The Influence of Different Pre-Treatments on the Quality and Nutritional Characteristics in Dried Undersized Yellow Kiwifruit
, Urszula Tylewicz 2,*, Silvia Tappi 2, Marco Dalla Rosa 2, Pietro Rocculi 2 and Santina Romani 2Round 1
Reviewer 1 Report
The manuscript describes very interesting study on the evaluation of the effect of various pre-drying methods on the characteristics of functionally harvested kiwifriut snacks derived from waste materials. The article has been prepared in a very careful way, however, some issues should be corrected before possible publication.
Title:
The title is too general, it has little reference to the work that has been done. Please change the title of the article to indicate what research has been carried out, for example: The influence of different drying methods on the quality characteristics and the content of bioactive compounds in undersized yellow kiwifruit.
Introduction:
Line 43: please add reference.
Materials and methods:
Lines 80-82: Why was trehalose used in osmotic dehydration and not the widely used sucrose? Why was the ratio of 1:4, fruits: trehalose assumed? Why was it written: ...in order to avoid concentration changes of the solution during the treatment? After all, somotic dehydration is performed in order to obtain changes in the sugar concentration in the solution.
The manuscript lacks the calculated ratio of water loss to solid gain in osmotically dehydrated samples.
Discussion:
In the discussion of the results there is no data of the results concerning the influence of pre-tremornet OD on the assessed quality parameters in comparison to other commonly used sugars.
Conclusion:
Conclusion too general too little detailed. The last sentence requires improvement.
Author Response
The manuscript describes very interesting study on the evaluation of the effect of various pre-drying methods on the characteristics of functionally harvested kiwifriut snacks derived from waste materials. The article has been prepared in a very careful way, however, some issues should be corrected before possible publication.
Answer: Thank you very much for your valuable comment. The manuscript has been revised according to your suggestions.
Title:
The title is too general, it has little reference to the work that has been done. Please change the title of the article to indicate what research has been carried out, for example: The influence of different drying methods on the quality characteristics and the content of bioactive compounds in undersized yellow kiwifruit.
Answer: The tittle has been changed to: “The influence of different pre-treatments on the quality and nutritional characteristics in dried undersized yellow kiwifruit”.
Introduction:
Line 43: please add reference.
Answer: The following reference was added in the reference with the number [4]
Sagar, N. A.; Pareek, S.; Sharma, S.; Yahia, E. M.; Lobo, M. G. Fruit and Vegetable Waste: Bioactive Compounds, Their Extraction, and Possible Utilization. Compr Rev Food Sci F.2018, 17,3, 521-531.
Materials and methods:
Lines 80-82: Why was trehalose used in osmotic dehydration and not the widely used sucrose?
Answer: Trehalose was used in order to evaluate the possibility to replace sucrose in the dehydration process. Trehalose is a naturally occurring dietary disaccharide, with almost half the sweetness of sucrose, and has a low cariogenic potential when compared to sucrose and moderate glycaemic index with low insulinemic response. Moreover, trehalose is able also to preserve lipid bilayers of the cell membrane from physical stresses during the dehydration and therefore can protect biomolecules.
The following sentence was added “Trehalose was chosen because of its potential positive effect in the preservation of biomolecules and a low cariogenic potential when compared to sucrose [18, 19]”.
Why was the ratio of 1:4, fruits: trehalose assumed? Why was it written: ...in order to avoid concentration changes of the solution during the treatment? After all, somotic dehydration is performed in order to obtain changes in the sugar concentration in the solution.
Answer: The ratio 1:4 was chosen on the bases of a previous research [11]. During the osmotic dehydration it is important to have an unchanged driving force within the entire process, while the changes in the sugar concentration occur in the fruit mass. Therefore, a high fruit to solution ratio can avoid a too fast dilution of the osmotic solution and keep the driving force unchanged.
The manuscript lacks the calculated ratio of water loss to solid gain in osmotically dehydrated samples.
Answer: In this manuscript we focused on the final changes of the qualitative and nutritive characteristics after the drying process, therefore the water loss and solid gain was not investigated into details. Anyway, from the preliminary study the water loss to solid gain ratio was in the range of 3.5 -3.6, showing a good efficiency of the process.
Discussion:
In the discussion of the results there is no data of the results concerning the influence of pre-tremornet OD on the assessed quality parameters in comparison to other commonly used sugars.
Answer: The discussion was added in lines 244-251: “It has been reported in the literature that different pre-treatment could have an influence on colour parameters of the treated products. Tylewicz et al. [24] showed an increase if the luminosity (L*) in kiwifruit samples treated with OD in trehalose solution, while no differences were observed when sucrose was used in the osmotic solution. Similarly, the PEF pre-treatment alone resulted in significant changes of colour parameters in kiwifruit samples [25]. However, in the present work the effect of the pre-treatment were evaluated only in the combination with the drying process and did not showed any statistical differences.
Conclusion:
Conclusion too general too little detailed. The last sentence requires improvement.
