Abstract
dc:description.abstractSolar radiation influences virtually all biological process on earth. Yeasts, the microbial driver of ethanol fermentation, evolved on the surface of vegetation and had to adapt to survive photonic assault. Past research has demonstrated that white light affects yeast metabolism along with the ability to entrain circadian rhythms, although no known genetic mechanism accounts for this. High intensity narrow wavelength light-emitting diodes were employed to illuminate synthetic cultures under fermentation. Multiple colors along the visible spectrum were used, corresponding to the peak absorbance wavelengths of Saccharomyces sp. yeast. Impacts in primary metabolite evolution were found, dependent on wavelength. Longer wavelengths produced higher amounts of acetic acid and glycerol; shorter wavelengths produced more ethanol. Because past research showed light timing had pronounced effects, illumination schemes on the scale of milliseconds to hours were tested for ethanol production. Light schemes on the scale of enzymatic reactions, yeast generation times, and circadian rhythms produced the most ethanol. Discrete blocks and duration of illumination were used to elucidate where light had the most influence over yeast metabolism and fermentation. Late lag phase and mid log phase illumination impacted ethanol fermentation more than any other period of time. Light effects were tested on apple juice to see if they extended from synthetic media to natural products. Significant impacts on ethanol production were discovered and flavor/aroma impacts were noted. Light, color, intensity, and timing have all been shown to control and affect fermentation with both positive and negative effects established.
Degree
thesis:*- Name thesis:degree_name
- Doctor of Philosophy
- Level thesis:degree_level
- doctoral
- Discipline thesis:degree_discipline
- Food Science and Technology
- Department dc:contributor.department
- Food Science and Technology
- Grantor dc:publisher
- Virginia Tech
- Year dc:date.issued
- 2021
Author and committee
dc:creator, dc:contributor.*- Author dc:creator
-
- Hurley, Eldon Kenneth Jr.
- Chair dc:contributor.committeechair
-
- Williams, Robert C.
- Committee members dc:contributor.committeemember
-
- Marcy, Joseph E.
- Senger, Ryan S.
- O'Keefe, Sean F.
Subjects
dc:subject × 4Rights
dc:rights- Statement dc:rights
-
- In Copyright
- Licence dc:rights.uri
Identifiers
dc:identifier.*- Dc Identifier Other
- vt_gsexam:30909
- OAI identifier oai:identifier
- oai:vtechworks.lib.vt.edu:10919/112678