Comparative Study between Current Practices on Cassava Drying by Small-Size Enterprises in Africa

Round 1

Reviewer 1 Report

Article present limited results of technical experiment with the use of two type of cassava dryers. The technical experiment seems to be succesfull, however organisational and economic aspects are very limited and poor.

Article has a very narrow scope of the subject of study. It compare technical and partly economical efficiences of the two type of dryers, of which that more advanced pneumatic dryer seems, without doing research,  more innovative and efficient without studies.

There is lack of knowledge and information on the enterprise in which experiment was done, about the whole small-scale processing (drying) sector, about   links of small scale drying firms with farming cassava sector and relation  of this sector to more advanced large cassaava processing industry. Cost calculations needs  improvement and better erxplanation.

 To whom the research results are addressed?

 

Author Response

• “Article present limited results of technical experiment with the use of two type of cassava dryers. The technical experiment seems to be successful, however organisational and economic aspects are very limited and poor”

The organizational aspect has been further explained (lines 117–118 and lines 121–122) and the economic aspect expanded (lines 273–277 and lines 473–478).

• “Article has a very narrow scope of the subject of study. It compares technical and partly economical efficiencies of the two type of dryers, of which that more advanced pneumatic dryer seems, without doing research, more innovative and efficient without studies.”

Indeed, a study comparing only the energy efficiency of those two dryers would not be necessary. For material that can be pneumatically conveyed, like wet cassava grits, pneumatic dryers will virtually be always more efficient than fixed-bed dryers because of the better contact between the solid and the hot air. The text on lines 53–54 and line 108 has been edited to make this clearer and to better explain that objective of this study was not to determine which dryer is more efficient but to find out which dryer is better for the small-scale cassava processing operation. For this reason, energy efficiency was evaluated, along with product quality and costs.

• “There is lack of knowledge and information on the enterprise in which experiment was done, about the whole small-scale processing (drying) sector, about links of small scale drying firms with farming cassava sector and relation of this sector to more advanced large cassava processing industry. Cost calculations needs improvement and better explanation”

A description of the processing enterprise operation and its links with the cassava farming sector has been added (lines 117–118) and Figure 1 (line 130) amended accordingly. The role of the large-scale cassava processing industry in Africa has been added  (lines 46–49) and the explanation on cost calculations have been improved (lines 273–275).

• “To whom the research results are addressed?”

The application of the findings has been added (lines 109–112).

Author Response File: Author Response.pdf

Reviewer 2 Report

This research work shows an extensive comparison between the two most common cassava drying machines employed at small scale in Africa. The topic is suitable for the scope of the journal and the MS is well written. However, I have a big concern regarding the significance of the results. The authors state that the confidence level of the statistical analyses is only 5%, which is not strong enough to extract reliable conclusions. I do not know if this is a mistake. Typically, the confidence level is 95%...

Specific comments:

Keywords: some of them are not named in the text. If they are so important to be keywords they should appear explained in the text. Are some of them synonyms of the compared drying machines?

Figure 2 (a): top view or side view?

Statistical analysis: Line 154: 5% of significant level? Maybe the authors wanted tos ay 95%? Otherwise the significance is too low to be considered. Please, check the rest of the MS in this sense.

Tables: better specify that different letters indicate significant differences instead that the same letters indicate no significant differences. It is better to put more stress in differences.

Table 3: please, indicate the letters as superscrips as in the other tables.

Author Response

• “This research work shows an extensive comparison between the two most common cassava drying machines employed at small scale in Africa. The topic is suitable for the scope of the journal and the MS is well written. However, I have a big concern regarding the significance of the results. The authors state that the confidence level of the statistical analyses is only 5%, which is not strong enough to extract reliable conclusions. I do not know if this is a mistake. Typically, the confidence level is 95%.”

Differences were considered significant when the p-value was less than alpha (p < α), and an alpha of 0.05 was used (α = 5%). Lines 168–171 have been added to the Statistical Analysis section to better explain it.

• “Keywords: some of them are not named in the text. If they are so important to be keywords, they should appear explained in the text. Are some of them synonyms of the compared drying machines?”

The keywords have been incorporated into the text and alternative names are now described (line 59, lines 62–63, lines 78–79).

• “Figure 2 (a): top view or side view?”

Figure 2a shows a top view of the fixed-bed dryer and Figure 2b shows a side-view of the pneumatic dryer. To make it easier to understanding additional isometric views of each dryer have been added (line 164).

• “Statistical analysis: Line 1 54: 5% of significant level? Maybe the authors wanted to say 95%? Otherwise the significance is too low to be considered. Please, check the rest of the MS in this sense.”

Difference were considered significant when p-value was less than 0.05 (p < 0.05).

• “Tables: better specify that different letters indicate significant differences instead that the same letters indicate no significant differences. It is better to put more stress in differences.”

Tables footnote has been rewritten (lines 293–294, lines 336–337, and lines 417–418).

• “Table 3: please, indicate the letters as superscripts as in the other tables.”

Tables footnote has been amended (lines 293–294, lines 336–337, and lines 417–418).

