Development of biosensor technology for the measurement and control of off-note flavours in the Scotch Whisky industry

This project is a collaboration with the Scotch Whisky Research Institute (SWRI). The aim of the project is to investigate the potential of developing biosensor-based technology to identify and quantify compounds present in whiskies that would be perceived as off-notes by the consumer, with the aim of developing rapid quality control techniques that could be used in the production environment.

Since flavour is the primary driver of consumer acceptability in Scotch Whisky, it is vital that the industry monitors, controls and optimises the flavour of their products. Currently the industry takes two approaches to the measurement of flavour, chemical analysis (eg, GCMS) and sensory evaluation by trained human assessors. Analytical methods fail to account for the effects of mixtures of compounds, and may lack the required sensitivity, whereas human assessment has an unavoidable level of variability.

This project will explore biological measurements which mimic actual perception of flavour, focusing on the development of specific biosensors for the detection of the main off-note flavours that can develop as whisky matures in oak casks. To be useful, the biosensor device must be sensitive, specific, and give a rapid response at the point of use, without requiring samples to be transferred to a laboratory.

Transcriptional biosensors rely on the response of genetic promoter elements to particular molecules. Sensors based on live cells can not be used outside a laboratory setting, but this can be overcome by the use of cell-free transcription-translation (TX/TL) systems, or even simpler transcription-only (TXO) systems, which are simple, cheap, and can give responses visible by eye within minutes (Millacura et al, 2020).

This project aims to develop biosensors of this type to detect four classes of compounds: 'musty' (anisoles, especially 2,4,6-trichloroanisole); 'sour' (acetic acid); 'solvent' (ethyl acetate); and 'phenolic' (phenols and cresols). This requires discovery of suitably responsive promoters and introducing them into TX/TL and TXO systems for evaluation.

Where known promoters exist which respond to the desired targets, these may be synthesised and tested against pure compounds and then samples supplied by SWRI. Secondly, various bacteria will be exposed to vapours of the target chemicals to empirically determine which promoters are activated. Promising promoters will be further improved through directed evolution.

In parallel with this, an improved sensor format will be developed which is suitable for the testing environment. Such a platform could also be valuable in many other applications.

The successful candidate will be able to liaise with whisky producers, with SWRI providing industry contacts and a forum to present and discuss results. Additionally they will join a cohort of students within the IBioIC PhD training programme, as well as the interdisciplinary Centre for Synthetic and Systems Biology (SynthSys), where they will be encouraged to make full use of the expertise and world-class facilities available, to gain in-depth training in relevant experimental techniques and transferable skills to support their future career developmen