Effect of Solubilization pH on the Bioactive and Technological Properties of Baru Pulp Protein Concentrates

Baru (Dipteryx alata), a fruit native to the Brazilian Cerrado, is a source of proteins and bioactive compounds. During the production of protein concentrates from the pulp, extraction conditions may influence the recovery of these compounds and the characteristics of the resulting product. Thus, the objective of this study was to evaluate the effect of solubilization pH on the production of protein concentrates from baru pulp, with regard to phenolic acid content, antioxidant capacity, and instrumental color. The baru pulp (epicarp and mesocarp) was used to obtain protein concentrates by employing two alkaline solubilization pH values (pH 10 and 12), followed by acid precipitation (pH 4.8) (Leonel et al., 2025). Phenolic compound fractions, including extractable and non-extractable fractions, were obtained from the concentrates produced at pH 10 (CPP10) and pH 12 (CPP12). The extracts were evaluated for total phenolic acid content (Arvouet et al., 1994) and antioxidant capacity using the DPPH assay (Brand-Williams et al., 1995). Instrumental color parameters (L*, a*, b*, C*, h°, and ΔE*) were determined in the protein concentrates. Differences between treatments were evaluated using Student’s t-test (p < 0.05). CPP10 exhibited a lower total extractable phenolic acid content (13.66 ± 1.44 mg GAE/100 g) compared with CPP12 (21.44 ± 1.03 mg GAE/100 g), as well as a lower total non-extractable phenolic acid content (32.56 ± 0.96 mg GAE/100 g vs. 38.02 ± 1.55 mg GAE/100 g). This difference may be related to the lower alkalinity of the medium, which may limit the solubilization and disruption of interactions between phenolic compounds and the matrix. The antioxidant capacity was also lower in CPP10 than in CPP12, both for the extractable compounds (147.50 ± 2.83 µmol TE/100 g vs. 158.40 ± 4.36 µmol TE/100 g) and the non-extractable compounds (129.36 ± 8.40 µmol TE/100 g vs. 174.43 ± 4.38 µmol TE/100 g), in agreement with the lower phenolic acid content. Regarding color, CPP12 showed higher lightness (L* = 44.90 ± 0.24), greater intensity of red (a* = 5.67 ± 0.03) and yellow (b* = 15.72 ± 0.20) tones, and higher chroma (C* = 16.71 ± 0.18) than CPP10 (L* = 43.16 ± 0.64; a* = 3.89 ± 0.11; b* = 11.19 ± 0.40; C* = 11.85 ± 0.34). The h° values were similar (70.18 ± 0.26° and 70.79 ± 1.14°, respectively), whereas the ΔE* of 5.17 indicated an overall color difference between the concentrates. The greater color intensity observed in CPP12 was accompanied by a higher content of bioactive compounds, suggesting their contribution to the color of the concentrates. Therefore, higher solubilization pH favored phenolic acid recovery and antioxidant capacity, while altering color parameters, highlighting its potential for producing baru pulp protein concentrates with greater bioactive compound retention.