NOPROBLEM - Novel tasty dairy products obtained through intelligent resource management

Diacetyl, an important contributor to the buttery aroma of many fermented dairy
products, is formed by lactic acid bacteria present in the starter culture. Mesophilic starters are efficient producers of diacetyl, but are unsuited for production of certain harder cheeses, because of the high temperatures needed to attain cheese firmness. Such cheeses are made using thermophilic starters, that unfortunately are poor diacetyl formers, and taste is thus compromised (pers. comm. Søren Lillevang, Arla Foods). Besides the butter flavour content, another important factor is butter flavour formation rate. There are several cheese products where butter flavour is formed very slowly, in the course of several weeks of storage, and for some dairy products, technical issues limit butter flavor formation.
In the current project we wish to address these issues while at the same time create value from processed whey streams that currently are discarded as pig-feed.
1) We want to make the mesophilic starter more thermotolerant, so that it can be
used for making harder cheese variants.
2) Produce diacetyl from whey side-streams which can be added to various dairy
products/sold.
One way to make the mesophilic starter more thermotolerant is through adaptive
evolution, an approach we previously have used with great successs (Chen et al.,
2015), and which will be applied in this project as well.
We have optimized one of the starter culture bacteria into being extremely efficient at producing diacetyl from sugar (Liu et al., 2016). To attain a rich buttery flavor in dairy products, less than