Screening of Different Ageing Technologies of Wine Spirit by Application of Near-Infrared (NIR) Spectroscopy and Volatile Quantification
, Ilda Caldeira 4,5, Rita Roque 1, Soraia I. Pedro 1, Sílvia Lourenço 4 and Sara Canas 4,5Round 1
Reviewer 1 Report
Revision is attached in the document.
Comments for author File: 
Comments.doc
Author Response
We thank the comments and suggestions posed by the Reviewer 1. All of them were taken into account to increase the manuscript’s quality. Responses to the Reviewer comments and references to changes made in the manuscript are presented in the attached document.
Accordingly, the manuscript was carefully reviewed, and the changes made are marked in blue.
Reviewer 2 Report
The research is adequately conducted and the manuscript properly written, but I indicate a revision of several parts including mainly the multivariate approach (section 3.3) and the conclusions, as described below. Furthermore, the article should be completed by detailed information about the ageing experiments, including the wood treatments, and a specification of the micro-oxygenation parameters, for now only included as a cited reference.
- Line 25: "The results suggest"... it seems to me more of a confirmation than a new finding.
- The degree of toasting and the manufacturer for wood barrels and staves, and the size of the used staves, needs to be specified (lines 80-81).
- How many staves have you used for this experiment? Please include also the surface-to-volume ratio (lines 87-90).
- Micro-oxygenation protocol is referenced to other sources (lines 82-83), but the key parameters need to be placed also in the text (e.g. oxygen intake per month, instrument, diffusers).
- Please specify the post-hoc tests used and the p-value used.
- Line 110: use abbreviations, e.g. "mg/L".
- Section 2.3: do you have any reference for NIR measurements? How you determined the instrumental methodology to be used?
- Table 3 needs to be reformatted as it is difficult to read. Why the use of "BA" instead of "AB" in some occurrences (e.g. TC 180 and 360 days vs 1B)?
- PCA part: 8 PCAs were made,to me it seems quite confusing. While I may understand the need for one PCA approach for NIR data, and another approach for chemical data, I don't completely understand why single PCAs were made for each sampling time. I suggest to try a PCA at least for all chemical parameters and evaluate the possible outcome.
- Lines 331-359 (except lines 341-343, 355-356) should be included as a discussion part, or before the multivariate approach.
- Conclusions: I don't understand the statement related to the 90% accuracy rate in determining the ageing characteristics (lines 368-370). How you obtained and validated this result?
- Please indicate the most relevant NIR spectral regions in the conclusions (lines 371-373).
Author Response
We thank the comments and suggestions posed by the Reviewer 1. All of them were taken into account to increase the manuscript’s quality. Responses to the Reviewer comments and references to changes made in the manuscript are presented in attached document.
Accordingly, the manuscript was carefully reviewed, and the changes made are marked in magenta.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Auhors did revision properly.
Author Response
We thank the time that the Reviewer spend to review our manuscript to increase their quality.
Reviewer 2 Report
The manuscript improved significantly with the exception of the multivariate part. The authors kept their multivariate approach with little or no modification to the manuscript. I continue to think that this approach is very confusing: in the whole manuscript there are 23 indications of "PC1" and 14 indications of "PC2", belonging to 8 different PCAs. If the authors want to keep that approach I think that a distinct indication of the PCAs, PC1 and PC2 in the text and figures needs to be done (e.g. an indication of the ageing time such as A-PC1 or 540-NIR-PC1, or similar).
In their reply, the authors explained very well the concept behind their PCA approach: "Indeed, the great influence of ageing time overlaps the differences promoted by the wood species and ageing technologies." I think that this concept needs to be included in the manuscript.
As a consequence of this statement, the first paragraph of conclusions needs to be better explained, since the PCA approach appliedo to NIR data was able to discriminate samples not "with" but "only inside" each sampling time.
Author Response
We thank the comments and suggestions posed by the Reviewer 2. All of them were taken into account to increase the manuscript’s quality. Responses to the Reviewer comments and references to changes made in the manuscript are presented below.
Accordingly, the manuscript was carefully reviewed, and the changes made are marked in blue.
Author Response File: Author Response.docx
