Investigation of the Maturity Changes of Cherry Tomato Using Magnetic Resonance Imaging
Round 1
Reviewer 1 Report
The reviewed manuscript is a concise report on the topic of new potential diagnostic applications of MRI. With the increased availability of MRI instruments, improved static field homogeneities, field gradients and transmission/detection electronics it is tempting to check the information content of MR images for all kinds of proton-containing heterogeneous structures, including various fruits.
The authors did find a numerical parameter that might quantify the cherry tomato maturity, namely, a pericarp-to-locule signal intensity ratio for the MR images recorded in the "proton density" regime. To this extent, the manuscript is goal-driven, well written and deserves to be published in Applied Sciences. However, I do have some minor corrections.
Minor points
- Page 1, line 32. The first sentence of the introduction is superfluous.
- Page 2, line 51. Ref. [1]. Should it be Ref. [2]?
- Page 2, line 105. Please specify which oil was used.
- Section 2.2. Please specify that the pulse sequence was designed to obtain images in which the pixel brightness is proportional to the proton density (in contrast to widely used T1/T2-weighted images or other techniques, such as FLASH).
- Section 2.2. Please add the resulting image resolution (0.2x0.2x1 mm, I believe).
- Section 2.2. Please specify explicitly along which plane of the tomato fruit the 2D images were recorded.
- Section 2.2. Please add the overall duration of one experiment.
- Page 5, line 146 and/or Figure 5b. Please indicate which regions and which intensity spikes are due to vascular bundles within the placenta.
- Page 5, line 157. "mobile water". It seems to me that the mobility of the water molecules does not play a role here, as the images were not relaxation-time-weighted.
- Figure 6. Figures 6 and 7 contain the same images. It is advisable to move the labels from Figure 6 to Figure 7 and delete Figure 6.
- Page 6, line 180. "...ratio was based on MSI of oil reference...". It would be more clear if the exact mathematics would be explained: what was divided by what.
- Figure 8, right column. The y-axes should be labelled differently as a) it is the intensity _ratio_ and b) it has no units.
- Figure 8 discussion. How were the plotted numbers averaged? (over four regions, over six images, over three runs of the experiment? Please specify). How were the margins of error calculated?
- Figure 8 discussion. I am concerned that the main finding (more homogeneous water distribution between pericarp and locule parts in ripe tomatoes), clearly visible in Figure 7, kind of disappears if one takes into account the large margins of errors shown in Figure 8. Perhaps this is an artefact of an unlucky selection of regions and automatic averaging procedure. This is worth addressing in the text.
- Conclusions. I would recommend to recapitulate the main funding in the conclusion as well.
Language/spelling (rephrasing advised)
- Page 1, line 35. "it also for proper differences"
- Page 1, line 37. "are classified as externally and internally"
- Page 2, line 69. "images of processing tomatoes"
- Page 2, line 70. "breaker-right red"
- Page 3, line 115. "amount of proton"
- Page 6, line 178. "data acquired 54 samples"
Author Response
Point 1: Page 1, line 32. The first sentence of the introduction is superfluous.
Response 1: removed
Point 2: Page 2, line 51. Ref. [1]. Should it be Ref. [2]?
Response 2: changed to [2] on line 50
Point 3: Page 2, line 105. Please specify which oil was used.
Response 3: changed to olive oil on line 103
Point 4: Section 2.2. Please specify that the pulse sequence was designed to obtain images in which the pixel brightness is proportional to the proton density (in contrast to widely used T1/T2-weighted images or other techniques, such as FLASH).
Response 4: I mentioned Gradient Echo (GRE) pulse sequence whose intensity is proportional to the proton density on line 96.
Point 5: Section 2.2. Please add the resulting image resolution (0.2x0.2x1 mm, I believe).
Response 5: I added a resolution of a spatial voxels of 3.8 10-11 m3 on line 101
Point 6: Section 2.2. Please specify explicitly along which plane of the tomato fruit the 2D images were recorded.
Response 6: The images were acquired along axial plane. However, it’s not important to mention it due to MRI’s 3D capability.
Point 7: Section 2.2. Please add the overall duration of one experiment.
Response 7: I added it on line 101.
Point 8: Page 5, line 146 and/or Figure 5b. Please indicate which regions and which intensity spikes are due to vascular bundles within the placenta.
Response 8: I added vascular bundles on the figure and explained about intensity spikes on line 146
Point 9: Page 5, line 157. "mobile water". It seems to me that the mobility of the water molecules does not play a role here, as the images were not relaxation-time-weighted.
Response 9: I replaced “mobile water” into “protons” on line 156
Point 10: Figure 6. Figures 6 and 7 contain the same images. It is advisable to move the labels from Figure 6 to Figure 7 and delete Figure 6.
