Influence of substituting wheat flour with quinoa flour on quality characteristics and in vitro starch and protein digestibility of fried-free instant noodles

Wheat flour (WF) was substituted with different level of quinoa core flour (QCF), quinoa whole flour obtained by grinding mill (GQWF) and flour mill (RQWF) equipment separately, to develop QCF, GQWF and RQWF-formulated fried-free instant noodles. Tensile properties and quality attributes of dough, and cooking qualities, texture properties and sensory analysis of noodles were investigated. Substitution with quinoa flour decreased optimal cooking time and iodine contrast index of noodles, while cooking loss was not affected by quinoa flour. Water absorption capacity of RQWF30-noodle was lower than that of WF-noodle. The hardness of QCF and RQWF formulated noodles was significantly higher than that of WF-noodle, while the hardness, chewiness, elasticity and resilience of GQWF-noodle were inferior to WF-noodle. Microstructure results showed that quinoa flour containing-noodles had larger and uneven pores than that of WF-noodles. The sensory indicators of noodles were better when substitution level of quinoa flours was ≤20%. Substitution with quinoa whole flour decreased protein digestibility and reducing sugar released during in vitro starch digestion of noodles. These findings revealed that substitution with quinoa flours (≤20%) may have the potential to develop noodles with both low reducing sugar released and desirable textural attributes.