Effect of the Processing Conditions on the Supercritical Extraction and Impregnation of Rosemary Essential Oil in Linear Low-Density Polyethylene Films
, Adrián Rojas 2,3, Arman Babhadiashar 4, María José Galotto 2,3,5, Nedasadat Saadati Ardestani 6 and Seyed Ali Sajadian 7,8,*Round 1
Reviewer 1 Report
This manuscript described supercritical CO2 extraction of essential oil from rosemary leaves and evaluate the antioxidant activity of impregnated LLDPE films. The work is interesting for agricultural products and the food industry. Other comments are listed below:
1. In Fig.4 and Fig.6, each graph has only two data points, which is not suitable for dot and line charts.
2. Figure 7. FTIR spectra, the characteristic peaks of essential oils in impregnated LLDPE are not visible and should be removed.
3. Table 7. The author discussed the mechanical properties of the neat LLDPE film and impregnated LLDPE film. Please add the stress-strain curves data.
4. English writing and chart formatting should be standardized.
Author Response
Reviewer 1:
This manuscript described supercritical CO2 extraction of essential oil from rosemary leaves and evaluate the antioxidant activity of impregnated LLDPE films. The work is interesting for agricultural products and the food industry. Other comments are listed below:
Comment 1. In Fig.4 and Fig.6, each graph has only two data points, which is not suitable for dot and line charts.
Reply 1.
Thank you for your comment. As you know, the Figs.4 (a-c) and 6 present the effect of one factor in each step while the other factors are constant and these Figs are results obtained from Design expert software.
Comment 2. Figure 7. FTIR spectra, the characteristic peaks of essential oils in impregnated LLDPE are not visible and should be removed.
Reply 2.
According to the reviewer’s comment, the graphs have been separated and some bands of the essential oil extract such as 2915, 2847.9, 1462.79, 718.67 cm-1 are in common with LLDPE. The authors prefer that the FTIR of all cases remain in the text.
Comment 3. Table 7. The author discussed the mechanical properties of the neat LLDPE film and impregnated LLDPE film. Please add the stress-strain curves data.
Reply 3. Stress-strain curves of the neat LLDPE and Impregnated LLDPE with rosemary essential oil was added.
Comment 4. English writing and chart formatting should be standardized.
Reply 4.
The English writing in the entire article has been reviewed by a professional English traductor. Chart formatting was standardized in the entire manuscript.
Reviewer 2 Report
Comments
The research study on Supercritical fluid extraction of essential oil from rosemary and impregnation LLDPE) films which is an interesting topic. But in order to increase usefulness and significance of the study, it needs a revision before being considered suitable for readers and there are some points should be revised.
-Abstract
>The abstract need to be improved. It should include a very concise version of methods, results, and conclusions.
>Lines 31-32 and Lines 27-29, are the same results?
-Introduction
> Should be improved
Methods
2.1. Materials
> Please explain from when the plants were obtained and who identified the plant. Please provide the voucher specimen number for the plant.
2.2.3. Supercritical Solvent Impregnation process
> Please delete Line 144-150 because the authors show this information in Fig 2.
2.2.4. Gas chromatography-mass spectrometry (GC-MS)
>Add reference of Van den Dole and Kratz method.
2.2.5. Antioxidant activity of impregnated films
>The authors mention the antioxidant activity of rosemary essential oil extract. How about impregnated LLDPE films, please add information on how the authors prepare the sample for measuring antioxidant activity.
> Is there a statis used for analysis, please add.
Results and Discussion
> Should be improved
3.2 Gas chromatography results
>Line 2564, The authors mention that “use rosemary essential oil extract obtained by SC-CO2 263
extraction at the optimal conditions.” The term “optimal conditions” should be clarified in detail.
>We found the not consistent writing compounds’ s name, sometimes start with a capital letter.
-Table 3
> Please add extra two columns for adding retention time and retention indices.
> Percentage should revise to % of total
> Please delete the compounds that did not found in rosemary essential oil from Table 3.
Conclusion
> Please include the optimum condition that uses for rosemary essential oil extraction and impregnation of LLDPF. Further study should be provided.
Additional,
Please check through the manuscript and revise
-µl to µl L
-space before °C
-IC50 to IC50
-et al should not be italic
Comments for author File: 
Comments.pdf
Author Response
Reviewer 2.
