Abstract

In the future, sustainability in the dairy industry will require creative and scale-able solutions for better utilization of the primary solid component in milk: lactose. One promising avenue of “up-cycling” underutilized lactose is converting it to valuable rare sugars. Rare sugars like D-tagatose and D-allulose are increasing in popularity extremely quickly. D-tagatose and D-allulose are hexose sugars, D-allulose being an epimer of D-fructose and D-tagatose an isomer of D-galactose. They have excellent functional properties in food systems with clean sweetness profiles similar to sucrose. Critically, they also have excellent nutritional characteristics, such as low caloric values and low glycemic indices. The heart of this project has been to demonstrate the feasibility of co-producing D-allulose and D-tagatose from lactose, which has not been previously demonstrated. A further goal of the research was to demonstrate how D-allulose and D-tagatose can be successfully paired with dairy proteins to produce higher protein, lower sugar consumer goods with excellent flavor and nutritional characteristics. To produce D-allulose and D-tagatose from a lactose feedstock, four enzymes from thermophilic organisms were cloned and expressed in E. coli: β-galactosidase (Geobacillus stearothermophilus), L-arabinose isomerase (Geobacillus stearothermophilus US100), D-glucose isomerase (Weizmannia coagulans), and D-allulose epimerase (Arthrobacter globiformis). A single-pot reaction mixture yielded 9.9 + 1.5 mg mL-1 D-allulose and 10.7 + 1.1 mg mL-1 D-tagatose after 24 hours at 70°C. Higher lactose concentrations (300 mg vs. 100 mg vs 33 mg) resulted in higher D-tagatose concentrations (p<0.001) under varied reaction parameters. However, higher lactose concentrations did not yield higher D-allulose concentrations. These experiments demonstrate that a single-pot synthesis of D-tagatose and D-allulose is feasible and, with more optimization, could be used in industrial applications. Application work found that whey protein can be combined with rare sugars to create acceptable lower-sugar, gluten-free muffins and cookies. Simplex centroid mixture designs defined combinations of wheat flour alternates from different fat, protein, and fiber ingredients for both applications. Ninety-one randomized baked muffin blends and forty-seven different cookie blends were analyzed and compared for physical and basic sensory attributes. Muffins and cookies with D-allulose or D-tagatose differed from those containing sucrose in the water activity and crust color (lightness, L*). The purchase intent of sugar-substituted muffins was comparable to that of the control muffins when consumers were informed of the sugar content of the product.

Degree

PhD

College and Department

Life Sciences; Microbiology and Molecular Biology

Rights

https://lib.byu.edu/about/copyright/

Date Submitted

2024-11-21

Document Type

Dissertation

Keywords

allulose, tagatose, rare sugars, lactose, dairy, waste

Language

english

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Life Sciences Commons

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