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.
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