An Electronic Nose Technology to Quantify Pyrethroid Pesticide Contamination in Tea

Round 1

Reviewer 1 Report

This work addresses a problem of sure interest: the detection of pesticides on tea plants. The use of a sensor system used as an electronic nose could facilitate and speed up the detection of these food contaminants. However, the drafting of this article presents several critical issues listed below:

Abstract:

A clear reference to the commercial device is missing. The type of sensors used is not indicated. The authors define the electronic nose reported as "their" but in the following it is indicated that they use a commercial one. Throughout the article the word "chemosensor" is never mentioned.

1. Introduction
Row 45: "... biological olfactory sensors." It should be "... biological olfactory receptors" or "... biological olfactory systems".

Row 48: The authors assert that there are still no electronic nose applications for detecting pesticides on tea plants, but, as reported by the following article, a company has developed such a system. A more in-depth bibliographic research that also includes commercial devices is suggested.
See: "https://www.thehindu.com/business/Industry/now-an-enose-to-sniff-out-pesticides-in-tea/article8630545.ece"

2. Materials and Methods

Row 63: A description of the measurement set-up is completely missing. How are the signals taken from the individual sensors of the PEN3? Are the possible variations in temperature and humidity taken into consideration? What size has the conical flask have?
Row 69. Wrong name of the company
Row 71: The reference [20] is not easily accessible. Authors should cite other references or make explicit the method they refer to in the text.
Row 75: In the text indicates a sampling flow of 600 ml / min but in the specifications of the PEN3 a maximum of 400 ml / min is indicated. The authors should explain this data discrepancy.
Row 88: "Ri is the signal ratio input", I don't understand why "input", please explain.
Row 89: Please specify what "zero gas" is.

3. Results

Row 107-109: These sentences must be removed as they are part of the "Instructions for Authors".
Row 111: The characteristics description of the individual sensors is missing.
Fig.1: In figure 1 the third graph is identified with the letter (b) while it must be identified with (c), moreover the colors used in the graphics and legend are slightly different. The yellow square on the graphs is not visible.
Fif.2: The variance regarding "zero gas" data seems rather excessive. The authors should comment on this particularity.
Row 130-132: in this sentence it is stated that the W5S, W1S, W1W, and W2W sensors can be used as an optical sensor array. Since these devices are chemosensors based on MOS technology, I do not understand how they can be used to make an optical device. Authors are asked to clarify this sentence.

4. Discussion

Row 188-189: I don't think the statement "our electronic nose" can be considered correct. The authors did not produce a new sensor system but they have merely processed the data coming out of the PEN3.
Row 193-194: The sentence says that five sensors have been identified but only four are reported in the parenthesis.
Row 204-208: These sentences should be reformulated more clearly.
Row 209-214: As asserted by the authors in the measurements carried out, there could be numerous sources of interference which, however, were not taken into account during the measurements. The reported data could therefore be affected by error. A more in-depth assessment of the effects of the interferers on the measures would have been appropriate.

References:

Row 243: "DiBenedetto" should be "Di Benedetto"
Row 257: In the title "he" should be "The"
Row 263: "progress" should be "Progress"
Row 264: "dynamics" should be "Dynamics"
Row 292: "Ccharacteristic " should be "characteristic "

Author Response

Please see attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

I find this work a useful demonstration of how an e-nose can be used in a quality food Scenario. I think that the work is well written and needs only some little corrections.

Abstract

The phrase “We screened a group of electronic nose sensors” can lead to misunderstandings. Electronic nose sensors can be confused with electronic nose system also because the authors don’t specify the electronic nose system used. Is better to clarify that authors use an Airsense Pen3 E-nose in which they screened the gas sensors.

Introduction

At line 48 the references are too poor and old. In this years more and more articles deal with e-nose in the food-quality applications.

Material and methods

the paragraph 2.2 is titled “Selection and optimization of….”

but it describes the test protocols. Another Paragraph (3.1) has the same name. I think is better to change paragraph 2.2 in “Test Protocols and measurement strategy”

Results

Paragraph 3.1: is not clear how much is the value of the parameter that exclude a sensor. In the LA analysis shown in fig1 it seems to be the area delimited by the lines at 0.3 for both axes. Is it true?

The caption in Fig 2 must be reviewed. There is something wrong in the description of the fig d (same sensors of the fig e). Also at the end of the caption it seems that something is gone lost.

Discussion

The showed Results are quite encouraging in terms of precision. Authors talk about that tea leafs flavour time evolution can interferes on calibration repeatability but they don't show regarded experimental results. So they deduce this statement only by the references?

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The authors responded to all the comments made by the referees and the work can be published on CHEMOSENSORS