Development of a multi-parameter sensing system for process analytical technology application in the food and beverage industry

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Scanlon, Shauna
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University College Cork
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Food and beverage quality and safety have become of significant importance over the past decade and assuring the highest standards of process control is a key priority. Consumers have increasingly high expectations when it comes to the quality of their food products and are progressively looking for quality seals and trust marks on food and beverages, and expect manufacturers to produce these products to the highest standards. In 2004, the Food and Drug Administration (FDA) introduced a Process Analytical Technology (PAT) initiative for industries. This outlined the opportunities that exist for improvement on conventional manufacturing, through improvements in process development and control. PAT is described as a system for designing, analysing and controlling manufacturing through the timely measurements of the critical attributes, which lead to a products end quality. In this way, quality is built into the product, rather than determined through end product testing. Electrochemical sensing technology has the potential to change the way we see quality control analysis in the food and beverage industry. Electrochemical sensors can provide a cheap, portable and easy to use method of PAT application in quality control analysis. In this work, two electrochemical sensors for beverage analysis are developed- one for the detection of caffeine and the other for the determination of pH. By integrating these sensors into a multi-parameter system, it is possible to get real time quality control updates during beverage processing. Chapter 1 of this thesis provides a general introduction to PAT and the state of the art technologies in the food and beverage industry. Emphasis is placed on electrochemical sensing and carbon electrodes. Chapter 2 describes the development of an electrochemical sensor for caffeine detection. Characterisation of a screen printed graphite electrode was carried out, with optimisation of pre-treatment procedure and surface modification. It was found that a pre-treatment procedure of cyclic voltammetry (CV) scans in mild acid was the best electrode pre-treatment, with 0.25% Nafion being the best surface modification material. The caffeine content of caffeine standard solutions was determined. An electrochemical sensor for the determination of pH was developed in Chapter 3. An Iridium Oxide (IrOx) coated screen printed electrode proved very efficient for pH determination in various Britton-Robinson buffers, with 40 CV cycles deemed the most suitable coating method. In Chapter 4, the developed caffeine and pH sensors were tested in real beverage samples, the main one being a PepsiCo Acidulant sample containing caffeine, Phosphoric Acid and caramel. The pre-cleaned, Nafion-modified graphite electrode for the detection of caffeine proved very efficient with an average range of caffeine recovered of 96-102 % over 150 sensors, and an average accuracy of 96.5 %, when compared to HPLC analysis. The sensor had a limit of detection of 5.5 µM. The IrOx pH sensor showed super-Nernstian responses of -68.4 to -72.5 mV/pH unit. The average accuracy of the IrOx sensor when compared to a benchtop pH meter was 99.2 %, over 200 sensors. Chapter 5 describes the design and development of an integrated multi-parameter system, for caffeine and pH sensing. Three prototypes of the device were developed, each improving on the previous through testing and consultation with PepsiCo engineers and scientists. Lab-based testing of the device was carried out, with efficient results both form an analytical and engineering perspective. Finally, Chapter 6 summarises the goals set out and achieved in this research, with plans for future work. The potential future directions for electrochemical sensing, in general, are also discussed.
Caffeine , pH , Electrochemistry , Process analytical technology , Screen printed electrode , Food and beverage
Scanlon, S. 2018. Development of a multi-parameter sensing system for process analytical technology application in the food and beverage industry. PhD Thesis, University College Cork.