Thermal oxidation studies on reduced folate, L-5-methyltetrahydrofolic acid (L-5-MTHF) and strategies for stabilization using food matrices.
The thermal stability of L-5-methyltetrafolic acid (L-5-MTHF) was investigated in model/buffer systems and food systems. L-5-MTHF degradation followed first-order reaction kinetics with relatively greater (P < 0.01) stability at pH 4 compared to pH 6.8 in the buffer systems. This was confirmed using cyclic voltammetry. The stability (for example, k-values) of L-5-MTHF in an oxygen controlled environment improved (P < 0.001) proportionally when in the presence of increasing molar ratios of sodium ascorbate (NaAsc). The addition of NaAsc to L-5-MTHF after heat treatment was also effective at returning thermally oxidized L-5-MTHF back to its original form. A scheme was developed to explain the degradation and regeneration of L-5-MTHF. The importance of antioxidant protection of L-5-MTHF from thermal oxidation was extended using 2 distinct food systems; namely skim milk and soy milk, both with known antioxidant capacities. We conclude that the antioxidant activity of food components can enhance the stability of L-5-MTHF.
Food Nutrition and Health, Faculty of Land and Food Systems, Univ of British Columbia, Vancouver, BC V6T 1Z4, Canada.
Yazheng
Y
Liu
Stephen
S
Tomiuk
Elodie
E
Rozoy
Stephan
S
Simard
Laurent
L
Bazinet
Timothy
T
Green
David D
DD
Kitts
D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000378:metabolism; D019587:Dietary Supplements; D005511:Food Handling / Q000379:methods*; D006358:Hot Temperature; D007700:Kinetics; D010084:Oxidation-Reduction; D013763:Tetrahydrofolates / Q000378:metabolism*
D000975:Antioxidants; D013763:Tetrahydrofolates; D001205:Ascorbic Acid; C005984:5-methyltetrahydrofolate