The development of analytical approaches to profile Scotch Whisky colour

  • Megan Holden

Student thesis: Doctoral Thesis


Attenuated total reflectance mid-infrared (ATR-MIR) spectrometry and liquid chromatography – mass spectrometry (LC-MS) have been investigated as techniques for profiling Scotch Whisky colour (naturally derived and that originating from E150a caramel). ATR-MIR was initially implemented to investigate caramel colourants and it was found that profiles dominated by colour constituents could be obtained by analysing dried residues of caramel solutions. Using this approach, it was possible to differentiate between legally permitted E150a caramels and the three other EU recognised classes (not permitted in Scotch). It was also possible to obtain unique profiles for different E150a formulations. These distinctions between caramels were maintained when dissolved in a typical blend whisky, a finding that could provide the opportunity to use E150a caramels as inherent authenticity markers in Scotch. Additional factors such as changing caramel concentration, varying the blend matrix, and caramel fade were also investigated in this work and found in some cases to influence spectra.Work progressed from the above findings to compare multivariate data analysis tools for the prediction of caramel identities, based on their characteristic spectra. PCA with GLSW and PC-DFA were found to be most successful but would require background whisky matrices to be accounted for during calibration. Analysis of LC-MS data complemented that of ATR-MIR, showing the potential to distinguish between caramel materials as described above. The advantage of ATR-MIR over LC-MS is its adaptability for field studies as a portable device, LC-MS on the other hand has the ability to identify components responsible for sample distinctions and it was possible in this work to find components characteristic of different caramels. Advanced software also enabled tentative structures to be assigned to some components.Additional studies using LC-MS highlighted its potential for other applications relating to Scotch, for example components characteristic of different cask histories and maturation ages were found.
Date of Award29 Apr 2016
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsFibre Photonics & Scotch Whisky Research Institute
SupervisorAlison Nordon (Supervisor) & Walter Johnstone (Supervisor)

Cite this