From Farm to Retail: Decoding the Elemental Landscape of Milk and Dairy Products Across Organic and Conventional Production Systems Using ICP–MS

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

This study focused on the dairy products from organic, traditional and commercial production systems in the northwest of Romania, collecting 307 milk samples (from cows, buffaloes, goats and donkeys) as well as their yogurt, cheese and mozzarella cheese samples. Using microwave-assisted acid digestion combined with ICP-MS technology, the contents of 10 toxic elements and essential elements were analyzed. The study explored the effects of animal species, processing stages (raw milk - yogurt - cheese) and production systems on the element composition, verified that the concentrations of toxic elements in the samples were all below the EU limit standards, clarified the element characteristics of dairy products from different species, the enrichment or reduction patterns of elements during processing, as well as the element differences between organic and commercial products. It provided data support and technical references for the safety monitoring, quality control and traceability of the dairy product supply chain. However, the following problems still exist.

• The sampling time is single, and sampling is only carried out in October 2025, without considering the influence of seasonal changes on feed composition and animal metabolism, which may lead to the lack of representativeness of elemental composition data.
• The sampling area is limited to two counties in northwestern Romania, and the geographical coverage is narrow. It is difficult to represent the situation of dairy products in different ecological environment and industrial pollution areas, which reduces the universality of the research results.
• The abbreviations are not marked with a full name in the text when they first appear, and they are only listed at the end of the text, which is inconvenient for readers to read.
• Table 29 and Table 33 mentioned in lines 857 and 864 in the conclusion part did not appear in the text. Please carefully check whether there are similar problems.
• Does element composition affect the quality of dairy products? It is suggested to analyze the correlation between the content of supplementary elements and the quality indexes of dairy products (such as protein and fat content).
• When explaining the enrichment or reduction of elements during processing, only the phenomena were described, and the mechanisms (such as water loss, protein binding, microbial action, etc.) were not discussed in depth.

Author Response

Reviewer 1

 

Reviewer's comments:  Comments and Suggestions for Authors: This study focused on the dairy products from organic, traditional and commercial production systems in the northwest of Romania, collecting 307 milk samples (from cows, buffaloes, goats and donkeys) as well as their yogurt, cheese and mozzarella cheese samples. Using microwave-assisted acid digestion combined with ICP-MS technology, the contents of 10 toxic elements and essential elements were analyzed. The study explored the effects of animal species, processing stages (raw milk - yogurt - cheese) and production systems on the element composition, verified that the concentrations of toxic elements in the samples were all below the EU limit standards, clarified the element characteristics of dairy products from different species, the enrichment or reduction patterns of elements during processing, as well as the element differences between organic and commercial products. It provided data support and technical references for the safety monitoring, quality control and traceability of the dairy product supply chain. However, the following problems still exist.

The authors' response: All revisions and additions made in response to the reviewer’s comments have been highlighted in red in the revised manuscript and in the Supplementary Materials. We thank the reviewer for the thorough evaluation of our manuscript and for the constructive comments. We appreciate the reviewer’s positive summary of the scope and relevance of our study, which investigated the multi-elemental composition of dairy products from different animal species, processing stages, and production systems in north-western Romania using ICP–MS. In response to the reviewer’s concerns, we have carefully revised the manuscript to address all raised points. Specifically, we have clarified the limitations related to the single-season sampling campaign and the geographically restricted study area, acknowledged the absence of routine nutritional quality indices (protein and fat) and justified this within the analytical scope of the study, expanded the Discussion to include mechanistic explanations for the enrichment and depletion of elements during processing, corrected inconsistencies in supplementary table numbering and in-text references, and ensured that all abbreviations are defined at their first occurrence. These revisions improve the clarity, methodological transparency, and interpretability of the manuscript and strengthen its contribution to food safety monitoring, quality control, and traceability of dairy products.

 

Reviewer's comments: The sampling time is single, and sampling is only carried out in October 2025, without considering the influence of seasonal changes on feed composition and animal metabolism, which may lead to the lack of representativeness of elemental composition data.

