Investigating the impact of sugar type and nitrogen source on Maillard-associated flavors in sparkling wine.

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Traditional method sparkling wine i.e., Champagne, is produced from a second alcoholic fermentation in the actual bottle that customer buys. The low temperature second fermentation requires sugar addition to the base wine, usually alongside yeast nutrients (yeast assimilable nitrogen {YAN mg N/L}). This is necessary for a healthy fermentation in the stressful base wine environment that includes high acid levels, low pH levels, high alcohol levels (10-11.5% v/v), sulfur dioxide (SO2) and carbon dioxide (CO2). The residual sugar level (g/L) after the first fermentation is usually below 1 g/L, and consists of higher fructose levels than glucose. Nowadays, the sugars used at this stage of production are usually granulated sugar, or specially prepared concentrated grape juice. Interest in sugar alternatives in food production has increased in recent years primarily due to health concerns yet examination of their effect on sparkling wine flavor, specifically Maillard-associated compounds that bestow caramel, nutty and roasted flavor, has yet to be undertaken. Therefore, my five year project has been designed to investigate the kinetics of compounds that result from the second fermentation with organic and inorganic nitrogen. Additionally, a comparison of granulated sugar to different types of sugar is planned, which will include: liquid sugar, stevia, dextrose, glucose, berry fruit sugar and yellow sugar. Further investigation regarding the contribution, at the later stage production (yeast removal), of different types of sugars to the caramel, nutty and roasted flavors by sensory, and chemical analysis will take place. Novel sugars combined with an innovative sparkling wine method never studied before, will be utilized to examine amino acids interaction with different sugars in sparkling wine. Chemical and sensory analysis of wines will continue over several years until the wines are ready for commercial release in accordance with wine industry practice. The use of sparkling wine as a medium to study Maillard-associated flavor compounds will lead to new information regarding formation. An increased understanding of the synthesis and stability of these compounds in acidic beverages could ultimately lead to their control for specific flavors, and acceleration of flavor development that will also have financial implications to the manufacturer. Therefore, the long-term objective of my research program is to predict the flavor profile of sparkling wine by modelling sensory outcomes from chemical composition to enable the acceleration of flavor development to reduce cellar aging time, and energy input during production. The short-term objectives are to establish the influence of sugar type, the source of sugar, acid level, and nitrogen source on Maillard-associated compounds in sparkling wine for both the second fermentation, and sweetening of the final wine.