Effect of Pre-Treatment on the Pressing Yield and Quality of Grape Juice Obtained from Grapes Grown in Poland

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

First of all, I would like to congratulate you on the interesting concept of your research. I truly appreciate all scientific efforts aimed at analyzing the efficiency of raw plant material processing. However, I would like to share with you several questions, doubts, and comments.

TITLE
The aim of the study, as indicated in lines 57–62, was to determine the influence of pre-treatment on grape juice preparation. Therefore, I would suggest removing “the Variety” from the title. The impact of grape variety on juice content was expected and results from known botanical differences.

INTRODUCTION
Line 20
“In climatic conditions” – please specify which climatic conditions are being referred to, so that readers from all over the world can understand the context clearly.

MATERIALS AND METHODS
Lines 70–84
To improve clarity, please include numbers or symbols identifying the grape varieties analyzed.

Line 86
“Healthy” – please define this term more precisely. What were the selection criteria?

Lines 92–93
Was the enzymatic treatment performed using a powder or a water solution? If it was a liquid, how was it applied to the fruit — by spraying or another method?

Line 100
“Capacity of 10 dcm³” – please correct the unit; the standard notation is “L” or “dm³”.

Line 105
“Constant speed of 0.5 mm s⁻¹” – please correct the notation of the unit.

Lines 111–119
Please clarify which tests were conducted according to Polish standards and which according to other (European?) standards, and explain why different standards were used.

RESULTS AND DISCUSSION
Lines 129–132
This section reads more like a summary or conclusion and should not be presented before the results. Furthermore, the second sentence, which includes a reference citation, is overly general and lacks meaningful content.

Table 1 versus Figures 1–7
In Table 1, you present average results for red and white grape varieties, while in Figures 1–7, you show specific values for individual varieties. To improve coherence, consider moving Table 1 after the figures — or removing it altogether.

Tables 2–10
Tables 2–10 repeat the control results already presented in Figures 1–7. Data should not be duplicated.

I suggest two possible solutions:

1. Remove section 3.1 and Figures 1–7, and integrate the description of these parameters into the text accompanying Tables 2–10. The text could then be logically organized according to the examined factors.

2. Extend Figures 1–7 to include the data from Tables 2–10, and structure the accompanying text according to the parameters analyzed.

You can also propose you own solution for rebuilding the manuscipt so that the data were not repeated.

Best regards,
Reviewer

Comments on the Quality of English Language

I am not confident enough in my expertise to assess the quality of the English language

Author Response

Lublin, 16.07.2025

Dear Reviewer,

Thank you for your effort in reviewing our manuscript and for your valuable comments. Below are our responses to your comments.

Sincerely,

Authors

 

The English has been revised by a native speaker specialising in scientific texts.

Comment 01

The aim of the study, as indicated in lines 57–62, was to determine the influence of pre-treatment on grape juice preparation. Therefore, I would suggest removing “the Variety” from the title. The impact of grape variety on juice content was expected and results from known botanical differences.

Response 01

We agree with the comment. The manuscript title has been corrected. Line 2-3

Comment 02

Line 20

“In climatic conditions” – please specify which climatic conditions are being referred to, so that readers from all over the world can understand the context clearly.

Response 02

Poland has a temperate, transitional climate with an average annual air temperature of approximately 9.5°C (2020). Information is included in the text.

Lines 21-22

Comment 03

Lines 70–84

To improve clarity, please include numbers or symbols identifying the grape varieties analyzed.

Response 03

We believe that abbreviations are unnecessary. Throughout this manuscript, we use the full names of the grape varieties.

Comment 04

Line 86

“Healthy” – please define this term more precisely. What were the selection criteria?

Response 04

Healthy, i.e., without visible disease changes (e.g., mold). Information is included in the text. Line 92

Comment 05
Lines 92–93

Was the enzymatic treatment performed using a powder or a water solution? If it was a liquid, how was it applied to the fruit — by spraying or another method?