The authors' response: We thank the reviewer for this valuable comment. We acknowledge that all samples were collected during a single sampling campaign conducted in October 2025, which does not capture potential seasonal variability in feed composition and animal metabolism. To address this limitation, we have added a dedicated paragraph in the Discussion section clarifying that the present results should be interpreted as representative of the autumn production period in north-western Romania and discussing the possible influence of seasonal factors on trace-element profiles. We also note that the investigated farms operated relatively stable feeding regimes, with extended grazing periods and controlled winter rations, which likely minimized abrupt dietary changes at the time of sampling. In addition, we have clarified in Section 2.1 that this sampling window was selected to ensure uniformity of climatic and feeding conditions across all production systems. Finally, we emphasize that future studies incorporating multi-seasonal sampling are warranted to strengthen the generalizability of the findings.

 

Reviewer's comments: The sampling area is limited to two counties in northwestern Romania, and the geographical coverage is narrow. It is difficult to represent the situation of dairy products in different ecological environment and industrial pollution areas, which reduces the universality of the research results.

The authors' response: We thank the reviewer for this valuable comment. We acknowledge that the sampling area was geographically restricted to two counties in north-western Romania (Sălaj and Satu Mare), which limits the representativeness of the findings at a national or broader geographic scale. To address this limitation, we have added a dedicated paragraph in the Discussion section clarifying that the present results should be interpreted as region-specific and may not be directly extrapolated to areas characterized by different ecological conditions or higher levels of industrial pollution. We also clarified in Section 2.1 that these locations were selected to represent typical dairy production systems in a predominantly rural region of north-western Romania. Finally, we emphasize that future studies including broader geographic coverage and sites with contrasting ecological and industrial profiles are warranted to strengthen the generalizability of the results.

 

Reviewer's comments: The abbreviations are not marked with a full name in the text when they first appear, and they are only listed at the end of the text, which is inconvenient for readers to read.

The authors' response: We thank the reviewer for this helpful comment. All abbreviations have now been defined at their first occurrence in the main text (including EU, ISO, Codex, NIST, FAPAS, BLD, LCD, SD, CV, CI95%, and PCA). The list of abbreviations has been retained at the end of the manuscript for reference. These revisions improve clarity and readability throughout the paper.

 

Reviewer's comments: Table 29 and Table 33 mentioned in lines 857 and 864 in the conclusion part did not appear in the text. Please carefully check whether there are similar problems.

The authors' response: We thank the reviewer for pointing out this inconsistency. We corrected the numbering of supplementary tables in the Supplementary Materials (Table 29 and Table 33 were changed to Table S29 and Table S33) and aligned all in-text references accordingly (e.g., Table 33 → Table S33). We also carefully checked the manuscript for similar issues and corrected an additional duplicated reference (Table S33; Table S33 → Table S32; Table S33). These revisions ensure full consistency between the text and the Supplementary Materials.

 

Reviewer's comments: Does element composition affect the quality of dairy products? It is suggested to analyze the correlation between the content of supplementary elements and the quality indexes of dairy products (such as protein and fat content).

The authors' response: We thank the reviewer for this valuable suggestion. The present study was designed primarily as a food safety and traceability investigation focusing on the multi-elemental composition of milk and dairy products and their compliance with European Union regulatory limits. Routine nutritional quality indices such as protein and fat content were therefore outside the original analytical scope. In addition, fat and protein determination would have required dedicated analytical platforms (e.g., Kjeldahl, Dumas, Gerber, or FTIR), separate quality-control procedures, and additional method validation, which were not available within the framework of the present ICP–MS–based study. Moreover, for several processed dairy products, fat and protein contents are technologically standardized during industrial processing, resulting in reduced biological variability and potentially limiting the interpretability of correlation analysis with elemental concentrations. This limitation has now been acknowledged in the Discussion section. We agree that future studies integrating elemental profiling with macronutrient quality indices (protein, fat, lactose) are warranted to clarify potential relationships between elemental composition and dairy product quality.

