Survivability of Salmonella Pathogens and Physicochemical Characteristics of Powder Goat Milk Stored under Different Storage Treatment Regimens
Round 1
Reviewer 1 Report
In the overall context, the paper can be improved by adding more citations in the results and discussion to strengthen the analysis. Also, some of the information can be condensed for the physico-chemical properties and the nutritive value by merging some of the tables and graphics. Specific comments are as below.
Title: correct 'power' goat milk (did you mean powder?)
Material and Methods
L120: Please also elaborate on how it was ensured that the Salmonella cocktail was uniformly distributed in the powder samples. Please also explain how the survival rate was determined and add reference to the protocol used.
L 284 and 287: Figures 2 and 3 are not clear. Please provide originals.
L335: The significant difference in pH needs to be explained. There is no discussion on why it should happen.
Results and discussion
Consider adding more citations while discussing your results to improve the analysis and interpretation of the data.
Consider merging some of the tables and graphics to condense the data to avoid overlaps, as appropriate. This will help with more clear interpretation.
Author Response
Reviewer #1
“In the overall context, the paper can be improved…………analysis. Also, some of the information… tables and graphics.”
<Ans> The reviewer #1 gave very constructive and positive suggestions to improve the manuscript by: (1) addition of citations in the text of the results and discussion section, and (2) condensed discussion with merging some tables and figures. We accepted these suggestions, and revised the text in Results and Discussion section. The graphics are combined graphics, and Table 1 has been deleted because the Reviewer #2 suggested the deletion of Table 1. We hope the revised version would be acceptable to the two reviewers.
“Title: correct ‘power’ goat milk”
<Ans> Yes, it was our oversight, and we are sorry for this error, and appreciate the reviewer #1’s careful reading and suggestion on this mistake.
Material and Methods
“L120: Please also elaborate on how it was ………in the powder samples. Please also explain how the survival rate………….protocol used.”
<Ans> To ensure uniformly distribution of Salmonella cocktail, we manually shaken sample contain bottles by hand for two minutes in all direction (Text lines 120-124). Survival rate was determined by following process: The number of concentration of colony count of duplicate samples were count at enumeration and then converted to CFU/g were calculated by using formula [ (number of colonies x dilution factor )/ volume of culture plate].
The survival rate of Salmonella counts was determined by using the MS. Excel scientific notation to calculate CFU/g and resulting cell count values were converted to Log CFU/g using MS. Excel Log calculation formula. The average of duplicate cell counts was calculated as Log CFU/g. We added the references of protocol used for the inoculation procedure in the revised text as the Reviewer requested. The references to the protocol were added to the text (Line 119). The protocol used in our study was the modified procedure of the two references shown below:
Hyeon, J.Y., Park, C., Choi, I.S., Holt, P.S. and Seo, K.H. Development of multiplex real-time
PCR with Internal amplification control for simultaneous detection of Salmonella and
Cronobacter in powdered infant formula. International Journal of Food Microbiology
2010, 144(1), pp.177-181.
Koseki, S., Nakamura, N. and Shiina, T. Comparison of desiccation tolerance among Listeria monocytogenes, Escherichia coli O157: H7, Salmonella enterica, and Cronobacter
sakazakii in powdered infant formula. Journal of Food Prot. 2015, 78(1), pp.104-110.
“L284 and 287: figures 2 and 3…………….provide originals.”
<Ans> The reviewer has a good point in this comment. However, we tried several times to make the Weibull model curve clear. The clarity was not improved even with the originals. We have attempted to make more clearer curve and increase the font size of X- and Y-axis legends, but the improvements were not substantial.
“L335: The significant difference in pH…………….why it should happen.”
<Ans> The reviewer’s comment on this premise of the pH differences between temperature treatments appears to be very good remark. We mentioned the possible reason for the results in the revised text. The exact reason for the lower pH in PGM samples stored at 25oC compared to those at 4°C is not known. However, more proteolysis can occur and/or organic acids can be generated at higher storage temperature treated samples.
Results and discussion
“Consider adding more citations……………interpretation of the data.”
<Ans> The reviewer’s request for addition of more citations is very good suggestion. We have added four more references in the revised version of Results and Discussion section. However, there are very limited powder milk studies available especially in goat milk or sheep milk products in this area of literature.
“Consider merging some of the tables…………….clear interpretation.”
<Ans> We feel Reviewer #1’s this comment is good and constructive, and compatible with those of Reviewer #2. Thus, we deleted Table 1, because the data are redundant with Figure 1. In addition, Figure 4 and Figure 5 have been merged into one Figure as Figure 4A and 4B, in order to condense the data and more organized presentation.
