Effect of Freeze–Thaw Cycles on Physicochemical and Functional Properties of Ginger Starch
Eduardo Morales-Sánchez
Round 1
Reviewer 1 Report
The manuscript has investigated the effects of freeze-thaw cycles on the physicochemical and functional properties of ginger starch. The topic is interesting; However, the manuscript has several problems:
1. L 10 and 11; "The resistance starch ... promote starch retrogradation". This sentence seems unnecessary.
2. L 16 and 463, C-type.
3. L 20, ... indicating "higher" thermal stability.
4. L 36, ... fresh "product".
5. Please mention more basic information about starches and their application in the food industry (e.g., thickener, gelling agent, stabilizer, etc.) in the introduction section based on the 10.1111/ijfs.13222.
6. L 55, Please define all types of resistant starches.
7. Part 2.2; Explain more about the isolation process of the starch.
8. L87 and 88; Please check the style of references. They should be changed to Wang et al. [8] and wang et al. [9]. Check the entire manuscript.
9. Part 2.3; Please mention the reference.
10. L 168; "W0" not "W0". Please check the entire manuscript.
11. L 233; Express the company name and the version of the software.
12. L 244, 245; "It can be seen ... intact starch granules". This sentence needs to be changed.
13. Part 3.3; Please divide the pasting properties into another part.
Author Response
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Author Response File: 
Author Response.pdf
Reviewer 2 Report
Dear authors, I recomended to accept the paper after minor revisions.
There are lots of non-space mistakes like "-20 °C" (line 91).
FTIR equipment: Please, add brand and model.
Table 1: on the last line put the subscript letters.
Line 257: a-g
Line 327-329: it is not possible to compare with the ultrasound process, they are different things.
I recomended to accept the paper after minor revisions.
Author Response
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Author Response File: Author Response.pdf
Reviewer 3 Report
The starch from ginger is a byproduct that is produced as a result of the extraction of bioactive compounds from ginger. The process of generating resistant starch entails subjecting starch to alternating cycles of high and low temperatures to induce retrogradation. In this study, the main objective of the authors was to investigate the effect of varying freeze-thaw cycles on ginger starch and to examine the resultant impact on the functional constituents, physicochemical attributes, and structural characteristics of ginger starch. The study's findings indicate that there was a significant increase (p < 0.05) in the content of resistant starch, amylose, total starch, and recrystallization in ginger starch as the number of freeze-thaw cycles increased. The X-ray diffraction pattern of freeze-dried ginger starch revealed the presence of a crystal structure of the Ca-type. The outcomes of Fourier-transform infrared spectroscopy indicated an increase in the value of A1047/1022, which suggests that the process of the freeze-thaw cycle is likely to enhance the degree of starch recrystallization. In relation to the physical and chemical characteristics, freeze-thawed starch exhibited distinct differences from gelatinized starch, as evidenced by its reduced swelling power, elevated solubility, diminished peak viscosity and breakdown, which collectively suggest enhanced thermal stability. The findings suggest that the utilization of freeze-thaw treatment can effectively enhance the production of resistant starch from ginger starch and mitigate starch hydrolysis, thereby demonstrating the feasibility of developing low-glycemic index food products. It is anticipated that ginger starch possesses the potential as a viable substrate for novel functional food applications.
The study is quite interesting; however, there are serious flaws in the study. I would like to see the following suggestions incorporated before the paper can be accepted.
• In equations 1 and 2, the spelling of “resistant” is incorrect.
• Section 2.2: Starch does not form a solution in water. It is a suspension.
• During the freezing process, how the starch granules were stabilized in the suspension. As a matter of fact, as soon as the homogenization process of the starch suspension is stopped, the starch granules begin to settle. So, I fear that the starch granules would have settled during the freezing process.
• Thawing at different temperatures should be performed. The experiments should be performed at 30 oC, 40 oC, 50 oC, and 70 oC.
