Review Reports - Quality of Milled Rice from Large-Scale Dried Paddy Rice by Hot Air Combined with Radio Frequency Heating

Round 1

Reviewer 1 Report

Please see attached file.

Comments for author File: Comments.docx

Author Response

Journal: ProcessesManuscript ID: processes-1506845Title: Efficiency of Drying Paddy Rice and Quality of Milled Rice Using Hot Air Dryer in Combination with Radio Frequency Heating in a Large-Scale Process

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RESPONSE TO REFEREE 1We would like to thank the referee for reading and giving us the encouraging comments. Overall, the authors revised the manuscript as kindly suggested by the referee.

This is very useful study issue for paddy rice drying industry. However, it needs to be explained how to operate in this HA/RF equipment, because the temperature of paddy rice is the main factor affecting quality of rice.

Ans: The explanation was revised in line 93- 107.

Title: The title can be changed to “Quality of Milled Rice from Large-Scale Dried Paddy Rice by Hot Air Combined with Radio Frequency Heating”

Ans: This was revised as suggested by the referee.

Abstract: What is the temperature of hot air? How to control the temperature of radio frequency? Is the different temperature of 45, 50, 55 and 60^oC set by measuring the temperature of paddy rice?

Ans: The explanation was revised in line 14-18.

Abstract: The drying efficiency is only determined by drying time, not mentation for drying energy consumption.

Ans: The author illustrated the specific energy consumption and electricity cost in Table 1 and 6, respectively. The abstract was also revised suggested by the referee in line 22-23.

Keywords: “convective drying” can be changed to “hot air drying”.

Ans: This was revised as suggested by the referee.

Materials and Methods: Figure 1 is only a picture, and Figure 2 schematic diagram did not show clearly the inside mechanism of the industrial scale continuous flow hot air dryer with radio frequency heating.

Ans: The author replaced the Figure 2 with a revised figure with more detail.

Materials and Methods: Reader did not understand how to control temperature of RF and hot air, and the temperature of rice paddy did not measured. How the sample was operated during continuous 360~660 min drying system?

Ans: The explanation was revised in line 93- 107.

Results and Discussions: The moisture content of paddy rice was shown in dry basis, which should be changed to kg water/ kg dry material, and did not multiple 100%.

Ans: The author replaced this information with an average moisture diffusivity (D_eff) data instead as shown in Table 1.

Results and Discussions: Figure 3 and Figure 4 need to exchange sequence. Normally, we should have the drying curve and then drying rate curve obtained from the information of drying curve.

Ans: The Figure 4 was removed as also recommend by the referee 2.

Results and Discussions: Figure 3: The drying rate of paddy at first 30 min was wrong, because the HA-RF energy to support for sensible heat and then convert to latent heat for phase change.

Ans: In this study, each drying circulation took about 30 minutes and the data collection was collected every 30 minutes. As the author see it, the data collection interval should be done in shorter interval to demonstrate clearer detail.

Results and Discussions: The Figure 3, Figure 4 and Figure 5 need the inside scale in both x and y axial, and the outside frame.

Ans: The author revised as suggested by the referee.

Results and Discussions: The Figure 6 is not suitable, please change to Table.

Ans: The data was revised and shown in Table 1.

Conclusions: Overall, the hot air with RF heating paddy rice had shorter drying time, but obtain higher fissure percentage, worse quality and sensory evaluation especially at HA/RF 60 operation. However the temperature of RF was setting at 45, 50, 55 and 60^oC, which was similar the convectional drying; therefore, both the changes of temperature and weight of rice paddy during HA/RF drying need to be measured.

Ans: The temperature of the paddy during the drying process was measured every 30 minutes and the weight of the paddy before and after drying was also measured to determine the amount of water evaporated after drying. Furtherly, the author illustrated specific energy consumption and electricity cost in Table 6.

The revised manuscript was attached. Please see the attachment.
Thank you very much.

Best regards,
Karn Chitsuthipakorn

Reviewer 2 Report

The manuscript is very interesting, and it is relevant for the food industry. However, it is important to attend to the following recommendations:

Why was the germination index in rice not evaluated?
The sensory evaluation carried out needs to be described in more detail.
I recommend removing Figure 4, Figure 5 is enough to describe the process.
It is better to include Figure 6 in a Table and separate the variables of interest.
I recommend applying a diffusive model to describe the drying kinetics, since it is the main phenomenon that occurs in a dehydration process. Try it.
In color determinations, I recommend calculating the ΔE for the RF drying treatments compared to the control.
As it is an industrial scale scaling, it is important to include a cost comparison between conventional treatment and that assisted by radio frequencies. Please include it.

Author Response

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RESPONSE TO REFEREE 2We would like to thank the referee for reading and giving us the encouraging comments. Overall, the authors revised the manuscript as kindly suggested by the referee.

(1) Why was the germination index in rice not evaluated?

Ans: The study focused on the drying of paddy rice intended for consumption, so the germination index was not investigated. The authors are of the opinion that germination index is necessary in case of drying paddy rice for seed industry.

(2) The sensory evaluation carried out needs to be described in more detail

Ans: The explanation was revised in line 167-180.

(3) I recommend removing Figure 4, Figure 5 is enough to describe the process.

Ans: The Figure 4 was removed as recommend by the referee.

(4) It is better to include Figure 6 in a Table and separate the variables of interest.

Ans: This was revised as suggested by the referee and shown in Table 1.

(5) I recommend applying a diffusive model to describe the drying kinetics, since it is the main phenomenon that occurs in a dehydration process. Try it.

Ans: The data was revised and shown in Table 1.

(6) In color determinations, I recommend calculating the ΔE for the RF drying treatments compared to the control.

Ans: The data was revised and shown in Table 3.

(7) As it is an industrial scale scaling, it is important to include a cost comparison between conventional treatment and that assisted by radio frequencies. Please include it.

Ans: The author illustrated the specific energy consumption and electricity cost in Table 6.

The revised manuscript was attached. Please see the attachment.

Thank you very much.

Best regards,
Karn Chitsuthipakorn

Round 2

Reviewer 1 Report

The authors have correct my comments; therefore, I agree this manuscript to be published.

Reviewer 2 Report

Accept in present form