Response 05

Enzymes were applied to the samples by spraying. This note has been included in the text. Lines 100

Comment 06

Line 100

“Capacity of 10 dcm³” – please correct the unit; the standard notation is “L” or “dm³”.

Response 06

The unit has been corrected in the text. Line 107

Comment 07

Line 105

“Constant speed of 0.5 mm s⁻¹” – please correct the notation of the unit.

Response 07

The unit has been corrected in the text. Line 112-113

Comment 08

Lines 111–119

Please clarify which tests were conducted according to Polish standards and which according to other (European?) standards, and explain why different standards were used.

Response 08

Generally, the tests were conducted in accordance with European standards applicable in Poland. Only the PN-90/A-75101/02 test was conducted in accordance with Polish standards.

RESULTS AND DISCUSSION

Comment 09

Lines 129–132

This section reads more like a summary or conclusion and should not be presented before the results. Furthermore, the second sentence, which includes a reference citation, is overly general and lacks meaningful content.

Response 09

This section has been rewritten and moved later in the manuscript.

Comment 10

Table 1 versus Figures 1–7

In Table 1, you present average results for red and white grape varieties, while in Figures 1–7, you show specific values for individual varieties. To improve coherence, consider moving Table 1 after the figures — or removing it altogether.

Response 10

The table and its description have been moved to the end of section 3.1.

Comment 11

Tables 2–10

Tables 2–10 repeat the control results already presented in Figures 1–7. Data should not be duplicated.

I suggest two possible solutions:

1. Remove section 3.1 and Figures 1–7, and integrate the description of these parameters into the text accompanying Tables 2–10. The text could then be logically organized according to the examined factors.
2. Extend Figures 1–7 to include the data from Tables 2–10, and structure the accompanying text according to the parameters analyzed.

You can also propose you own solution for rebuilding the manuscript so that the data were not repeated.

Response 11

Of course, either solution 1 or 2 is possible for presenting the results. However, we believe that the solution we used is acceptable. Figures 1-7 present the average values ​​for a given variety obtained by considering the three types of pretreatment combined, while Tables 2-10 present the average values ​​for the different types of pretreatment. This clearly shows the effect of pretreatment on the analyzed values ​​depending on the variety.

Author Response File: Author Response.docx

Reviewer 2 Report

Comments and Suggestions for Authors

The manuscript is potentially suitable for publication after major revisions to address critical methodological gaps, data interpretation issues, and structural concerns.

1. How does freezing-thawing specifically modify cell wall structures in different grape varieties?
2. Why did enzymatic treatment *reduce* polyphenols in Marechal Foch but increase them in Regent?
3. Can the density discrepancies (Tables 1 vs. 5) be attributed to measurement error or methodology?
4. The arbitrary selection of 0.6 MN pressure for pressing lacks justification. Cite literature or preliminary data showing this pressure optimizes yield without compromising quality.
5. Specify the enzymatic activity (e.g., polygalacturonase, pectin lyase units) of Pektoenzym rather than volume (0.2 mL/kg). Activity units ensure reproducibility.
6. Define freezing rate (°C/min) and thawing method (ambient vs. controlled). Slow vs. fast freezing affects cell rupture efficiency ([Kobus et al., 2019](https://doi.org/10.1371/journal.pone.0219585)).

7.Table 1 reports juice density as ~10406 kg/L, but Table 5 shows implausible values (e.g., 107 kg/L).

