Testing the Efficacy of a Prototype That Combines Ultrasound and Pulsed Electric Field for Extracting Valuable Compounds from Mitragyna speciosa Leaves
Round 1
Reviewer 1 Report
The work “Testing of a Prototype Combining Ultrasound and Pulsed Electric Field on Extracted Valuable Compounds of Mitragyna speciosa Leaves” submitted for review is interesting.
However, the text should be revised to improve its scientific quality:
- line 25: the name of the species should be written in italics;
- the scientific value of the work would be increased by including in chapter 2.2 a block diagram of the PEF-US apparatus prototype;
- the paper does not include details on the validation of the procedure for determining mitragynine in extracts using UHPLC MS/MS. There is no data such as: purity of the standard used, preparation of the standard curve, amount of sample dosed onto the chromatographic column. There is no sample chromatogram of the analyzed extract;
- the missing DOI should be supplemented in the cited literature;
- line 386 is Journal of Chromatography and should be: J. Chromatogr. A.
Author Response
We would like to thank the reviewer for the careful and thorough reading of this manuscript and for the thoughtful comments and constructive suggestions, which help to improve the quality of this manuscript. Those changes are in red font within the manuscript. Please see below, in red, for a point-by-point response to the reviewers’ comments and concerns.
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Review of the Article entitled: " Testing of a Prototype Combining Ultrasound and Pulsed Electric Field on Extracted Valuable Compounds of Mitragyna speciosa Leaves”
This study delves into the exploration of employing a combination of pulsed electric field (PEF) and ultrasound (US) apparatus to extract mitragynine from dried leaves of Mitragyna speciosa. The research involved testing four different operational modes of the apparatus: PEF, US, US + PEF, and PEF + US, in comparison with a traditional maceration method. The findings, obtained through liquid chromatography/mass spectrometry (LC-MS/MS) analysis, unveiled significant variations in mitragynine content extracted from the Mitragyna speciosa leaves using these different modes. The combined PEF + US mode achieved the highest mitragynine extraction yield. To gain further insights into the structural and functional alterations in Mitragyna speciosa leaves induced by these extraction methods, the study employed scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR).
Overall, this study demonstrates the potential of PEF and US devices as environmentally friendly alternatives for the extraction of mitragynine from Mitragyna speciosa leaves. Furthermore, the findings suggest that these techniques could have implications for enhancing agricultural product applications.
Overall, I find the article to be well-written and supported by robust experimental results and images, underscoring the significance of the research topic. However, there are certain corrections and concerns that I believe the authors should address before the article is published.
Comments and corrections are listed below:
Page 1, lines 3-5: The proposal is to slightly modify the title of the work, for example: “Testing of the Efficacy of a Prototype that Combines Ultrasound and Pulsed Electric Field for Extracting Valuable Compounds of Mitragyna speciosa Leaves”;
Page 1, lines 8-14: Affiliation number 4 is missing;
Page 1, line 16: Please change the following sentence: “…apparatus to produce mitragynine extracts from…” as follows: “…apparatus to extract mitragynine from…”;
Page 1, lines 22-24: “Moreover, the total energy consumption under the combination technique was 25.0% lower than that with PEF assistance.” This information is not shown in the manuscript. Please explain;
Page 1, lines 26-27: Change the next sentence: “This study demonstrated that PEF and US devices may be regarded a green alternative technique and may help with agricultural product application.” as follows: “This study demonstrated that a combination of PEF and US devices may be regarded a green alternative technique and can assist in streamlining the implementation of agricultural products.”;
Page 1, lines 32-34: Please rephrase the next sentence: “One of the Rubiaceae family, Mitragyna speciosa Korth (Kratom), is a native tree that popularly cultivated in Thailand, Indonesia, and Malaysia, and is also known as Thom, Ketum, Biak, and Thang [1].” as follows: Mitragyna speciosa Korth (commonly referred to as Kratom) belongs to the Rubiaceae family and is a native tree widely cultivated in Thailand, Indonesia, and Malaysia. It is also recognized by various local names such as Thom, Ketum, Biak, and Thang.”;
Page 1, line 34: Correct “Kraatom” into “Kratom”;
Page 2, line 46: Instead of “have more or fewer deficiencies and limitations” please use “are associated with a range of drawbacks and constraints”;
Page 2, lines 51-52: After mitragynine use a full stop in the next sentence: “…were chosen to maximize the content of mitragynine.” Afterwards instead of: “and it was found that the best yield of mitragynine was obtained when UAE was used [4].” please use the next sentence: “The results indicated that the highest mitragynine yield was achieved through the utilization of UAE.”;
Page 2, lines 53-54: Instead of “…optimized condition of the UAE was modeled at 25 °C, 15 minutes of sonication time, and a 10 mL/g of solvent to solid ratio [5].” please write: “optimal setting for UAE with the following parameters: 25 °C temperature, 15 minutes of sonication, and a solvent-to-solid ratio of 10 mL/g was developed.”;
Page 2, lines 64-65: Instead of “…extracted mitragynine from M. speciosa leaves using a newly built pulsed electric field-ultrasound (PEF-US) system.” please write “…utilized a newly constructed pulsed electric field-ultrasound (PEF-US) system to extract mitragynine from M. speciosa leaves.”;
Page 2, lines 65-66: Instead of “PEF-US extraction efficiency was equivalent to other modes, including PEF, US, US + PEF, and simple maceration.” please write “The efficiency of mitragynine extraction using the PEF-US method was comparable to other extraction methods, including PEF, US, a US and PEF combination, and conventional maceration.”;
Page 2, lines 66-70: Instead of the following text: “We believe this is the first time PEF + US has been used to treat mitragynine. In addition, energy consumption was examined. SEM and FTIR were used to examine changes in the structural and functional features of plant materials after employing four distinct modes of the prototype.” please write “Notably, this marks the inaugural application of PEF combined with the US for mitragynine extraction. Furthermore, energy consumption associated with these extraction techniques was assessed, while SEM and FTIR were employed to investigate alterations in the structural and functional characteristics of the plant materials when subjected to the four distinct modes of extraction.”;
Page 2, lines 75-77: Change the following text: “…into a fine powder form (1.0 mm) and used for the experiments.
