Dear Editors and Reviewers:
Thank you for your letter and for the reviewers’ comments concerning our manuscript entitled “Realtime Monitoring of Xylitol Fermentation by Micro-Raman Spectroscopy”(LANL-2014-0001). Those comments are all valuable and very helpful for revising and improving our paper, as well as the important guiding significance to our researches. We have studied comments carefully and have made correction which we hope meet with approval. Revised portion are marked in red in the paper. The ma in corrections in the paper and the responds to the reviewer’s comments are as flowing:
Responds to the reviewer’s comments:
1. Response to comment (Reviewer 1): (The proposed method was established with the lack of the process of the optimization. The curve was adopted to illustrate the changes of absorption peak in the process of fermentation, but the absorption peak couldn’t be confirmed the identical to the reference peak of xylitol. It needs more data to prove the reliability of the method)
Response: C onsidering the Reviewer’s suggestion, the experiment of high performance liquid chromatography (HPLC) is added to verify the reliability of the Raman data. Raman paek is a kind of inelastic scattering paek（not absorption peak）, Raman spectrum of the standard xylitol and xylose solutions was uesd to selecte the most appropriate characteristic bands of xylitol and xylose for our experiment based on their comparative strength without overlap with other bands.
2. Response to comment(Reviewer 1): (The literature data(table 1) was used in
this paper, but different shifts and strength would be obtained using different Raman spectrometers, so data shall be carried out according to the experimental results in the support of literature.)
Response: different experimental conditions has a great influence on the peak intensity. but little effect on the peak raman shift, This is the basis of the Raman qualitative.
3. Response to comment(Reviewer 1): (The references shows different styles.)
Response:The format of the reference has been corrected.
4. Response to comment(Reviewer 2): (The medium is a complex mixture and includes yeast extract. Yeast extract will contain many of the characteristic Raman peaks that the authors ascribe to the yeast cells.)
Response:every sample of yeast cells pallet had been washed twice（suspension and centrifugation）to ensure impurity elimination, in addition , yeast extract is obtained after plasmolysis and complete hydrolase autolyzed, remove the cell wall and insoluble productsaccording to the production process of yeast extract. so the process for purifing the yeast cells pallet is reasonable.
5. Response to comment(Reviewer 2): ( The spectral resolution is stated to be 1.2 cm-1; however, the spectra are smoothed....No details of the smoothing algorithm used are provided. This affects the spectral resolution.. )
Response:we added the processing methods of Raman spectra in section of Data analysis.
6. Response to comment(Reviewer 2): (In Figure 3, the peak at 866 cm-1 .....