• Since the starch molecules have a considerable amount of water molecules, the authors should perform Raman spectroscopy rather than FTIR spectroscopy for characterizing the starch.
Author Response
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Author Response File: Author Response.pdf
Reviewer 4 Report
Introduction:
Author mention that freeze thaw cycles are enough to increases RS from any starch. In the literature there are not articles that show that freeze thaw cycles increase up 20% AR. Really, only increase the first time and after remain in the same value. There are not effect from cycles, at less with significance.
Add references with the physicochemical characteristics of ginger starch.
Line 57. Add references that show that for retrogradation there are a more stable structure.
Line 58. Add references that show that applying freeze thaw cycles, these cycles increment AR in any starch.
Line 67. Add that references about results from your laboratory.
Line 68-70. Add references to probe that sentence.
Materials and methods
Table 1. results shown that freeze thaw starch remain as granules for that reason had the RS quantity as native. Only gelatinized starch had different value because starch was heated at 100o C. Then, though author made more freeze thaw cycles there was not AR increases. That means that freeze thaw was not the real variable to change RS.
DRX, viscosity, swelling and solubility shown that freeze thaw starch has the same characteristics. Freeze thaw samples were not gelatinized and remain as native starch. There was not significance change in its physical properties.
Author Response
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Author Response File: Author Response.pdf
Reviewer 5 Report
The paper "Effect of Freeze-thaw Cycles on Physicochemical and Functional Properties of Ginger Starch" is an original experimental study focused on treating ginger starch with different freeze-thaw cycles and investigating the effect on the functional components, physicochemical properties, and structural properties of ginger starch. The authors have done a lot of good work. The explanation of the phenomena observed is quite satisfactory whereas the text is fairly well written and exhibits an element of originality. However, some below-mentioned comments should be considered before publication in the Processes.
1. Introduction needs to be improved and restructured to show better the work's originality and importance. Moreover, it seems that the novelty of the work with respect to the literature, and the state of the art are not well highlighted in the paper. Therefore, the novelty of the present article should be clearly explained. Also, a clear statement on what was intended to be investigated (expectations, aims, hypotheses) would be helpful (line 68-75 is quite vague).
2. In the introduction part, the authors did not mention the drawbacks of natural starch before mentioning the modification ways of starch and before explaining the resistant starch. Please, add some relevant references from the literature. For this purpose, you can use (1) Carbohydrate Polymers 269 (2021) 118250, (2) Polym Adv Technol. 2020;31:1256–1269
3. It is well known that moisture content and relative humidity environments play a significant role in the gelatinization and retrogradation (crystallization) of starch. Thus, what conditions were used for the prepared samples before analysis? I highly recommend adding the used conditions in the sample preparation section (2.2).
4. The authors should provide the source of native starch (unmodified starch) in the materials section.
5. The work presents the potential in extending the investigation for such material. Maybe, for further works, evaluating the effects of aging of the modified starched and performing the chemical analysis such as solid-state NMR might provide interesting results.
6. Please, define any abbreviation before using it. For example, in line 56, RS3.
7. The conclusion section sounds good.
8. There are some errors. Please, check the manuscript.
There are some errors. Please, check the manuscript.
Author Response
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Author Response File: Author Response.pdf
Round 2
Reviewer 1 Report
The manuscript is now suitable for publication.
Reviewer 3 Report
Since you already have the data. It will be better if you could include the results of your preliminary experiments conducted various temperature to enhance the production of resistant starch as SUPPLEMENTARY INFORMATION for the benefit of the readers.
Minor English corrections required.
Reviewer 4 Report
Enthalpy is not the energy required for the double-helix structure of starch to dissociate. That is an interpretation, it is not an absolute true
Gelatinization is not the melting of starch.
Reviewer 5 Report
The authors have taken my comments seriously and made proper revisions accordingly. The revised manuscript is now suitable in terms of its technical quality and originality for publication in processes.
