Fermentation, Probiotics, and Peptides


Fermented foods have been touted as great sources of probiotics and kefir is no exception. Kefir is an acidic, fermented milk that has traced its origins to thousands of years ago in the Caucasus Mountains of Eurasia. It has a sour taste that is similar to yogurt. Commercial products are often sold as unflavored or flavored with fruit and sweeteners and it can be consumed alone or used to make smoothies. During the milk fermentation process, the Dallas Lab out of the University of California, Davis, has identified 25 bioactive “kefir peptides”. The kefir peptides were thought to have been released by native milk proteases and microorganisms. The sequences identified ranged in activity from antimicrobial, antihypertensive, opioid, anti-oxidative, ACE-inhibition, and immunomodulatory functions.1 Similarly, a lab out of the Friedrich-Alexander Universität Erlangen, in Nürnberg, Germany, has identified 236 peptides in kefir, many released from the caseins, in particular from β-casein. These peptides were not found in unfermented milk. Of these, they identified sixteen bioactive peptides. They also found that there was a large difference in the number of peptides found, depending upon if the kefir was produced with kefir grains or commercial kefir starter culture. The largest number of peptides were found to derive from β-casein, amino acids 28–56, independent of starter used to produce the kefir.2


  1. D.C. Dallas et al., Food Chemistry, 197, 273 (2016). Retrieved from http://www.dallaslab.org/publications-1/
  2. J. Ebner, et al,. J Proteomics, 117, 41 (2015). Retrieved from https://www.ncbi.nlm.nih.gov/pubmed/25613046


Industry News , Biologically Active Peptides

Denise Karounos

See all articles from Denise Karounos

Denise Karounos joined Peptides International in October 2016. After completing her BS in chemistry from West Virginia University, she spent time as an organic chemist at Bachem Bioscience synthesizing peptides and amino acid derivatives. Denise has experience with both solid and solution-phase peptide synthesis, and has worked under both research and cGMP settings. After completing her MBA from Saint Joseph’s University, Denise transitioned into product management of peptides and amino acid derivatives. In her marketing role, she had many duties including but not limited to product management, market research, creating and producing marketing materials, handling US catalog distribution and customer database, email marketing, quoting and inside sales, sales calls, and coordinating and attending trade conferences. 

At PI, Denise's duties encompass both sales and marketing, bringing to bear her extensive lab and sales support experience. Contact her today and see how Denise can assist you with your peptide research project.