RESUMO
By-products from the industrialization of oilseeds, particularly chia, can be sustainably used for the development of new functional products. In this work, wheat breads supplemented with up to 10 mg of chia expeller hydrolysate/g of flour were prepared, obtaining fortified breads with acceptability for consumption, according to a preliminary consumer research study based on an affective test employing a five-point hedonic scale of global acceptance. In this context, protein hydrolysates of the chia expeller were produced using Alcalase, reaching a degree of hydrolysis of 54.3 ± 1.6% with an antioxidant activity of 55.8 ± 0.4% after 6 h incubation at 25 °C in the presence of the enzyme. These peptides showed appropriate techno-functional properties and chemical compositions suitable for the further development of bakery products. Taken together, our approach and the development of a fortified bread with plant-based bioactive peptides provide a novel and eco-friendly alternative for the recovery of nutrients from agro-industrial waste. More importantly, these enriched breads could exert beneficial effects on human health by exploiting the antioxidant properties of functional peptides derived from the chia expeller.
RESUMO
This report describes the purification of an aspartic protease (salpichroin) from ripe fruits of Salpichroa origanifolia (Solanaceae) starting with precipitation using organic solvents and anionexchange chromatography with 32.1% recovery and 13.4-fold purification. SDS-PAGE and zymograms of this enzyme showed a single band corresponding to an apparent molecular mass of approximately 32 kDa. The biochemical and kinetic characterization of the pure enzyme showed an acidic behavior with an optimal pH value around 3.0-4.5 with hemoglobin and 5.5-6.0 with casein. Salpichroin activity was inhibited by pepstatin but not by phenylmethylsulfonyl fluoride, E-64, EDTA or 1,10-phenanthroline, thus suggesting an aspartic protease behavior. Salpichroin hydrolyzed natural substrates, such as casein and hemoglobin, with high specific activity. Kinetic studies conducted with the synthetic peptide H-Pro- Thr-Glu-Phe-p-(NO2)-Phe-Arg-Leu-OH showed lower affinity (Km 494 µM) than other representative aspartic proteases. By investigating the cleavage of oxidized insulin ß-chain to establish the hydrolytic specificity of salpichroin, we found six cleavage sites on the substrate of peptide bonds similar to those of chymosin. MALDI-TOF/TOF-MS of the tryptic ingel digest of salpichroin showed that the isolated protease shared homologous sequences with other plant proteases of the A1 aspartic protease family. This is the first report concerning the isolation and biochemical characterization of an aspartic protease isolated from Salpichroa origanifolia fruits.