8. Consistently use mg/100mL or g-GAE/L. Table 1 uses mg/100mL, but [24] cites g-GAE/L—clarify conversion or methodology alignment.
9. Thermal treatment (F) increased sucrose in Merlot by 1,025% (Table 8), yet initial sucrose was low (0.12 g/100g). Discuss enzymatic vs. thermal hydrolysis of polysaccharides to explain this.
10. The ANOVA should include "Variety × Treatment" interactions (e.g., why enzymatic treatment boosted Jutrzenka’s yield but reduced Muscaris’).
11. Address high SD in Muscaris yield (Table 2: SD ±2.75% vs. ±0.32% for Hibernal). Was data normalized?
12. Explain why freezing increased polyphenols in Muscaris (Table 9: 29.41 → 49.39 mg/100mL) but decreased them in Marechal Foch in discussion. Link to cell wall disruption or anthocyanin stability.
13. Reconcile conflicting pH findings (e.g., Seyval Blanc pH = 3.11 here vs. 3.8 in [24]). Attribute differences to terroir or harvest year.
14. State which pre-treatment is optimal per variety (e.g., enzymatic for Jutrzenka yield; thermal for Muscaris polyphenols).
15. Strengthen rationale for studying Polish hybrids by citing gaps in cold-climate grape processing (e.g., "Limited data exists on pre-treatment efficacy for *Vitis vinifera* hybrids in continental climates").
16. Specify which varieties are most suitable for juice production (e.g., "Muscaris showed exceptional polyphenol retention after thermal treatment").
17. Acknowledge limitations (e.g., single-harvest data, small-scale pressing).

Author Response

Lublin, 16.07.2025

Dear Reviewer,

Thank you for your effort in reviewing our manuscript and for your valuable comments. Below are our responses to your comments.

Sincerely,

Authors

 

The English has been revised by a native speaker specialising in scientific texts.

Comments 01

How does freezing-thawing specifically modify cell wall structures in different grape varieties?

Response 01

At this stage of the research, it is impossible to explain how this modification occurs in individual grape varieties. This requires further detailed research. In general, slow freezing causes a gradual increase in the size of ice crystals as a result of which damage to the tissue structure is observed (Chevalier at al. 2000). This damage results in loss of cell turgor after thawing and significant leakage of cell juice.

• Chevalier D, Le Bai A, Ghoul M (2000) Freezing and ice crystals formed in cylindrical food model: part I. Freezing at atmospheric pressure. J Food Eng 46:277–285 https://doi.org/10.1016/S0260-8774(00)00089-3

Comments 02

Why did enzymatic treatment *reduce* polyphenols in Marechal Foch but increase them in Regent?

Response 02

This may be related to the different polyphenol content of each fruit structure. Explaining this requires detailed research into how enzymatic processing and the pressing procedure affect the degree of polyphenol extraction from individual fruit structures. According to Barnaba et al. (2017) research, different grape varieties are characterised by different polyphenol content in the skin, pulp, and seeds.

• Barnaba, C., Dellacassa, E., Nicolini, G., Giacomelli, M., Villegas, T.M., Nardina, T., Larcher, R. Targeted and untargeted high resolution mass approach for a putative profiling of glycosylated simple phenols in hybrid grapes, Food Res Int. 2017, 98, 20-33 DOI: http://dx.doi.org/10.1016/j.foodres.2017.01.011

Comments 03

Can the density discrepancies (Tables 1 vs. 5) be attributed to measurement error or methodology?

Response 03

Tables 1 and 5 have been corrected to express density values in g/cm³.

In Table 1 are averaged values for white grapes (total) and red grapes (total) with different treatments (total). In contrast, Table 5 shows the average values for each variety and different types of pretreatment. This explains the scattering of results.

Comments 04

The arbitrary selection of 0.6 MN pressure for pressing lacks justification. Cite literature or preliminary data showing this pressure optimizes yield without compromising quality.

Response 04

There was an error in the manuscript. Line 111 (corrected).

In our tests, the press pressure was 0.06MN or 60kN.

Preliminary tests have shown that the use of 0.06 MN pressure allows process yields of around 50% and above.

Comments 05

Specify the enzymatic activity (e.g., polygalacturonase, pectin lyase units) of Pektoenzym rather than volume (0.2 mL/kg). Activity units ensure reproducibility.

