Bioactive Vitamin C Content from Natural Selected Fruit Juices
Round 1
Reviewer 1 Report
From a scientific point of view, the article presents no news. It is a known fact that vitamin C deteriorates quickly. There are standardized methods for determining vitamin C. The determination method is insufficiently described.
Author Response
Dear Reviewer ,
We would like to thank you for carefully reading of our manuscript (ID: applsci-2249728) entitled “Bioactive Vitamin C Content from Natural Selected Fruits Juices”. We appreciate your comments and constructive recommendations, which have contributed to the improvement of our manuscript. Here, we present separate answers to your comments. We also send the modified file via the online submission process.
Comment 1
From a scientific point of view, the article presents no news. It is a known fact that vitamin C deteriorates quickly. There are standardized methods for determining vitamin C.
Answer 1: The indicated reviewer’s opinion is valid, although from our point of view, we wanted to remind in our article how important the role of vitamin C is, and to point out to potential consumers ways to store products in a way that is safe primarily to protect against the loss of this ingredient. Existing packaging on the market (various artificial, plastic materials) can affect changes in the concentration of this valuable ingredient. Providing current information on changing concentrations of this ingredient, depending both on the method of storage , time and type of packaging is in our opinion justified and worth signalling and informing consumers. This ingredient has recently ( pandemic time) been recognized as one of the elements that should be provided to maintain proper immunity. Providing it from natural raw materials is one of the criteria for its best assimilability. With knowledge of the loss of this component or lack thereof, the consumer can direct its correct supplementation. And this was, in a sense, our novelty, updating existing information on vitamin C levels for selected juices.
Comment 2
The determination method is insufficiently described.
Answer 2: Thank you very much for the comment and your advice. Based on the above comment, we have modified the determination methods of this paper as follows:
Preparation of solutions
One percent starch indicator solution was prepared by adding 0.5 g of soluble starch to 50 cm3 of near - boiling water.
Iodine solution was prepared by dissolving 5.0 g of potassium iodide (KI) and 0.268 g of potassium iodate (KIO3) in 200 cm3 of distilled water followed by addition of 3 M sulphuric acid (H2SO4). The solution was made up to 500 cm3 in a graduated cylinder and then transferred to a beaker.
Vitamin C standard solution was prepared by dissolving 0.250 g of vitamin C in 100 cm3 of water and then diluted to 250 cm3 with water in a volumetric flask.
Standardising Solution and Titration
Vitamin C solution (25 cm3) was the vitamin C solution was transferred into a 100 cm3 titration flask and 10 drops of 1% starch solution was added. This was titrated with the iodine solution until the first blue colour which persisted for about 20 seconds was observed. Juice samples (25 cm3) were titrated exactly the same way as the standard. The initial and final volume of iodine solution required to produce the colour change at the endpoint was recorded. The titration was performed in triplicate in all case.
Above mentioned information has been introduced into the manuscript.
Reviewer 2 Report
The manuscript entitled “Bioactive Vitamin C Content from Natural Selected Fruits Juices” is valuable and with potential interest to the readers of the Applied Sciences journal. However, several issues must be considered for manuscript quality improvement. The authors can find below a few observations.
In abstract:
What kind of fruits and/or vegetables are used for the elaboration of juices? The juices is the main raw materials of the study and in the first section of manuscript they are not mention. At the end of introduction the main objective with mention of fruits juices are presented. This information should be in the abstract.
In Introduction:
- In Line 31, when the vitamin C appears, please add the “vitamin C (ascorbic acid, AA)” in less of this information appears in the next Line;
- Add reference from the statements presented from Line 33-37.
- Eliminate the repetition sentence in Lines 37-39.
The main goal of the study and the experimental design consider the storage temperature and time and the packaging material and more details should be given, for example instead sentence in Page 3, Line 101-102 “Furthermore, the decrease in vitamin C values was analysed based on the 101 storage conditions (storage temperature, storage time, and packing material).” Rephrased as “The effect of storage as temperature, time and packaging material used for evaluate the maintenance of vitamin C in the studied fruit juices was performed during X days.”
In Materials and Methods:
The fruits used for elaboration were obtained from different source as domestic, organic production and supermarket. In this sense, the authors could be given more information regarding the domestic and organic production by mention of the GPS coordinates for each and the name of supermarket. Also, the images and/or photographs could be enriching the study.
The juices preparation needs reformulation for better understanding and in this lights I suggest the addition of a flowchart for schematic visualization of unit operations.
In the second paragraph, evidence of the characteristics and attributes of the selected fruits were presented and I suggest the followed initial sentence:
The fruit selected for the present study shows the followed characteristics: a suitable for organic production (winter apple variety REDCATS), not susceptible to diseases and resistant to pests ...."
Moreover, more details information regarding the packaging material used for fruits juices is necessary, such as what kind of plastic, the volume capacity of each one, the samples were stored in both materials, glass or plastic?
In Analytical Procedure
Description of the Experiment
Page 4, Line 151-152 “In choosing the storage temperature, favoured values were acceptable to consumers to avoid loss of vitamin C content (t1 = 4 oC, t2 = 23 oC, 152 t3 = -18 oC) in the fruit samples, The study focusses the behaviour of Vit. C in fruits juice, not the fruit samples…
Page 4, Line 169, please correct the following “…vitamin C. his section may…”
Iodometric Determination of Vitamin C Content
The sentences “Before juicing, the fruit samples were washed. Stones (autumn plum, late 175 peach) and nuclear (winter apple, winter pear) were removed from the fruit samples.” needs to be presented before in the juice preparation.
Page 4, Line 175-176: “Before juicing, the fruit samples were washed. Stones (autumn plum, late 175 peach) and nuclear (winter apple, winter pear) were removed from the fruit samples.” The sentence must be presented in the juice preparation.
