Effects of Chinese chestnut powder on starch digestion, texture properties, and staling characteristics of bread

Chestnut is a high nutritional value food that has been widely used as a tonic in traditional Chinese medicine. As an emerging functional food ingredient, Chinese chestnuts are rich in a range of bioactive nutrients such as starch, dietary fiber, fat, protein, trace metal element and vitamins A, B, C, D and other nutrients. In our study, Chinese chestnut powder (CCP) were added into bread formulation at 2%–6% levels (based on flour weight) to produce fresh bread with enhanced anti-staling characteristics and starch digestion inhibitory ability. The texture properties, retrogradation enthalpy, water distribution, and estimated glycemic index (eGI) of wheat bread containing CCP as a functional additive were also investigated. The results showed that incorporation of CCP apparently affected bread texture, resulting in increased hardness, as well as decreased the specific volume of wheat bread. These influences were generally proportional to the amount of CCP used. It was found that adding too much CCP resulted in a dark red color, showing increased significantly higher total color difference (ΔE) and L values. Conversely, addition of CCP significantly reduced starch digestion rate and digestion extent in bread, and the reduction degree was positively related to the amount of CCP applied. The greatest reduction in eGI value from 79.40 (control) to 75.02 (6% CPP bread) was observed. Meanwhile, the content of resistant starch of 6% CPP bread was about 1.36 times higher than that of control bread. CCP also reduced crumb water loss and drove the water shift from the bound to the mobile state after stored for 7 days. The retrogradation enthalpy analyses further confirmed that CCP inhibited starch retrogradation and recrystallization. These results suggested that Chinese chestnut powder could be incorporated into fresh bread to provide health functions, such as lowering potential glycaemic response and improving anti-staling characteristics of bread.