The research study on Supercritical fluid extraction of essential oil from rosemary and impregnation LLDPE) films which is an interesting topic. But in order to increase usefulness and significance of the study, it needs a revision before being considered suitable for readers and there are some points should be revised.
-Abstract
Comment 1. The abstract need to be improved. It should include a very concise version of methods, results, and conclusions.
Reply 1. The abstract was revised
Comment 2. Lines 31-32 and Lines 27-29, are the same results?
Reply 2. lines 31-32 were deleted from the revised version of the manuscript.
-Introduction
Comment 3. Should be improved
Reply 3. According to the reviewer comments, the introduction was improved.
Methods
2.1. Materials
Comment 4. Please explain from when the plants were obtained and who identified the plant. Please provide the voucher specimen number for the plant.
Reply 4. Rosemary was provided by Eram Botanical Garden that it is located in the city of Shiraz in Fars province (Iran).
2.2.3. Supercritical Solvent Impregnation process
Comment 5. Please delete Line 144-150 because the authors show this information in Fig 2.
Reply 5. Line 144-150 were deleted.
2.2.4. Gas chromatography-mass spectrometry (GC-MS)
Comment 6. Add reference of Van den Dole and Kratz method.
Reply 6. This reference was added.
2.2.5. Antioxidant activity of impregnated films
Comment 7. The authors mention the antioxidant activity of rosemary essential oil extract. How about impregnated LLDPE films, please add information on how the authors prepare the sample for measuring antioxidant activity.
Reply 7. According to reviewer comment, this section has been explained with more details.
The DPPH inhibition (I%) was calculated with Eq (4):
|
I%=(Ablank–Asample/Ablank)×100 |
(3) |
In Eq. (4), Ablank is the absorption of the control reaction and Asample indicates the absorption of the rosemary essential oil extract sample. The half maximal inhibitory concentration (IC50) is defined as the potency of a substance in inhibiting a specific biological function. The graph inhibition percentage against essential oil extract concentration was plotted. Then, rosemary essential oil extract concentration providing 50% inhibition (IC50) was determined from this plot. The antioxidant activity of the rosemary essential oil was measured three times and the mean IC50 value was reported. In addition, for the determination of the IC50 values of the impregnated LLDPE films, 1000 mg of the different film samples were immersed in 25 mL of methanol for 24 hours to extract the essential oil from the polymeric structures and generate a stock solution. After that, five samples with different con-centration of the essential oil extract were prepared using each stock solution. In the next step, each sample was introduced in 4 mL of a 6 × 10−5 M DPPH solution and the absorbance of each sample was measured at 515 nm.
Comment 8. Is there a statis used for analysis, please add.
Reply 8. According to the reviewer’s comment, standard deviations and P-value have been added to Table 6.
Results and Discussion
Comment 9. Should be improved.
Reply 9. According to the reviewer comments, the result and discussion was improved.
3.2 Gas chromatography results
Comment 10. Line 2564, The authors mention that “use rosemary essential oil extract obtained by SC-CO2 263 extraction at the optimal conditions.” The term “optimal conditions” should be clarified in detail.
Reply 10. The optimal conditions were added “The chemical compositions of the rosemary essential oil extract obtained by SC-CO2 extraction at the optimal conditions (25 MPa, 318 K, and 0.15 mm) was listed in Table 3.”
Comment 11. We found the not consistent writing compounds’ s name, sometimes start with a capital letter.
Reply 11. The compounds’ s name in this section were revised.
-Table 3
Comment 12. Please add extra two columns for adding retention time and retention indices.
Reply 12. The reviewer suggestion was taken into account and a extra column showing the retention index was added to Table 3.
Comment 13. Percentage should revise to % of total
Reply 13. Percentage was replaced by symbol (%)
Comment 14. Please delete the compounds that did not found in rosemary essential oil from Table 3.
Reply 14.
Thanks, according to the reviewer’s comment, it has been modified.
Conclusion
Comment 15. Please include the optimum condition that uses for rosemary essential oil extraction and impregnation of LLDPF. Further study should be provided.
Reply 15. The optimum condition of rosemary essential oil extraction and impregnation of LLDPE were added to conclusion.
Additional,
Comment 16. Please check through the manuscript and revise
-µl to µl L
-space before °C
-IC50 to IC50
-et al should not be italic
Reply 16. Thanks for your attention, Authors corrected this phrases.
Round 2
Reviewer 1 Report
The supplemented stress-strain curve looks a little strange, why not give the full curves and just the strain of 320-480%?
