Yeast Biotransformations with Chris White and Nick Impellitteri – BeerSmith Podcast #336

Dr Chris White and Nick Impellitteri join me this week to discuss yeast genetics, biotransformations and thiols in beer.

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Topics in This Week’s Episode (51:42)

This week I welcome Dr Chris White and Nick Impellitteri. Chris is President of White Labs Inc, at top provider of brewing yeast worldwide and 2015 winner of the AHA Governing Committee award for a lifetime of achievement in brewing. He is also the author of the book “Yeast” which is the ultimate reference on brewing yeast.
Nick is a biomaterials scientist and genetic engineer who started Yeast Bay in 2013 in the Bay area, a provider of unique brewing yeasts produced in collaboration with White Labs.
We start with a brief discussion with returning guest Chris White about some of the new projects going on at White Labs.
First time guest Nick Impellitteri tells a bit about his story and how he got started as founder of The Yeast Bay. Nick is involved in a collaboration with White Labs where many of his yeasts are produced by White Labs for craft breweries worldwide.
Chris starts by describing a project he worked on several years ago to map the genetic family tree for 96 brewing yeast strains and what we’ve learned from that.
Nick talks about his new lager strain Cream City Lager Yeast and how he is evaluating new yeast strains using modern genetics.
Chris explains how we’re just starting to map specific yeast genes to individual flavors and aromas in beer.
He also describes some interesting results comparing genes from two of the worlds most popular lager yeast strains: Saaz and Frohberg and how one largely dominates large lager production.
Chris discusses the STA1 gene which can in some cases cause diastaticus. Chris tells us why STA1 is important but also the limitations.
Nick explains how biotransformations are really important for many IPA styles. There are two major types of biotransformation important in the process: Terpenes and thiols and Nick tells us about terpene biotransformation of hop aroma compounds like Geraniol and Linalool. Terpenes can be bound or free.
Chris explains the biotransformation of thiols, including both bound and free thiols, and how yeast plays a major role.
Chris tells us why yeast genetics plays an important role in thiol transformation in the form of the IRC7 gene. Again the presence of the gene is not enough, as it must be activated.
Chris tells us about his new yeast strain WPL077, Tropicale Yeast Blend which takes a natural approach. Tropicale is not a genetically modified yeast, but is instead carefully selected to free thiols and produce tropical fruity flavors in a finished beer. This approach is different than many competitors who are using genetically modified yeasts.
Nick joins in to talk about projects he is working on to genetically engineer new yeast strains, along with certain advantages and disadvantages that come from the approach.
Chris and Nick both provide their closing thoughts.

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