Response 10: I didn’t changed the Figures. However, I rephrased sentences related
Point 11: Page 6, line 180. "...ratio was based on MSI of oil reference...". It would be more clear if the exact mathematics would be explained: what was divided by what.
Response 11: I rephrased the all sentence on line 183-184.
Point 12: Figure 8, right column. The y-axes should be labelled differently as a) it is the intensity _ratio_ and b) it has no units.
Response 12: I changed it to intensity ratio with no units on Figure 8.
Point 13: Figure 8 discussion. How were the plotted numbers averaged? (over four regions, over six images, over three runs of the experiment? Please specify). How were the margins of error calculated?
Response 13: For example, mean and std of signal intensity from 4 square regions from a slice image were calculated, and then same calculation was done on 5 more slice images. Finally I calculated mean and std of signal intensity representing values of a sample. Statistical analysis beyond mean values and error bars were not performed.
Point 14: Figure 8 discussion. I am concerned that the main finding (more homogeneous water distribution between pericarp and locule parts in ripe tomatoes), clearly visible in Figure 7, kind of disappears if one takes into account the large margins of errors shown in Figure 8. Perhaps this is an artefact of an unlucky selection of regions and automatic averaging procedure. This is worth addressing in the text.
Response 14: I’m in agreement with the reviewer, the conclusion really are not justified since the std dev is so high. Note the S/N ratio is only ~4 (2/0.5). The conclusions are justified looking at the images qualitatively. It might be to filter the time domain signal (e.g. Gaussian filter) to reduce the high frequency noise and that would likely significantly reduce the std dev for further in-depth study.
Point 15: Conclusions. I would recommend to recapitulate the main funding in the conclusion as well.
Response 15: I rephrased the all sentence on line 195-202.
Language/spelling (rephrasing advised)
- Page 1, line 35. "it also for proper differences" -> rephrased properly
- Page 1, line 37. "are classified as externally and internally" -> rephrased properly
- Page 2, line 69. "images of processing tomatoes" -> rephrased properly
- Page 2, line 70. "breaker-right red" -> rephrased properly
- Page 3, line 115. "amount of proton" -> rephrased properly
- Page 6, line 178. "data acquired 54 samples" -> rephrased properly
Reviewer 2 Report
The authors report an interesting study on the utility of Magnetic Resonance (MR) imaging in monitoring the maturity stages of cherry tomato. The method was applied on three different varieties (Tiara, Tiara TY, and Unicorn) showing similar results. The main internal structural changes concern the pericarp region where the MR images revealed the evolution in water content. The results are analyzed qualitatively and quantitatively. Similar conclusion has been reached in previous reports on regular tomatoes, cited in references 12 and 13. This work could be suitable for publication in Applied Sciences after the following minor comments are addressed:
Minor comments:
1. The English could be improved. Examples of typos:
Line 17 “changes”
Line 35 rephrase the sentence “While modern …agricultural products.”
Line 37 : “classified as externally and internally” ??
Line 56: the sentence is not clear “ … on kiwi fruits found water ..”
Etc.
2. The first sentence in the Introduction part should be removed.
3. Line 115: oil reference should be specified.
4. Line 187: The sentence “This result proves the qualitative analysis is right” should be rewritten more explicitly. The authors should recall the main findings.
5. The reference 13 should be completed.
Author Response
Point 1: 1. The English could be improved. Examples of typos:
Line 17: “changes”
Line 35: rephrase the sentence “While modern …agricultural products.”
Line 37: “classified as externally and internally” ??
Line 56: the sentence is not clear “ … on kiwi fruits found water ..”
Etc.
Response 1: revised all on line 17, 34-35, 36, and 55. Also, the manuscript was revised and edited by a native English author.
Point 2: The first sentence in the Introduction part should be removed.
Response 2: removed
Point 3: Line 115: oil reference should be specified
Response 3: changed to olive oil on line 103
Point 4: Line 187: The sentence “This result proves the qualitative analysis is right” should be rewritten more explicitly. The authors should recall the main findings.
Response 4: I revised that section on line 85-86.
Point 5: The reference 13 should be completed.
Response 5: I completed all reference citation according to journal referring format on line 214-251.
Reviewer 3 Report
The discussed paper presents study of MRI changes representing tomato ripening process. Such studies have been reported before. In my opinion the authors did not sufficiently justify the novelty of their approach.
The description of experiment is limited in comparison to other papers presenting MRI studies on tomatoes.
