Respected Author,

The manuscript reports the results related to the possibility of using a direct injection mass spectrometer based on proton transfer reaction (PTR-MS) to monitor the transient changes of the volatile organic compounds (VOCs) during dulce de leche production.
The manuscript analyzes the aroma compound profile, the evolution of volatiles, and physicochemical changes during the processing of dulce de leche, a traditional dairy product from Latin America.

The topic is very interesting, and the authors performed a great number of experiments. In the present paper, the Authors provided an excellent explanation of the results, with clear scientific discussion and a great contribution to the studied field. The manuscript is very clearly written and very understandable.

Few minor suggestions:

Page 4 of 26, Line 30: “sugar (16.5%) glucose (5%)” – Confusing part – For better understanding please provide information related to the sugar used in the formulation.

Page 13 of 26 – Lines 27-38: “For the purposes of this discussion, it is intriguing to conclude that, according to the correlation map of Figure 5, the measurements based on mass fingerprint profile could be used to predict also the textural and rheological changes of a fluid subjected to extensive heating. Further studies should be encouraged to use electronic noses devices based on PTR-MS to further understand the impact of texture and viscosity on the aroma evolution.” - In order to better understand the potential of practical application please provide better explanation should the electronic noses devices based on PTR-MS be used to predict the textural, rheological and other physicochemical changes based on mass fingerprint profile, or to predict its impact on the aroma evolution. Perhaps the authors should pay a little more attention to a better explanation of the possibilities of the practical application of the described method.

The authors should also consider whether any of the compounds formed during the Maillard reaction have a negative impact on health.