Response

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