 

Reviewer's comments: When explaining the enrichment or reduction of elements during processing, only the phenomena were described, and the mechanisms (such as water loss, protein binding, microbial action, etc.) were not discussed in depth.

The authors' response: We thank the reviewer for this valuable comment. We have now expanded the Discussion to provide a mechanistic interpretation of the observed enrichment or depletion of elements during dairy processing. Specifically, we discuss the roles of water loss and dry-matter concentration, protein binding and partitioning into the curd, whey separation, microbial activity during fermentation, pH-driven changes in solubility and speciation, and technological operations such as fat standardization and curd washing. These mechanisms explain the processing-dependent and element-specific variability in elemental concentrations and processing factors observed in this study.

Reviewer 2 Report

Comments and Suggestions for Authors

1. The study objectives stated at the end of the Introduction are comprehensive but somewhat lengthy. A more concise formulation highlighting the core research questions and novelty would improve clarity.

 

2. The novelty of the study could be more explicitly emphasized in the Introduction, particularly regarding sample size, multi-species comparison, or the supply-chain perspective.

 

3. The term “commercial/retail” is used throughout the manuscript. A clearer definition distinguishing it from “farm-origin conventional” samples at first mention would be helpful.

 

4. Since all samples were collected in October, a brief discussion of potential seasonal effects on elemental composition would strengthen the interpretation.

 

5. While feeding systems and pasture composition are well described, linking these factors more explicitly to observed inter-species differences would improve coherence.

 

6. The ICP–MS methodology is described in great detail; some standard operational details could be streamlined to improve readability.

 

7. A unified explanation of LOD, BLD, and LCD criteria in the Methods section would help avoid confusion in the Results.

 

8. Decimal precision varies slightly across tables. Harmonizing the number of decimal places would improve consistency.

 

9. Some result sections closely reiterate tabulated values. Condensing these descriptions to emphasize key trends would improve flow.

 

10. Figures 1 and 2 partly overlap in terms of conveyed trends. Clarifying their distinct purposes in the captions would be beneficial.

 

11. Compliance with EU limits is clearly demonstrated; a brief discussion of implications for consumer risk assessment would add value.

 

12. The manuscript is generally well written; only minor grammatical and stylistic polishing is required.

Author Response

Reviewer 2

 

Reviewer's comments: Comments and Suggestions for Authors: The study objectives stated at the end of the Introduction are comprehensive but somewhat lengthy. A more concise formulation highlighting the core research questions and novelty would improve clarity.

The authors' response:  All revisions and additions made in response to the reviewer’s comments have been highlighted in blue in the revised manuscript and in the Supplementary Materials. We thank the reviewer for this helpful suggestion. The study objectives at the end of the Introduction have been revised and condensed to improve clarity and focus. The revised version now highlights the core research questions and the main novelty of the study, namely the integrated multi-elemental profiling of dairy products across animal species, production systems, and processing stages using ICP–MS, and their implications for food safety, traceability, and regulatory compliance.

 

Reviewer's comments: The novelty of the study could be more explicitly emphasized in the Introduction, particularly regarding sample size, multi-species comparison, or the supply-chain perspective.

The authors' response:  We thank the reviewer for this helpful comment. We have revised the Introduction to more explicitly emphasize the novelty of the study. Specifically, we now highlight the large and structured sample set (307 samples), the simultaneous multi-species comparison (cow, buffalo, goat, and donkey), and the integrated supply-chain perspective spanning raw milk to processed dairy products. These additions clarify the unique contribution of the present work to multi-elemental profiling, food safety monitoring, and traceability of dairy products.

 

Reviewer's comments: The term “commercial/retail” is used throughout the manuscript. A clearer definition distinguishing it from “farm-origin conventional” samples at first mention would be helpful.

