Ecuador Andean purple corn (Zea mays L.) was subjected to a germination process at 15–40 °C for 24–168 incubation hours. Purple corn protein concentrates (PCPCs) were obtained by alkaline extraction at pH 8.0 and pH 10.0, followed by an isoelectric precipitation process at pH 4.0, pH 5.0 and pH 6.0. Proteins and phenolic content of PCPCs was calculated. PCPC antioxidant properties were determined by the ferric-reducing antioxidant power (FRAP) in vitro method and by the 2,2-azinobis, 3-ethyl-benzothiazoline-6-sulfonic acid, (ABTS) in vitro method. Andean purple corn seeds were able to germinate under the germination conditions tested in this study. The higher percentage of germination was of 63.33% at 168 h/25 °C. The PCPCs protein profile was characterized for the presence of six bands with molecular weights of 14.50 kDa, 20.12 kDa, 25.18 kDa, 41.85 kDa, 59.59 kDa, and 65.87 kDa. Germinated PCPC presented a high TPC content with ranges of 605.71–1820.00 mg gallic acid equivalents (GAE)/g PCPC dry weight (DW), germinated PCPC/72 h/25 °C presented a higher value of 1820.00 mg GAE/g PCPC, DW. All germinated PCPCs samples assayed presented strong antioxidant activity when measured by the ABTS and FRAP methods. Germinated PCPC/144 h/35 °C presented high antioxidant activity by ABTS with 804.35 µmol Trolox equivalents (TE)/g PCPC DW and germinated PCPC/144 h/30 °C presented a high value by the FRAP method, 987.83 µmol TE/g PCPC DW.

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).