Inga paterno is an underutilized legume whose seeds are a good source of protein. However, the cottony sarcotesta is the most consumed part of the plant. Given that sprouting has been shown to enhance the nutritional value of legumes, this study investigated how sprouting duration influences the total phenolic content (TPC) and antioxidant activity (TAC) of I. paterno seed flour.
I. paterno seeds were sprouted at 23°C with 78% RH for 0, 2, 4, 6, 8, or 10 days. The sprouted seeds were ground into flour. Then, each flour was mixed with methanol solution (20:80), stirred at 25°C for 24 hours, and centrifuged to obtain the supernatant. TPC and TAC were determined by the Folin–Ciocalteu method and DPPH• or ABTS•+ radical scavenging assays, respectively. One-way ANOVA and Tukey's test were used to analyze the data (p ≤ 0.05).
TPC exhibited a range of 5.54 to 12.09 mg gallic acid equivalents per gram of dry matter (dm), with a significant increase after 4, 6, 8, and 10 days of sprouting. DPPH-based TAC values ranged from 4.28 ± 0.11 to 9.87 ± 0.14 μM Trolox equivalents (TE) per gram of dm, while ABTS-based TAC values ranged from 17.41 ± 0.51 to 26.40 ± 0.50 μM TE per gram of dm. Significant increases in DPPH-based TAC were observed after the 4th day and at all subsequent sprouting times, while ABTS-based TAC significantly increased after the 2nd and 8th days of sprouting. The observed changes may be attributed to the breakdown of phenolic compounds bound to plant cell walls, as well as to the activation of metabolic pathways that modify antioxidant metabolites.
This study demonstrates that sprouting I. paterno seeds for 4 days enhances the nutritional value of the resulting flour. However, further investigation is necessary to evaluate other potential nutritional modifications fully.
