Physical and textural properties of functional edible protein films from soybean using an innovative 3D printing technology.

Increasing market demand for sustainable, environmentally friendly edible film materials has called for the development of new customizable production methods utilizing emerging technologies such as 3D printing. We hereby report a new method to generate functional edible soy protein isolate films prepared from three types of soybeans (AR-R11-7999, MO-S17-17168, and MO-S17-19874R) using an innovative 3D printing technology. The protein contents in AR-R11-7999, MO-S17-17168, and MO-S17-19874R soybean meals and their corresponding protein isolates were 40.0, 39.1, and 39.9; and 84.5, 84.7, and 87.3 % (w/w, dry basis), respectively. Response surface methodology was used to maximize the tensile and puncture strength and minimize the thickness of the 3D-printed edible films using protein concentration, plasticizer concentration (glycerol), and drying time as the independent variables. The optimized film production conditions were determined as soy protein concentration: 8.91%, plasticizer concentration: 3.00%, and drying time: 3.98 h with a desirability value of 0.7428. The optimized conditions were then successfully verified with the original soybean lot with a nonsignificant difference in physical properties. At the optimized conditions, the 3D-printed edible films using three soybean lots revealed: 0.108-0.114 mm thickness; 14.79-16.07 MPa tensile strength; 6.97-8.20 N puncture strength; 90.81-91.53, -1.89 to -1.31, and 14.85-17.25 were color parameters L*, a*, and b*, respectively; 1.22-1.36 g/cm 3 density; and 104.4-105.7% elongation at break ratio (%). PRACTICAL APPLICATION: Edible soy protein films produced by an extrusion-based 3D printing approach are highly customizable and precise, and could be produced at an industrial scale. This newly produced environment-friendly soy protein-based edible film can serve as an alternate packaging to synthetic plastics and reduce the environmental landfill problem while adding value to soybean produced in the mid-south United States.