Non-Conventional Yeasts as Alternatives in Modern Baking for Improved Performance and Aroma Enhancement
Round 1
Reviewer 1 Report
Zhou et al., reviewed non-conventional yeasts for improved performance and aroma enhancement. Overall, the manuscript contains many general information regarding conventional yeasts, which is a good strategy to bring authors attentions to compare the conventional yeasts with the non-conventional ones. However, this makes the reader difficult to identify the properties of non-conventional ones because of the limited information provided. It is suggested that the authors could focus on those non-conventional ones, for example, their background, applications, and more.
Author Response
- Zhou et al., reviewed non-conventional yeasts for improved performance and aroma enhancement. Overall, the manuscript contains many general information regarding conventional yeasts, which is a good strategy to bring authors attentions to compare the conventional yeasts with the non-conventional ones.
Response: We would like to thank the reviewer for the complement. It is with interest that we highlighted the importance of non-conventional yeasts in baking.
- However, this makes the reader difficult to identify the properties of non-conventional ones because of the limited information provided. It is suggested that the authors could focus on those non-conventional ones, for example, their background, applications, and more.
Response: We would like to thank the reviewer for drawing our attention to these issues. We focused on the background traits of the non-conventional yeasts that are only applicable to baking. There are three attributes we feel we discussed extensively in this review, which are the fermentative capacity of non-conventional yeasts in cereal flour sugars, including their ability to improve bread aroma, the origin of fermentation as a indispensable trait found in both conventional and nonconventional baker´s yeasts and the ability of non-conventional yeasts to tolerate baking associated stresses. We also feel the gaps, limitations and challenges outlined the background of yeasts that could be used for baking and the challenges such as inability to tolerate many baking associated stresses, streamlined metabolism of the sugars found in cereal flour. In addition, since the review is written to fit in the Special Issue in Fermentation: "Non-Saccharomyces Yeasts as Aroma Enhancers in Fermented Products", we only focused on fermentation and aromas.
Reviewer 2 Report
In my opinion the presented manuscript is interesting , but requires some refinement.
Is there any more information about the basic physical characteristics of yeast?
Too general description of aroma formation by unconventional yeasts (references only with GC-MS)
Together, GC-MS / MS and LC-MS / MS are a powerful quantitative tool for the analysis of agrochemicals, secondary metabolites, toxins and other traceable biologically active devices. The gas chromatograph enables complex mixtures, while the spectrometer equipped with two analyzers records the parent and daughter ions formed in the process of electron ionization. Information about the molecular weight of a chemical, the classes used by the mass spectrometer (MS), is often not enough to identify it. Analysis of the fragmentation pattern on tandem mass spectrometers (MS / MS) enables the identification of many television programs. Chromatograms created on the basis of the fragmentation ions of the scenario have a small number of peaks, making them less likely to strike a mutual overlap, which is extremely important in food, biological or environmental samples. This allows to asking my the next question. Are there no publications which characterized the products of these yeasts with GC-MS / MS. This would be the answer to whether the unconventional yeast are GRAS.
Author Response
- In my opinion the presented manuscript is interesting, but requires some refinement.
Response: We would like to thank the reviewer for the complement.
- Is there any more information about the basic physical characteristics of yeast?
Response: We would like to think that information on utilisation of a wide range of flour sugars, ability to ferment them and the ability to withstand baking associated stresses are the most important attributes towards development of non-conventional yeasts as alternative baker´s yeasts. We have since taken this course in this review.
- Too general description of aroma formation by unconventional yeasts (references only with GC-MS).Together, GC-MS/MS and LC-MS/MS are a powerful quantitative tool for the analysis of agrochemicals, secondary metabolites, toxins and other traceable biologically active devices. The gas chromatograph enables complex mixtures, while the spectrometer equipped with two analyzers records the parent and daughter ions formed in the process of electron ionization. Information about the molecular weight of a chemical, the classes used by the mass spectrometer (MS), is often not enough to identify it. Analysis of the fragmentation pattern on tandem mass spectrometers (MS/MS) enables the identification of many television programs. Chromatograms created on the basis of the fragmentation ions of the scenario have a small number of peaks, making them less likely to strike a mutual overlap, which is extremely important in food, biological or environmental samples. This allows to asking my the next question. Are there no publications which characterized the products of these yeasts with GC-MS/MS. This would be the answer to whether the unconventional yeast are GRAS.
Response: The authors agree with the fact that there are other more powerful analytical tools than GC-MS, however, there is scarce information related to volatiles production by non-conventional yeasts in the bakery and analyses using LC-MS/MS, GC-MS/MS for example. We commented on all the research work we found related to the contribution of non-conventional yeasts to bread aroma and in all of them GC or GC-MS or sensory analyses were commonly employed as analytical tools.
Regarding GRAS or QPS status of the non-conventional yeasts, there are comments on this in lines 52, 121 and 418.
Reviewer 3 Report
Dear Authors,
After the review process, I have several comments: you should include new data that are based on the S.c. utilization as a lab in vivo tools. These aspects are relevant in the bioavailability and bioactivities of functional (polyphenols) extracts after in vitro digestion. Also, the bioactive potential of functional products and bioavailability of phenolic compounds could be relevant in bread production and obtaining products with functional properties. References from the introduction are too old, more than five years; you should insert new references that use Saccharomyces strains.
Best regards.
Author Response
- After the review process, I have several comments: you should include new data that are based on the S.cerevisiae utilization as a lab in vivo tools. These aspects are relevant in the bioavailability and bioactivities of functional (polyphenols) extracts after in vitro digestion.
Responses: We would like to thank the reviewer for drawing our attention to these issues. Despite being interest information, we wish to exclude that info at is not relevant to fermentation and aromatic attributes of non-conventional yeasts as baker’s yeasts, which is the focus of the Special Issue "Non-Saccharomyces Yeasts as Aroma Enhancers in Fermented Products".
- Also, the bioactive potential of functional products and bioavailability of phenolic compounds could be relevant in bread production and obtaining products with functional properties.
Response: The bioactive and functional attributes of phenolic compounds are important but they do not fit in the Special Issue so we only focused on fermentation and aromas.
- References from the introduction are too old, more than five years; you should insert new references that use Saccharomyces strains.
Response: We have now inserted new references.
Round 2
Reviewer 1 Report
Zhou et al., reviewed non-conventional yeasts for improved performance and aroma enhancement. Overall, the manuscript contains many general information regarding conventional yeasts, which is a good strategy to bring authors attentions to compare the conventional yeasts with the non-conventional ones. However, this makes the reader difficult to identify the properties of non-conventional ones because of the limited information provided. It is suggested that the authors could focus on those non-conventional ones, for example, their background, applications, and more.
Author Response
This review tries to show a comparison between conventional baker´s yeast and non-conventional ones (NCY) regarding their potential to be used in baking. To this purpose, first we present the drawbacks and limitations of conventional baker´syeast and afterwards show some examples of NCY that have potential to overcome those dificulties (examples in lines 189-191, 197-201, 258-261, 322-340). This is done taking into account the most relevant traits of interest in baking (assimilation and fermentation of flour sugars, tolerance to several stresses and aroma synthesis).
However, despite being several NCY presenting potential, just few attempts have been done to test these species in baking and this is why is not possible to be more extensive in the description of applications. These few attempts are described in subsection “6. Aromatic diversity of non-conventional yeasts: a key trait sought for in baking yeasts”.
Reviewer 2 Report
I have not comments
Author Response
.
Reviewer 3 Report
Dear Authors,
No more comments than the first phase of the review.
Best regards.
Author Response
.