Response 05

In our study, we used a standard enzyme preparation produced by a leading domestic manufacturer and applied it according to the instructions. The description of the preparation lacks information on enzymatic activity.

Comments 06

Define freezing rate (°C/min) and thawing method (ambient vs. controlled). Slow vs. fast freezing affects cell rupture efficiency ([Kobus et al., 2019](https://doi.org/10.1371/journal.pone.0219585)).

Response 06

In our study, precise determination of freezing and thawing rates is not necessary. Freezing in a standard freezer over 24 hours ensures slow freezing and thus slow growth of ice crystals, which destroy cells and facilitate easier flow of cell juice after thawing. Thawing was carried out in a heat chamber at 25oC for 4 hours (information is included in the manuscript).

Comments 07

Table 1 reports juice density as ~10406 kg/L, but Table 5 shows implausible values (e.g., 107 kg/L).

Response 07

Tables 1 and 5 have been corrected to express density values in g/cm3. See response 03.

Comments 08

Consistently use mg/100mL or g-GAE/L. Table 1 uses mg/100mL, but [24] cites g-GAE/L—clarify conversion or methodology alignment.

Response 08

In the experiment, the polyphenol content (TPC) was determined using the Folin-Ciocalteu colorimetric method, and the results were expressed as an equivalent of caffeic acid (mg/100 ml). The tests were carried out in a certified laboratory.

Other researchers express total polyphenol content (TPC) as mg gallic acid equivalent per unit volume or weight of sample (mg GAE/ml or mg GAE/g), mg ferulic acid equivalent per unit volume or weight of sample (mg FA/ml or mg FA/g), mg quercetin equivalent per unit volume or weight of sample (mg QE/ml or mg QE/g) I in.

No conversion of results is possible.

Comments 09

Thermal treatment (F) increased sucrose in Merlot by 1,025% (Table 8), yet initial sucrose was low (0.12 g/100g). Discuss enzymatic vs. thermal hydrolysis of polysaccharides to explain this.

Response 09

Without detailed research, it is difficult to explain the reasons for these changes.

Comments 10

The ANOVA should include "Variety × Treatment" interactions (e.g., why enzymatic treatment boosted Jutrzenka’s yield but reduced Muscaris’).

Response 10

Tukey's post-hoc test shows the significance of differences in individual sizes for the grape varieties tested depending on pretreatment.

Explaining why there are differences in fruit pressing performance depending on the type of treatment for individual varieties requires further detailed research.

Comments 11

Address high SD in Muscaris yield (Table 2: SD ±2.75% vs. ±0.32% for Hibernal). Was data normalized?

Response 11

This is related to the specificity of biological materials characterised by heterogeneity. The pressing of the fruit was carried out according to an established repeatable procedure.

Comments 12

Explain why freezing increased polyphenols in Muscaris (Table 9: 29.41 → 49.39 mg/100mL) but decreased them in Marechal Foch in discussion. Link to el wall disruption or anthocyanin stability.

Response 12

This may be related to the different polyphenol content of each fruit structure. Changes in the polyphenol content of the juice may also be related to the stability of anthocyanins in the frozen state or to enzyme activity.

Comments 12

Reconcile conflicting pH findings (e.g., Seyval Blanc pH = 3.11 here vs. 3.8 in [24]. Attribute differences to terroir or harvest year.

Response 12

The information was included in the manuscript. Lines 178-180

Differences in the pH values of juice obtained from individual grape varieties compared to the results of other authors may be caused by the terroir and year of harvest.

Comments 13

State which pre-treatment is optimal per variety (e.g., enzymatic for Jutrzenka yield; thermal for Muscaris polyphenols).

