Identification of Phytochemical Compounds, Functional Properties and Antioxidant Activity of Germinated Purple Corn Protein Concentrate and Its Gastrointestinal Hydrolysates

Purple corn seeds germinated at 25 °C and 35 °C for 5 days were used to obtain purple corn protein concentrate (PCPC25 and PCPC35). PCPC25 and PCPC35 were subject to gastrointestinal hydrolysis. PCPC and its hydrolysates were used to evaluate their functional and biological properties. Total flavonoid content (TFC), total flavonol content (TFLC), total anthocyanin content (TAC) and total proanthocyanin (TAP) were determined. The polyphenols and flavonoids were identified by UPLC-QDa. Protein solubility (PS), water and oil absorption capacity (WAC and OAC) were determined. The antioxidant activity was evaluated by the FRAP, ABTS and DPPH methods. PCPC35 showed the highest TFLC values (11,091.37 mg rutin equivalents (RE)/100 g dry weight DW), and TFL presented values of 7975.59 mg RE/100 g DW. The PCPCs presented better functional properties than the hydrolysates. PCPC25 presented a PS of 59.43%PS at pH 8.0, 27.77%WAC and 24.94%OAC. PCPC25 and PCPC35 showed high values of antioxidant activity. PCPC25 showed ABTS values (570.97 µmol trolox equivalents (TE)/g DW) and FRAP (772.85 µmol TE/g DW). PCPCs hydrolysates were less active with ABTS values (74.12 µmol TE/g DW) and FRAP (59.42 µmol TE/g DW).