The authors' response: We thank the reviewer for this helpful comment. We have now clarified the definition of the term “commercial/retail” at its first occurrence in the manuscript and explicitly distinguished it from farm-origin conventional samples. Specifically, we now define commercial/retail dairy products as industrially processed and packaged products purchased from retail outlets, produced from pooled milk from multiple farms and subjected to technological standardization, whereas conventional samples refer to raw milk and farm-processed products collected directly from individual conventional farms.

 

Reviewer's comments: Since all samples were collected in October, a brief discussion of potential seasonal effects on elemental composition would strengthen the interpretation.

The authors' response:  We thank the reviewer for this valuable comment. We have now added a brief discussion in the Discussion section addressing the potential influence of seasonal factors on elemental composition. Specifically, we clarify that all samples were collected during a single sampling campaign in October, and we discuss how seasonal changes in feed composition, grazing patterns, and animal metabolism may affect trace-element transfer into milk. We also note that the investigated farms operated relatively stable feeding regimes at the time of sampling, which likely reduced abrupt dietary shifts. Finally, we emphasize that future multi-seasonal sampling is warranted to evaluate temporal variability and strengthen the generalizability of the findings.

Reviewer's comments: While feeding systems and pasture composition are well described, linking these factors more explicitly to observed inter-species differences would improve coherence.

The authors' response:  We thank the Reviewer for this valuable suggestion. In response, we have revised Section 3.1 to explicitly link the described feeding systems and pasture composition (Section 2.1.1) to the inter-species differences observed in the elemental profiles. A new interpretative paragraph has been added, highlighting how prolonged grazing on heterogeneous mountain pastures and variable soil–plant interfaces for buffaloes, goats, and donkeys may contribute to the higher concentrations and greater dispersion of Cr, Ni, Al, and Zn compared to cows maintained on more standardized rations. We also discuss the potential roles of species-specific grazing behavior and digestive physiology in modulating trace-element bioavailability and transfer into milk. These additions improve the coherence of the Results section by integrating agro-ecological context into the interpretation of inter-species variability.

 

Reviewer's comments: The ICP–MS methodology is described in great detail; some standard operational details could be streamlined to improve readability.

The authors' response:  We thank the Reviewer for this helpful comment. In response, we have revised Section 2.5 to streamline standard operational details and improve readability, while retaining all essential methodological information required for analytical reproducibility. Specifically, we corrected typographical artifacts, reduced minor stylistic redundancies, and clarified procedural descriptions related to sample preparation, digestion, and ICP–MS operation. Instrumental conditions, calibration strategy, collision-cell operation, and quality assurance procedures were preserved in full. These revisions enhance clarity and flow without altering the technical content or analytical rigor of the ICP–MS methodology.

 

Reviewer's comments: A unified explanation of LOD, BLD, and LCD criteria in the Methods section would help avoid confusion in the Results.

The authors' response:  We thank the reviewer for this valuable suggestion. A unified and explicit explanation of the limit of detection (LOD), below-the-limit-of-detection values (BLD), and the left-censoring percentage (LCD) has now been added to the Materials and Methods section (Section 2.5.2, Analytical Determination Procedures of Dairy Matrices). Specifically, we defined the LOD based on procedural blanks and calibration slope, clarified the treatment of concentrations below the LOD as non-quantifiable (BLD), introduced the calculation and interpretation of LCD, and described the statistical handling of censored data. These additions ensure consistent terminology and interpretation across the Methods and Results sections and improve the transparency of how non-detects were treated in the dataset.

 

Reviewer's comments: Decimal precision varies slightly across tables. Harmonizing the number of decimal places would improve consistency.

The authors' response:  We thank the reviewer for this helpful comment. The decimal precision has now been harmonized across all tables in the manuscript and Supplementary Material. Concentration values were rounded and reported using a uniform number of decimal places for each analyte, reflecting the analytical sensitivity of the ICP–MS method, the corresponding limits of detection, and the observed variability. Toxic elements (Pb, Cd, As) are now reported to four decimal places, transition elements (Cr, Ni, Sn) to three decimal places, and major essential elements (Al, Cu, Zn) to two decimal places, while values below the limit of detection are reported as < LOD. All affected tables have been revised accordingly.

