Physicochemical, Microbiological, and Sensory Properties of Set-Type Yoghurt Supplemented with Camel Casein Hydrolysate
Round 1
Reviewer 1 Report
Fermentation- 2253274
General comments:
This manuscript analyses the effects of camel and cow casein hydrolysates on several physicochemical and sensory properties of yoghurt. Title should be modified because Authors did not obtain rheological properties; they have measured textural properties with a dubious method. This is a lack of this paper, since it should be important to compare the differences in thixotropy and viscoelasticity due to both casein hydrolysates. The novelty of this manuscript is poor since it is similar to previous studies such as Zhao et al., 2006; Ma et al., 2019…etc. the presentation is poor and some graphics should be changed.
Specific comments:
1.- Line 66: “cow of raw skim milk” revise English!!.
2.- Line 107: what probe? Diameter? Authors should indicate the method for obtain hardness, cohesiveness and springiness. “The probe penetrated the samples”, what is the geometry of sample?. Authors should consider that penetration proofs cannot provide texture profiles. TPA analysis are made using compression tests with an adequate percentage of compression, which should be previously tested and explained. Check!
3.- Line 161: “addition of the casein hydrolysates significantly decreased the fermentation times”. This sentence cannot be deduced from data of Figure 3. Please, introduce error bars and letters to indicate the significant values. In Figure 3 write numbers with black colour to distinguish adequately the values see template of instructions for authors.
4.- Lines 179-180: “The rate of pH decrease was significantly (P < 0.05) higher in treated samples” This sentence cannot be deduced from data of Figure 4. Authors should include the error bars and letters to indicate the significant values in both Figs 4 a,b. Revise the complete Figure 4 which is unclear, use the same format than in Figure 1. Write numbers with black colour to distinguish adequately the values, revise y, x-axis (unclear) etc.
5.- Line 201: For Figure 5 idem comment than previous to include error bars and letters for significance to show the statistical analysis. Indicate legend to understand L and W (x-axis).
6.- Figures 5 and 6 should be unified in Figure 5a,b.
7.- Table 2 should be reformed, to improve its intelligibility. Authors should include the significant letters to distinguish the statistical differences among samples. To verify data of both Table 1 and Table 2 Authors should include (Appendix) the textural profiles of different samples to indicate if there are or not comparable, indicating the percentage of compression. Authors should consider that according to the compression level, texture profiles (force vs deformation/time) might be different (not comparable).
8.- Figure 7 : complete legends. Include error bars and letters of significance to distinguish statistically samples.
9.- Lines 323-324: “sensory attributes of the yoghurts were significantly improved by the addition of hydrolysates especially with 1.0% camel casein hydrolysate” This sentence is contradictory with data of table 3 which shows the same letter for sample 1L vs control indicating no significant differences for both fresh and after 21 days.
10.- References: Write in the all list the same kind of script to separate the Journal’s pages.
Line 217: the reference [36] was mentioned before than [35]. Revise! Write the references based on guide. For example, Lines 339 (Food Chem.), Lines 341, 343, 347, 352, 367, 378, 389, 401, 405, 411, 422 after Journal there is not come, etc. Line 352: write with small letters Int. Line 363: the scientific name with cursive letter. (Int. J.). Line 365: write volume with cursive letter without bold. Line 374: For books, year is written with normal letter (non bold), revise “In” this is not a chapter in an edited book. Line 386: write correctly volume with cursive letter. Line 396: write correctly the point in Technol. Line 399: write the point in J. ; Line 423: write the points adequately. Lines, 411, 414, 416, 424: write volume with cursive letter. Line 411: include page range. Line 376: write the journal without bold. Include year and volume.
Author Response
Responses to the Editor’s and Reviewers' Comments
We appreciate very much the editor and the reviewers for the constructive comments, which have helped us significantly to improve our manuscript. We also thank the editor and the reviewers for the effort and time put into the review of the manuscript. Each comment has been carefully considered point by point and responded. Responses to the reviewers and changes in the revised manuscript are as follows.
