Available at: https://digitalcommons.calpoly.edu/theses/2739
Date of Award
9-2022
Degree Name
MS in Agriculture - Food Science and Nutrition
Department/Program
Food Science and Nutrition
College
College of Agriculture, Food, and Environmental Sciences
Advisor
Jim Prince
Advisor Department
Food Science and Nutrition
Advisor College
College of Agriculture, Food, and Environmental Sciences
Abstract
A two-year study was conducted to assess the effects of cofermentation on red wine varietals. During the winemaking process, wines can be made from two or more varieties by picking, crushing and fermenting them together, a practice known as cofermentation. They can also be blended either after the completion of alcoholic fermentation or after malolactic fermentation. In the first year of the study, two grape varieties, Merlot (Mer), and Malbec (Mal) were cofermented. On the second year, a third varietal, Petite Sirah (PS) was also studied. Cofermented wines containing every possible binomial combination of the varietals was made and one trinomial on 2019. The cofermented wines were compared to monovarietal wines and also to wines that were produced by blending either after alcoholic fermentation or after malolactic fermentation. The phenolic profile of the wines was followed from the onset of fermentation up to 36 months of bottle aging for the 2018 vintage and in the case of the 2019 vintage, up until 250 days after crushing. In 2018, cofermented wines and wines that were blended after malolactic fermentation had an anthocyanin profile that was more similar to Malbec than to Merlot, while the tannin profile was more resemblant of Merlot. In 2019 cofermentation improved the anthocyanin content when compared to post alcoholic and post malolactic blend only when the three varietals were cofermented. A sensory analysis with 10 trained individuals was conducted on the 2018 vintage. It was demonstrated that Malbec wines had a higher amount of red fruit aromas while Merlot wines were perceived as being more astringent. Cofermented and post malolactic fermentation blended wines were indistinguishable to panelists and blending after alcoholic fermentation produced wines that highlighted the individual varietal character.