Effect of Mixed Cultures on Microbiological Development in Berliner Weisse Beer
Round 1
Reviewer 1 Report
Comments and Suggestions for Authors
The objective of this study was to monitor the fermentation behavior of six strains used in the past for traditional commercial Berliner Weisse beer production. This results show that it is possible to produce an acidic and tart beer using a mixed population of the microorganisms previously selected. End pH values and acidity reached levels acceptable for Berliner Weisse beer. However, it took approximately two months of bottle conditioning at 12°C so that the beers fermented with the three microorganisms could be considered acidic. Some issues need to be improved.
(1) 'hours' should be 'days' in this paper.
(2) Table 4 should be improved.
(3) In Highlights, there should be a statement that the method compared favourably with the results in the literature.
(4) 2. Material and Methods there should be a statement that what are F1, F2......
Comments on the Quality of English Language
Minor editing of English language required
Author Response
Dear revisor,
we made all the modification in the revised manuscript with green color. Thanks for the review.
The manuscript addresses a practical approach to be used by brewers during sour beer production when they are looking for microbiological parameters in relation to final beer quality. In addition, it addresses the topic of Brettanomyces spp. use in brewing, a subject that was less reported.
Introduction: while the title and the study main objective is related to traditional commercial Berliner Weisse, in the introduction is not provided any information on this type of beer, its characteristics, and WHY was taken into account as study subject in a Brazilian context (as written in the Abstract).
Answer: We modified and removed the Brazilian context
Line 93: on what kind of information you rely when you make the statement “There seems to be a trend…”. Please, be more specific.
Answer: We modified in the manuscript and explaining. Line 90-93
There seems to be a tendency for breweries to use a triad Saccharomyces, lactic acid bacteria, and Brettanomyces strains to produce mixed fermented sour beers, specially for Berliner Weisse style.
✅Line 102: is it “On the other end”? or hand?
Answer: We modified to hand (line 100)
✅Line 116-117: Please add all the study objectives, not only “an evaluation of the isolation and culturabilty capacity of these strains on selective media”, according to your results.
Answer: line 110-129
In this study, the sour beer selected was Berliner Weisse. According to Beer Judge Certification Program (BJCP), this beer style is characterized as a pale color, refreshing, low-alcohol German wheat beer with a clean lactic sourness and a very high carbonation level. A light bread dough malt flavor supports the sourness, which shouldn’t seem artificial. Any Brettanomyces funk is restrained. The wheat aroma may present as uncooked bread dough in fresher versions; combined with the acidity, may suggest sourdough bread. The receipt may content wheat malt, typically 50% of the grist with the remainder typically being Pilsner malt. A symbiotic fermentation with top-fermenting yeast and Lactobacillus (various strains) provides the sharp sourness, which may be enhanced by blending of beers of different ages during fermentation and by extended cool aging. German brewing scientists believe that Brettanomyces is essential to get the correct flavor profile, but this character is never strong. Compared to a lambic, is generally not as acidic and has a clean lactic sourness with restrained to below sensory threshold funk. Also lower in alcohol content (BJCP, 2021).
The objective of this study was to monitor the fermentation behavior of six strains used in the past for traditional commercial Berliner Weisse beer production. When working with mixed cultures in a brewery it is important to be able to separate different microorganisms and ascertain that cross contamination is not occurring. For that reason an evaluation of the isolation and culturabilty capacity of these strains on selective media was carried, looking for scape up to input some innovations in sour beer production, who has potential to innovate in Berliner Weisse and Catharina Sour styles and other.
Line 183 &187: Please explain what represent S1, S2, l1 and L2 and their origins
Answer: line 190-192, 195-196 and Table 2
✅Line 287: is it vital strains or vital stains?
Answer: we modified to vital strains
Line 296: please explain what F1 (and the other Fn) represents
Answer: Table 2
Line 309: can you explain how significant is the difference in the initial CFU levels, respectively between 5x106 (equivalent of 0.5x107) and 1x107? They are almost the same (107 CFU/mL)
Answer: line 483-486
So the pitch rate used, and the CFU results after all, were twice the number of cells that were added. The fact that the relationship between Saccharomices, Lactobacilli and Brettanomyces did not maintain after fermentation ends was one of the most decisive factors for the decline in the production of traditional Berliner weisse.
✅Line 498: delete Colomer et al. (repetitive info)
Answer: we removed
✅Line 506: the affirmation “studies on bacterial growth for beer production are relatively sparse” is too generic; several reports on lactic bacteria use in sour beer can be addressed in the discussions’ section (e.g. https://doi.org/10.1002/jib.569)
Answer: we add more references about
✅Lines 517-546: results obtained on Brettanomyces are insufficiently compared to data reported by other authors, from different point of view, including data already listed in the references like Colomer et al., 2020 (e.g. https://doi.org/10.1002/jib.580)
Answer: we added more references and made a better discussion about
✅Line 555: is it “selecting” or “isolating”? selection is for different useful parameters...
Answer: we corrected the mistake
Line 563: which results are supporting the conclusion ”Autolysis might be an interesting source of nutrients”?
Answer: we add more references to justify what was observed in the discussion.
Reviewer 2 Report
Comments and Suggestions for Authors
The manuscript addresses a practical approach to be used by brewers during sour beer production when they are looking for microbiological parameters in relation to final beer quality. In addition, it addresses the topic of Brettanomyces spp. use in brewing, a subject that was less reported.
