Synergistic Modulation of Cookie Quality, Sensory Profile, and In Vitro Starch Digestibility by Nannochloropsis Microalgae Incorporation into a Corn Oil-Based Emulsion Gel System

To change the saturated fatty acid composition of traditional cookies and enhance their functionality, corn oil-based emulsion gels were innovatively used as a substitute for butter. The study also investigated the impact of adding powder on the overall quality of cookies. Under optimal conditions comprising a 6:4 oil-to-water ratio, 3% gelatin concentration, and 0.1% grape seed polyphenol concentration, the prepared emulsion gel achieved an oil retention rate of 84.5%. Following the incorporation of the emulsion gel, the sensory score of the composite sample WZ significantly increased. The texture became softer, and a greenish-brown color, more acceptable to consumers, was developed. In vitro digestion analysis further revealed that the combined incorporation of Nannochloropsis gaditana powder and the emulsion gel reduced the RDS content from 59.6% to 54.0%,while increasing RS content to 25.8%, thereby effectively retarding the rate of in vitro starch digestion. This study utilized a corn oil-GSP/gelatin emulsion gel as a butter substitute in combination with microalgae incorporation, thereby achieving concurrent health enhancement and quality improvement of cookie products. The approach provides a feasible technical strategy and theoretical foundation for developing novel baked foods that exhibit favorable sensory properties and controlled starch digestion characteristics.