The authors referred the equation 1 in “Iodine titration is based on oxidation-reduction reactions (oxidation-reduction 177 method) according to equation (1)” however I only see the Eq 2.
The obtained results of vitamin C in fruits juice was expressed as…Please complete.
Data analysis
The authors were mentioned the soil samples in the data analysis? Why the evaluation of analysis of significant difference between the fruit juice and the studied variables (time and temperature storage and packaging material) was not considered?
In Results and Discussion
The subsection 3.1, does not make sense, in my opinion, because no results was presented.
3.1.1. Vitamin C Content in Juices Stored in Glasses Containers
In “…for longer periods loses its vitamin activity, lower its vitamin activity…” Attention to repetition.
In overall the authors should be reviewed the manuscript and the way they presented and discussed the results since a repetition of same parts of section it is evident, for example the sentence in the Line 229 and 230 “Vitamin C content in the storage of grapefruit citrus juice in the refrigerator (t1 = 4C) in glass packaging materials decreased following 1st day: -0.58%; 2nd day: -7.25%; 3rd day: -12.75%; 7th day: -13.33% (Table 1). “ is the same of the results in the Table. However, if presented as in the range of low and higher decrease value is better, in my opinion.
In Line 283, please corrected “…decrease -by 4.55…”
In Line 311 “According to Bieniasz, the fruit gradually decreases 311 ascorbic acid content with increasing temperature or storage time [51].” The reference number should be after the author name at the beginning of sentence.
The same at Line 331 “According to Zhao, the degradation and loss of vitamin C content may have been 331 influenced by chemical changes due to oxidation and enzymatic activity that may occur 332 after freezing the fruit [66].”
This can be observed in several section along the manuscript, please reviewed.
Below the table 1, in addition to indicating that the results represent the average of 3 determinations, the standard deviation must also be highlighted.
3.1.2. Vitamin C Content in Juices Stored in Plastics Containers
In Line 341 “…In his research…” please correct.
Please rephrased the Line 345-347 to “Vitamin C content in grapefruit citrus juice stored in plastic packaging in the refrigerator (t1 = 4 °C) and after the 1st day, is greatly reduced (-6.9 %), and in the coming days, the decline is even greater, from the 2nd day to 7th day, as -8.41% and-347 18.84%, respectively. Also, the Line 348-350 as “ The results showed that grapefruit juice when stored in the plastic container and after three weeks at t1 = 4 oC, the ascorbic acid content decreased.
3.2. Correlation among Vitamin C Content and Storage Conditions
In this section, a rephrase regarding the presentation and discussion of the presented results in table 2 is necessary since a repetition is evident.
Author Response
Dear Reviewer ,
We would like to thank you for your careful and detailed reading of our manuscript (ID: applsci-2249728) entitled “Bioactive Vitamin C Content from Natural Selected Fruits Juices”. We appreciate your comments and constructive recommendations that contributed to the improvement of our manuscript. Here we provide separate responses to your comments. We are also submitting the revised manuscript through the online submission process. All corrections introduced to the manuscript are in red colour.
Reviewer’s comments:
The manuscript entitled “Bioactive Vitamin C Content from Natural Selected Fruits Juices” is valuable and with potential interest to the readers of the Applied Sciences journal. However, several issues must be considered for manuscript quality improvement. The authors can find below a few observations.
In abstract:
What kind of fruits and/or vegetables are used for the elaboration of juices? The juices is the main raw materials of the study and in the first section of manuscript they are not mention. At the end of introduction the main objective with mention of fruits juices are presented. This information should be in the abstract.
Response to Reviewer
Answer 1: Thank you very much for the comment and your advice. Based on the above comment, we have modified the Abstract of this paper as follows:
Abstract: The content of vitamin C in fruit juices can be lowered by alterations in storage and temperature. The study compared storage circumstances (temperature, duration, and packaging type) to determine which variable had the biggest influence on changes in the vitamin C content of juices (grapefruit, mandarin, peach, apple, pear, plum). Fruit juices held in glass (plastic) containers at 4 °C saw vitamin C losses in the range of 0.0-10.9% (2.4-17.4%) in 24 hours, 1.4-22.6% (5.2-25.3%) in 48 hours, and 2.8-37.0% (6.0-39.0%) in three days. By raising the storage temperature to 23 °C, vitamin C losses in glass (plastic) containers were found to be 1.4-19.1% (5.2-22.2%), 2.8-20.9% (5.9-25.9%), and 4.5-43.5% (6.0-38.7%) of the value after 24 hours, 48 hours and three days. When decreasing the temperature to -18 °C in fruit juices stored in glass (plastic) containers were losses of vitamin C in 24 hours in the range of 1.5-19.6% (3.0-20.0%), in 48 hours 4.5-26.1% (4.5-26.1%) and three days 6.0-43.1% (5.8-43.5%) of the value. The effect of temperature on vitamin C concentration has been proven. Fruit juice’s vitamin C is more stable when kept in glass containers as opposed to plastic ones, which have a limited shelf life.
In Introduction:
- In Line 31, when the vitamin C appears, please add the “vitamin C (ascorbic acid, AA)” in less of this information appears in the next Line;
- Add reference from the statements presented from Line 33-37.
- Eliminate the repetition sentence in Lines 37-39.
The main goal of the study and the experimental design consider the storage temperature and time and the packaging material, and more details should be given, for example instead sentence in Page 3, Line 101-102 “Furthermore, the decrease in vitamin C values was analysed based on the 101 storage conditions (storage temperature, storage time, and packing material).” Rephrased as “The effect of storage as temperature, time and packaging material used for evaluate the maintenance of vitamin C in the studied fruit juices was performed during X days.”