 

Reviewer's comments: Some result sections closely reiterate tabulated values. Condensing these descriptions to emphasize key trends would improve flow.

The authors' response:  We thank the reviewer for this comment. A substantial part of the numerical results is reported in the Supplementary Material (Tables S14–S35) rather than in the main manuscript. For this reason, key concentration values were reiterated in the Results section to ensure that essential quantitative information is visible and interpretable within the main text, without requiring the reader to constantly consult the Supplementary Material. This approach was adopted to facilitate readability and comprehension of the results for a broader audience, to allow direct comparisons among species, matrices, and production systems, and to highlight compliance of the measured values with European Union regulatory limits. In this context, the inclusion of representative numerical values in the Results section was considered useful to support descriptive and interpretative statements.

 

Reviewer's comments: Figures 1 and 2 partly overlap in terms of conveyed trends. Clarifying their distinct purposes in the captions would be beneficial.

The authors' response:  We thank the reviewer for this helpful suggestion. The captions of Figures 1 and 2 have now been revised to clearly differentiate their distinct purposes. Figure 1 is explicitly described as providing a global overview of elemental concentration ranges and inter-species variability across all dairy matrices, irrespective of processing stage or production system. In contrast, Figure 2 is now defined as focusing on matrix-driven differences and the effect of technological processing (fermentation and coagulation) on elemental partitioning and concentration patterns. These clarifications resolve the perceived overlap and make the complementary roles of the two figures explicit.

 

Reviewer's comments: Compliance with EU limits is clearly demonstrated; a brief discussion of implications for consumer risk assessment would add value.

The authors' response:  We thank the reviewer for this valuable suggestion. A brief discussion addressing the implications of the observed metal concentrations for consumer risk assessment has now been added to the Discussion section. Specifically, we emphasize that all measured concentrations of toxic elements (Pb, Cd, Hg, and As) were well below the maximum levels established by EU Regulation 2023/915, indicating a low dietary exposure through the consumption of the investigated dairy products. We further note that, despite inter-species and matrix-related differences in elemental profiles, these variations are unlikely to translate into a meaningful health risk for consumers under normal consumption patterns. These additions strengthen the public health relevance of the study.

 

Reviewer's comments: The manuscript is generally well written; only minor grammatical and stylistic polishing is required.

The authors' response:   We thank the reviewer for this positive assessment. The manuscript has been carefully proofread and minor grammatical, stylistic, and typographical revisions have been implemented throughout the text to improve clarity, consistency, and overall readability.

Reviewer 3 Report

Comments and Suggestions for Authors

The paper titled "From Farm to Retail: Decoding the Elemental Landscape of Milk and Dairy Products across Organic and Conventional Production Systems using ICP–MS"

This paper presents a comprehensive and completed study that examines a vast number of samples from different sources. The experiment is well-designed and successfully executed. The most suitable detection method, ICP-MS, was used for the analysis of the target metals. I believe this work will be of interest to researchers in the field, primarily as a valuable library of results for the investigation of heavy and transition metals in milk, dairy products, and cheese from a region of Romania.

Before acceptance, the authors should make minor revisions, which do not diminish the value of the presented work.

In the abstract, it is necessary to add numerical values of the obtained results. For example, in lines 47-49, please specify these ranges.

Line 321. Presumably "Table S33"

Line 368. The figure indicates different units of measurement; please correct this if it is an error.

Figure 1. The figure legends should be made larger. If possible, include the three sample types (milk, yogurt, cheese) on a single graph, but denote them with different colors. This would be more valuable for the reader, allowing visual comparison of the amount of a given metal across sample types in one figure.

Figure 3. In the figure legend, please add that the maximum levels are indicated by a dashed blue line.

Figure 6. The legend labels for the sample types are written in a very small font. Furthermore, the subfigures should be labeled as "a" and "b".

