Increasing the Sustainability of the Coffee Agro-Industry: Spent Coffee Grounds as a Source of New Beverages

Round  1

Reviewer 1 Report

The topic is interesting. The use of waste products rich in organoleptically active compounds is the right trend.

During the reading of the manuscript, some questions and comments came up and pointed below:

Page 2, line 70: The word „ portuguese” should be replaced with „ Portuguese”.

Page 2, lines 79-81: Better will be: „Prior to extraction, SCG was mixed with water using water (mL) to material (g) ratio 20:1. The extraction conditions were as follow microwave power 71 %, pressure 120 psi, time 20 min.”

Page 2, lines 83 and 84: Instead of the term „… in the concentration of …” better will be used term: „..to a final concentration of …”

Page 2, line 88: The name of the yeast Saccharomyces cerevisiae should be given in italics. Please, check the whole text.

Page 3, line 99: The word „erlenmeyer” should be replaced with „Erlenmeyer”.

Page 3, line 106: The sentence: „Fermentations were incubated at 30 ºC and 150 rpm.” should be supplemented: „Fermentations were incubated at 30 ºC with continuous stirring at 150 rpm.”

Page 4, lines 153-154: The authors wrote that: „… the split ratio was 15 mL/min.” Split ratio should be given for example: 10:1, 5:1, 100:1, etc.

Page 4, Pages 158-162: What was the recovery values of the used extraction method?

Page 5, lines 235-237: The authors wrote: “In fermented beverage 1 (F1) the most present compound was acetaldehyde (339.6 mg/L), followed by the higher alcohols isobutanol and isoamylic (2–methyl–1–propanol and 3–methyl–1–butanol) (152.1 mg/L and 106.8 mg/L, respectively”

This sentence will be more clear in the following form: “In fermented beverage 1 (F1) the most present compound was acetaldehyde (339.6 mg/L), followed by two higher alcohols, i.e. 2–methyl–1–propanol (152.1 mg/L) and 3–methyl–1–butanol (106.8 mg/L).”

Page 6, lines 246-247: The authors wrote: “… isopentyl alcohol (2-methyl-1-butanol)..”. Isopentyl alcohol is the chemical name of isoamyl alcohol, i.e. 3-methyl-1-butanol. The chemical name of 2-methyl-1-butanol is “active amyl alcohol”.

Page 6, lines 249-250:

Is - “…….. highest concentration were isoamyl alcohols, isobutanol, 2-methyl-1-butanol …”.

Should be – “……highest concentration were isoamyl alcohol, isobutyl alcohol, active amyl alcohol …” or “……highest concentration were 3-methyl-1-butanol, 2-methyl-1-propanol, 2-methyl-1-butanol …”

Page 7, line 302: The word „2–furanmetahnol” should be replaced with „2–furanmethanol”.

Page 7, lines 329-331: Moreover, furfural is compound occurring during processes that involve heating or roasting, for example roasting of coffee beans.

Author Response

The topic is interesting. The use of waste products rich in organoleptically active compounds is the right trend. Done

During the reading of the manuscript, some questions and comments came up and pointed below:

Page 2, line 70: The word „ portuguese” should be replaced with „ Portuguese”. Done

Page 2, lines 79-81: Better will be: „Prior to extraction, SCG was mixed with water using water (mL) to material (g) ratio 20:1. The extraction conditions were as follow microwave power 71 %, pressure 120 psi, time 20 min.” Done

Page 2, lines 83 and 84: Instead of the term „… in the concentration of …” better will be used term: „..to a final concentration of …” Done

Page 2, line 88: The name of the yeast Saccharomyces cerevisiae should be given in italics. Please, check the whole text. Done

Page 3, line 99: The word „erlenmeyer” should be replaced with „Erlenmeyer”. Done

Page 3, line 106: The sentence: „Fermentations were incubated at 30 ºC and 150 rpm.” should be supplemented: „Fermentations were incubated at 30 ºC with continuous stirring at 150 rpm.” Done

Page 4, lines 153-154: The authors wrote that: „… the split ratio was 15 mL/min.” Split ratio should be given for example: 10:1, 5:1, 100:1, etc. Done

Page 4, Pages 158-162: What was the recovery values of the used extraction method? We have an article in preparation about the method and the response factors for several of these compounds (not for everyone). But it has not been published yet. Therefore, in this work, the concentrations are presented as 4-nonanol equivalents.

Page 5, lines 235-237: The authors wrote: “In fermented beverage 1 (F1) the most present compound was acetaldehyde (339.6 mg/L), followed by the higher alcohols isobutanol and isoamylic (2–methyl–1–propanol and 3–methyl–1–butanol) (152.1 mg/L and 106.8 mg/L, respectively” Done

This sentence will be more clear in the following form: “In fermented beverage 1 (F1) the most present compound was acetaldehyde (339.6 mg/L), followed by two higher alcohols, i.e. 2–methyl–1–propanol (152.1 mg/L) and 3–methyl–1–butanol (106.8 mg/L).” Done

Page 6, lines 246-247: The authors wrote: “… isopentyl alcohol (2-methyl-1-butanol)..”. Isopentyl alcohol is the chemical name of isoamyl alcohol, i.e. 3-methyl-1-butanol. The chemical name of 2-methyl-1-butanol is “active amyl alcohol”. Done

Page 6, lines 249-250:

Is - “…….. highest concentration were isoamyl alcohols, isobutanol, 2-methyl-1-butanol …”.

Should be – “……highest concentration were isoamyl alcohol, isobutyl alcohol, active amyl alcohol …” or “……highest concentration were 3-methyl-1-butanol, 2-methyl-1-propanol, 2-methyl-1-butanol …” Done

Page 7, line 302: The word „2–furanmetahnol” should be replaced with „2–furanmethanol”. Done

Page 7, lines 329-331: Moreover, furfural is compound occurring during processes that involve heating or roasting, for example roasting of coffee beans. Done

Reviewer 2 Report

This paper describes the characteristics of coffee byproducts and shows the possibility that coffee byproducts may be applied to various foods. I have not found serious errors and data acqusition process seems reasonable. Therefore, I'd like to support the publication of this paper as a reviewer of mdpi.

Author Response

Thank you very much for your feedback. Best Regards.

Reviewer 3 Report

The introduction provides sufficient background and includes all relevant references (with DOI identifiers). The design of the study is appropriate; analytical methods and organoleptic procedures appear adequately described. Obtained results are clearly presented and evaluated; final conclusions are supported by obtained data.

Author Response

Thank you very much for your feedback. Best Regards.