Response to Reviewer
Answer 2: Thank you very much for the comment and your advice. Based on the above comment, we have modified the text in Introduction as follows:
A wide variety of foods contain vitamin C (ascorbic acid, AA) in different concentrations [1]. In addition, vitamin C is added to foods as a nutrient (to compensate for processing losses) and antioxidant [2,3].
Also, to prevent the browning of fresh or canned fruits and vegetables [4,5] or to avoid haze formation in brewing products (e.g., beer) [6]. In addition, it promotes iron absorption and collagen formation [7]. Furthermore, it is often added to fruit juices, fruit-flavoured beverages, juice-infused sodas, smoothies, cereal-based products, and milk [8].
We eliminated the repetition sentences: It promotes iron absorption and collagen formation. Furthermore, it is often added to fruit juices, fruit-flavoured beverages, juice-infused sodas, smoothies, cereal-based products, and milk [4].
The effect of storage including factors such as temperature, time and packaging material used on the maintenance of vitamin C, was evaluated in the studied fruit juices and carried out during the course of one, two, three, and seven days, as well as over further two and three week periods.
In Materials and Methods:
The fruits used for elaboration were obtained from different source as domestic, organic production and supermarket. In this sense, the authors could be given more information regarding the domestic and organic production by mention of the GPS coordinates for each and the name of supermarket. Also, the images and/or photographs could be enriching the study.
The juices preparation needs reformulation for better understanding and in this lights I suggest the addition of a flowchart for schematic visualization of unit operations.
In the second paragraph, evidence of the characteristics and attributes of the selected fruits were presented and I suggest the followed initial sentence:
The fruit selected for the present study shows the followed characteristics: a suitable for organic production (winter apple variety REDCATS), not susceptible to diseases and resistant to pests ....”
Moreover, more details information regarding the packaging material used for fruits juices is necessary, such as what kind of plastic, the volume capacity of each one, the samples were stored in both materials, glass or plastic?
Response to Reviewer
Answer 3: Thank you very much for the comment and your advice. We have modified the text in the Materials and Methods to reflect your suggestion.
The vitamin C content was determined in 6 fruits, namely citrus fruits (grapefruit, mandarin - Clementin) and organic fruits From domestic sources (Slovakia, GPS coordinates: 48°18’16.8 "N 18°03'28.4"E), 4 fruits (late peach, winter apple, winter pear and autumn plum) were grown as organic fruits (Figure 1). Citrus fruits 2 species were purchased from supermarket chains (grapefruit, mandarin variety Clementin HERNANDINA)(Tesco Stores, SR, a.s. GPS coordinates: 48°18'42.8"N 18°04'10.5"E).
|
(a) |
(b) |
Figure 1. Organic fruits used for juice preparation: (a) late peach, (b) winter pear.
The unit procedure for the preparation of fruit juices is shown schematically in Figure 2.
Figure 2 Scheme of unit operation for the preparation of fruit juices.
The fruit selected for the present study shows the followed characteristics: a suitable for organic production (winter apple variety REDCATS), not susceptible to diseases and resistant to pests (winter apple variety REDCATS, winter pear variety Lucasova, autumn plum variety TOPTASTE), requires warmer locations (winter pear variety Lucasova), does not suffer from frosts and is resistant to low temperatures (autumn plum variety TOPTASTE, late peach variety Suncrest), perfect detachment from the stone, abundant, regular fruiting (late peach variety Suncrest).
The containers to storing and carrying fruit juices were suitable for food purposes, made from durable glass and plastic (PET, Polyethylene terephthalate), airtight and waterproof—suitable for the refrigerator and freezer -20°C to 110°C. The glass and plastic packaging material used for each fruit juice sample had a volume of V=100 cm3.
In Analytical Procedure
Description of the Experiment
Page 4, Line 151-152 “In choosing the storage temperature, favoured values were acceptable to consumers to avoid loss of vitamin C content (t1 = 4 oC, t2 = 23 oC, 152 t3 = -18 oC) in the fruit samples, The study focusses the behaviour of Vit. C in fruits juice, not the fruit samples…
Page 4, Line 169, please correct the following “…vitamin C. his section may…”
Response to Reviewer
Answer 3: Thank you very much for carefully reading our content. Thank you very much for your suggestions and remarks. Based on the above comment, we have modified the Description of the Experiment as follows:
Finally, the values obtained from the analyses were compared with each other to determine and indicate the best conditions for storing the juice in terms of maintaining the highest concentrations of vitamin C.
We have elimininated: his section may be divided by subheadings. It should provide a concise and precise description of the experimental results, their interpretation, as well as the experimental conclusions that can be drawn.
Iodometric Determination of Vitamin C Content
The sentences “Before juicing, the fruit samples were washed. Stones (autumn plum, late 175 peach) and nuclear (winter apple, winter pear) were removed from the fruit samples.” needs to be presented before in the juice preparation.
Page 4, Line 175-176: “Before juicing, the fruit samples were washed. Stones (autumn plum, late 175 peach) and nuclear (winter apple, winter pear) were removed from the fruit samples.” The sentence must be presented in the juice preparation.
The authors referred the equation 1 in “Iodine titration is based on oxidation-reduction reactions (oxidation-reduction 177 method) according to equation (1)” however I only see the Eq 2.
The obtained results of vitamin C in fruits juice was expressed as…Please complete.
Response to Reviewer
Answer 4: Thank you very much for the comment and your advice. Based on the above comment, we have modified the Iodometric Determination of Vitamin C Content as follows:
Following sentences have been moved: “Before juicing, the fruit samples were washed. Stones (autumn plum, late peach) and nuclear (winter apple, winter pear) were removed from the fruit samples.” before in the juice preparation (2.1.1. Preparation of Fruit Juices).
