Improving bioactivities of Jatropha curcas protein hydrolysates by optimizing with response surface methodology the extrusion cooking process

• Optimization of extrusion cooking process by response surface methodology.
• Extrusion cooking process improves bioactivities of Jatropha protein hydrolysates.
• Protein hydrolysates with antioxidant capacity.
• Protein hydrolysates with antihypertensive activity.

Bioactive peptides, as product of hydrolysis of diverse food proteins, exert various biological roles of great interest in health care. Several pre-hydrolysis treatments of food proteins are commonly used to improve specific bioactivities of protein hydrolysates. In this study, we employed an optimized extrusion cooking process before applying an enzymatic hydrolysis in order to increase bioactivities of Jatropha protein hydrolysates (JPH). Response surface methodology (RSM) was used to study the influence of two main independent variables of the single-screw extruder operation conditions: extrusion temperature (ET) and screw speed (SS). Bioactivities such as antioxidant capacity (AOXC) and antihypertensive activity (ACEI-activity) were selected as response variables. The model was statistically appropriate to describe both responses. Results revealed that both ET and SS significantly influence on AOXC, while only the ET showed influence on ACEI-activity. According to the numerical method used of RSM, the optimum operation conditions were ET = 160 °C and SS = 200 rpm. Optimized JPH exhibited a significant increase in both responses AOXC and ACEI-activity. Along with this increase, optimized JPH presented greater protein degree of hydrolysis indicating the presence of short biologically active peptides. Additionally, extrusion cooking process decreased the levels of the major antinutritional factors commonly present in raw Jatropha cake. Overall, this study might contribute to appraise Jatropha as a suitable source of bioactive compounds for the development of nutraceutical products highlighting the economic importance of this crop, and shows extrusion cooking process as appropriate method to improve food quality and increase protein digestibility.