Manuscript number: D: fermentation-2253274
Title: Microbiological, Rheological and Sensory Properties of Set Type
Yoghurt Supplemented with Camel Casein Hydrolysate
COMMENTS FROM REFEREE: Thank you for your thoughtful and thorough review of our manuscript.
Reviewer
1 - Title should be modified because Authors did not obtain rheological properties; they have measured textural properties with a dubious method.
Response: we appreciate your suggestion. As you suggested, we have modified the title to: Physicochemical, Microbiological, and Sensory Properties of Set Type
Yoghurt Supplemented with Camel Casein Hydrolysate …….Lines 2 and 3
2 - Some graphics should be changed.
Author Response: We modified Figures 1, 3, 4a and b, 5, 6, and 7, and combined Figures 5 and 6 in one Fig.
Fig. 1
Specific comments:
1 - Line 66: “cow of raw skim milk” revise English!
Acid casein was prepared from camel and cow of raw skim milk.
Author Response:
Acid casein was prepared from camel and cow raw skim milk.
2 - Line 107: what probe? Diameter?
Texture profile analysis (TPA) was performed using Brookfield CT3 texture analyzer (Commerce Boulevard Middleboro MA 02346 USA) to determine the textures of the yoghurts.
Author Response: We appreciate your comments. The probe descriptions were indicated in Material and Methods chapter under subtitle Texture profile analysis
It was explained in lines 107-110
Texture profile analysis (TPA) was performed using Brookfield CT3 texture analyzer (Commerce Boulevard Middleboro MA 02346 USA) to determine the textures of the yoghurts using Acrylic cylindrical probe 25.4 mm diameter, 35 mm long.
reviewer comment; The probe penetrated the samples”, what is the geometry of sample?
Author Response: The TPA experiments performed in the yoghurt cub
Lines 110-111 The probe penetrated the samples to a depth of 15 mm at a speed of.0.5 mm/s.
3.- Line 161: “addition of the casein hydrolysates significantly decreased the fermentation times”. This sentence cannot be deduced from data of Figure 3. Please, introduce error bars and letters to indicate the significant values.
Author Response: As shown in figure 3. we introduced error bars and letters to indicate the significant values.
Fig. 3
4.- Lines 179-180: “The rate of pH decrease was significantly (P < 0.05) higher in treated samples” This sentence cannot be deduced from data of Figure 4. Authors should include the error bars and letters to indicate the significant values in both Figs 4 a,b. Revise the complete Figure 4 which is unclear, use the same format than in Figure 1. Write numbers with black colour to distinguish adequately the values, revise y, x-axis (unclear) etc.
Author Response: We introduced error bars and letters to Fig. 4 a and b to indicate the significant values. Fig. 4 a and b revised according to the template of instructions for authors.
Fig.4
5.- Line 201: For Figure 5 idem comment than previous to include error bars and letters for significance to show the statistical analysis. Indicate legend to understand L and W (x-axis).
Author Response: We introduced error bars and letters to Fig. 5 to indicate the significant values. L and W letters changed to camel and cow respectively.
6.- Figures 5 and 6 should be unified in Figure 5a, b.
Author Response: we agree and combined figures 5 and 6 in in one figure (Fig. 5 a and b)
Fig 5. (a,b)
Fig. 5: Viability of total bacterial count of yoghurt made from cow milk with different levels of camel and cow casein hydrolysate after storage for one day at 4°C (a) and after three weeks (b)
7.- Table 2 should be reformed, to improve its intelligibility. Authors should include the significant letters to distinguish the statistical differences among samples.
Response: We reformed data in Table 2 and added the significant letters to distinguish the statistical differences among samples.
We changed the Table within the article text.
Authors should consider that according to the compression level, texture profiles (force vs deformation/time) might be different (not comparable).
Author Response: In my opinion under the same condition (The probe penetrated the samples to a depth of 15 mm at a speed of.0.5 mm/s at 4 °C in the same package) we can compare in this case the parameters of TPA. If any of the above factors changes, the parameters' values will change as well.
8.- Figure 7: complete legends. Include error bars and letters of significance to distinguish statistically samples.