(1)
The titration was repeated three times for each fruit juice sample. The obtained results of vitamin C in fruits juice were expressed as mean values of three determinations. The values obtained from the analyses were subsequently compared to determine the optimum conditions for retaining the highest possible amount of vitamin C in the stored juice.
Data analysis
The authors were mentioned the soil samples in the data analysis? Why the evaluation of analysis of significant difference between the fruit juice and the studied variables (time and temperature storage and packaging material) was not considered?
Response to Reviewer
Answer 5: Thank you very much for the comment and your advice. Based on the above comment, we have corrected the Data analysis as follows:
As previously mentioned, the measured values obtained from fruit juice and the studied variables were analysed using selected statistical methods. First, Spearman’s rank correlation coefficient was applied to calculate the degree of interdependence among the observed variables [59]. The Spearman correlation was used to determine the relationship between the time and temperature storage and packing material in fruit samples.
In Results and Discussion
The subsection 3.1, does not make sense, in my opinion, because no results was presented.
3.1.1. Vitamin C Content in Juices Stored in Glasses Containers
In “…for longer periods loses its vitamin activity, lower its vitamin activity…” Attention to repetition.
In overall the authors should be reviewed the manuscript and the way they presented and discussed the results since a repetition of same parts of section it is evident, for example the sentence in the Line 229 and 230 “Vitamin C content in the storage of grapefruit citrus juice in the refrigerator (t1 = 4C) in glass packaging materials decreased following 1st day: -0.58%; 2nd day: -7.25%; 3rd day: -12.75%; 7th day: -13.33% (Table 1). “ is the same of the results in the Table. However, if presented as in the range of low and higher decrease value is better, in my opinion.
In Line 283, please corrected “…decrease -by 4.55…”
In Line 311 “According to Bieniasz, the fruit gradually decreases 311 ascorbic acid content with increasing temperature or storage time [51].” The reference number should be after the author name at the beginning of sentence.
The same at Line 331 “According to Zhao, the degradation and loss of vitamin C content may have been 331 influenced by chemical changes due to oxidation and enzymatic activity that may occur 332 after freezing the fruit [66].”
This can be observed in several section along the manuscript, please reviewed.
Below the table 1, in addition to indicating that the results represent the average of 3 determinations, the standard deviation must also be highlighted.
Response to Reviewer
Answer 6: Thank you very much for the comment and your advice. Based on the above comment, we have corrected the Data analysis as follows:
The subsection 3.1 was deleted.
The repetition was deleted. Analyses have confirmed that citrus fruit juice that is exposed to higher temperatures for longer periods loses its vitamin activity, and deteriorates its flavour, aroma, and colour [64–65].
Vitamin C content in the storage of grapefruit citrus juice in the refrigerator (t1 = 4 °C) in glass packaging materials decreased between a low (1st day: -0.58%) and high rate (7th day -13.33%) (Table 1).
At room temperature (t2 = 23 °C) in glass packaging material, in winter, apple juice after 1st stored decrease by -4.55% after the vitamin C content by and after the 2nd day of storage, was -6.82%.
According to Bieniasz [51], the fruit gradually decreases ascorbic acid content with increasing temperature or storage time.
According to Zhao [66], the degradation and loss of vitamin C content may have been influenced by chemical changes due to oxidation and enzymatic activity that may occur after freezing the fruit.
Lee and Coates [67] analyses have confirmed that citrus fruit juice exposed to higher temperatures for longer periods loses its vitamin activity, lowers its vitamin activity, and deteriorates.
According to Phillips et al. [70], the higher the temperature, the higher the loss of vitamin C.
Nagy [39] established that frozen concentrated orange juice (FCOJ) and reconstituted FCOJ always have the highest levels of vitamin C compared to freshly squeezed or not-from-concentrate (NFC) juice and are above the 100% US RDA values.
The same was found in the study by Berry et al. [71], who monitored the ascorbic acid level in citrus juice during storage and found that the shelf life in plastic bottles was considerably shorter than that in glass bottles.
The results of Qaderi et al. [30] confirmed that the degradation of vitamin C content might have been influenced by chemical changes due to oxidation and enzymatic activity that may occur after freezing of the fruit.
Furthermore, Bisset and Berry [75] showed the best retention of ascorbic acid in glass bottles compared to polyethylene containers.
Nagy [39] pointed out that the citrus juice richest in vitamin C is orange juice, followed by grapefruit, lemon and mandarin.
The subsequent content of vitamin C was the second highest in mandarin-Clementin juice, which agrees with the study of Martí et al. [38], who reported that “Mediterranean mandarin and Clementine (Citrus reticulata Blanco) reach the highest values of vitamin C”.
According to authors Nagy and Smoot [91], high temperatures during storage cause loss of ascorbic acid, which is the most important factor.
The results were expressed as mean values (SD± 0.1 or SD± 0.2) of three determinations.
3.1.2. Vitamin C Content in Juices Stored in Plastics Containers
In Line 341 “…In his research…” please correct.
Please rephrased the Line 345-347 to “Vitamin C content in grapefruit citrus juice stored in plastic packaging in the refrigerator (t1 = 4 °C) and after the 1st day, is greatly reduced (-6.9 %), and in the coming days, the decline is even greater, from the 2nd day to 7th day, as -8.41% and-347 18.84%, respectively. Also, the Line 348-350 as “ The results showed that grapefruit juice when stored in the plastic container and after three weeks at t1 = 4 oC, the ascorbic acid content decreased.
