Assessment of the Spoilage Microbiota and the Growth Potential of Listeria monocytogenes in Minced Free-Range Chicken Meat Stored at 4 °C in Vacuum: Comparison with the Spoilage Community of Resultant Retail Modified Atmosphere Packaged Products
Round 1
Reviewer 1 Report
Comments and Suggestions for AuthorsIn my opinion, the manuscript should be shortened (some elements of the manuscript are irrelevant for the goal of this study, e.g., introduction section - lines 38-39, etc.; the same results should not be presented in both a table and a diagram) and the number of references should be limited to several recent years.
Moreover, the issue of Listeria monocytogenes requires clarification; why was not the meat tested for L. monocytogenes? why did the samples were inoculated with ca. 3 log cfu/g of Listeria monocytogenes? what determined this level?
The conclusions need improvement. Conclusions should be general and should not be a repetition of other sections.
Author Response
Dear Reviewer 1
Attached please find a PDF file with our itemized responses to your comments.
Sincerely,
John Samelis
Author Response File: 
Author Response.pdf
Reviewer 2 Report
Comments and Suggestions for AuthorsSince you compare the results with a previous study using MAP I’d suggest not mentioning this in the title. It is misleading because the work is not part of this study. The focus of this study is the microbial content in VP poultry. The 2 studies should have been combined into one study. I tend to think the studies were separated to increase “paper count”. It is valid to compare data with previous studies. But in this study, data and graphs are repeated. All material was already available at the time of the first study so it could have been combined. That way, the previous article may even had a higher impact.
The only reason why I don’t reject this paper is because it is well written. Of course, figures help to better understand the differences and therefore it is required to repeat the data of the previous study. But this is also a reason why it is close to rejection for me.
Introduction
Line 50-63: Since you look at organic or free-range poultry, it may also be good to provide data to compare the microbial load with non-organic/free-range housing systems, even though you may reference yourself. However, even if limited, some other data could be shown as well.
Line 80-85: You may need to rephrase the sentence on LAB spoilers and total LAB count. On one hand you say LAB growth is retarted and on the other hand the abundance of LAB is increased. It’s understandable what you mean but not at first read.
Line 98: Typo -> microaerophilic, not microaerohilic
Materials and methods
Line 143-148: What was the inoculation of the strain to grow in BHI? 1 %? Origin frozen stock or agar plate?
Line 171-172: Did MRS contain Tween80?
Line 169-186: I assume all media were purchased from Lab M unless otherwise stated. It is important to tell the manufacturer because there are differences in growth behavior, especially MRS.
Line 207-221: Why didn’t you use MALDI-TOF? Phenotypic assays can help but are not always reliable. 16S identification is nowadays also not a big work anymore.
Line 235-251: If you compare the data with a previous study, don’t mention this in material and methods.
Line 253-261: Were the plates prepared in duplicate? How many biological resp. technical replicates were prepared?
Results
Line 264-275: To compare the batches better statistically, wouldn’t it have been better to have more replicates of the variation AA?
Line 335: Just a note: MRS is not a selective media. Mloulds, yeast, staphylococci etc. grow as well, depending on incubation conditions.
Line 341-345: It could be discussed to move this comparison to the discussion section.
Table 2: Could also be presented as bar chart. Sometimes, visual differences are better read.
Line 378-380: I’m not sure whether I understand this sentence correctly. Again, it is related to how you talk about prevalence.
Line 405: Any idea what caused the malty off-odor?
Line 418-419: Depends on the natural microbiota which may inhibits growth with the cost of off-odor.
Line 436-437: This conclusion is not valid!
Line 443-444: Did you make sure it’s the same strain?
Line 460-461: 16S is not valid to differentiate isolates. You need to better seperate phenotypic and molecular characterization.
Line 469: Typo: melibiose
Table 3: What does +/+d mean? What does account for a very weak reaction?
Line 497-498: You don’t need to repeat data from your previous study in this table. You can compare the data in discussion.
Line 525-526: Even though the concept of strains is currently under discussion, sugar profile only is not valid join isolates as a single strain.
Line 531: not all Facklamia sp. Are pathogenic. They are often found in cheese rind.
Line 534-536: Not surprising. MRS is optimal for lactobacilli, but not selective.
Line 539: Standard MRS allows the growth of Enterococcus sp. With acetic acid to pH 5.7 adjusted MRS might inhibit some strains. But gthis kind of MRS is never mentioned in M&M.
Line 543-545: Might be added to discussion.
Figure 1 and 2: Skip one of them, I suggest skip Figure 1. It is related to Figure 2.
Line 591: Why accidentally?
Line 605-609: This could be moved to discussion and compared there with the conclusion that packaging method had no influence. That way, no data had to be repeated in this article.
Figure 3: In this case, a line graph may be better.
Line 628-629: The data should already have been included in this article.
Discussion
Line 784-786: So, you discuss in the other paper already the results of this paper? Another reason why you better combined those 2 papers…
The “non-growth” of L. monocytogenes should be discussed more intensively.
Comments on the Quality of English LanguageThe english is very good. Some typos have been found.
Author Response
Dear Reviewer 2,
Attached please find a PDF file with our itemized responses to your comments.
Sincerely,
John Samelis
Author Response File: Author Response.pdf
