Development and Optimization of a Highly Sensitive Sensor to Quinine-Based Saltiness Enhancement Effect

Round 1

Reviewer 1 Report

The article “Development and Optimization of a Highly Sensitive Sensor to Quinine-Based Saltiness Enhancement Effect” aims to design a highly sensitive sensor which can be used to measure the saltiness enhancement effect. This article could contribute to explain the mechanism of the saltiness enhancement effect.

However, some points should be explained more clearly.

1.     Is saltiness enhancement effect of quinine important in practical application? The significance of studying quinine-based saltiness enrichment is not fully explained.

2.     In two-point identification test part, are these ten panelists experts?

 

3.     The Y-axis in Figure 6 is incorrect. And why not add the data of 0 mM quinine to show the saltiness enhancement effect more clearly?

Comments for author File: Comments.pdf

Author Response

1. Is saltiness enhancement effect of quinine important in practical application? The significance of studying quinine-based saltiness enrichment is not fully explained.

Response: Currently, the salt-reduced foods using the saltiness enhancement effect produced from quinine have not been developed yet. The development of this sensor is assumed to be supportive to novel salt-reduced food products base on quinine.
We added it to line 330.

2. In two-point identification test part, are these ten panelists experts?

Response: The sensory test on the saltiness enhancement effect was performed in collaboration with the Taste & Aroma Strategic Research Institute Co., Ltd. (Tokyo, Japan).
Ten well trained panelists (four male and six female adults) were enrolled in this study. The panelists were selected by their ability to detect taste substances with high sensitivity, and have been trained approximately once a week.
We added it to line 217.

3. The Y-axis in Figure 6 is incorrect. And why not add the data of 0 mM quinine to show the saltiness enhancement effect more clearly?

Response: We checked the compiled version of the article and we confirmed that the Y-axis has been different. Because we have designed a parasite graph with two Y-axes on both sides of the figure.
The reason is that all the figures in this paper has been produced by pgfplots embedded with the code of LaTeX. The version compiled on my PC (actually from overleaf) is right. As other figures have been correctly produced, we think the compiler of sensors only has different result on "axis y line*=right".
To get rid of compiling issues, we replace the code with the picture this time. Please kindly check it.

The data of 0 mM quinine can be found in Figure 2 (-81.12, 2.7). The reason why we were not showing the data of 0 mM quinine in the figure is that the graph was semilog on the X-axis where 0 can not be included.

Reviewer 2 Report

The present study aims a new saltiness sensor with the lipid/polymer membrane to quantify the saltiness enhancement effect of quinine. The present review has 43 references but most of the are not recent. 

The paper is well structured throughout, and the conclusions are supported by the results. The design and presentation of the research are acceptable, but I would suggest that the Introduction part could be more detailed, with more cited articles.

 There is redundant content throughout the text.

The conclusions should be more detailed, given the depth of the study. The conclusions should be more detailed, given the depth of the study. The authors should study the usage of lipid/polymer membranes on novel taste sensors to evaluate the saltiness enhancement effect accurately because the mechanism of the saltiness enhancement effect has not been established in this study.

Author Response

Response: Recent references have been added to review the electronic tongues and taste sensors. Details on electronic tongues and taste sensors have also been added to tell the advantages and disadvantages so that it is easy to compare the two. The introduction part has been modified to be more detailed.
For the conclusion, the results discussed in Section 4 have been included. The aim of the study has been clarified to develop a taste sensor to measure the saltiness enhancement effect based on quinine as it was found to have this effect in this article.
Please kindly check it in the conclusion section.

Reviewer 3 Report

1. Can this taste sensor be like same as humans perceive the taste of any product?

2. Is this taste sensor accurate in terms of organoleptic other characters such as perception of aroma and texture feel?

3. Does your taste sensor just measures saltiness in products? Or other flavours or tastes as well?

4. This part of the intro is too long make it short. Avoid repetitions.

Comments for author File: Comments.pdf

Author Response

1. Can this taste sensor be like same as humans perceive the taste of any product?
Response: The taste sensor is based on the idea of global selectivity, so that it should be able to percerve taste of any product and the response should be linearly related to human scale.
We added it in line 35.

2. Is this taste sensor accurate in terms of organoleptic other characters such as perception of aroma and texture feel?
Response: This taste sensor is not able to measure other characters like aroma or texture feel.
We added this part in line 64.

3. Does your taste sensor just measures saltiness in products? Or other flavours or tastes as well?
Response: The taste sensing system has been designed under the concept of global selectivity, which means the sensor should be highly selective to taste substances in the same class of taste. For instance, the saltiness taste is generally produced by the sodium ions in the food (as the Na+ channel in human gustatory system is responsible for this), but there are also other components for Lithium and Cesium ions (though not been clarified on mechanisms).
The taste sensor should thus produce a consistent response (same selectivity) to such ions, as they are all for the saltiness taste.
As for other tastes, such as quinine for bitterness, the taste sensor should not selective to this substance unless there are saltiness substance (at a low level of concentration) in the food.
Therefore, this taste sensor does not measure other flavours or tastes in the food to sustain global selectivity of the saltiness taste.

4. This part of the intro is too long make it short. Avoid repetitions.
Response: We have modified this part in the article please kindly check it.

Round 2

Reviewer 1 Report

All my questions  have been properly answered.