Introduction: while the title and the study main objective is related to traditional commercial Berliner Weisse, in the introduction is not provided any information on this type of beer, its characteristics, and WHY was taken into account as study subject in a Brazilian context (as written in the Abstract).
Line 93: on what kind of information you rely when you make the statement “There seems to be a trend…”. Please, be more specific.
Line 102: is it “On the other end”? or hand?
Line 116-117: Please add all the study objectives, not only “an evaluation of the isolation and culturabilty capacity of these strains on selective media”, according to your results.
Line 183 &187: Please explain what represent S1, S2, l1 and L2 and their origins
Line 287: is it vital strains or vital stains?
Line 296: please explain what F1 (and the other Fn) represents
Line 309: can you explain how significant is the difference in the initial CFU levels, respectively between 5x106 (equivalent of 0.5x107) and 1x107? They are almost the same (107 CFU/mL)
Line 498: delete Colomer et al. (repetitive info)
Line 506: the affirmation “studies on bacterial growth for beer production are relatively sparse” is too generic; several reports on lactic bacteria use in sour beer can be addressed in the discussions’ section (e.g. https://doi.org/10.1002/jib.569)
Lines 517-546: results obtained on Brettanomyces are insufficiently compared to data reported by other authors, from different point of view, including data already listed in the references like Colomer et al., 2020 (e.g. https://doi.org/10.1002/jib.580)
Line 555: is it “selecting” or “isolating”? selection is for different useful parameters...
Line 563: which results are supporting the conclusion ”Autolysis might be an interesting source of nutrients”?
Author Response
Dear reviewer
we modificed all the suggestions with green color.
Introduction: while the title and the study main objective is related to traditional commercial Berliner Weisse, in the introduction is not provided any information on this type of beer, its characteristics, and WHY was taken into account as study subject in a Brazilian context (as written in the Abstract).
Answer: We modified and removed the Brazilian context
Line 93: on what kind of information you rely when you make the statement “There seems to be a trend…”. Please, be more specific.
Answer: We modified in the manuscript and explaining. Line 90-93
There seems to be a tendency for breweries to use a triad Saccharomyces, lactic acid bacteria, and Brettanomyces strains to produce mixed fermented sour beers, specially for Berliner Weisse style.
✅Line 102: is it “On the other end”? or hand?
Answer: We modified to hand (line 100)
✅Line 116-117: Please add all the study objectives, not only “an evaluation of the isolation and culturabilty capacity of these strains on selective media”, according to your results.
Answer: line 110-129
In this study, the sour beer selected was Berliner Weisse. According to Beer Judge Certification Program (BJCP), this beer style is characterized as a pale color, refreshing, low-alcohol German wheat beer with a clean lactic sourness and a very high carbonation level. A light bread dough malt flavor supports the sourness, which shouldn’t seem artificial. Any Brettanomyces funk is restrained. The wheat aroma may present as uncooked bread dough in fresher versions; combined with the acidity, may suggest sourdough bread. The receipt may content wheat malt, typically 50% of the grist with the remainder typically being Pilsner malt. A symbiotic fermentation with top-fermenting yeast and Lactobacillus (various strains) provides the sharp sourness, which may be enhanced by blending of beers of different ages during fermentation and by extended cool aging. German brewing scientists believe that Brettanomyces is essential to get the correct flavor profile, but this character is never strong. Compared to a lambic, is generally not as acidic and has a clean lactic sourness with restrained to below sensory threshold funk. Also lower in alcohol content (BJCP, 2021).
The objective of this study was to monitor the fermentation behavior of six strains used in the past for traditional commercial Berliner Weisse beer production. When working with mixed cultures in a brewery it is important to be able to separate different microorganisms and ascertain that cross contamination is not occurring. For that reason an evaluation of the isolation and culturabilty capacity of these strains on selective media was carried, looking for scape up to input some innovations in sour beer production, who has potential to innovate in Berliner Weisse and Catharina Sour styles and other.
Line 183 &187: Please explain what represent S1, S2, l1 and L2 and their origins
Answer: line 190-192, 195-196 and Table 2
✅Line 287: is it vital strains or vital stains?
Answer: we modified to vital strains
Line 296: please explain what F1 (and the other Fn) represents
Answer: Table 2
Line 309: can you explain how significant is the difference in the initial CFU levels, respectively between 5x106 (equivalent of 0.5x107) and 1x107? They are almost the same (107 CFU/mL)
Answer: line 483-486
So the pitch rate used, and the CFU results after all, were twice the number of cells that were added. The fact that the relationship between Saccharomices, Lactobacilli and Brettanomyces did not maintain after fermentation ends was one of the most decisive factors for the decline in the production of traditional Berliner weisse.
✅Line 498: delete Colomer et al. (repetitive info)
Answer: we removed
✅Line 506: the affirmation “studies on bacterial growth for beer production are relatively sparse” is too generic; several reports on lactic bacteria use in sour beer can be addressed in the discussions’ section (e.g. https://doi.org/10.1002/jib.569)
Answer: we add more references about
✅Lines 517-546: results obtained on Brettanomyces are insufficiently compared to data reported by other authors, from different point of view, including data already listed in the references like Colomer et al., 2020 (e.g. https://doi.org/10.1002/jib.580)
Answer: we added more references and made a better discussion about
✅Line 555: is it “selecting” or “isolating”? selection is for different useful parameters...
Answer: we corrected the mistake
Line 563: which results are supporting the conclusion ”Autolysis might be an interesting source of nutrients”?
Answer: we add more references to justify what was observed in the discussion.