For example, what kind of oil was used as a reference? mineral? hydrocarbon? edible? The tube was relatively far from the fruit - did the authors check the effect of positioning (field distribution/homogeneity)?. The cavity was quite big - how were the tomatoes secured during scan?
Pictures 2 and 3 do not provide important information. Figure 4 may benefit from different system of point indication, without crossed lines. It will be a good idea to provide justification for point selection.
Figure 5 (1D) represents green maturity stage - the difference between pericarp and locule. It will be interesting to see 1D profile for red (mature) tomato.
The two sentences: "However, the signal intensity from placenta region is low compared to pericarp and locule regions. Very strong signal intensity from vascular bundles was observed from placenta region in cherry tomato." need clarification or more detailed labeling of the picture.
Picture 6 is part of picture 7, which needs labeling in the picture, without consulting the extended title.
Picture 8 - the use of colors is confusing. The tendencies are difficult to spot. Description in the text is limited and does not include the indications from the picture.
The conclusion: "This study showed that MRI technique is a versatile tool to examine the internal structure changes of agricultural produce harvested at different maturity stages nondestructively." is in my opinion not supported by the discussion of obtained results.
Usually the differences are examined by statistical methods. If such analysis was performed (apart from mean values and error bars), it should be included in the text.
In case of maturity assessment, what are the advantages of MRI over visual inspection?
There are problems with the text, including the first sentence as an example:
"The introduction should briefly place the study in a broad context and highlight why it important."
Author Response
Point 1: The description of experiment is limited in comparison to other papers presenting MRI studies on tomatoes.
For example, what kind of oil was used as a reference? mineral? hydrocarbon? edible? The tube was relatively far from the fruit - did the authors check the effect of positioning (field distribution/homogeneity)?. The cavity was quite big - how were the tomatoes secured during scan?
Response 1: While the tube may appear to be far from the tomato in the image, the tube is ~ 1 cm away and within the homogeneous field region of the magnet. The reference tube is located in a position such that its signal does not influence the tomato image signal.
Point 2: Pictures 2 and 3 do not provide important information. Figure 4 may benefit from different system of point indication, without crossed lines. It will be a good idea to provide justification for point selection.
Response 2: We believe that Figure 2 and 3 are helpful to demonstrate typical image data sets and hence are important for many readers.
Point 3: Figure 5 (1D) represents green maturity stage - the difference between pericarp and locule. It will be interesting to see 1D profile for red (mature) tomato.
Response 3: I added add a 1D profile for a red tomato.
Point 4: The two sentences: "However, the signal intensity from placenta region is low compared to pericarp and locule regions. Very strong signal intensity from vascular bundles was observed from placenta region in cherry tomato." need clarification or more detailed labeling of the picture.
Response 4: The text has been revised to highlight the differences.
Point 5: Picture 6 is part of picture 7, which needs labeling in the picture, without consulting the extended title.
Response 5: I added labels to the rows and columns in figure 7.
Point 6 Picture 8 - the use of colors is confusing. The tendencies are difficult to spot. Description in the text is limited and does not include the indications from the picture.
Response 6: We have added to the text and highlighted (in the text) the important line color (purple) and ratio label PL.
Point 7: The conclusion: "This study showed that MRI technique is a versatile tool to examine the internal structure changes of agricultural produce harvested at different maturity stages nondestructively." is in my opinion not supported by the discussion of obtained results.
Response 7: The conclusion has been revised.
Point 8: Usually the differences are examined by statistical methods. If such analysis was performed (apart from mean values and error bars), it should be included in the text.
Response 8: Statistical analysis beyond mean values and error bars were not performed.
Point 9: In case of maturity assessment, what are the advantages of MRI over visual inspection?
Response 9: The main advantage of MRI over visual inspection is we can monitor internal physicochemical changes according to fruit maturity changes on intact fruits.
Point 10: There are problems with the text, including the first sentence as an example:
Response 10: I deleted the part. The text throughout the manuscript has been revised and improved.
Author Response File: 
Author Response.docx
Round 2
Reviewer 3 Report
The text was improved by adding more data and describing the results more thoroughly.
Modification of Figure 5 was not updated in the text (line 143). Is it typical to find vascular bundles in pericarp or the spike represents some other feature?
The addition of "protons" in line 159 may be confusing as the sense in MRI description is not always the same as general chemical meaning (acidity).
Author Response
Point 1: Modification of Figure 5 was not updated in the text (line 143). Is it typical to find vascular bundles in pericarp or the spike represents some other feature?
Response 1: We modified that phrase on line 139-145.
Point 2: The addition of "protons" in line 159 may be confusing as the sense in MRI description is not always the same as general chemical meaning (acidity).
Response 2: We deleted that sentence to avoid confusing on line 160