Author Response: Figure 7 changed to Figure 6 and We introduced error bars and significant letters to the graph.
Fig 6. Instead of Fig. 7
9.- Lines 323-324: “sensory attributes of the yoghurts were significantly improved by the addition of hydrolysates especially with 1.0% camel casein hydrolysate” This sentence is contradictory with data of table 3 which shows the same letter for sample 1L vs control indicating no significant differences for both fresh and after 21 days.
Author Response: line 313- 314 –it was modified as follows:
The acceptability score for fresh sample 1L (1% camel casein hydrolysate) is 4.67ab while it recorded 4bc for control sample. However, after 21 days no significant differences were recorded (the same significant letter).
Reviewer 2
1 - The title of the work does not correspond to the content. In the paper.,
Author Response: We appreciate your comments very much. We have modified the title as suggested from Reviewer 1 to: Physicochemical, Microbiological, and Sensory Properties of Set Type Yoghurt Supplemented with Camel Casein Hydrolysate ….Line 2-3
3 - In the Materials and methods chapter, there is no literature support (citations) for the methods used.
Author Response: We added the relevant references to the Material and Methods.
Line 66-76 Acid casein was prepared from camel and cow of raw skim milk according to Salmen, et al (2012) with minor modifications. Briefly,
Salmen, S. H., Abu-Tarboush, H. M., Al-Saleh, A. A., & Metwalli, A. A. (2012). Amino acids content and electrophoretic profile of camel milk casein from different camel breeds in Saudi Arabia. Saudi journal of biological sciences, 19(2), 177-183.
2.2. Casein hydrolysate preparation
Author response Line 75-76 Casein hydrolysates were prepared using a modified method developed by Al-Saleh et al (2014). Trypsin enzyme was dissolved in 50 mM phosphate buffer at pH 7.0
Al-Saleh, A. A., Metwalli, A. A., Ismail, E. A., & Alhaj, O. A. (2014). Antioxidative activity of camel milk casein hydrolysates. Journal of Camel Practice and Research, 21(2), 229-237.
4 - The conditions for sensory evaluation are not described. It is not clear whether this was a sensory or organoleptic evaluation - the heading says "Sensory characteristics", while in the text the authors use the term "organoleptic"
Author Response: We use sensory evaluation. In the text sensory evaluation mentioned 11 times while organoleptic mentioned only one time.
5 - It is not written how long it took to incubate the samples to reach pH 4.6 and on what basis the percentage addition of casein hydrolysates was determined.
Author Response: if you referred to Fig. 3 (Fig. 3. Fermentation times of yogurt with added casein hydrolysates.)
6 - On line 137, the authors write that "[...] the method measures only amino acids and very small peptides" and on line 150 that the SDS-PAGE method it is not suitable to detect small peptide proteins [...] so why was SDS-PAGE performed if it was known that it was not a suitable tool to determine small peptide proteins - inconsistent.
Author Response: We appreciate your comments very much. The principle of
O-phthaldehyde method (OPA) is the reaction with only the terminal amino groups. The poly peptide chain contains only one free amino group but, after hydrolysis it contains many of free amino groups depending on the degree of hydrolysis. However, PAGE-SDS depends on the speed of migration according to the molecular weight off the protein molecule. The sensitivity of PAGE-SDS (using glycine in current buffer) to detect small peptides is about 6 KD but, with using tricine you can detect more less molecular weight molecules. In our study we use PAGE-SDS with glycine. No bands were detected in lanes 1 and 3 (Fig. 2) so, the protein molecules were extensively hydrolysed.
7 - Figure 1 is for me unnecessary, it is a bit too much form over substance - why make a graph for 2 values?
Author Response: The Figure gives direct impression on changes in degree of hydrolysis.
8 - Figures 4a and 4b are unreadable
Author Response: We changed and combined the Figure in new form as mentioned in item No 4 with the first Reviewer 1 suggested.
9 - Figure 7 - no differentiation of bars on the graph (different colours), why only 0% and 0.5% concentrations are shown on the graph?
