Maximizing Phenolics, γ-Aminobutyric Acid, and Antioxidant Capacity in White Corn Sprouts Through H2O2 Soaking Concentration and Germination Time Optimization

White corn (Zea mays L.) is a staple grain in the Mexican diet and an important source of carbohydrates, proteins, dietary fiber, vitamins, minerals, and bioactive compounds. This study evaluated the effects of H2O2 elicitation and germination time on germination performance, bioactive compounds, and antioxidant capacity of white corn sprouts. Response surface methodology, based on a rotatable central composite design (13 treatments) was used to optimize H2O2 concentration (0–50 mM) during 24 h soaking and germination times ranging from 0 to 96 h. Optimal conditions were 20 mM H2O2 and 92 h germination, yielding 94% germination, 236.94 mg GAE/100 g free phenolic content, 21.63 mg/100 g GABA, and 6311.06 µmol TE/100 g antioxidant capacity (ABTS). Under these conditions, protein, GABA, and gallic acid contents, as well as antioxidant activity, increased by 9.26%, 34.01%, 30.95%, and 27.24%, respectively, compared with germinated grains without elicitor treatment. These findings demonstrate that H2O2-assisted germination is an effective strategy for enhancing the nutritional and functional properties of white corn sprouts.