Response to Reviewer
Answer 7: Thank you very much for the comment and your advice. Based on the above comment, we have corrected the Data analysis as follows:
In this research, the most important were thermal processing, type of container, handling, and storage.
Vitamin C content in grapefruit citrus juice stored in plastic packaging in the refrigerator (t1 = 4 °C) and after the 1st day, is greatly reduced (-6.9 %), and in the coming days, the decline is even greater, from the 2nd day to 7th day, as -8.41% and -18.84% (Figure 2a).
The results showed that grapefruit juice when stored in the plastic container and after three weeks at t1 = 4 oC, the ascorbic acid content decreased to 35.1%.
3.2. Correlation among Vitamin C Content and Storage Conditions
In this section, a rephrase regarding the presentation and discussion of the presented results in table 2 is necessary since a repetition is evident.
Response to Reviewer
Answer 8: Thank you very much for the comment and your advice. Based on the above comment, we have corrected a rephrased this section as follows:
The fruits used to make juices go through several extraction procedures during preparation, which might change the amount of various chemicals in the finished product [38]. The breakdown of ascorbic acid, according to several writers, is mostly caused by heat treatment and storage duration [76–82]. Therefore, correlation relationships between the vitamin C content of the tested fruit juices (grapefruit, mandarin-Clementin, peach, apple, pear, and plum) stored in glass and plastic containers at various temperatures and the number of storage days (to 21 days) had to be found using statistical methods (Table 2). The strength of the link between the observable characteristics was determined using Spearman's rank correlation coefficient.
Table 2. The correlation coefficients between the amount of vitamin C (mg/100 g) present in fruit juices kept in glass and plastic containers at various temperatures and for varying lengths of time.
The correlation coefficient between the vitamin C concentration of grapefruit, peach, pear, and plum juices at t1 = 4 oC in glass packing and storage period was very tight (Table 2). There was a high degree of correlation between the vitamin C concentration of grapefruit juice and storage period at t2 = 23 oC in glass containers. The connection between the components of the other juices under examination, in contrast, was very tight. There was a very tight correlation between the vitamin C content of the late peach juice and storage period in glass containers at t3 = -18 oC. There found a high degree of correlation coefficient in various fruit liquids.
The correlation coefficient between the vitamin C content of grapefruit juice and the storage duration was very tight at the temperature t1 = 4 oC in plastic containers (Table 2). Mandarin, peaches, apple juices, and storage duration all demonstrated a high degree correlation value. Pear juice and plum juice displayed significant correlation coefficients with storage duration. The correlation coefficient between the vitamin C content of grapefruit juice and mandarin juice and storage period was very tight correlation coefficient at temperature t2 = 23 oC in plastic containers. There found a high degree correlation coefficient between other fruit liquids. The correlation coefficient between the amount of vitamin C in peach juice and the storage was very tight when peach juice was stored in plastic containers at t3 = -18 oC. Grapefruit juice, mandarin-Clementin, winter pear, and autumn plum juices all had a high degree of correlations with storage time. Winter apple juice and storage duration had a statistically significant degree of correlation.
Reviewer 3 Report
Dear authors, I have read and reviewed the MS entitled Bioactive Vitamin C Content from Natural Selected Fruits Juices. This research brings some novelty in analysing vitamin C content in some Slovakian fruits, but the general idea is well known.
I have some observations:
-please revise English language, it is difficult to understand in some parts
-please use passive voice all over the text
-please remove or correct text at line 169-172
-at 211, a mention is made of soil samples. There are no results for soil samples in the article. Please correct
-there is no control in the experiment. Maybe add some commercial fruit juices for this?
-please use italics for scientific Latin denominations
-please add info on the harvest time of the fruits, where possible
Author Response
Dear Reviewer ,
We would like to thank you for carefully reading of our manuscript (ID: applsci-2249728) entitled “Bioactive Vitamin C Content from Natural Selected Fruits Juices”. We appreciate your comments and constructive recommendations, which have contributed to the improvement of our manuscript. Here, we present separate answers to your comments. We also send the modified file via the online submission process. All corrections have been introduced into the text of the manuscript in red colour.
Reviewer’s comments:
Dear authors, I have read and reviewed the MS entitled Bioactive Vitamin C Content from Natural Selected Fruits Juices. This research brings some novelty in analysing vitamin C content in some Slovakian fruits, but the general idea is well known.
I have some observations:
-please revise English language, it is difficult to understand in some parts
-please use passive voice all over the text
Response to Reviewer
Answer 1: The English revision has been made also in the range in the passive voice.
I have some observations:
-please remove or correct text at line 169-172
Response to Reviewer
Answer 2: We eliminated following text:
his section may be divided by subheadings. It should provide a concise and precise description of the experimental results, their interpretation, as well as the experimental conclusions that can be drawn.
I have some observations:
-at 211, a mention is made of soil samples. There are no results for soil samples in the article. Please correct
Response to Reviewer
Answer 2: Thank you for your attention and for your comment. Based on the above comment, we have modified the text as follows:
As previously mentioned, the measured values obtained from fruit juice and the studied variables were analysed using selected statistical methods. First, Spearman’s rank correlation coefficient was applied to calculate the degree of interdependence among the observed variables [59]. The Spearman correlation was used to determine the relationship between the time and temperature storage and packing material in fruit samples.
I have some observations:
-there is no control in the experiment. Maybe add some commercial fruit juices for this?