Reviewer 2 Report
The authors have studied the survival of Salmonella in power goat milk under different treatments.
Comments:
Line 231. Log CFU0 with "0" subscript.
Line 232. Log CFU(t)0 with "(t)0" subscript.
Line 237. Results. This section includes the Discussion so it should be "Results and Discussion".
Line 246. Change "7.103 CFU/g" to "7.10 Log CFU/g". And include that the initial mean counts were for the three batches.
Lines 247 and 248. Change "bacteria" to "cells".
Line 253. Change "1.15 CFU/g" to "1.15 Log CFU/g".
Figure 1. Clarify that the results are for the three batches. Eliminate the count numbers along the survival lines. Change X-axis to XY-scatter chart.
Table 1. It is not necessary.
Lines 265-276 (paragraph plus Table 2). Move right before section 3.2.
Table 2. Include the temperatures in the title.
Figures 2 and 3. Improve quality for better visualization. Be careful to obtain both figures with the same measures (right now they are different). Eliminate "and water activity 0.33" from the title because it is not necessary and it is confusing. Eliminate "using IPMP 2013" from the title because it is not necessary.
Line 293. Change "(CFU/g)" to "(Log CFU/g)".
Author Response
Reviewer #2
“Line 231.Log CFUO with “O”subscript.”
<Ans> We have corrected the Log CFU0 to Log (CFU0) in the paragraph.
“Line 232. Log CFU9t)0 with “(t)0”subscript.”
<Ans> We have corrected the Log CFU(t)0 to Log CFU(t)0 in the paragraph, as requested.
“Line237. Results. This section includes…………….and Discussion.”
<Ans> Yes, it was our oversight. We are sorry for our mistake, and appreciate the reviewer#2 for the careful reading and correction.
“Line 246. Change “7.103 CFU/g………..And include…………….the three batches.”
<Ans> We have corrected the 7.103 CFU/g to 7.10 Log CFU/g in paragraph and also described the suggested sentence in the text, as the reviewer requested.
“Line 247 and 248. Change bacteria to cells.”
<Ans> The word “bacteria” was changed to “cells”, as suggested.
“Line 253. Change…………..Log CFU/g.”
<Ans> We have corrected 1.15 CFU/g to 1.15 Log CFU/g”.
“Figure 1. Clarify that the results……………..XY-scatter chart.”
<Ans> Each data point in Figure 1 shows the average cell count value of three batches for two different temperature treatments. The pattern of survival trend for each batch were similar to the mean value at specific storage temperature. Therefore, we displayed the graphic as mean values for representing all three batches at two different temperature treatments (4 and 25°C). We removed the count number on the survival graphic lines. However, we kept the graphic lines to show the clear survival trends of Salmonella cells in the powder goat milk samples, while changed X-axis to XY-scatter chart, as the reviewer suggested.
“Table 1. It is not necessary.”
<Ans> We agree with this comment where the reviewer’s suggestion is better and acceptable, so that we removed the Table 1 in the text.
“Line 265-276 (paragraph plus Table 2)………………….section 3.2.”
<Ans> We have corrected the paragraph and table position as requested.
“Table 2. Include………………the title.”
<Ans> We added the temperature in the Table 2, as requested.
“Figure 2 and 3. Improve quality for better……………..Eliminate”and water activity……………….confusing. ……………it is not necessary.”
<Ans> At the reviewer’s request and suggestions, we tried to improve the quality of the two figures. However, even with the original Weibull model curves, the curve lines and the Y-axis and X-axis legends were not much improving. We noticed that the only way to make the figure visible is that the figures have to be enlarged the sizes. However, we tried our best to make the figures better visualization. In addition, we removed the unnecessary words from Figure 2 and 3 legends, as requested.
“Line 293. Change…………(Log CFU/g).”
<Ans> We have corrected the (CFU/g) to Log (CFU/g) in the paragraph, as suggested. We greatly value the thorough review and great insights of Reviewer 1 in review of our manuscript.
Finally, we are very grateful for the two reviewers for sorting out our overlooked mistakes and errors in the manuscript. In addition, the reviewer’s suggestions on merging and/or deleting the tables and figures have enhanced the Results and Discussion section to make more focused and clearer presentation of our research results. We acknowledge that the two reviewers have great insights and knowledge on our research article, and made important contributions to the revision of our manuscript.
