PhD Précis: Jack Muir

Jack, who’s in the second year of his PhD at the University of Canterbury, gives us a simplified view of a complicated business.

What drew you to chemical and process engineering?

I’ve always enjoyed chemistry and mathematics, and chemical and process engineering gave me the opportunity to learn more about these topics with a focus on applying them to solve real-world problems. The degree covers a wide range of topics, so I was able to discover subjects I enjoyed but hadn’t tried before, such as programming. I’ve also always had an interest in biology and completing a minor in bioprocess engineering allowed me to incorporate this interest.

Please explain your research

My research is focused on modelling the precipitation of calcium tartrate crystals in wine. This can be very tricky for winemakers to predict and treat, as common tests used for potassium bitartrate are not suitable for calcium tartrate. Factors such as calcium and tartrate levels as well as the pH can give some indication but do not satisfactorily predict if a wine will crystalise. The crystals also take a very long time to form and can occur months after the wine has been bottled and sent out for sale. This is why being able to predict if crystals will form would be useful, as then winemakers could treat the wines beforehand.

How have you developed the model?

I’ve adapted a mathematical model for precipitation in dairy that was created by a previous PhD student to better fit a wine system. Wines have many compounds that all interact and affect the likelihood of calcium tartrate precipitation, so models with only a few chemicals typically aren’t accurate. My model accounts for a large number of key chemicals that will impact the wine environment and the formation of calcium tartrate. The results of this model will then be compared to the results seen in actual wine samples, which will be used to form recommendations for winemakers.

What’s most challenging about this research?

Wines are very complex solutions; they have so many different chemicals that interact. These depend on the type of grape, growing conditions, processing techniques, and additives. They can also react and change over time and can start to oxidise when exposed to air. The ethanol content of wine also makes it trickier to model, as much of the data available for the modelling equations is for aqueous (water-based) systems. Figuring out how to adapt this for mixtures of ethanol and water has been a challenge. For the experimental side of my research, I need to measure the chemical composition of wine. Figuring out the best methods to use can be difficult as most methods have pros and cons. Some of the chemicals I’m interested in aren’t regularly tested for by the wine industry so there aren’t many established methods. Tests that might work fine for simple solutions can be inadequate if the other chemicals in wine interfere.

And most satisfying?

Well, it’s always incredibly satisfying when I run the model and it matches experimental results on the first try! I also like that I’m working on research with practical applications that could solve actual problems for the wine industry.

Who has helped you with this PhD?

I’ve had a lot of help from my supervisor Ken Morison, and the research is funded by Bragato Research Institute. We also have some great lab managers and technicians in our department that help with some of the day-to-day practical aspects of research.