Response to Reviewer
Answer 3: In Slovakia there is no obligation to inform about the content of vitamin C on juice packaging. Therefore, it is difficult for us to refer to commercial products. We can only refer to the following data issued by the USDA
http://www.akv.sk/index.php@option=com_content&task=view&id=1096&Itemid=30.html
Please find our following examples:
Apple = 5 mg/100g
Apple juice = 1 mg/100g
Orange with pommes = 45 mg/100 g,
Orange juice, fresh = 50 mg/100g
According to REGULATION (EU) No 1169/2011 OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL
of 25 October 2011
on the provision of food information to consumers, amending Regulations (EC) No 1924/2006 and (EC) No 1925/2006 of the European Parliament and of the Council, and repealing Commission Directive 87/250/EEC, Council Directive 90/496/EEC, Commission Directive 1999/10/EC, Directive 2000/13/EC of the European Parliament and of the Council, Commission Directives 2002/67/EC and 2008/5/EC and Commission Regulation (EC) No 608/2004
Nutrition declaration
Under EU law, prepacked food that is sold in the EU must bear a label informing consumers about its energy and nutrient content. This is called ‘nutrition declaration' and must appear directly on the package or on a label attached to it. The nutrition declaration must include the following information:
- energy value
- amounts of fat, saturates, carbohydrate, sugars, protein and salt
The following nutrients can be indicated voluntarily in the nutrition declaration:
- mono-unsaturates
- polyunsaturates
- polyols
- starch
- fibre
- any of the vitamins or minerals permitted by law
Foods that do NOT require a nutrition declaration are listed in annex 5 of the regulation.
ANNEX XIII
REFERENCE INTAKES
PART A — DAILY REFERENCE INTAKES FOR VITAMINS AND MINERALS (ADULTS)
- Vitamins and minerals which may be declared and their nutrient reference values (NRVs) for Vitamin C 80 mg
I have some observations:
-please use italics for scientific Latin denominations
Answer 4: We used italics for scientific Latin denominations:
- samples from citrus fruits with enough juice (grapefruit, mandarin-Clementin HERNANDINA, Spain (Citrus clementina)) were extracted by mechanical pressure (juicer). Then the juice was centrifuged to remove solid particles (seeds, pulp) and to obtain a transparent sample.
- samples from fruits with a higher amount of pulp (late peach variety Suncrest (Prunus persica var. Persica), winter apple variety REDCATS (Malus domestica), winter pear variety Lucasova (Pyrus communis), autumn plum variety TOPTASTE (Prunus domestica) using a screw juicer (PHILCO PHJE 5030, Fast Plus, a.s., Bratislava, Slovakia), then the juice was centrifuged.
I have some observations:
-please add info on the harvest time of the fruits, where possible
Answer 5: Based on your advice we have added in text following:
Fruit juice processing was influenced by the harvesting season, which was as follows: late peach variety Suncrest (Prunus persica var. Persica) - mid-8th month, winter apple variety REDCATS (Malus domestica), and winter pear variety Lucas (Pyrus communis) - early 9th month, autumn plum variety TOPTASTE (Prunus domestica) - mid-10th month.
Reviewer 4 Report
The main objective of this work was to determine the vitamin C content of fruit samples based on their storage conditions.
In general, this manuscript presented relevant results on the effect of storage temperature, storage time and packaging material on the vitamin C content of some fruit samples.
There are some specific comments listed below:
Page 1, Introduction:
It is known that the subject of vitamin C in fruits is much investigated in the literature. However, I suggest adding slightly more recent references to the Introduction item. One only article from 2023 by the authors themselves was cited.
Page 5:
Item 3.1 “Studies by different authors have concluded that fruits and their juices are one of the most important suppliers of dietary vitamin C [41, 60–63]. The enormous contribution of fruit juices in beneficial effects on the risk of diseases has also been pointed out in reports by other authors [41,60,62].”
It is not a result obtained by the authors. This paragraph should be moved to the “Introduction” item.
Item 3.1.1. “Vitamin C Content in Juices Stored in Glasses Containers”
All the time the authors refer to the results with the type of storage material, in this case glass containers. Thus, there is no need to cite in the text all the time the type of material once it is described in the subitem. Please check and rewrite.
This same observation applies to subitem 3.1.2, for juices stored in plastic containers.
Page 11, item 3.2 “During the process of preparation of the fruits used to obtain juices undergo different extraction processes, which may alter the content of different compounds in the product [38]. Many authors state in their works that the degradation of ascorbic acid is mainly due to heat treatment and storage time [76–82].”
Once again, this paragraph is not the result of this research and should be moved to the introduction.
Page 12, Table 2: I do not think it is necessary to present the correlation coefficient in this table 2. I believe that it is sufficient to present these results in the text of the article.
Page 15, Conclusions
The conclusions are consistent with the evidence and arguments presented in this study, however, in the affirmative “Not without significance is also the synergism of several factors indicated in work, which affect the losses of this valuable food component”, it is necessary adding what factors the authors are considering here.
Author Response
Dear Reviewer,
We would like to thank you for carefully reading of our manuscript (ID: applsci-2249728) entitled “Bioactive Vitamin C Content from Natural Selected Fruits Juices”. We appreciate your comments and constructive recommendations, which have contributed to the improvement of our manuscript. Here, we present separate answers to your comments. We also send the modified file via the online submission process. All corrections have been introduced into the text of the manuscript in red colour.
Reviewer’s comments:
The main objective of this work was to determine the vitamin C content of fruit samples based on their storage conditions.
In general, this manuscript presented relevant results on the effect of storage temperature, storage time and packaging material on the vitamin C content of some fruit samples.
Page 1, Introduction:
It is known that the subject of vitamin C in fruits is much investigated in the literature. However, I suggest adding slightly more recent references to the Introduction item. One only article from 2023 by the authors themselves was cited.
Response to Reviewer
Answer 1: We added following references to the Introduction item.