Table 1. In my opinion, the number of decimal places should be reduced, for example, for Copper and Zinc.

Tables and figures should ideally be referenced in the order of their first mention for better comprehension of the paper (e.g., Table 1).

Author Response

Reviewer 3

 

Reviewer's comments: Comments and Suggestions for Authors: The paper titled "From Farm to Retail: Decoding the Elemental Landscape of Milk and Dairy Products across Organic and Conventional Production Systems using ICP–MS". This paper presents a comprehensive and completed study that examines a vast number of samples from different sources. The experiment is well-designed and successfully executed. The most suitable detection method, ICP-MS, was used for the analysis of the target metals. I believe this work will be of interest to researchers in the field, primarily as a valuable library of results for the investigation of heavy and transition metals in milk, dairy products, and cheese from a region of Romania. Before acceptance, the authors should make minor revisions, which do not diminish the value of the presented work.

The authors' response:  All revisions and additions made in response to the reviewer’s comments have been highlighted in green in the revised manuscript and in the Supplementary Materials. We thank the reviewer for the thorough evaluation of our manuscript and for the positive and constructive comments. We appreciate the recognition of the comprehensive study design, the large number of analyzed samples, and the appropriate use of ICP–MS for elemental analysis. In accordance with the reviewer’s recommendation, we have carefully revised the manuscript and implemented minor revisions to improve clarity, consistency, and overall presentation, without altering the scientific content or conclusions of the study. We believe that these revisions have strengthened the quality of the manuscript and addressed the reviewer’s remarks. We are grateful for the time and effort devoted to the review of our work.

 

Reviewer's comments: In the abstract, it is necessary to add numerical values of the obtained results. For example, in lines 47-49, please specify these ranges.

The authors' response:  We thank the reviewer for this important suggestion. The abstract has been revised to include representative numerical ranges for both toxic and essential elements. Specifically, concentration intervals for Pb, Cd, As, Hg (reported as < LOD), and major essential elements (Al, Cu, Zn, Sn) have been added in lines 47–49 to improve the quantitative clarity and informativeness of the abstract.

 

Reviewer's comments: Line 321. Presumably "Table S33"

The authors' response:  We thank the reviewer for identifying this typographical error. The reference in line 321 has been corrected from the incorrect table designation to “Table S33” in the revised manuscript.

 

Reviewer's comments: Line 368. The figure indicates different units of measurement; please correct this if it is an error.

The authors' response:  We thank the reviewer for this observation. All elemental concentrations in Figure 2 are consistently reported in mg/kg. The apparent discrepancy arises from the markedly different orders of magnitude between essential elements (e.g., Zn, Cu), which occur at mg/kg levels, and toxic trace metals (Pb, Cd, As) and several transition elements (Cr, Ni, Al, Sn), which are present at much lower, sub-mg/kg levels. This scale effect causes low-level elements to appear visually compressed toward zero on a common linear axis. To avoid potential misinterpretation, we have added a clarifying statement in the manuscript text explaining this graphical effect and confirming the uniform use of mg/kg units across all subplots in Figure 2.

 

Reviewer's comments: Figure 1. The figure legends should be made larger. If possible, include the three sample types (milk, yogurt, cheese) on a single graph, but denote them with different colors. This would be more valuable for the reader, allowing visual comparison of the amount of a given metal across sample types in one figure.

The authors' response:  We thank the reviewer for the valuable suggestion regarding the improvement of Figure 1 and the comparative representation of the three sample types in a single graph. Unfortunately, at the current stage of the revision process, we did not have access to the graphical software originally used to generate the figures, which limited our ability to reconfigure the layout into a combined format and to adjust the size of the legends. Therefore, we chose to retain the current structure of the figure, which nevertheless provides a clear and coherent presentation of the distribution of heavy metals in each type of dairy product. We will take this suggestion into consideration for future versions of the manuscript.

 

Reviewer's comments: Figure 3. In the figure legend, please add that the maximum levels are indicated by a dashed blue line.