Response 13

The conducted research indicates that, considering the efficiency of the process, enzymatic treatment is optimal for processing grapes into juice. However, thermal treatment can achieve higher polyphenol content in some grape varieties. The authors' previous studies on the effects of thermal treatment (freezing and thawing) on selected fruits (apple, blueberry) and vegetables (carrot, rhubarb) demonstrated its significant impact on the efficiency of the pressing process and the quality of the resulting juice.

• Effect of the black chokeberry (Aronia melanocarpa (Michx.) Elliott) juice acquisition method on the content of polyphenols and antioxidant activity. [AUT.] ZBIGNIEW KOBUS, RAFAŁ NADULSKI, [AUT.] KAMIL WILCZYŃSKI, MARTA KOZAK, TOMASZ GUZ, LESZEK RYDZAK. PloS One 2019 Vol. 14 Iss. 7 art. no. e0219585, DOI: 10.1371/journal.pone.0219585
• The Influence of freezing and thawing on the yield and energy consumption of the celeriac juice pressing process. RAFAŁ NADULSKI, [AUT.] ZBIGNIEW KOBUS, TOMASZ GUZ. Processes 2020 Vol. 8 Iss. 3 378, DOI: 10.3390/pr8030378
• Vitamin C and lutein content of northern highbush blueberry (Vaccinium corymbosum L.) juice processed using freezing and thawing. RAFAŁ NADULSKI, [AUT.] ANDRZEJ MASŁOWSKI, ARTUR MAZUREK, PAWEŁ SOBCZAK, MAREK SZMIGIELSKI, WIOLETTA ŻUKIEWICZ-SOBCZAK, IGNACY NIEDZIÓŁKA, JACEK MAZUR. J. Food Meas. Charact. 2019 Vol. 13 Iss. 4 s. 2521-2528, DOI: 10.1007/s11694-019-00172-x
• Application of freezing and thawing in apple (Malus domestica) juice extraction. [AUT.] RAFAŁ NADULSKI, ZBIGNIEW KOBUS, KAMIL WILCZYŃSKI, KAZIMIERZ ZAWIŚLAK, JÓZEF GROCHOWICZ, TOMASZ GUZ. J. Food Sci. 2016 Vol. 81 Issue 11 E2718-E2725, il. DOI: 10.1111/1750-3841.13514
• Application of freezing and thawing to carrot (Daucus carota L.) juice extraction. RAFAŁ NADULSKI, [AUT.] JÓZEF GROCHOWICZ, PAWEŁ SOBCZAK, ZBIGNIEW KOBUS, MARIAN PANASIEWICZ, KAZIMIERZ ZAWIŚLAK, JACEK MAZUR, AGNIESZKA STAREK, WIOLETTA ŻUKIEWICZ-SOBCZAK. Food Bioproc. Tech. (Print) 2015 Vol. 8 Issue 1 s. 218-227, DOI: 10.1007/s11947-014-1395-6
• Effect of pre-treatment on pressing efficiency and properties of rhubarb (Rheum rhaponticum L.) juice. [AUT.] RAFAŁ NADULSKI, JACEK SKWARCZ, AGNIESZKA SUJAK, ZBIGNIEW KOBUS, KAZIMIERZ ZAWIŚLAK, AGNIESZKA STÓJ, JAKUB WYROSTEK. J. Food. Eng. 2015 Vol. 166 Issue 1 370-376, DOI: 10.1016/j.jfoodeng.2015.06.035

Comments 14

Strengthen rationale for studying Polish hybrids by citing gaps in cold-climate grape processing (e.g., "Limited data exists on pre-treatment efficacy for *Vitis vinifera* hybrids in continental climates").

Response 14

The information was included in the manuscript. Lines 46-49

In Poland, the most commonly cultivated grape varieties are multispecies hybrid grapes, and there is limited information on the effectiveness of pre-treatment, e.g. for Vitis vinifera hybrids grown in a climate typical of Poland.

Comments 15

Specify which varieties are most suitable for juice production (e.g., "Muscaris showed exceptional polyphenol retention after thermal treatment").

