Abstract:
In this study, the effects of adding anthocyanins (0.45~2.70 g/100 g rice flour) extracted from
Lycium ruthenicum Murr on the quality improvement of steamed rice bread were investigated through textural profile, gas cell distribution, and sensory evaluation. The mechanisms underlying the effects of anthocyanins on the starch gel network and fermentation of steamed rice bread were investigated based on rheology and Fourier transform infrared spectroscopy (FTIR). The results revealed that the optimal amount of supplementary anthocyanin extract was 1.80 g/100 g rice flour, which gave rise to steamed rice bread with a hardness of 14.02 N, a specific volume of 1.78 mL/g, and a sensory evaluation score of 76.63. The red shift of the –OH stretching vibration peak in the FTIR spectrum indicated that anthocyanin extracts might bind to starch molecules through hydrogen bonds. The increase of R
1052/1022 in the deconvolution curve suggested that the addition of anthocyanin extracts increased the short-range order of starch. The rheological results showed that anthocyanin extracts decreased the complex modulus (|G
*|) of rice paste and promoted the expansion of gas cell chambers in the steamed rice bread. In addition, anthocyanins acted as an indicator for the fermentation process based on their pH-dependent color, giving a bright color and good appetite to the steamed rice bread. In conclusion, the addition of anthocyanin extracts from
Lycium ruthenicum Murr could promote the gelation and fermentation of steamed rice bread by regulating the starch gel network, resulting in quality improvement.