Author Response: We agree and modified the Figure to figure 6 as mentioned in item No 8 and as Reviewer 1 suggested.
10 - why
Responses to the Editor’s and Reviewers' Comments
We appreciate very much the editor and the reviewers for the constructive comments, which have helped us significantly to improve our manuscript. We also thank the editor and the reviewers for the effort and time put into the review of the manuscript. Each comment has been carefully considered point by point and responded. Responses to the reviewers and changes in the revised manuscript are as follows.
Manuscript number: D: fermentation-2253274
Title: Microbiological, Rheological and Sensory Properties of Set Type
Yoghurt Supplemented with Camel Casein Hydrolysate
COMMENTS FROM REFEREE: Thank you for your thoughtful and thorough review of our manuscript.
Reviewer
1 - Title should be modified because Authors did not obtain rheological properties; they have measured textural properties with a dubious method.
Response: we appreciate your suggestion. As you suggested, we have modified the title to: Physicochemical, Microbiological, and Sensory Properties of Set Type
Yoghurt Supplemented with Camel Casein Hydrolysate …….Lines 2 and 3
2 - Some graphics should be changed.
Author Response: We modified Figures 1, 3, 4a and b, 5, 6, and 7, and combined Figures 5 and 6 in one Fig.
Fig. 1
Specific comments:
1 - Line 66: “cow of raw skim milk” revise English!
Acid casein was prepared from camel and cow of raw skim milk.
Author Response:
Acid casein was prepared from camel and cow raw skim milk.
2 - Line 107: what probe? Diameter?
Texture profile analysis (TPA) was performed using Brookfield CT3 texture analyzer (Commerce Boulevard Middleboro MA 02346 USA) to determine the textures of the yoghurts.
Author Response: We appreciate your comments. The probe descriptions were indicated in Material and Methods chapter under subtitle Texture profile analysis
It was explained in lines 107-110
Texture profile analysis (TPA) was performed using Brookfield CT3 texture analyzer (Commerce Boulevard Middleboro MA 02346 USA) to determine the textures of the yoghurts using Acrylic cylindrical probe 25.4 mm diameter, 35 mm long.
reviewer comment; The probe penetrated the samples”, what is the geometry of sample?
Author Response: The TPA experiments performed in the yoghurt cub
Lines 110-111 The probe penetrated the samples to a depth of 15 mm at a speed of.0.5 mm/s.
3.- Line 161: “addition of the casein hydrolysates significantly decreased the fermentation times”. This sentence cannot be deduced from data of Figure 3. Please, introduce error bars and letters to indicate the significant values.
Author Response: As shown in figure 3. we introduced error bars and letters to indicate the significant values.
Fig. 3
4.- Lines 179-180: “The rate of pH decrease was significantly (P < 0.05) higher in treated samples” This sentence cannot be deduced from data of Figure 4. Authors should include the error bars and letters to indicate the significant values in both Figs 4 a,b. Revise the complete Figure 4 which is unclear, use the same format than in Figure 1. Write numbers with black colour to distinguish adequately the values, revise y, x-axis (unclear) etc.
Author Response: We introduced error bars and letters to Fig. 4 a and b to indicate the significant values. Fig. 4 a and b revised according to the template of instructions for authors.
Fig.4
5.- Line 201: For Figure 5 idem comment than previous to include error bars and letters for significance to show the statistical analysis. Indicate legend to understand L and W (x-axis).
Author Response: We introduced error bars and letters to Fig. 5 to indicate the significant values. L and W letters changed to camel and cow respectively.
6.- Figures 5 and 6 should be unified in Figure 5a, b.
Author Response: we agree and combined figures 5 and 6 in in one figure (Fig. 5 a and b)
Fig 5. (a,b)
Fig. 5: Viability of total bacterial count of yoghurt made from cow milk with different levels of camel and cow casein hydrolysate after storage for one day at 4°C (a) and after three weeks (b)
7.- Table 2 should be reformed, to improve its intelligibility. Authors should include the significant letters to distinguish the statistical differences among samples.
