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Dairy co-products such as acid whey, whey permeate, and milk permeate represent a disposal burden for producers and have limited means for valorization. Bioconversion of residual lactose via fermentation can create an avenue for upcycling these dairy effluents. Brettanomyces claussenii is a yeast that can produce acetic acid, a component of functional beverages such as kombucha, under aerobic conditions. When lactose is cleaved into its monomers, B. claussenii may be able to selectively ferment glucose while retaining galactose, a low glycemic sugar. Two studies were conducted to evaluate the potential for value addition of diary effluents: the use of response surface methodology to determine optimized levels of fermentation parameters in synthetic media and the development of a prototype, fermented acid whey beverage served for sensory evaluation. Both studies propose methods to create a more sustainable processing option for the dairy industry while developing a value-added product. Fermentations were inoculated with B. claussenii and an external lactase enzyme cleaved lactose into its monomers. Using response surface methodology, the optimized levels of agitation (RPM), yeast inoculation level (log CFU/mL), initial pH, and time (days) were evaluated for maximum acetic acid production and galactose retention in synthetic media to emulate dairy effluents. It was found that the optimized levels were 171.5. RPM, 13.25 days, 5 log CFU/mL B. claussenii inoculation level, and a pH of 6.5. At these optimized settings, the predicted acetic acid concentration was 9.25 g/L, 95% confidence interval (CI) [7.44, 11.05], and a residual galactose concentration of 30.37 g/L, 95% CI [24.44, 36.30]. A validation study was run to determine if acetic acid values and galactose retention fell within the predicted 95% CI. At the optimized levels, galactose retention fell within the 95% CI, while there was less acetic acid produced than predicted by the model. Future studies beyond the scope of this research will further assess the metabolism of B. claussenii. Another proposed method of upcycling the dairy effluents was to develop a fermented acid whey prototype beverage. Fifteen liters of acid whey were inoculated with B. claussenii, aerated at 300 L/hr, and fermented until density stabilized for three consecutive days. The beverage was carbon filtered and flavored to develop three flavors for sensory evaluation, blood orange ginger, pineapple, and berry lime. A consumer acceptance test was conducted at the Cornell Sensory Evaluation Center, where panelists (n=98) were asked about overall hedonic liking, just-about-right scales for different attributes, and purchase intent. Panelists were blinded to the fact that the beverages were produced from acid whey, and a commercial kombucha was served as a control. Consumers were asked about their purchase intent before knowing the beverages were made from acid whey, and again at the end of the study once shown information about product claims. Uninformed purchase intent for all three beverages indicated that 19% of people would buy the beverages. However, after revealing that the products were made with acid whey, which proposes a sustainable processing option and has functional properties, 47% of panelists indicated that they would purchase it. Panelists were asked their reasoning for purchase intent, and 66% of respondents selected sustainability as a driving factor, 61% cited taste, and 53% mentioned vitamins and minerals. Reformulating the beverages based on panelist feedback and highlighting sustainability, vitamins, and minerals in marketing can propose a means for upcycling acid whey. These studies emphasize potential options for the dairy industry to valorize dairy effluents via fermentation.

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79 pages


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acetic acid; dairy effluents; fermentation


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Union Local


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Alcaine, Samuel David

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Snyder, Abigail B

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Food Science and Technology

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M.S., Food Science and Technology

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Master of Science

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dissertation or thesis

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