Impact of Fat Content and Lactose Presence on Refractive Index in Different Types of Cow Milk
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
Overall, if I understand this correctly, the results in Table 2 for neff”, particle size (not sure if that’s x or a; that should be better defined), f, and alpha are determined by some best fit to the measured data. That fitting method is never described and the quality of the fit should be discussed (in lieu of listing uncertainties for neff”, particle size, f and alpha in Table 2).
Furthermore, Fig. 7 seems to indicate that there should be several particle sizes and f’s considered in estimating neff (and alpha). That discrepancy should also be discussed!
Other things:
Features missing from Table 1: (1) Extinction of the polarizer by wavelength. (2) Angular resolution to which the polarizer may be set to 0 or 90 deg and its affect on the extinction uncertainty (even if that's negligible).
Eqs. (1) and (4): I believe the word, “sen,” should be “sin.”
Line 143: is ni complex?
Line 146: how is h measured and what is its uncertainty?
Eq. (4) and line 148: k0 should be defined.
Figs. 2, 4, 5 and 6: Font is too small and hard to read.
Eq. (5) and afterward: n(lambda)’ is defined in eq. (6), but that’s too far after eq. (5). It should be defined immediately after eq. (5) for the reader’s ease.
Eq. (7) and line 184: is nm complex?
Eq. (8): is this correct? I’m used to seeing the x parameter defined as x = kr, not x = 2kr.
Starting at line 199 and afterward, there’s no Fig. 3, so Figs. 4-7 and all their references in the text should be Figs. 3-6!
Fig. 5 extends from Fig. 4, which covered 450-800 nm (I think, hard to read!), as reflectance data at 525 nm and then 525 nm is used the rest of the way. There’s no discussion as to why 525 nm was chosen or why the entire spectrum isn’t used/needed. That seems to be a lot of unused information!
Fig. 7 caption: all the symbols used in the drawings should be defined. They have some implied meaning.
Comments on the Quality of English Language
Para. 2.2.5, lines 135-140 should be rewritten. There’s no need to use 2nd person.
Author Response
Please see the attachment.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsAuthors introduce an innovative and cutting-edge approach to characterize different types of cow's milk based on their optical properties, aiming to establish a straightforward yet comprehensive method. They have used fundamental optical parameters with low-cost equipment to characterize the milk. One can easily understand their analysis with graduate level knowledge. I think this work is suitable for applied science. However, in current form, I cannot recommend this article to publish in applied sciences.
1. Abstract and introductions are written well. In Section 2, most of the sentences are very difficult to understand. I think authors must rewrite in better way for example lines 13, 14 in page 5 and lines 15 and 16 in page 6.
2. In table 1, power: 150 W, I think it is electrical power, but authors must clearly mention otherwise readers may confuse with laser power.
3. Angular pitch :0.1. I think it is degree.
4. Authors should provide the details of how they derived equations or references. For example, Eq 1 and 3.
5. What is sen(theta).
6. Figs. 2,4,5, and 6 are very bad and I could not understand anything.
7. I think authors can give particle size in micrometres in table 2.
Comments on the Quality of English Language
Section 2 has to be improved
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Reviewer 3 Report
Comments and Suggestions for AuthorsThe manuscript demonstrates an interesting application of fundamental optical principles, characterizing different types of cow milk. It shows that there is still great potential for class optics. However, a few concerns have to be addressed before the paper can be considered for publication.
1. In the abstract, the first sentence says that the method is “innovative and cutting-edge”. I would rather suggest the authors be cautious when using these words.
2. The measurement setup should be calibrated before use. There is no description of the calibration process in the paper.
3. In Table 2, the real parts of the refractive indices have an uncertainty of 0.0002. However, there is no uncertainty in the imaginary part of the refractive indices. In addition, the paper should also introduce how many samples are measured, and error bars are always important to show the reliability of the experiment.
Comments on the Quality of English Language
I strongly suggest the authors have a native speaker to revise the manuscript thoroughly.
Author Response
Please see the attachment.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
Comments and Suggestions for AuthorsThe revised manuscript looks complete and now it can be published in Applied Sciences
Reviewer 3 Report
Comments and Suggestions for AuthorsThe authors have addressed my concerns.
Comments on the Quality of English LanguageIt has been improved.