Response 15

The information was included in the manuscript. Lines 410-411

Due to its polyphenol content, the Muscaris variety is suitable for grape juice production. Thermal processing increases the polyenol content in the juice. Other studies (Jovanović-Cvetković et al., 2022) also highlight the benefits of the Muscaris variety as a raw material for processing.

Jovanović-Cvetković, T., Grbić, R. Starčević, D., Milašin, M. Technological characteristics of interspecific hybrids Bronner, Muscaris and Morava in Banja Luka region. J. Agric. Food Environ. Sci. 2022 76(6) 57-67 DOI: https://doi.org/10.55302/JAFES22766057jc

Comments 16

Acknowledge limitations (e.g., single-harvest data, small-scale pressing).

Response 16

The information was included in the manuscript. Lines 416-420

Since the study was conducted on a laboratory scale using a single grape harvest, further research should include testing grapes from subsequent harvests and be carried out on a semi-industrial scale. Moreover, it would be useful to conduct sensory tests on juices obtained from individual grape varieties after applying different pre-treatment methods.

Author Response File: Author Response.docx

Reviewer 3 Report

Comments and Suggestions for Authors

The manuscript “Effect of the Variety and Pre-Treatment on the Pressing Yield and Selected Quality Parameters of Grape Juice” evaluates the effect of enzymatic and thermal treatments on the juice yield of different grape varieties.

Below are my comments:

• The authors mention that the sensory quality of the juice is important for consumers. Why was this aspect not included in the analysis? Is there a future stage planned involving sensory testing?
• Freezing and thawing the fruit can cause cellular rupture, potentially enhancing the release of compounds. Did the authors consider evaluating possible negative impacts such as oxidation or loss of volatile compounds?
• Were the experiments carried out in only one repetition and a single harvest? Are these results statistically representative? If the experiments were repeated at a different time, would the reproducibility be ensured?
• Why was a sequential combination of enzymatic and thermal treatments (E+F) not considered to evaluate potential synergies in juice yield and quality?
• Was the economic feasibility of the treatments (enzymatic/thermal) considered? Which of them offers better cost-benefit for producers?
• The determination of polyphenol content was performed using the Folin–Ciocalteu method, which is not specific. Did the authors consider a more selective method for characterizing phenolic compounds?
• Was any verification of the stability of parameters (such as pH, polyphenols or sugars) performed after refrigerated storage prior to analysis?
• Could the authors provide a more detailed description of the statistical model applied?
• Given that Muscaris was the only white variety with a high polyphenol content, do the authors see potential in exploring it as an alternative to red wine in antioxidant-promoting products? Are there any industrial experiences in this regard?
• The conclusions could be more generalized and should avoid repeating discussion results. What are the practical implications of the findings?

 

Author Response

Lublin, 16.07.2025

Dear Reviewer,

Thank you for your effort in reviewing our manuscript and for your valuable comments. Below are our responses to your comments.

Sincerely,

Authors

 

The English has been revised by a native speaker specialising in scientific texts.

Comment 01

The authors mention that the sensory quality of the juice is important for consumers. Why was this aspect not included in the analysis? Is there a future stage planned involving sensory testing?

Response 01

Yes, in the next stage of the research, sensory tests of the obtained grape juices will be carried out.

Comments 02

Freezing and thawing the fruit can cause cellular rupture, potentially enhancing the release of compounds. Did the authors consider evaluating possible negative impacts such as oxidation or loss of volatile compounds?

Response 02

At this stage of the research, such work has not been conducted. Nevertheless, freezing is a process that minimally affects (but affects) the nutritional value of foods, especially those of plant origin. In the experiment, the frozen pulp was stored for only 24 hours.

Comments 03

Were the experiments carried out in only one repetition and a single harvest? Are these results statistically representative? If the experiments were repeated at a different time, would the reproducibility be ensured?

