Thesis
Influence of nitrogen supplementation of Cabernet Sauvignon and synthetic grape musts on growth of Pediococcus spp. after alcoholic fermentation
Washington State University
Master of Science (MS), Washington State University
2018
Handle:
https://hdl.handle.net/2376/103019
Abstract
Often considered spoilage microorganisms, Pediococcus spp. are frequently isolated from red wines from Washington State. Their presence has been attributed to high pH, high sugar content, and nutrient deficiencies in grape musts, conditions that also prompt winemakers to add nutrients to ensure successful alcoholic fermentation. As such, proliferations of Pediococcus spp. may be due to excessive supplementation of musts with nutrients not consumed during alcoholic fermentation. To assess the impact of excessive nitrogen supplementation, Cabernet Sauvignon musts were prepared to contain variable levels of yeast assimilable nitrogen (YAN): low (66.9 mg N/L), medium (219 mg N/L supplemented with amino acids), medium (198 mg N/L comprised largely of ammonium), and high (438 mg N/L). Additionally, synthetic grape musts were comprised of either low (55.2 mg N/L), medium (250 mg N/L), or high (530 mg N/L) YAN. All musts were fermented with Saccharomyces cerevisiae prior to inoculation of Pediococcus spp. (P. damnosus OW-2, P. inopinatus OW-8, P. parvulus WS-7C, WS-29A, OW-1, and P. pentosaceus ATCC 33316). For all treatments, increased must supplementation produced wines with greater residual nitrogen. Cabernet Sauvignon wines containing the greatest residual amino acid concentrations (high YAN) supported the best growth of Pediococcus spp., with the exception of P. pentosaceus which did not grow under any conditions. Conversely, limited to no growth was observed in synthetic wines regardless of nitrogen treatment where populations entered decline soon after inoculation. Slight recovery in culturability was observed for strains WS-7C, WS-29A, OW-1, OW-2, and OW-8 in low YAN wines despite lacking residual nitrogen, most likely attributable to low ethanol and residual sugars present in this stuck fermentation. In an attempt to improve growth, low and high YAN synthetic wines were supplemented further with peptone, yeast extract, liver extract, Tween™ 80, cysteine, asparagine, manganese sulfate, biotin, or calcium pantothenate. The addition of yeast extract greatly improved growth in low YAN wines for all six strains while peptone improved growth for five of the six suggesting the presence of important growth factor(s) for Pediococcus in these compounds.
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Details
- Title
- Influence of nitrogen supplementation of Cabernet Sauvignon and synthetic grape musts on growth of Pediococcus spp. after alcoholic fermentation
- Creators
- Megan Elizabeth Wade
- Contributors
- Charles G. Edwards (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Food Science, School of
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525198101842
- Language
- English
- Resource Type
- Thesis