Answer: The conclusions were rewritten as follows:
The obtained results showed that OD pre-treatment applied alone resulted in a good retention of TPC and AA measured by DPPH method, while PEF treatment alone showed a high content in vitamin C and AA assessed by ABTS method. In both samples the values were similar to those of control samples. However, the shortest drying times required for the OD and PEF pretreated samples could have an additional positive effect on the sustainability of the overall process, by saving the energy required for the process. In general, an increased number of processing steps had a negative influence on the retention of the bioactive compounds and on the antiradical activity in all samples, while the color differences among them, although significant in certain cases, did not indicate a negative effect of any treatment.
In order to possibly scale-up the applied single/combined processing steps in a real industrial scenario, a further study is necessary considering both the energy and managing costs and the stability and nutritional quality of the obtained products, particularly in terms of environmental and economic sustainability.
Reviewer 2 Report
The paper “Sustainable processing of undersized yellow kiwifruit to develop dried snack with high nutritional functionality” by Mannozzi et al. deals with the characterization of kiwifruit dried snacks obtained by different pretreatments, and/or using a different drying protocol. The paper is clearly written, the methods and statistical analyses are robust and the conclusions are adequately supported by the results.
For this reason, I recommend publication of this paper. In the following I list some minor points that the authors could consider before publication:
Abstract:
Line 25: “Instead, ABTS method showed the better AA […]” the better AA should instead be “the best AA”
Introduction:
line 46: “those fruit” should be those fruits
Materials:
Line 114: “[…] dried kiwifruit sample whit 10 mL […]” with is mispelled
Results:
Line 157: “Fresh kiwifruit samples were characterized by L*, h° and C color parameter […]” the symbol C* (and not C) was used previously
Table 3: in the superscripts used to show the results of the ANOVA analysis, some capital letters (that indicate differences between the three drying temperatures considered) are missing.
Line 206: “The behavior of the antiradical activity in all obtained samples is strongly depended […]” should be “[…] strongly dependent”
Discussion:
Lines 252-257: these two sentences are not clear, and I would suggest rephrasing them.
If no Supplementary Material is provided please remove lines 318-319.
Author Response
The paper “Sustainable processing of undersized yellow kiwifruit to develop dried snack with high nutritional functionality” by Mannozzi et al. deals with the characterization of kiwifruit dried snacks obtained by different pretreatments, and/or using a different drying protocol. The paper is clearly written, the methods and statistical analyses are robust and the conclusions are adequately supported by the results.
For this reason, I recommend publication of this paper. In the following I list some minor points that the authors could consider before publication:
Answer: Thank you very much for your valuable comments and acceptance of the publication after minor revision.
Abstract:
Line 25: “Instead, ABTS method showed the better AA […]” the better AA should instead be “the best AA”
Answer: The sentence was changed as suggested by the reviewer.
Introduction:
line 46: “those fruit” should be those fruits
Answer: The change was made.
Materials:
Line 114: “[…] dried kiwifruit sample whit 10 mL […]” with is misspelled
Answer: The change was made.
Results:
Line 157: “Fresh kiwifruit samples were characterized by L*, h° and C color parameter […]” the symbol C* (and not C) was used previously
Answer: C was changed to C* as it was reported in M&M section.
Table 3: in the superscripts used to show the results of the ANOVA analysis, some capital letters (that indicate differences between the three drying temperatures considered) are missing.
Answer: We are really sorry for this mistake. The capital letters related to the significant differences among the h° and C* parameters of PEF samples dried at three temperature were added.
Line 206: “The behavior of the antiradical activity in all obtained samples is strongly depended […]” should be “[…] strongly dependent”
Answer: The change was made.
Discussion:
Lines 252-257: these two sentences are not clear, and I would suggest rephrasing them.
Answer: The sentences were rephrased as follows:
“One of the reasons why kiwifruit is widely appreciated by the consumers is related to its high nutritional quality.
Polyphenols are compounds which can influence the characteristics of plant materials, including colour, bitterness, and antioxidant activity”
If no Supplementary Material is provided please remove lines 318-319.
Answer: The conclusions were rewritten as follows:
The obtained results showed that OD pre-treatment applied alone resulted in a good retention of TPC and AA measured by DPPH method, while PEF treatment alone showed a high content in vitamin C and AA assessed by ABTS method. In both samples the values were similar to those of control samples. However, the shortest drying times required for the OD and PEF pretreated samples could have an additional positive effect on the sustainability of the overall process, by saving the energy required for the process. In general, an increased number of processing steps had a negative influence on the retention of the bioactive compounds and on the antiradical activity in all samples, while the color differences among them, although significant in certain cases, did not indicate a negative effect of any treatment.
In order to possibly scale-up the applied single/combined processing steps in a real industrial scenario, a further study is necessary considering both the energy and managing costs and the stability and nutritional quality of the obtained products, particularly in terms of environmental and economic sustainability
