Pineapple Waste Cell Wall Sugar Fermentation by Saccharomyces cerevisiae for Second Generation Bioethanol Production

Round 1

Reviewer 1 Report

The paper “Pineapple waste cell wall sugar fermentation by Saccharomyces cerevisiae for second generation bioethanol production” is focused on the evaluation of pineapple waste cell wall sugars as an alternative source of second-generation bioethanol by a commercial strain of Saccharomyces cerevisiae. This topic is of relevant interest in the concept of sustainable agriculture, suggesting an applicative process to increase the bioethanol production. The experimental plan is well organized and the methods are clearly described in detail and therefore reproducible. The paper merits to be published after a minor revision, regarding in particular:

Legend of Table 1. Eliminate proximate

Table 2 and 3:  At the foot of the table, specify the abbreviation UA = uronic acid

Line 257 Correct Figure 1 shows……

Lines 274–275 The second part of this sentence need to be corrected. Instead of “whereas in the soluble fraction could be detected Xyl, Ara, Glu and UA”, for example “…..,whereas Xyl, Ara, Glu and UA could be detected in the soluble fraction”

Line 277 S. cerevisiae in italics

Lines-278 ……., the yeast was…     Better to say: this yeast species….

Line 303 S. cerevisiae in italics

Line 317 … spp. should not be written in italics

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Salafia F., Ferracane A. and Tropea A. investigated the bioconversion of pineapple waste (peel and core only) to bioethanol by simultaneous saccharification and fermentation. This study indicates the possibility of using pineapple waste as a fermentation medium, which has already been shown previously.

Comments:

1. What is the novelty of the study? For example, how is the study different from the previous one (reference 25: Tropea A. et al. Journal of Biological Research (Italy), 2015), where the same substrate was used, the same enzymes, carried out by SSF, and ethanol was obtained with the same concentration of 3.9% (v/v)? The novelty should be specifically reflected in the introduction.
2. In the part of the literature review, well-known, widely cited publications in the field of bioconversion of pineapple waste into bioethanol are ignored, for example:

Chintagunta AD, Ray S, Banerjee R. An integrated bioprocess for bioethanol and biomanure production from pineapple leaf waste // JOURNAL OF CLEANER PRODUCTION. 2017.  V. 165. P. 1508-1516. DOI: 10.1016/j.jclepro.2017.07.179.

Segui Gil L, Fito Maupoey P An integrated approach for pineapple waste valorisation. Bioethanol production and bromelain extraction from pineapple residues // JOURNAL OF CLEANER PRODUCTION. 2018. Vol. 172. P. 1224-1231 DOI: 10.1016/j.jclepro.2017.10.284.

Casabar JT, Unpaprom Y, Ramaraj R. Fermentation of pineapple fruit peel wastes for bioethanol production // BIOMASS CONVERSION AND BIOREFINERY. 2019.  Vol. 9(4). P. 761-765. DOI: 10.1007/s13399-019-00436-y.

3. The introduction talks about the prospects of such pineapple waste as fruit peel and crown for obtaining bioethanol, and only peel and core were taken for the study. Why?
4. The yield of ethanol should be presented, calculated not from the loss of dry matter, but from the initial concentration of dry matter.

Please note that throughout the text it is necessary to bring to uniformity the way of separating the integer and fractional parts of numbers (dot or comma).

Author Response

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Author Response File: Author Response.pdf

Reviewer 3 Report

General comments

In this study, the authors produced ethanol from pineapple wastes via simultaneous saccharification and fermentation using Saccharomyces cerevisiae. The authors detected Glucose, Xylose, and Uronic Acid at the beginning of the fermentation whereas glucose and mannose comprised the majority of soluble sugar fractions. The final fermentation substrate was mainly pentoses and ethanol production reached 85% of the theoretical yield. The protein content also increased tremendously during the process. However, there are many significant issues in their manuscript that need to be addressed.  First, figures and tables are not presented well thereby affecting the overall presentation of scientific data. Second, there are typographical (typos) and grammatical errors in this paper that need to be corrected to ensure clarity. Finally, the authors should take note of the clarity of their main text, presentation and interpretation, and discussion.  I would recommend the resubmission of this paper after addressing the following issues:

Specific comments

Abstract

1. Please specify the specific Saccharomyces cerevisiae used in the study.
2. First letters of sugars (i.e. Glucose, Xylose, Uronic Acid, and Mannose) should not be capitalized.
3. Page 1, Line 21: I think 32,12 % is a typo instead write 32.12 %. This type of error was observed in the whole manuscript. Please modify.
4. Page 1, Line 23-24: I think the first letters of the words “Theoretical Yield” should not be capitalized instead write theoretical yield.
5. Page 1, Line 24: Typo similar to above mentioned comment (4.45 % instead of 4, 45 %).

Materials and Methods

1. Please cite appropriate reference(s), if there is any, for lines 97, 101, 104, 109, 114, 131, 157-162, and 191-206.

Results and Discussions

1. Please check for grammatical errors, spelling, and punctuations.
2. Page 5, lines 219-220: Check for the spelling of light blue.
3. Page 5, lines 224-226: Did the authors detect D-galacturonic acid via HPLC? If yes, please include this data.
4. Also, specify the configuration of sugars for example “arabinose”. There is D-arabinose and L-arabinose, which of which?

Figure and tables:

1. Page 5, figure 1: Please increase the resolution and remove the line background.
2. Page 5-6, Tables 1, 2, and 3: Please refer to comment number 3 (Abstract).
3. Tables 1 and 2 should be presented in figures to make them catchier and more understandable. Numbers presented in these tables might be confusing for the readers.

 

 

 

 

 

 

Author Response

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Author Response File: Author Response.pdf