The powder of 10% (w/v) was used in all extraction experiments; specifically, 100 g of powder was mixed with 1000 mL of extraction solvent [4].” as follows “…into a fine powder form (with a particle size of 1.0 mm). The resulting fine powder was mixed with extraction solvent at a concentration of 10% (w/v) [4].”;
Page 2, lines 79-80: After “…adjusted to reach” please add “the volume of”. Instead of “with 1% of acetic acid in 80% ethanol.” please write: “while maintaining a composition of the extraction solvent.”;
Page 3, lines 84-87: Change the following sentence: “The PEF-US equipment layout consisted of a high-voltage generator with a 20 kV of a maximum voltage, a pulse generator, an ultrasonic horn, a chamber, and an air pump. This device can be operated in four modes: PEF, US, US+PEF, and PEF+US .” as follows: “The configuration of the PEF-US equipment included several key components, such as a high-voltage generator capable of reaching a maximum voltage of 20 kV, a pulse generator, an ultrasonic horn, a chamber, and an air pump. This apparatus is versatile, offering four operational modes: PEF, US, US+PEF, and PEF+US.”;
Page 3, lines 102-103: Delete: “for PEF extraction.”;
Page 3, lines 103-104: Instead of “kept” use “stored”. Instead “used within 24 h.” write “it was utilized, within a 24-hour timeframe.”;
Page 3, line 108: Delete “for US extraction”;
Page 4, line 118: Instead of “stood” please use “left”;
Page 4, line 119: Instead “was a control sample” write “served as a control sample”;
Page 4, line 124: Please check the type of filter used for the preparation: “a 0.22 m nylon filter”;
Page 5, line 174: Please explain the following equation: y = 131,610x + 49,454; R2 = 0.9963;
Page 5, lines 183-184: Please explain how did you calculate these numbers: 8.08 - 18.48%; 16.91- 28.16%;
Page 7, lines 226-228: Instead of “Thus, the combination of PEF and US can benefit mitragynine extraction by reducing energy consumption. Therefore, it might be potential to apply in industrial extraction as a green technology.” please write “Therefore, the utilization of PEF and US in combination presents an opportunity to enhance mitragynine extraction while simultaneously reducing energy consumption. Consequently, this approach holds promise for potential application as an eco-friendly technology in industrial extraction processes.”;
Page 7, lines 228-230: “Moreover, the energy consumption under this prototype was equivalent to the extraction of aromatic plants [24] and rosemary [25] by microwave extraction at 4.2 kJ/kg.”. From Table 1 the energy consumption for PEF + US was 3.72 kJ/kg, which is lower than 4.2 kJ/kg. Maybe it is better to add “almost” before “equivalent”;
Page 7, line 238: Rephrase the sentence: “While the use of US changed rough the to be surface “;
Page 8, lines 251-253: According to the Figure (d) is for PEF + US, and (e) is for US + PEF. Please correct;
Page 8, lines 262-263: Please complete this sentence. What is weak: “The weak C-H, C=C, C-C, and C-O were attributed to the higher amount of active molecules being disintegrated into extraction solvents..”;
Page 8, lines 264-265: This part of the text is not so clear: “The use of the combined US and PEF methods This phenomenon was consistent with the mitragynine content, as presented in Table 1.”;
Page 9, line 272: Please replace the word “followed” with “observed”;
Page 9, line 275: Please delete “extraction” after “maceration”;
Page 9, line 275: “PEF + US” is repeated. Also, delete the word “extracts”;
Page 9, line 276: Add “a” before “helpful”. Replace “unknow” with “unknown”;
Page 10, lines 281-282: Please rephrase the title of the Table 2. For example: “Table 2. UHPLC-MS/MS Analysis Results: Mitragynine MS/MS Data in Maceration and PEF + US Extracts";
Page 10, line 285: Instead of “produce plant extracts” please write “obtain plant extracts with an enhanced content of valuable compounds”;
Page 10, line 286: Instead of “synthesis” please write “extraction”;
Page 10, line 287: Please list the extractions used in the study;
Page 10, line 292: After “different” please add “extraction”;
Page 11, line 301: Please finish the sentence: “(in Thai)”;
Page 12, For reference 10 please state the status of publication (accepted / in press);
References 10, 14, 19, 24, 25, 27, 28: Please use abbreviated names of journals.
The quality of the English language is at a satisfactory level. The reviewer pointed out minor errors to the authors
Author Response
We would like to thank the reviewer for the careful and thorough reading of this manuscript and for the thoughtful comments and constructive suggestions, which help to improve the quality of this manuscript. Those changes are in red font within the manuscript. Please see below, in red, for a point-by-point response to the reviewers’ comments and concerns.
Author Response File: Author Response.pdf
