de Pablo Group: Johnny Alfaro

Graduate Student

de Pablo Group

Start date:

August 2013


  • Address

    Eckhardt Research Center
    Room 251
    5640 South Ellis Avenue
    Chicago, IL 60637

  • Email


Probiotics are strains of lactic acid bacteria that have been applied to the treatment of gastro-intestinal diseases and shown to improve the digestion of dairy products in sensitive population. Even though probiotics have proved to possess beneficial effects on human health, once they are produced, their life span is usually reduced to a couple of hours. This situation occurs when bacteria stay in contact with water; for example, in their culture medium or exposed to the environment. To tackle this problem, several methods have been developed to reduce the negative effect of water and to extend the lifetime of probiotics.

Freeze-drying is a method that can increase the lifetime of bacteria from a couple of hours to several months or even years. Freeze-drying helps to remove water using conditions that guarantee that most bacteria will survive the process.

In my research, I explore aggressive freeze-drying conditions to attain long-term stability and an aesthetically appealing product, while considering the economics of the process. My research is focused on the development of aggressive freeze-drying protocols that achieve these goals using experimental and modelling techniques.


Johnny Alfaro was born and raised in San Jose, Costa Rica. He obtained his B.S. in Chemical Engineering (2011) and B.S. in Music with emphasis in Voice (2013) from Universidad de Costa Rica. As an undergraduate student, he earned several distinctions for obtaining the best GPA in Chemical Engineering (2008, 2009) and in Music (2011, 2012), as well as the award for obtaining the best GPA of Universidad de Costa Rica in 2012. Before he joined the PME in August 2013, he served as a lecturer in the Chemical Engineering Department and as a researcher in the Forest Products Laboratory of Universidad de Costa Rica. His research at the time was focused on studying new methods to preserve tropical hardwoods against different natural enemies, such as white-rot fungi and weathering.

Since his arrival to Chicago, in addition to his research work, he serves in the Pritzker School of Molecular Engineering Safety Committee representing the de Pablo group. He is also appointed as Guest Graduate Student in the Materials Science Division at Argonne National Laboratory. Currently, he is part of a program in Science Communication organized by the Museum of Science and Industry and Pritzker Molecular Engineering (PME), in which he is developing a science workshop for middle school students. In June 2016, he was appointed as a Chicago Center for Teaching (CCT) Fellow to help his peers in PME to explore and improve their teaching skills. Outside of PME, he participates in the Vocal Studies program offered by the Music Department at the University of Chicago, where he has continued to explore his voice under the supervision of soprano Patrice Michaels.

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