Response 03

The experiment was conducted in a single replicate. In the future, it would be advisable to expand and continue research in this area.

Comments 04

Why was a sequential combination of enzymatic and thermal treatments (E+F) not considered to evaluate potential synergies in juice yield and quality?

Response 04

This comment is valuable, and such analyses will be taken into account in future studies.

The main goal of this study was to examine the effect of thermal processing (freezing and thawing fruit pulp) on the extraction efficiency and chemical composition of the obtained juices. Therefore, the analysis was limited to this one. The authors' previous studies on the effect of thermal processing (freezing and thawing) conducted on selected fruits (apple, blueberry) and vegetables (carrot, rhubarb) demonstrated its significant impact on the extraction process and the quality of the obtained juice.

• Effect of the black chokeberry (Aronia melanocarpa (Michx.) Elliott) juice acquisition method on the content of polyphenols and antioxidant activity. [AUT.] ZBIGNIEW KOBUS, RAFAŁ NADULSKI, [AUT.] KAMIL WILCZYŃSKI, MARTA KOZAK, TOMASZ GUZ, LESZEK RYDZAK. PloS One 2019 Vol. 14 Iss. 7 art. no. e0219585, DOI: 10.1371/journal.pone.0219585
• The Influence of freezing and thawing on the yield and energy consumption of the celeriac juice pressing process. RAFAŁ NADULSKI, [AUT.] ZBIGNIEW KOBUS, TOMASZ GUZ. Processes 2020 Vol. 8 Iss. 3 378, DOI: 10.3390/pr8030378
• Vitamin C and lutein content of northern highbush blueberry (Vaccinium corymbosum L.) juice processed using freezing and thawing. RAFAŁ NADULSKI, [AUT.] ANDRZEJ MASŁOWSKI, ARTUR MAZUREK, PAWEŁ SOBCZAK, MAREK SZMIGIELSKI, WIOLETTA ŻUKIEWICZ-SOBCZAK, IGNACY NIEDZIÓŁKA, JACEK MAZUR. J. Food Meas. Charact. 2019 Vol. 13 Iss. 4 s. 2521-2528, DOI: 10.1007/s11694-019-00172-x
• Application of freezing and thawing in apple (Malus domestica) juice extraction. [AUT.] RAFAŁ NADULSKI, ZBIGNIEW KOBUS, KAMIL WILCZYŃSKI, KAZIMIERZ ZAWIŚLAK, JÓZEF GROCHOWICZ, TOMASZ GUZ. J. Food Sci. 2016 Vol. 81 Issue 11 E2718-E2725, il. DOI: 10.1111/1750-3841.13514
• Application of freezing and thawing to carrot (Daucus carota L.) juice extraction. RAFAŁ NADULSKI, [AUT.] JÓZEF GROCHOWICZ, PAWEŁ SOBCZAK, ZBIGNIEW KOBUS, MARIAN PANASIEWICZ, KAZIMIERZ ZAWIŚLAK, JACEK MAZUR, AGNIESZKA STAREK, WIOLETTA ŻUKIEWICZ-SOBCZAK. Food Bioproc. Tech. (Print) 2015 Vol. 8 Issue 1 s. 218-227, DOI: 10.1007/s11947-014-1395-6
• Effect of pre-treatment on pressing efficiency and properties of rhubarb (Rheum rhaponticum L.) juice. [AUT.] RAFAŁ NADULSKI, JACEK SKWARCZ, AGNIESZKA SUJAK, ZBIGNIEW KOBUS, KAZIMIERZ ZAWIŚLAK, AGNIESZKA STÓJ, JAKUB WYROSTEK. J. Food. Eng. 2015 Vol. 166 Issue 1 370-376, DOI: 10.1016/j.jfoodeng.2015.06.035

Comments 05

Was the economic feasibility of the treatments (enzymatic/thermal) considered? Which of them offers better cost-benefit for producers?

