Date of Award
Master of Science (MS)
Food, Nutrition, and Culinary Science
Water-soluble vitamins, such as vitamin C and vitamin B, exist in various food stuffs, including vegetables, fruits, fortified grains, milk, and meat, etc. Those vitamers play essential roles in many biochemical functions in human body, thus are significant components for maintaining human health. However, the stability of vitamers is susceptible to many factors, such as light, temperature, metal ions, levels of oxygen concentration, and moisture contents, etc. As vitamers are prone to further degradation, their bioactivities can be remarkably affected and even lost in food processing and food products.In this study, effect of different metal ions (i.e., Na+, K+, Ca2+, Mg2+, Zn2+, Cu+, Cu2+, Fe2+, Fe3+) on the stability of ascorbic acid (AA, vitamin C, or VC) and nicotinic acid (NA, vitamin B3, or VB3) was investigated during a storage time of 24 hours, for which an HPLC system (Agilent Technologies, Inc., Loveland, CO, USA) with a Phenomenex Prodigy (150mm × 4.6 mm, 5µm) analytical column was used to determine the stabilities of the aforementioned two vitamins at temperature of 40ºC. The mobile phase of the HPLC consisted of solvent A: 0.02% phosphoric acid in water (pH values of 3.15), and solvent B: acetonitrile. Starting with 90% of solvent A and 10% of solvent B, an isocratic elution was performed for 5 minutes at a flow rate of 0.5 ml min-1. The following wavelengths were chosen for detection of the aforementioned two vitamins: 254 nm for AA, and 260nm for NA. The effects of metals ions on the stabilities of VC and VB3 were studied in terms of their degradation kinetics by their respective model systems. Although both vitamins exhibited the first-order kinetics in their respective model systems, they have shown significantly different degradation rate under different conditions. A lower rate constant of degradation was found for the VB3 (k = 0) in all metal ions solutions, while a dramatically higher rate of degradation was found for the VC with Cu+ and Cu2+ solutions. A significant degradation of AA was observed when it was mixed with 5 ppm, 10 ppm, 25 ppm and 50 ppm of Cu+ solution, with a degradation rate (k) at 6.11 X 10-1 to 2.377. At 25 ppm, 50ppm ,75ppm, and 100 ppm of Na+, K+, Ca2+, Mg2+ solutions, AA degradation was not significant compared to the control. On the other hand, contents of VB3 were still remained 100% after storage time of 24 hours. Thus, VB3 is more stable than VC when they co-existed with different metal ions in the model system.
Huang, Jhongyan, "Effect of Metal Ions on Stability of Ascorbic Acid and Niacin Determined by HPLC" (2021). All Theses. 3653.