L-AA is naturally present in most fruits and vegetables, but humans are unable to synthesize it. The Recommended Dietary Allowances (RDA) are 75 and 90 mg/day for adult women and men, respectively [9,10]. L-AA is rapidly oxidized to DHAA, and its oxidation can be induced by exposure to high temperatures and pH,
light, presence of oxygen or metals (Fe3+, Ag+, Cu2+), and enzymatic action.