Zhang, X.; Meng, W.; Chen, Y.; Peng. Y. Browning inhibition of plant extracts on fresh-cut fruits and vegetables—A review. Journal of Food Processing and Preservation 2022, 46(5), e16532, https://doi.org/10.1111/jfpp.16532.
Lis, D.M.; Jorda, M.; Lipuma, T.; Smith, T.; Schaal, K.; Baar, K.Collagen and Vitamin C Supplementation Increases Lower Limb Rate of Force Development. International Journal of Sport Nutrition and Exercise Metabolism, 2022, 32, 65-73, https://doi.org/10.1123/ijsnem.2020-0313.
Beton-Mysur, K.; Brozek-Pluska, B. Raman Spectroscopy and Imaging Studies of Human Digestive Tract Cells and Tissues—Impact of Vitamin C and E Supplementation. Molecules 2023, 28, 137. https://doi.org/10.3390/molecules28010137
Jain, A.; Tiwari, A.; Verma, A.; Jain, S.K. Vitamins for Cancer Prevention and Treatment: An Insight. Curr. Mol. Med. 2017, 17, 321–340.
Kidoń, M.; Radziejewska-Kubzdela, E.; Biegańska-Marecik, R.; Kowalczewski, P.Ł. Suitability of Apples Flesh from Different Cultivars for Vacuum Impregnation Process. Appl. Sci. 2023, 13, 1528. https://doi.org/10.3390/app13031528.
Gonzalez, M.J.; Miranda-Massari, J.R.; Olalde, J. Chapter 9 - Vitamin C and mitochondrial function in health and exercise, Editor(s): Sergej M. Ostojic, Molecular Nutrition and Mitochondria, Academic Press, 2023, pp.225-242, ISBN 9780323902564, https://doi.org/10.1016/B978-0-323-90256-4.00016-3.
Page 5:
Item 3.1 “Studies by different authors have concluded that fruits and their juices are one of the most important suppliers of dietary vitamin C [41, 60–63]. The enormous contribution of fruit juices in beneficial effects on the risk of diseases has also been pointed out in reports by other authors [41,60,62].”
It is not a result obtained by the authors. This paragraph should be moved to the “Introduction” item.
Response to Reviewer
Answer 2: We moved this text into the introduction.
It is important to remember that not all fruits have the same composition and antioxidant capacity [38, 43–45]. The enormous contribution of fruit juices in beneficial effects on the risk of diseases has also been pointed out in reports by many authors. Studies by different authors have concluded that fruits and their juices are one of the most important suppliers of dietary vitamin C [41, 60–63]. It is therefore important to recognise which fruits have the highest vitamin C content and introduce them regularly into the diet [46].
Item 3.1.1. “Vitamin C Content in Juices Stored in Glasses Containers”
All the time the authors refer to the results with the type of storage material, in this case glass containers. Thus, there is no need to cite in the text all the time the type of material once it is described in the subitem. Please check and rewrite.
This same observation applies to subitem 3.1.2, for juices stored in plastic containers.
Response to Reviewer
Answer 3: We have corrected the text.
Page 11, item 3.2 “During the process of preparation of the fruits used to obtain juices undergo different extraction processes, which may alter the content of different compounds in the product [38]. Many authors state in their works that the degradation of ascorbic acid is mainly due to heat treatment and storage time [76–82].”
Once again, this paragraph is not the result of this research and should be moved to the introduction.
Page 12, Table 2: I do not think it is necessary to present the correlation coefficient in this table 2. I believe that it is sufficient to present these results in the text of the article.
Response to Reviewer
Answer 4: The text was moved into the introduction section.
The decrease in its values occurs depending on the time and method of storage [36–37]. During the process of preparation of the fruits used to obtain juices undergo different extraction processes, which may alter the content of different compounds in the product [38]. Many authors state in their works that the degradation of ascorbic acid is mainly due to heat treatment and storage time [76–82]. To best preserve vitamin C, it is recommended that foods containing vitamin C should not be stored at all or only minimally processed during cooking [35].
Page 12, Table 2: I do not think it is necessary to present the correlation coefficient in this table 2. I believe that it is sufficient to present these results in the text of the article.
Response to Reviewer
Answer 5: The value of the correlation coefficient was removed from the text of the manuscript and the values of this parameter have been left in the table.
.
Page 15, Conclusions
The conclusions are consistent with the evidence and arguments presented in this study, however, in the affirmative “Not without significance is also the synergism of several factors indicated in work, which affect the losses of this valuable food component”, it is necessary adding what factors the authors are considering here.
Response to Reviewer
Answer 5: The information has been added.
Round 2
Reviewer 1 Report
The authors have improved substantially the introduction part, pointed out the main fruit that contain vitamin C but they didn’t say anything about vegetable and herbs with high vitamin C content and consumed around the world (peperoni and parsley for example). It is important for readers to know that not only the fruits have high content in vitamin C, even the subject of article is fruit juices
In the section Material and method, row 147 please correct, temperature in refrigerator can’t be 110ºC
Row 159, please rephrase
In the row 284, the authors refers to grapefruits juice stored at 4 ºC providing different information than in row 265. Which one is correct? Maybe they want to refer to mandarine-Clementin juice in row 284. Please correct.
Row 413, correct is in plastic container, please correct
Rows 419-421 please rephrase. It isn’t clear
Row 443, values of vitamin C refers to apple or peach juice?
Row 525, which is the mean of the 7 X?
Author Response
Dear Reviewer,
We would like to thank you for carefully reading of our manuscript (ID: applsci-2249728) entitled “Bioactive Vitamin C Content from Natural Selected Fruits Juices”. We appreciate your comments and constructive recommendations, which have contributed to the improvement of our manuscript. Here, we present separate answers to your comments. We also send the modified file via the online submission process.
