Quality Identification of Sauce-Flavor Liquor Based on the Tyndall Phenomenon

Round 1

Reviewer 1 Report

The manuscript presents a very interesting and useful study. However, some points need to be improved before publication. The article is difficult to follow and the organization must be reviewed. For example,e the results section presents some information regarding methodology aspects. Finally, some important references are missing.

1. The abstract can be improved, in order to make it more impressive. Consider adding two lines at the beginning, and include more specific information (conditions).
2. Lines 38-39. The authors mentioned reports regarding Tyndall phenomenon in liquor. Please add more information. What do the reports say? What another related research has been done? Authors should add information related to previous studies carried out in the field of research.
3. Line 39. “It is the first to propose how to use the Tyndall phenomenon of liquor and light to identify the quality of liquor” The introduction should end with the objective of the study. Please add more information regarding the study variables.
4. Lines 41-46. This information belongs to the methodology section.
5. This section has no references. Please include the most relevant.
6. Fig 1. Please include the reference or Is the figure self-made?
7. Table II. Add +/- Standard deviation for the sample parameters and provide information regarding methods and statistically significant differences between samples.
8. The description of methods is very general and some techniques are missing. This section must be improved.
9. Results and discussion. This section contains information related to methods description, i.e. roughness of liquor simples, micromorphology. Please organize the information and only present the results in this section, stating the hypotheses to explain the results.
10. Conclusion. Please add more information regarding the importance of the obtained results in the food industry and possibilities of further or complementary analysis. 

Author Response

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Author Response File: Author Response.docx

Reviewer 2 Report

The manuscript is aimed at the urgent task of working out a simple and fast method for analyzing the quality of liquid products, specifically, liquors. Methods based on the observation of light scattering are actually appropriate here, since the angular pattern of the scattering intensity is directly determined by the size distribution of the scatterers. For instance, the presence of large particles leads to the predominance of small-angle scattering. Although the Tyndall effect has been used for a long time to test the size uniformity of colloids, I should note the novelty of the work in that the authors proposed a successful approach establishing an empirical correspondence between the intensity patterns of light scattered inside a transparent flask with the liquor sample under test and the exact sizes of sol particles measured in the same sample using atomic force microscopy. Important visual results have been obtained in terms of light path brightness, which is convenient for practice. In particular, the comparison of light scattering at different wavelengths is shown to increase the information content of the proposed method. Nevertheless, in my opinion, a lot of places in the text need clarification and improvement. Additionally, I encountered a number of linguistic misuses and misprints. Therefore, I recommend reconsidering the paper after major revisions. Below are my comments on the text:
1) Line 12: “Aim” should be corrected to “Aiming”
2) Line 17: Subject is needed for “analyzed”, e.g. “we analyzed”
3) Line 17: Does “the particle uniformity” mean “the particle size uniformity”? If so, please insert “size” before “uniformity”.
4) Line 17: “uniform the particles” in size? Please specify.
5) Lines 18-19: “pass” should obviously be replaced by “path”; it would be better to combine “the brighter” and “the lighter” together by writing “the brighter and lighter the Tyndall path”
6) Line 19: It is better to clarify "flooding" as "light flooding"
7) Line 21: “Identify quality” would be better replaced by “quality identification”. "Optical" is an adjective, a noun is necessary, e.g. "methods".
8) Lines 24-25: bad style, "it" is repeated frequently.
9) Line 48: It is more adequate to replace “attenuation process” by “attenuating action”.
10) Line 58: “is scattered by” should be corrected to “scatters”, since the particle causes light to scatter, and not otherwise.
11) Line 59: The scattering of “many rays of light at the same time” implies that the multiple scattering occurs. It is worthwhile to evaluate the degree of multiple scattering in liquors based on a presumable concentration of sol particles in the liquor. Could the particle concentration in the liquor samples be estimated from AFM measurements displayed in the Results section? It is known that the impact of multiple scattering is noticeable when the optical depth of the medium is greater than 2 (See, for example, J. Jönsson and E. Berrocal, Multi-Scattering software: part I: online accelerated Monte Carlo simulation of light transport through scattering media, Opt. Express, 2020, 28, 37612-37638). The optical depth is the natural logarithm of the transmittance of the medium. The optical depth can be calculated as the product of the extinction coefficient by the length of the medium. In turn, the extinction coefficient can be considered equal to the product of the particle volume concentration by the extinction cross section of a single particle. More reasoning should be given about Figure 1 in view of further comment 14.
12) Lines 71, 74: It is more adequate to replace “brightness is large” by “brightness is high”.
13) Lines 73, 76: It is more adequate to replace “scattering tends to be scattered” by “light scattering tends to be produced”.
14) Line 77: It is more adequate to replace “brightness is small” by “brightness is low”
15) Line 79, Figure 1: The sketch of light scattering is incomprehensible. Please answer the following questions. What are the yellow filled circles? Are they large particles of a size exceeding the light wavelength? What is the red circle? What does “optical line” mean? The black line that appears to represent a light ray breaks several times. Is this multiple scattering phenomenon? If so, what is the role of multiple scattering in the formation of the light-flooded area? What features of the scattering pattern are explained by the magnified yellow particle on which multidirectional arrowed lines bend? Please add a legend with a brief explanation for the figure. In fact, it is quite clear that the addition of multiple scattering enhances the scattering intensity at the side-scatter and near-backscatter angles, as a consequence, the brightness increases in the center of the light-flooded area and in the half of this area which is closer to the light source. (For more details, see Chapter 2.7 Monte Carlo Simulation, Valery V. Tuchin, Tissue Optics: Light Scattering Methods and Instruments for Medical Diagnostics, 2015, https://doi.org/10.1117/3.1003040, and Vermeulen A., Devaux C., Herman M., Retrieval of the scattering and microphysical properties of the aerosols from ground-based optical measurements including polarization. I. Method, Applied Optics, 2000, Vol. 39, No. 33, Fig.4 on page 6210)
16) Please describe all the elements of Figure 1 in the figure legend.
17) Line 80: “liquor being scattered by light” seems to be a misuse. It should be written contrariwise “light being scattered by liquor”.
18) Lines 110-111: The actions are apparently in the past tense, that is, “select” should be changed to “we selected”, and “conduct” to “conducted”.
19) Line 143: It is more adequate to replace “agglomeration phenomenon” by “agglomerates”
20) Line 158: “particles are arranged in disordered and aggregated” would be correctly written simply as “particles are disordered and aggregated”
21) Line 173, Figure 4: The numbers in the graphs are too small to be clearly read. Also, please unify the font size of the labels.
22) Line 175: “microscopic particles” should be “microscopic images of particles”. As I understand it, the results are shown for each of the four samples in the corresponding sequence; therefore, instead of the phrase “of the four liquor sample” it would be more appropriate to write “for each of the four liquor samples”.
23) Line 179: “the selective light scattering range is more accurate” looks awkward, and the meaning is completely unclear. Did you mean that it is necessary to accurately select the range of light wavelengths for scattering?
24) Line 180: “impassable particles” is an unconventional term, its meaning is not clear. Why can't light pass through them? Do they absorb light? Or do they scatter light strongly? Please rewrite more clearly.
25) Line 181: a misprint “nmd”
26) Line 181: What do you mean by “choice of light scattering”? Choice of scattering regime, Tyndall scattering or scattering by large particles? Alternatively, choosing the wavelength of the light to maintain Tyndall scattering regime “as the particle size increases from small to large”?
27) Line 190: Figure 5, in my view, does not display any essential information, since the situations shown can simply be described by one similarity criterion such as the ratio of the particle size to the wavelength of light (the so-called size parameter).
28) Line 200: Should there be “distributed” instead of “dispersed”?
29) Lines 142, 152, and 201: Should there be “liquor” instead of “wine”?
30) Lines 207-208: “identification differentiation”, the word “identification” is redundant here.
31) Line 200: “which is easy to be confused” would be more correctly written as “which can be easily confused”
32) Line 210: “the time to stabilize at the time of lighting” seems to mean “the time of lighting stabilization”?
33) Line 215: label “(b)” is missing in the left graph of Figure 6.
34) Line 216: The figure caption “The light intensity of 365 nm (a) and 395 nm (b) bands passing through different liquor samples varies with time” would be more correctly formulated as “Time variation of the light intensity of 365 nm (a) and 395 nm (b) lamp beads after passing through different liquor samples”.
35) Line 221: What does the “color depth” mean? Please clarify.
36) Lines 150, 222: “size distribution of high-quality liquor was concentrated” is composed in an unusual way. What is the meaning of “concentrated” in relation to distribution? Did you mean the size distribution was narrow?
37) Line 224-225: “the effect of this method is more accurate” is very hard to understand. Effect of the method on what? More accurate than what? Did you mean “this method is proven to be accurate”?
38) Line 227: “industrialization” should likely be “industry”?

