Incorporation of Huangjing flour into cookies improves the physicochemical properties and in vitro starch digestibility

Huangjing contains no starch but rich in health-promoting compounds. The effects of Huangjing flour (HJF) on the physicochemical properties and quality of cookies were investigated by partially replacing wheat flour with HJF. The addition of HJF increased water solubility of the mixed flour and improved the crispness of cookies. The starch was lower approximately 69%, but obtained 8% higher protein and fat content than the control. The resistant starch increased from 23.74 to 41.37 g 100g−1, which significantly reduced the in vitro digestibility of the cookies and resulted in a much lower estimated glycemic index (eGI) 53.67 (eGI<55) compared with 61.81 wheat flower control when 40% HJF was included. The microstructure of the products indicated that the exposure area of starch particles was greatly reduced by the addition of HJF. The onset temperature of gelatinization increased from 60.75 °C to 61.75 °C, and the enthalpy of gelatinization decreased from 1.68 to 0.88 J g−1 with the presence of 40% HJF, suggesting that the HJF could retard the gelatinization of the cookies. The above results demonstrate that inclusion of HJF into cookies improves the quality of cookies and also provides a strategy for the production of low-GI foods.