Comment 1
The authors have improved substantially the introduction part, pointed out the main fruit that contain vitamin C but they didn’t say anything about vegetable and herbs with high vitamin C content and consumed around the world (peperoni and parsley for example). It is important for readers to know that not only the fruits have high content in vitamin C, even the subject of article is fruit juices.
Answer 1: We appreciate your guidance and your opinion. The fruit juices made from several vegetables (tomato, carrot, cucumber, red pepper, green pepper, and white cabbage) as well as plant (chives, dandelion, nettle) samples will be included in a paper we are currently working on. We concentrate on the study of fruit juices based on storage conditions in a prepared paper. We did not include information about vitamin C content in vegetable and plant juices because of this.
Comment 2
In the section Material and method, row 147 please correct, temperature in refrigerator can’t be 110ºC.
Answer 2: Thank you very much for the comment and your advice. Based on the above comment, we have modified the text in the section Material and Method as follows:
The containers for storing and transporting fruit juices were suitable for food purposes, made from durable glass and plastic (PET, Polyethylene terephthalate), airtight and waterproof—suitable for the refrigerator and freezer.
Comment 3
Row 159, please rephrase.
Answer 3 Thank you very much for your advice. Based on the above advice, we have modified the text as follows:
Oxidation-reduction method - iodometry was used to measure the amount of vitamin C in the juice samples.
Comment 4
In the row 284, the authors refers to grapefruits juice stored at 4 ºC providing different information than in row 265. Which one is correct? Maybe they want to refer to mandarine-Clementin juice in row 284. Please correct.
Answer 4: Thank you very much for the comment and your advice. Based on the above comment, we have modified the text as follows:
Vitamin C content in the storage of mandarin-Clementin juice in the refrigerator (t1 = 4 °C) in glass packaging materials decreased following the 1st day: - 10.87%; 2nd day: -22.61%; 3rd day: -36.96%; 7th day: -47.39% (Table 1).
Comment 5
Row 413, correct is in plastic container, please correct
Answer 5: Thank you very much for the comment and your advice. We have modified the text as follows:
The contents of vitamin C in mandarin-clementin juice stored in a plastic container in a freezer (t3 = -18 °C) obtained by analysis are shown in Figure 4b.
Comment 6
Rows 419-421 please rephrase. It isn’t clear
Answer 6: Thank you very much for the comment and your advice. We have modified the text as follows:
The biggest difference was achieved after the 3rd day of storage when the vitamin C content in the juice stored in glass containers was 2.17% higher than in plastic containers. Nagy [53] established that frozen concentrated orange juice (FCOJ) and reconstituted FCOJ always have the highest levels of vitamin C compared to freshly squeezed or not-from-concentrate (NFC) juice and are above the 100% US RDA value.
Comment 7
Row 443, values of vitamin C refers to apple or peach juice?
Answer 7: Thank you very much for the comment and your advice. The values of vitamin C refer to late peach, and we corrected the mistake.
Comment 8
Row 525, which is the mean of the 7 X?
Answer 8: Thank you very much for the comment and your advice. We corrected row 525.
Reviewer 3 Report
Dear Authors, I have read the new uploaded manuscript entitled Bioactive Vitamin C Content from Natural Selected Fruits Juices. Thank you for accepting my observations and correcting the MS.
There are however, more issues that should be resolved:
-please change at line 213 "mass in moles" with "molecular weight"
-please check that you use everywhere superscript (line 240) where needed
-please check English language, there are still some innacuracies
-line 525 - you probably have to remove XXXXX
-is there any reason that mandarin - Clementine is written with a capital C?
-please consider using more punctuation, the text is somewhat difficult to understand.
-please use all over passive voice.
Author Response
Dear Reviewer,
We would like to thank you for carefully reading of our manuscript (ID: applsci-2249728) entitled “Bioactive Vitamin C Content from Natural Selected Fruits Juices”. We appreciate your comments and constructive recommendations, which have contributed to the improvement of our manuscript. Here, we present separate answers to your comments. We also send the modified file via the online submission process.
Dear Authors, I have read the new uploaded manuscript entitled Bioactive Vitamin C Content from Natural Selected Fruits Juices. Thank you for accepting my observations and correcting the MS.
There are however, more issues that should be resolved:
Comment 1
-please change at line 213 "mass in moles" with "molecular weight"
Answer 1: Thank you very much for the comment and your advice. Based on the above comment, we have changed at line 213 the text as follows:
M refers to the molecular weight of ascorbic acid (g.mol-1).
Comment 2
-please check that you use everywhere superscript (line 240) where needed
Answer 2: Thank you very much for the comment and your advice. Based on the above comment, we have checked superscript (line 240), and corrected as follows: “The vitamin C solution (25 cm3) was transferred into a 100 cm3 titration flask and 10 drops of 1% starch solution were added.” and we have made corrections throughout.
Comment 3
-please check English language, there are still some innacuracies
Answer 3: We appreciate your suggestion very much. We have reviewed the article's English once more in light of the aforementioned advice.
Comment 4
-line 525 - you probably have to remove XXX
Answer 4: Thank you very much for the comment and your advice. We corrected this line.
Comment 5
-is there any reason that mandarin - Clementine is written with a capital C?
Answer 5: Thank you very much for the comment and your advice. Based on the above advice we corrected in text “mandarin – Clementine” on “mandarin – clementine”.
Comment 6
-please consider using more punctuation, the text is somewhat difficult to understand.
Answer 6: Thank you very much for the comment and your advice. We added more punctuation to the text to make it more comprehensible based on the previous advice.
Comment 7
-please use all over passive voice.
Answer 7: Thank you very much for the comment and your advice. Based on the above advice we We have tried to correct the errors.