Author Response

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Author Response File: Author Response.docx

Round 2

Reviewer 2 Report

The comments have been satisfactorily addressed overall. The manuscript now looks consistent enough. However, some minor revisions are required. There is semantic confusion in lines 14-18: “effect on liquor”. Weren’t you interested in how the liquor itself could change under the influence of light? But it was rather the opposite. So, I suggest a slight editing of these lines as follows “The influence of different wavelengths of light on the light scattering in liquor was explored, and it was concluded that the ultraviolet and blue light bands have a certain efficiency in the identification of liquor; we analyzed relationship between the particle size uniformity of liquor colloids and liquor quality according to Tyndall phenomenon”. In lines 18-19, the fundamental cause of the observed effects both in path brightness and in flooding angle, obviously, is that the particles in higher quality liquor are more uniform, therefore “due to” must be attached to "particles”. So, I propose to rewrite this sentence as "We found that higher quality liquor has a brighter and lighter Tyndall path and a smaller light flooding angle due to the more uniform particles in it”. There is an error in line 22: “Identify identification” should be “Quality identification. In line 38, “the identification effect of light on sauce liquor” would be better written as “the identification efficiency of light in relation to sauce liquor”. In line 51, ”receiving device” is not necessary, since the detector is the receiving device, and “wine body” should be replaced by “liquor volume”. In lines 54-55, the active and passive voices are confused when writing about light scattering by particles. Particles are the subject, and light is the object that the subject acts on. So, when talking about light, it should be "the light is scattered by the particles", whereas, when talking about particles, it should be "the particles scatter the light". In Figure 1, it is more appropriate to replace “incoming” by “outcoming”, since the designated light rays are seen coming out of the liquor sample. In line 88, “wine” should be “liquor”. In lines 176 -177 “It has potential application value in the quality identification of sauce-flavor liquor and is suitable for the application of this method in industry”, “it" seems to stand for “this method”. Thus, this sentence would be consistently written as “This method has potential application value in the quality identification of sauce-flavor liquor and is suitable for industrial applications”.

Please revise the indicated points.

Author Response

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