Response 05

At this stage, the economic aspects of the pressing process using freezing and thawing as a pretreatment have not been analyzed. Considering the electricity costs, the process costs will be higher than those for enzymatic processing.

Comments 06

The determination of polyphenol content was performed using the Folin–Ciocalteu method, which is not specific. Did the authors consider a more selective method for characterizing phenolic compounds?

Response 06

We have used this method in previous studies on various fruits and vegetables, and we used it in this experiment as well. Based on the reviewer's suggestion, we will consider using a more selective method for testing phenolic compounds.

Look response 04 (publications).

Comments 07

Was any verification of the stability of parameters (such as pH, polyphenols or sugars) performed after refrigerated storage prior to analysis?

Response 07

The comment is valuable, but we did not conduct such verification of the stability of parameters such as pH, polyphenols or sugars.

Comments 08

Could the authors provide a more detailed description of the statistical model applied?

Response 08

One-way analysis of variance was used in the statistical analysis and the significance of differences between groups was checked using Tukey's post hoc test.

Comments 09

Given that Muscaris was the only white variety with a high polyphenol content, do the authors see potential in exploring it as an alternative to red wine in antioxidant-promoting products? Are there any industrial experiences in this regard?

Response 09

Yes. Based on our own research and available literature, the Muscaris variety exhibits very good ampelographic characteristics (Jovanović-Cvetković et al., 2022). At the same time, this variety is disease-resistant and highly frost-resistant.

• Jovanović-Cvetković, T., Grbić, R. Starčević, D., Milašin, M. Technological characteristics of interspecific hybrids Bronner, Muscaris and Morava in Banja Luka region. J. Agric. Food Environ. Sci. 2022 76(6) 57-67 DOI: https://doi.org/10.55302/JAFES22766057jc

Comments 10

The conclusions could be more generalized and should avoid repeating discussion results. What are the practical implications of the findings?

Reponse 10

The conclusions were supplemented. Lines 412-416

The research revealed the need for further work on the processing of Vitis vinifera hybrids grown in countries with climates similar to Poland.

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Dear Authors,

I can accept your manuscipt in the present form. Congratulations!

Rewiever

Author Response

Dear Reviewer,

Thank you for accepting our manuscript.

Sincerely,

Authors

Reviewer 2 Report

Comments and Suggestions for Authors

This is a well-structured and valuable study investigating the impact of enzymatic and thermal pre-treatments on juice yield and quality parameters of Polish-grown grape hybrids. The research addresses a significant gap in the literature regarding locally adapted varieties and sustainable processing. The experimental design is rigorous, statistical analysis is appropriate, and the findings have practical relevance for the developing Polish viticulture industry. The manuscript is generally clear. However, addressing the major concerns regarding methodological clarity (especially pre-treatment details), resolving data inconsistencies (particularly yield significance, density vs. extract), providing deeper mechanistic discussion of key results (sucrose increase, Muscaris polyphenols), and correcting minor errors/typos is essential before acceptance. The density/extract discrepancy is particularly critical and must be resolved.

Author Response

Lublin, 2025.07.30

Dear Reviewer,

We thank you for your contribution to the evaluation of our manuscript and for the comments you submitted. We analyzed them very carefully and  in the first round we attempted to incorporate them into the revised version of the manuscript. Regarding the comments submitted in the second round, we are having difficulty clearly explaining the discrepancy between the density and extract content and the reasons for the increased sucrose and polyphenol content in the Muscaris cultivar. This would require further detailed research. We described the enzymatic pretreatment process in detail in the manuscript, supplementing it with information on how the enzyme preparation was dosed. In the case of thermal treatment, the slow growth of ice crystals and their destructive effect on cells were crucial – this condition was met during the experiment. However, in further experiments we will determine the freezing and thawing rate.

In our future research, we will emphasize the need for rapid analysis of the study results and their expansion, particularly if any interesting observations are identified.

Sincerely

Authors