Production of Hydrolysate of Okara Protein Concentrate with High Antioxidant Capacity and Aglycone Isoflavone Content

Abstract This work aimed to evaluate the enzymatic hydrolysis of okara protein concentrate with respect to degree of hydrolysis (DH) in order to obtain a protein hydrolysate with high antioxidant capacity and aglycones isoflavone content. A central composite rotatable design was carried out to evaluate the influence of temperature (40 to 70°C), enzyme:substrate ratio (0.5 to 5.0%, g/100g protein) and pH (7.0 to 9.0) on DH. The optimal condition was 55°C, pH 9 and enzyme:substrate ratio of 5.0%, resulting a DH value of 35.5%. After protein hydrolysis at optimal condition, the antioxidant capacities of hydrolysate increased from 58.29 to 383.49 μM Trolox equivalent/g solids (ABTS method) and 2.41 to 15.32 μM Trolox equivalent/g solids (FRAP method) when compared with protein concentrate. The higher radical scavenging ability of hydrolysate was due to great amount of hydrophobic amino acids (34.92 g/100g protein). Moreover, the protein hydrolysate obtained under optimal condition had 3 times higher aglycone isoflavone content than non-hydrolyzed sample. These results showed that protein hydrolysis of okara could be an alternative approach to increase antioxidant activity and enrich aglycones isoflavone in this byproduct generated from soymilk industry.

Spray Drying of Pequi Pulp: Process Performance and Physicochemical and Nutritional Properties of the Powdered Pulp

The objective of this work was to optimize the spray drying of pequi pulp using maltodextrin as carrier agent and Tween 80 as surfactant agent. A central composite rotatable design was used to evaluate the influence of inlet air temperature (140 to 200°C), maltodextrin (15 to 30%) and surfactant (0 to 5%) concentration on the process performance and physicochemical and nutritional properties of the dried powdered pulp. The dependent variables were process yield (27.4 - 51.7%), outlet air temperature (106.5 - 135°C), energetic efficiency (29.9 - 44.8%), moisture content (0.25 - 1.43%), water activity (0.09 to 0.21), hygroscopicity (9.1 - 12.1 g adsorbed moisture/100g dry matter), vitamin C content (129.8 - 303.0 mg/g solids pequi) and total carotenoids content (8.2 - 94.9 mg carotenoids/g solids pequi). The spray drying of pequi pulp was optimized for maximum vitamin C and total carotenoids content using response surface methodology, which were attained at 152°C, surfactant concentration of 1% and maltodextrin concentration of 18%. The characterization of the pequi pulp powder obtained at the optimized condition evaluating the particles sizes, bulk density and porosity. The morphology showed spherical and smooth particles with several sizes.