Response: We reformed data in Table 2 and added the significant letters to distinguish the statistical differences among samples.
We changed the Table within the article text.
Authors should consider that according to the compression level, texture profiles (force vs deformation/time) might be different (not comparable).
Author Response: In my opinion under the same condition (The probe penetrated the samples to a depth of 15 mm at a speed of.0.5 mm/s at 4 °C in the same package) we can compare in this case the parameters of TPA. If any of the above factors changes, the parameters' values will change as well.
8.- Figure 7: complete legends. Include error bars and letters of significance to distinguish statistically samples.
Author Response: Figure 7 changed to Figure 6 and We introduced error bars and significant letters to the graph.
Fig 6. Instead of Fig. 7
9.- Lines 323-324: “sensory attributes of the yoghurts were significantly improved by the addition of hydrolysates especially with 1.0% camel casein hydrolysate” This sentence is contradictory with data of table 3 which shows the same letter for sample 1L vs control indicating no significant differences for both fresh and after 21 days.
Author Response: line 313- 314 –it was modified as follows:
The acceptability score for fresh sample 1L (1% camel casein hydrolysate) is 4.67ab while it recorded 4bc for control sample. However, after 21 days no significant differences were recorded (the same significant letter).
Reviewer 2
1 - The title of the work does not correspond to the content. In the paper.,
Author Response: We appreciate your comments very much. We have modified the title as suggested from Reviewer 1 to: Physicochemical, Microbiological, and Sensory Properties of Set Type Yoghurt Supplemented with Camel Casein Hydrolysate ….Line 2-3
3 - In the Materials and methods chapter, there is no literature support (citations) for the methods used.
Author Response: We added the relevant references to the Material and Methods.
Line 66-76 Acid casein was prepared from camel and cow of raw skim milk according to Salmen, et al (2012) with minor modifications. Briefly,
Salmen, S. H., Abu-Tarboush, H. M., Al-Saleh, A. A., & Metwalli, A. A. (2012). Amino acids content and electrophoretic profile of camel milk casein from different camel breeds in Saudi Arabia. Saudi journal of biological sciences, 19(2), 177-183.
2.2. Casein hydrolysate preparation
Author response Line 75-76 Casein hydrolysates were prepared using a modified method developed by Al-Saleh et al (2014). Trypsin enzyme was dissolved in 50 mM phosphate buffer at pH 7.0
Al-Saleh, A. A., Metwalli, A. A., Ismail, E. A., & Alhaj, O. A. (2014). Antioxidative activity of camel milk casein hydrolysates. Journal of Camel Practice and Research, 21(2), 229-237.
4 - The conditions for sensory evaluation are not described. It is not clear whether this was a sensory or organoleptic evaluation - the heading says "Sensory characteristics", while in the text the authors use the term "organoleptic"
Author Response: We use sensory evaluation. In the text sensory evaluation mentioned 11 times while organoleptic mentioned only one time.
5 - It is not written how long it took to incubate the samples to reach pH 4.6 and on what basis the percentage addition of casein hydrolysates was determined.
Author Response: if you referred to Fig. 3 (Fig. 3. Fermentation times of yogurt with added casein hydrolysates.)
6 - On line 137, the authors write that "[...] the method measures only amino acids and very small peptides" and on line 150 that the SDS-PAGE method it is not suitable to detect small peptide proteins [...] so why was SDS-PAGE performed if it was known that it was not a suitable tool to determine small peptide proteins - inconsistent.
Author Response: We appreciate your comments very much. The principle of
O-phthaldehyde method (OPA) is the reaction with only the terminal amino groups. The poly peptide chain contains only one free amino group but, after hydrolysis it contains many of free amino groups depending on the degree of hydrolysis. However, PAGE-SDS depends on the speed of migration according to the molecular weight off the protein molecule. The sensitivity of PAGE-SDS (using glycine in current buffer) to detect small peptides is about 6 KD but, with using tricine you can detect more less molecular weight molecules. In our study we use PAGE-SDS with glycine. No bands were detected in lanes 1 and 3 (Fig. 2) so, the protein molecules were extensively hydrolysed.
