Polyolefins such as polypropylene (PP) and polyethylene (PE) were the first polymers compounded with DDGS up to 30 wt% [118]. The mentioned work included a comparison of four types of biofiller such as big blue stem (BBS) grass, soybean hull, pinewood and DDGS in terms of the mechanical performance of the their biocomposites with PP and PE. The composite processing was performed in a twin screw extruder and mechanical properties tests were conducted. Generally, the studied biofillers increased the flexural and tensile moduli. However, DDGS increased the modulus not significantly in comparison with neat PE and PP. Moreover, the tensile and flexural strengths decreased drastically as a result of compounding with DDGS. In general, the authors of [118] came to a conclusion that DDGS is not a suitable biofiller because of the decreased mechanical properties of the studied DDGS/polyolefin composites. In another work, the composite of high density PE with DDGS has been produced via extrusion and injection molding technique with DDGS content of 25 wt% [119]. The effect of maleated polyethylene (MAPE) as the compatibilizer was studied. Moreover, DDGS was solvent-treated to remove its oil and polar extractables. It has been reported that the application of the MAPP with solvent-treated DDGS resulted in better tensile and flexural properties of the composite compared to the respective properties of the neat HDPE.