Author Response File: Author Response.pdf

Reviewer 3 Report

This manuscript presents an interesting discussion on the performance of two well-known drying processes, namely fixed-bed drying and pneumatic drying, for the drying of cassava. I find this manuscript well written and would support its publication in Applied Sciences journal, provided that the authors address the following points:

• Introduction:
  • There is a clear lack of more recent publications addressing the thermal characteristics of both these processes. There are indeed many papers published in the literature/peer-reviewed journals addressing the thermal characteristics of these processes through thermodynamic analyses, CFD, etc. (not for processing cassava but for many other types of materials). The authors should do a far more comprehensive literature search and mention/cite some of those papers.
  • The authors should provide a table in the Introduction highlighting the major characteristics/pros and cons of both drying processes (taking data/information from the literature). This information can be qualitative, since ins this manuscript the authors are studying and providing quantitative data in regards to processing efficiency.
  • At the end of introduction the authors mention the final conclusions. Conclusions should be provided in the corresponding Conclusions section, not in the Introduction.
• Materials and Methods:
  • Figure 1 (similarly to a few other figures) is of poor quality and it is not possible to see the full image because it is cut.
  • Figure 2, or another figure, should provide a detailed representation of both dryers, including all the components. This section only describes the various components of the dryers in the text but it is important to have a (more detailed) visual representation of the dryers.
• Results and Discussion
  • What are the CQAs (critical quality attributes) of the cassava grits and cassava flour, including the granule/particles size?

Author Response

• “There is a clear lack of more recent publications addressing the thermal characteristics of both these processes. There are indeed many papers published in the literature/peer-reviewed journals addressing the thermal characteristics of these processes through thermodynamic analyses, CFD, etc. (not for processing cassava but for many other types of materials). The authors should do a far more comprehensive literature search and mention/cite some of those papers.”

The Introduction section has been expanded (lines 71–75) and a table providing an overview of the thermal characteristics of both dryers added (line 76). Additionally, more recent references have been cited (lines 546–547, lines 551–552, lines 56–557, lines 558–559, lines 560–561, and lines 567–569).

• “The authors should provide a table in the Introduction highlighting the major characteristics/pros and cons of both drying processes (taking data/information from the literature). This information can be qualitative since ins this manuscript the authors are studying and providing quantitative data in regard to processing efficiency.”

A table has been added to the Introduction (line 76).

• “At the end of introduction, the authors mention the final conclusions. Conclusions should be provided in the corresponding Conclusions section, not in the Introduction.”

It has been removed from the Introduction section (lines 108–109).

• “Figure 1 (similarly to a few other figures) is of poor quality and it is not possible to see the full image because it is cut.”

All figures in the manuscript were prepared using a vector graphics format (EPS). Different than raster images, vector images do not use pixels, allowing it to be scaled up and down without any loss to the quality of the image. When the journal processed the file to send it for review, it might have converted the vector images to raster, reducing its quality. This issue, however, should not occur when the manuscript is published, as PDF files support vector images natively. Nevertheless, high-resolution raster images (TIFF) will be supplied complementary to the vector images. The issue of the image being cut in Figure 1 and Figure 3 has been corrected (line 130 and line 337).

• “Figure 2, or another figure, should provide a detailed representation of both dryers, including all the components. This section only describes the various components of the dryers in the text, but it is important to have a (more detailed) visual representation of the dryers”

A figure has been added to the manuscript depicting all the components of both dryers (line 164).

• “What are the CQAs (critical quality attributes) of the cassava grits and cassava flour, including the granule/particles size?”

While cassava starch, as a commodity, has clear and specific critical quality attributes, the same is not true for cassava flour, as a food. Lines 121–122 have been added explaining that wholesalers consider moisture content (mentioned in lines 328–329) and appearance (further explained in lines 421–423) when evaluating the product quality.

Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

The table 1 contents are not clear and needs e better explanation. What does mean number of ++ and numbers in [20]? Table needs also source of the data.

Authors responses for first rewiew  are acceptable.

Paper has been extended and improved to the level of acceptance after some minor improvements.

Conclusions still are limited, may be extended and improved for instance on reccomendations directed to producers, policy makers and researchers, ect.

Author Response

“The table 1 contents are not clear and needs e better explanation. What does mean number of ++ and numbers in [20]? Table needs also source of the data.”

Table 1 caption has been amended and an explanation about the meaning of the plus (+) sign has been added (lines 76–77). In addition, a footnote has been added to Table 1, clarifying that the numbers inside the square brackets (i.e. [20]) denote the sources of the data.

“Authors responses for first rewiew are acceptable. Paper has been extended and improved to the level of acceptance after some minor improvements.”

We would like to thank t Reviewers 1 for their helpful, constructive, and pertinent suggestions, as they helped us improve the quality and scientific expressiveness of this paper.

“Conclusions still are limited, may be extended and improved for instance on reccomendations directed to producers, policy makers and researchers, ect.”

Conclusions have been amended, explaining the importance of this research to cassava processors, policymakers, and researchers (lines 489–490). Accordingly, a mention to policymakers has been added to the Introduction section (line 112–113).

Author Response File: Author Response.pdf

Reviewer 2 Report

The authors have properly adressed all the suggestions. 

Author Response

“The authors have properly adressed all the suggestions.”

We would like to thank Reviewer 2 for their helpful, constructive, and pertinent suggestions, as they helped us improve the quality and scientific expressiveness of this paper.

Author Response File: Author Response.pdf