7 - Figure 1 is for me unnecessary, it is a bit too much form over substance - why make a graph for 2 values?
Author Response: The Figure gives direct impression on changes in degree of hydrolysis.
8 - Figures 4a and 4b are unreadable
Author Response: We changed and combined the Figure in new form as mentioned in item No 4 with the first Reviewer 1 suggested.
9 - Figure 7 - no differentiation of bars on the graph (different colours), why only 0% and 0.5% concentrations are shown on the graph?
Author Response: We agree and modified the Figure to figure 6 as mentioned in item No 8 and as Reviewer 1 suggested.
10 - why yoghurt containing casein hydrolysate from camel milk had different physicochemical characteristics than that with hydrolysate from cow's milk.
Author Response: This may be attributed to the concentration and ratios of casein fractions. Β-casein in camel casein represents more than 60% while it is about 28% in cow casein.
yoghurt containing casein hydrolysate from camel milk had different physicochemical characteristics than that with hydrolysate from cow's milk.
Author Response: This may be attributed to the concentration and ratios of casein fractions. Β-casein in camel casein represents more than 60% while it is about 28% in cow casein.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
The work reports already known facts. The effect of hydrolysates on the quality of fermented milk has been repeatedly confirmed. What is new is the use of camel's milk in the study, but the content of the paper does not indicate the validity of the use of this type of milk. The title of the work does not correspond to the content. In the paper, 3 trial variants were used, i.e. yoghurt without the addition of hydrolysates, with the addition of camel milk casein hydrolysate and cow's milk hydrolysate. I would have highlighted the comparisons between the two types of hydrolysate in the topic. The paper needs linguistic correction - lots of grammatical and spelling errors.
There are also a lot of punctuation and editing errors. In the Materials and methods chapter, there is no literature support (citations) for the methods used. The conditions for sensory evaluation are not described. It is not clear whether this was a sensory or organoleptic evaluation - the heading says "Sensory characteristics", while in the text the authors use the term "organoleptic". It is not written how long it took to incubate the samples to reach pH 4.6 and on what basis the percentage addition of casein hydrolysates was determined. On line 137, the authors write that "[...] the method measures only amino acids and very small peptides" and on line 150 that the SDS-PAGE method it is not suitable to detect small peptide proteins [...] so why was SDS-PAGE performed if it was known that it was not a suitable tool to determine small peptide proteins - inconsistent. No new methods were used in this study which would have affected the quality of the results obtained. Figure 1 is for me unnecessary, it is a bit too much form over substance - why make a graph for 2 values? Figures 4a and 4b are unreadable. The figures lack a legend with explained markings. Figure 7 - no differentiation of bars on the graph (different colours), why only 0% and 0.5% concentrations are shown on the graph? The appearance of the tables should be improved - values 'jump' between lines. Most unsatisfactory is the discussion, which lacks even an attempt to explain the differences in the hydrolysates - why yoghurt containing casein hydrolysate from camel milk had different physicochemical characteristics than that with hydrolysate from cow's milk? The discussion contains only the already known facts about the beneficial effects of hydrolysates on the quality of fermented milk and the survival of starter cultures
Author Response
Responses to the Editor’s and Reviewers' Comments
We appreciate very much the editor and the reviewers for the constructive comments, which have helped us significantly to improve our manuscript. We also thank the editor and the reviewers for the effort and time put into the review of the manuscript. Each comment has been carefully considered point by point and responded. Responses to the reviewers and changes in the revised manuscript are as follows.
Manuscript number: D: fermentation-2253274
Title: Microbiological, Rheological and Sensory Properties of Set Type
Yoghurt Supplemented with Camel Casein Hydrolysate
COMMENTS FROM REFEREE: Thank you for your thoughtful and thorough review of our manuscript.
Reviewer
1 - Title should be modified because Authors did not obtain rheological properties; they have measured textural properties with a dubious method.
Response: we appreciate your suggestion. As you suggested, we have modified the title to: Physicochemical, Microbiological, and Sensory Properties of Set Type
Yoghurt Supplemented with Camel Casein Hydrolysate …….Lines 2 and 3
2 - Some graphics should be changed.
