Innovative Applications of Salted Duck Egg By-Product (Liquid Albumen): Evaluating Substitutions in Pickled Pork Casings for Chinese Sausage Manufacturing
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsThis article presents a new approach for valorization of salted duck egg liquid albumen (LA) in the production of Chinese sausage. Results indicate high-quality sensory and textural improvement, however, severe methodological flaws, incomplete reporting of data (only proximate analysis), and superficial discussion of microbial safety are the main and strong limitations of this study.
Major comments:
Experimental design is not described for variables of major importance. For instance, sausage formulation is based on Huang approach with "minor modifications," which are not described. Proximate analyses were only performed once (n=1), which is a limitation for reliability of moisture and sodium.
ANOVA and Duncan's test are appropriate, but Table 1 contains irregular superscripting (all 21-day moistures superscripted 'a', ignoring differences). This is a sign of errors in post-hoc application. For AW, the discussion mentions no adverse effects but overlooks that values >0.90 for fermented sausages carry a risk of microbial growth (as noted).
Aroma quantitation (Equation 1) assumes linear peak-area response, but in the absence of calibration curves for volatiles, concentrations (ng/g) may be in error.
LA's protein content (25%) and salt can introduce allergens or pathogens (Salmonella from eggs); no microbial testing was conducted, despite high AW.
Sodium level noted in methods but not results is critical to health claims.
Measure wastewater reduction to support "reducing high-salinity wastewater." Limitations section does mention optimization need but ignores scalability.
Aroma methods (SPME-GC-MS) are described, but results are not provided within the provided pages, limiting evaluation. Sensory testing is consumer-relevant but biased toward young panelists, detail demographics and extent of training.
Abstract gives an overview of the purpose of the study. The most important is the statement of "no significant differences among all groups compared to the control group in terms of the proximate compositions, apparent color, and aroma component profiles". This is contrary to results in Table 1 related to moisture content.
The Introduction is Asian-focused and has no worldwide implications.
Material and method section shoud be changed. Critical steps lack precision. Sausage preparation includes "minor modifications" to Huang et al. which are unspecified.
Incorporate microbial/shelf-life assays and quality controls.
Discussion section needs to be improved. There are technical errors. Enhance analysis, include correlations (Pearson's r for moisture-TPA) and specifics.
The conclusions repeats considerably the abstract/discussion with minimal new information. Enhance novelty, quantify impacts. Insert a sentence of policy/industry relevance.
Minor editing is needed.
Author Response
Please refer to the attachment for the specific response.
Author Response File: 
Author Response.docx
Reviewer 2 Report
Comments and Suggestions for AuthorsThe article presents results on the evaluation of liquid albumen as a replacement for pickling solutions to produce sausages to valorise a by-product which can be difficult to discard in the food industry. It proposed an original approach for the use of food by-product which can be considered as safe and sustainable, proposing other food applications.
The article is quite original, but the introduction does not sustain the objective of the work in a clear way; materials and methods are coherent with the aim of the work and the methodology is appropriate to the study; the results are in some part well-presented and discussed, but some improvement are necessary; conclusions are not presented in a way that make them consistent with the evidence (see below).
Below there are some suggestions and doubts.
Title: I suggest reducing the title to make it more captivating and less descriptive.
Abstract: It should briefly present a state of the art (a brief introduction), the objective and the main determination, and the crucial results with brief conclusions. Please, reconsider it.
Introduction: I suggest some changes. First, please move line 36-43 before the market introduction (lines 34-35). Maybe adding some details about the production of Salted duck eggs. Same for HC. Please, explain better what it is and why it is a problem for the food industry. I suggest adding and reconsidering the introduction by adding some details and by sustaining the objective of the work by making examples about the use or not of other pickling liquids for the production of sausages.
Materials and Methods: About the preparation of samples, considering the different codes, I would appreciate a table to collect each code and corresponding treatment.
It would be better to specify that the determinations were done using AOAC methods before mentioning the methods number themselves.
For sensory evaluation, was the test referred to an Ethical committee? If yes, please indicate the permission of the committee.
Results: Please, rephrase lines 243-245 to make them more comprehensible.
Lines 219-231: discussions could be improved. Maybe authors can add some references about the application of semi-permeable coatings on similar food? Moisture content and then aw can be influenced by the transmission rate of water vapor considering the type of polymer that adheres to the food. Are there any similar polymeric sustainable films applied to food? Please, improve this part.
