Production of walnut beverage from walnut press waste using ultrasound and enzyme

In this study, walnut drink production from press cake that remains as waste from the production of walnut oil by cold pressing, using ultrasound technique and enzyme application (Alcalase 2.4 L FG) was investigated. Six different production procedures were used in the production of walnut beverages. The physical, chemical and sensory properties of the beverages were also determined. The walnut beverage produced by ultrasound/enzyme/formulation treatment from press cake without thin-shell had the highest zeta size (1321.15 nm), PDI (0.44), foaming capacity (28.00%), protein (2.58%), viscosity (4.91 cP at 10°C, 3.27 cP at 24°C), °Brix (8.87) and titratable acidity (%0.22) values, while the sample had the lowest total phenolic content (1201.05 mg GAE/L) and antioxidant activity value (DPPH: 2.47 mg Trolox Eq/L and ABTS: 7.78 mg Trolox Eq/L). The highest total phenolic content (2755.84 mg GAE/L) and antioxidant activity values (DPPH: 19.54 mg Trolox Eq/L and ABTS: 26.98 mg Trolox Eq/L) were determined in walnut beverage produced by ultrasound/ enzyme/formulation treatment from press cake containing thin-shell. The sample formed by conventional method from press cake containing thin-shell had the lowest protein (0.27%) and total phenolic content (966.04 mg GAE/L). The effect of enzyme application on the increase in protein content of the samples was higher than that of ultrasound application. Among the beverages evaluated by the panelists, only enzyme/ formulation samples without ultrasound technique received the highest odor, astringency, consistency, mouthfeel and overall taste scores. As a result of the study, it was determined that the walnut cake that obtained after walnut oil extraction can be successfully used in the production of walnut beverage by applying ultrasound technique and enzyme application. Thus, both the walnut oil with high economic value will be preserved and the walnut beverage with high nutritional value will be produced by walnut press cake. In this way, the walnut beverage can contribute to national economy and human nutrition.