Author Response: We modified Figures 1, 3, 4a and b, 5, 6, and 7, and combined Figures 5 and 6 in one Fig.
Fig. 1
Specific comments:
1 - Line 66: “cow of raw skim milk” revise English!
Acid casein was prepared from camel and cow of raw skim milk.
Author Response:
Acid casein was prepared from camel and cow raw skim milk.
2 - Line 107: what probe? Diameter?
Texture profile analysis (TPA) was performed using Brookfield CT3 texture analyzer (Commerce Boulevard Middleboro MA 02346 USA) to determine the textures of the yoghurts.
Author Response: We appreciate your comments. The probe descriptions were indicated in Material and Methods chapter under subtitle Texture profile analysis
It was explained in lines 107-110
Texture profile analysis (TPA) was performed using Brookfield CT3 texture analyzer (Commerce Boulevard Middleboro MA 02346 USA) to determine the textures of the yoghurts using Acrylic cylindrical probe 25.4 mm diameter, 35 mm long.
reviewer comment; The probe penetrated the samples”, what is the geometry of sample?
Author Response: The TPA experiments performed in the yoghurt cub
Lines 110-111 The probe penetrated the samples to a depth of 15 mm at a speed of.0.5 mm/s.
3.- Line 161: “addition of the casein hydrolysates significantly decreased the fermentation times”. This sentence cannot be deduced from data of Figure 3. Please, introduce error bars and letters to indicate the significant values.
Author Response: As shown in figure 3. we introduced error bars and letters to indicate the significant values.
Fig. 3
4.- Lines 179-180: “The rate of pH decrease was significantly (P < 0.05) higher in treated samples” This sentence cannot be deduced from data of Figure 4. Authors should include the error bars and letters to indicate the significant values in both Figs 4 a,b. Revise the complete Figure 4 which is unclear, use the same format than in Figure 1. Write numbers with black colour to distinguish adequately the values, revise y, x-axis (unclear) etc.
Author Response: We introduced error bars and letters to Fig. 4 a and b to indicate the significant values. Fig. 4 a and b revised according to the template of instructions for authors.
Fig.4
5.- Line 201: For Figure 5 idem comment than previous to include error bars and letters for significance to show the statistical analysis. Indicate legend to understand L and W (x-axis).
Author Response: We introduced error bars and letters to Fig. 5 to indicate the significant values. L and W letters changed to camel and cow respectively.
6.- Figures 5 and 6 should be unified in Figure 5a, b.
Author Response: we agree and combined figures 5 and 6 in in one figure (Fig. 5 a and b)
Fig 5. (a,b)
Fig. 5: Viability of total bacterial count of yoghurt made from cow milk with different levels of camel and cow casein hydrolysate after storage for one day at 4°C (a) and after three weeks (b)
7.- Table 2 should be reformed, to improve its intelligibility. Authors should include the significant letters to distinguish the statistical differences among samples.
Response: We reformed data in Table 2 and added the significant letters to distinguish the statistical differences among samples.
We changed the Table within the article text.
Authors should consider that according to the compression level, texture profiles (force vs deformation/time) might be different (not comparable).
Author Response: In my opinion under the same condition (The probe penetrated the samples to a depth of 15 mm at a speed of.0.5 mm/s at 4 °C in the same package) we can compare in this case the parameters of TPA. If any of the above factors changes, the parameters' values will change as well.
8.- Figure 7: complete legends. Include error bars and letters of significance to distinguish statistically samples.
Author Response: Figure 7 changed to Figure 6 and We introduced error bars and significant letters to the graph.
Fig 6. Instead of Fig. 7
9.- Lines 323-324: “sensory attributes of the yoghurts were significantly improved by the addition of hydrolysates especially with 1.0% camel casein hydrolysate” This sentence is contradictory with data of table 3 which shows the same letter for sample 1L vs control indicating no significant differences for both fresh and after 21 days.