Conclusions: Authors should briefly present which was the application of liquid albumen and repeat why it was applied. A brief summary of the best results obtained should be reported, and authors should strengthen the innovation of the sustainable approach for the production of sausages, proposing an industrial application.
Figures
Figure 1: I would appreciate a larger picture of the sausages. Same for Figure 2 and 3. Maybe a legend for acronyms would be better (even if the abbreviations have been already written). Figure 3 is barely readable.
Tables
Table 1 is almost not visible, for significance letters. I have barely seen them using zoom. May I suggest adapting the table in one page in horizontal?
Same for Table 2.
In general, I suggest reconsidering the table formatting in terms of size and distribution of data in the table and the resolution of the figures. They are too small in size and unreadable.
References are recent (published in the last five years) and seem to support data and findings, but they could be increased.
Author Response
Please refer to the attachment for the specific response.
Author Response File: Author Response.docx
Reviewer 3 Report
Comments and Suggestions for AuthorsI thoroughly enjoyed reviewing the manuscript which is recommended for major revision before it can be considered for publication. My comments along with some suggestions are noted below-
Title and Abstract section: The abstract has a concise summary of the background, objectives and key findings. But the abstract should briefly define the experimental design, Sustainability claims are overstated.
Section- Introduction: The introduction has the significance of reusing salted duck egg by-products. It is contextualized within the meat processing and food waste valorization fields. Nevertheless, the research gap heavily needs clearer articulation. The authors should state what remains unexplored about LA substitution in natural casing pickling. Its implications for texture, aroma and consumer perception. Plus , the introduction should present specific, testable hypotheses. The sustainability point needs support by providing a short statement about the environmental or economic benefit of duck egg by-product waste.
Materials and Methods section- The methodology section lacks essential information for reproducibility. Treatment of control group must be clearly described to confirm that all preprocessing steps are consistent across samples. Details of the pickling solutions (pH, ionic strength and protein content) is needed, as these parameters directly regulate casing structure. Could you include microbial safety verification since samples were stored up to 21 days at 4 °C? I am concerned about the potential food safety. The GC–MS method should have calibration details, internal standard validation, limits of detection and quantification protocols. In sensory evaluation work, details such as panelist demographics, randomization, blinding, serving order and ethics approval (if any) are missing.
Results section- Texture Profile Analysis (TPA) results are detailed , but the discussion often infers causal relationships (e.g., “improved hardness due to ionic effects”) without reporting/ connnectging direct evidence. These should be reframed via hypotheses supported by correlation analysis or mechanistic reasoning. The aroma results, analyzed via GC–MS, are underreported because the compound identification, quantification as well as confidence levels should be tabulated clearly. Authors may consider linking specific volatile compounds to sensory descriptors through multivariate analysis (e.g., PCA or PLS regression).
Section- discussion: Authors should provide more mechanistic reasoning supported by literature citations or direct analysis (e.g., discussing ionic strength’s effect on protein gelation or casing hydration). The relationship between LA composition and casing texture could be well-explained by molecular interactions between albumen proteins and collagen. The section should also have the limitations. For example, lack of microbiological assessment, absence of extended shelf-life studies and the relatively small sensory panel size. The sustainability claim should be made quantitatively.
Conclusion section- Statements such as “a win–win outcome” should be avoided in scientific writing. The authors should instead phrase their conclusion more cautiously, saying that the results are preliminary and that further validation under industrial conditions and larger-scale testing is recommended. Authors may suggest future research directions as inclusion of shelf-life assessment, microbial safety analysis and optimization studies using response surface methodology and/or other AI tools.
Author Response
Please refer to the attachment for the specific response.
Author Response File: Author Response.docx
Round 2
Reviewer 1 Report
Comments and Suggestions for AuthorsThe authors made significant changes, so the paper can be accepted.
Comments on the Quality of English LanguageMinor editing is needed.
Reviewer 2 Report
Comments and Suggestions for AuthorsI have not comments to Improve the manuscript. I think that the authors have well addressed the comments and properly modified the paper. I think that it could be accepted for publication.
Reviewer 3 Report
Comments and Suggestions for AuthorsAppreciate the kind efforts of the authors to address the comments provided earlier. The manuscript is of better quality.