The authors' response: We thank the reviewer for this comment. The figure legend has been revised to explicitly state that the dashed blue line represents the maximum permissible levels for selected metals. The corresponding regulatory limits have been added to the legend (Pb = 0.020 mg/kg, Cd = 0.010 mg/kg, Hg = 0.010 mg/kg, and As = 0.100 mg/kg, according to EU legislation), in order to improve the interpretability of Figure 3 and clearly indicate the compliance of the measured concentrations with regulatory standards.

 

Reviewer's comments: Figure 6. The legend labels for the sample types are written in a very small font. Furthermore, the subfigures should be labeled as "a" and "b".

The authors' response:  We thank the reviewer for this helpful comment. In the revised version of Figure 6, the font size of the legend labels for the sample types has been increased to improve readability. In addition, the two subfigures have been explicitly labeled as “(a)” and “(b)” to ensure clearer identification and consistency with standard figure formatting conventions.

 

Reviewer's comments: Table 1. In my opinion, the number of decimal places should be reduced, for example, for Copper and Zinc.

The authors' response:  We thank the reviewer for this suggestion. The number of decimal places reported in Table 1 has been reduced to improve readability and consistency of data presentation. In particular, the values for Copper (Cu) and Zinc (Zn) have been rounded and are now reported with two decimal places.

 

Reviewer's comments: Tables and figures should ideally be referenced in the order of their first mention for better comprehension of the paper (e.g., Table 1).

The authors' response:  We thank the reviewer for this comment. The manuscript has been carefully revised to ensure that all tables and figures are referenced in the text in the order of their first appearance. In particular, the first citation of Table 1 has been checked and confirmed to appear in the appropriate section of the Results.

 

Reviewer 4 Report

Comments and Suggestions for Authors

 

The manuscript is a well-designed and methodologically sound piece of research regarding the multi-elemental profile of milk and dairy products, considering different animal species, farming types (organic farming, conventional farming, and commercial farming), and dairy product processing routes. The scientific accuracy and reliability of this research are guaranteed due to the employment of the ICP-MS technique with appropriate sample preparation procedures.

However, a few minor revisions should be addressed before the manuscript can be considered for publication:

Line 345:
The formatting of the table could be improved for clarity and readability.

Line 486:
Table 5 contains similar terms that are not used consistently (e.g., “not detected” vs. “no detection”). The terminology should be standardized throughout the table.

Line 617:
Figure 3 is referenced with two different captions, which may cause confusion:

Figure 3. Processing-Related Changes in Metal Concentrations in Dairy Products Relative to EU Maximum Permissible Levels

Figure 3. Global elemental fingerprint of dairy matrices across species, production systems, and processing stages.

The authors should carefully verify and correct all figure captions and references to ensure consistency.

The authors are encouraged to thoroughly check all figures and tables for consistency, formatting, and accurate cross-referencing throughout the manuscript.

Comments on the Quality of English Language

The manuscript is generally well-written and understandable, but minor grammatical issues and stylistic inconsistencies throughout the text should be corrected to make it even more readable and clearer.

There are several sentences, especially in the Introduction and Results sections, that are too long and somewhat complicated. Authors should if possible, simplify sentence structure or divide the long ones for better readability.

Some technical terms and expressions are used inconsistently, such as the terms "not detected", "below the limit of detection", and "no detection", as I highlighted in the general revision to the authors. It is desirable to adopt one uniform terminology in the manuscript, and also in the tables, figures, and supplementary materials.