Author Response: line 313- 314 –it was modified as follows:
The acceptability score for fresh sample 1L (1% camel casein hydrolysate) is 4.67ab while it recorded 4bc for control sample. However, after 21 days no significant differences were recorded (the same significant letter).
Reviewer 2
1 - The title of the work does not correspond to the content. In the paper.,
Author Response: We appreciate your comments very much. We have modified the title as suggested from Reviewer 1 to: Physicochemical, Microbiological, and Sensory Properties of Set Type Yoghurt Supplemented with Camel Casein Hydrolysate ….Line 2-3
3 - In the Materials and methods chapter, there is no literature support (citations) for the methods used.
Author Response: We added the relevant references to the Material and Methods.
Line 66-76 Acid casein was prepared from camel and cow of raw skim milk according to Salmen, et al (2012) with minor modifications. Briefly,
Salmen, S. H., Abu-Tarboush, H. M., Al-Saleh, A. A., & Metwalli, A. A. (2012). Amino acids content and electrophoretic profile of camel milk casein from different camel breeds in Saudi Arabia. Saudi journal of biological sciences, 19(2), 177-183.
2.2. Casein hydrolysate preparation
Author response Line 75-76 Casein hydrolysates were prepared using a modified method developed by Al-Saleh et al (2014). Trypsin enzyme was dissolved in 50 mM phosphate buffer at pH 7.0
Al-Saleh, A. A., Metwalli, A. A., Ismail, E. A., & Alhaj, O. A. (2014). Antioxidative activity of camel milk casein hydrolysates. Journal of Camel Practice and Research, 21(2), 229-237.
4 - The conditions for sensory evaluation are not described. It is not clear whether this was a sensory or organoleptic evaluation - the heading says "Sensory characteristics", while in the text the authors use the term "organoleptic"
Author Response: We use sensory evaluation. In the text sensory evaluation mentioned 11 times while organoleptic mentioned only one time.
5 - It is not written how long it took to incubate the samples to reach pH 4.6 and on what basis the percentage addition of casein hydrolysates was determined.
Author Response: if you referred to Fig. 3 (Fig. 3. Fermentation times of yogurt with added casein hydrolysates.)
6 - On line 137, the authors write that "[...] the method measures only amino acids and very small peptides" and on line 150 that the SDS-PAGE method it is not suitable to detect small peptide proteins [...] so why was SDS-PAGE performed if it was known that it was not a suitable tool to determine small peptide proteins - inconsistent.
Author Response: We appreciate your comments very much. The principle of
O-phthaldehyde method (OPA) is the reaction with only the terminal amino groups. The poly peptide chain contains only one free amino group but, after hydrolysis it contains many of free amino groups depending on the degree of hydrolysis. However, PAGE-SDS depends on the speed of migration according to the molecular weight off the protein molecule. The sensitivity of PAGE-SDS (using glycine in current buffer) to detect small peptides is about 6 KD but, with using tricine you can detect more less molecular weight molecules. In our study we use PAGE-SDS with glycine. No bands were detected in lanes 1 and 3 (Fig. 2) so, the protein molecules were extensively hydrolysed.
7 - Figure 1 is for me unnecessary, it is a bit too much form over substance - why make a graph for 2 values?
Author Response: The Figure gives direct impression on changes in degree of hydrolysis.
8 - Figures 4a and 4b are unreadable
Author Response: We changed and combined the Figure in new form as mentioned in item No 4 with the first Reviewer 1 suggested.
9 - Figure 7 - no differentiation of bars on the graph (different colours), why only 0% and 0.5% concentrations are shown on the graph?
Author Response: We agree and modified the Figure to figure 6 as mentioned in item No 8 and as Reviewer 1 suggested.
10 - why yoghurt containing casein hydrolysate from camel milk had different physicochemical characteristics than that with hydrolysate from cow's milk.
Author Response: This may be attributed to the concentration and ratios of casein fractions. Β-casein in camel casein represents more than 60% while it is about 28% in cow casein.
Author Response File: Author Response.pdf
Round 2
Reviewer 2 Report
All my comments indicated in the review have been taken into account in the revised version of the article
