The role of lipids in determining the gas cell structure of gluten-free steamed oat cake

The stabilization of gas cells is crucial to obtain cake or bread products with a homogeneous crumb and is mainly depends on the proteins, starches, and lipids. Oats, in particular, are known for their high lipid content compared to other grains. However, the specific contribution of oat lipids to the gas chamber structure in gluten-free steamed oat cake is still unclear. Hence, to elucidate the potential mechanism involved, this study aimed to investigate the steaming characteristics of oat dough, as well as the protein-starch network matrix (including protein aggregation and structural properties), and the air/water interfacial characteristics (including foaming and surface tension properties) of oat dough liquor subjected to different defatting treatments. Results showed that by moderately removing lipids from samples (particularly ROF-D3 with 2.91% lipid content), gas retention ability, cell area fraction, and specific volume of the steamed oat cake were enhanced, which were 93.30 mL/ 100 mL, 36.27%, and 2.72 mL/g, respectively. Weak protein aggregation and an ordered protein secondary structure corresponding to a more open and stable protein network structure were observed in the ROF-D3 sample caused by moderate lipid removal. In addition, moderate removal of lipids obviously increased the extraction yield of oat dough liquor, in which lipid was evidently the dominant component. Compared to the ROF-D1 sample, the enhanced quality of the ROF-D3 sample can be attributed to the strongest foam stability and the increased air-water interface surface tension.