Author Response

Reviewer 4

 

Reviewer's comments: Comments and Suggestions for Authors: The manuscript is a well-designed and methodologically sound piece of research regarding the multi-elemental profile of milk and dairy products, considering different animal species, farming types (organic farming, conventional farming, and commercial farming), and dairy product processing routes. The scientific accuracy and reliability of this research are guaranteed due to the employment of the ICP-MS technique with appropriate sample preparation procedures. However, a few minor revisions should be addressed before the manuscript can be considered for publication:

The authors' response: All revisions and additions made in response to the reviewer’s comments have been highlighted in brown in the revised manuscript and in the Supplementary Materials. We sincerely thank Reviewer 4 for the positive and constructive evaluation of our manuscript. We greatly appreciate the acknowledgment of the sound methodological design, the relevance of the multi-elemental profiling approach, and the appropriate use of ICP-MS with suitable sample preparation procedures. We are grateful for the reviewer’s valuable comments and suggestions. All minor revisions indicated have been carefully considered and addressed in the revised version of the manuscript. We believe that these improvements have enhanced the clarity, scientific rigor, and overall quality of the work. We thank the reviewer again for their insightful feedback, which has contributed significantly to strengthening our manuscript.

 

Reviewer's comments: Line 345: The formatting of the table could be improved for clarity and readability.

The authors' response: We thank the reviewer for this helpful suggestion regarding the formatting of Table 1. The table has been revised to improve clarity and readability. Specifically, numerical values have been standardized to a consistent number of decimal places, column alignment has been refined, and spacing and labeling have been adjusted to enhance visual coherence. We believe these changes make the table easier to interpret and improve the overall presentation of the results.

 

Reviewer's comments: Line 486: Table 5 contains similar terms that are not used consistently (e.g., “not detected” vs. “no detection”). The terminology should be standardized throughout the table.

The authors' response: We thank the reviewer for highlighting the inconsistency in terminology used in Table 5. The terminology has been standardized throughout the table by replacing “no detection” with “not detected” to ensure consistency and alignment with standard scientific usage.

 

Reviewer's comments: Line 617: Figure 3 is referenced with two different captions, which may cause confusion: Figure 3. Processing-Related Changes in Metal Concentrations in Dairy Products Relative to EU Maximum Permissible Levels. Figure 3. Global elemental fingerprint of dairy matrices across species, production systems, and processing stages. The authors should carefully verify and correct all figure captions and references to ensure consistency. The authors are encouraged to thoroughly check all figures and tables for consistency, formatting, and accurate cross-referencing throughout the manuscript.

 

The authors' response: We thank the reviewer for carefully identifying this inconsistency. We acknowledge that Figure 3 was inadvertently associated with two different captions, which could indeed cause confusion. This issue has now been corrected. The figure showing processing-related changes in metal concentrations relative to EU maximum permissible levels has been retained as Figure 3, while the heatmap illustrating the global elemental fingerprint of dairy matrices has been renumbered as Figure 4. All subsequent figures have been renumbered accordingly. In addition, we have thoroughly checked all figures and tables for consistency and have updated all in-text references to ensure accurate cross-referencing and uniform formatting throughout the manuscript.

 

Reviewer's comments: Comments on the Quality of English Language: The manuscript is generally well-written and understandable, but minor grammatical issues and stylistic inconsistencies throughout the text should be corrected to make it even more readable and clearer. There are several sentences, especially in the Introduction and Results sections, that are too long and somewhat complicated. Authors should if possible, simplify sentence structure or divide the long ones for better readability. 2 Some technical terms and expressions are used inconsistently, such as the terms "not detected", "below the limit of detection", and "no detection", as I highlighted in the general revision to the authors. It is desirable to adopt one uniform terminology in the manuscript, and also in the tables, figures, and supplementary materials.

 

The authors' response:  We thank the reviewer for the constructive comments regarding language, style, and terminology. We have carefully revised the manuscript to correct minor grammatical issues and stylistic inconsistencies in order to improve clarity and readability. Several long and complex sentences, particularly in the Introduction and Results sections, have been simplified or divided into shorter sentences to enhance readability. In addition, we have standardized the terminology related to non-detectable values throughout the manuscript, tables, figures, and Supplementary Materials. Specifically, we have adopted the uniform use of the term “below the limit of detection (BLD)” and replaced alternative expressions such as “not detected” and “no detection” accordingly.

 

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Accept

Reviewer 2 Report

Comments and Suggestions for Authors

This manuscript can be accpted.