Application of near-infrared spectroscopy (NIRS) in the brewing industry for on-line determination of critical process parameters

Yeast and Fermentation Session
Lucas Vann, North Carolina State University, Raleigh, NC, USA
Co-author(s): Johnathon Layfield and John Sheppard, North Carolina State University, Raleigh, NC, USA

ABSTRACT: Traditional analytical methods used in the analysis of fermentation media suffer from a number of limitations. These techniques are often expensive and time-consuming in part due to the chemicals involved and the amount of sample preparation required. In addition, analysis is not always done in-house, and results are obtained hours, even days, after the samples are initially taken. The search for more rapid and efficient methods has led to the development and application of near-infrared spectroscopy (NIRS) in the bioprocessing industry. NIRS offers a number of advantages over existing chemical methods: analysis is quick and passive so there are no destructive effects to the sample or waste products produced, and sample preparation is not required. Analysis is also multivariate in that a single spectrum contains information about a number of analytes, and therefore several determinations can be made simultaneously. In addition, NIRS can be implemented in real time for maximum process monitoring and control capabilities. NIRS operates based on the principle that the atoms of molecules are in constant motion and vibrate at specific frequencies. Light frequencies that correspond to molecular vibrations are absorbed by the sample, and the resulting infrared spectrum comprises peaks of defined frequencies, band shapes, and heights that correlate to molecule concentrations present in the sample. To date, NIRS has been applied successfully in a variety of industrial processes: agricultural, food, chemical, and pharmaceutical, generally in the areas of raw material quality control, as well as intermediate and finished product testing. The present research explores its potential for on-line fermentation monitoring of cell number, specific gravity, sugar concentration, and alcohol concentration in a 300 L pilot-scale fermentor. Models were generated for each of these constituents, which overall exhibited favorable results. However, model predictions in dissimilar styles of beer did not exhibit satisfactory correlations suggesting that specific models would be required for each beer type. The findings support the possibility of incorporating NIRS into commercial brewing operations so that manufacturers can have a continuous “real time” assurance of quality through timely measurements of critical fermentation parameters. This would permit early fault detection and help to devise corrective actions to reduce the potential for lost batches while producing a more consistent end product.

Lucas Vann is a senior scientist in the Biomanufacturing Training and Education Center at North Carolina State University. He develops and teaches courses to NC State students, industry professionals, and FDA inspectors related to upstream biomanufacturing for the production of biopharmaceuticals and has extensive experience in the areas of fermentation, cell culture, process development, and automation. He has more than 10 years of upstream bioprocessing experience and is involved in industry-related bioprocess development projects at BTEC, where he provides strategic technical direction and guidance. He is currently pursuing a doctoral degree in bioprocessing at North Carolina State University, where he is conducting research specializing in bioprocess development and automation for process optimization. He holds both bachelor’s and master’s degrees in biosystems engineering from McGill University, where he helped design and develop a biosensor for fermentation process control.