Extraction of rutin from Tartary buckwheat milling fractions and evaluation of its thermal stability in an instant fried noodle system

Extraction conditions of rutin from buckwheat milling fractions were established and a rutin-enriched material (REM, 31.8 g/100 g of rutin) was successfully obtained by the ultrasonic-assisted ethanol method (steaming, 16-150 mesh particle size, 70% ethanol, and ultrasonication at 40 °C for 30 min). When REM was applied to instant fried noodles (1% and 2% by weight of wheat flour) for rutin fortification, the levels of rutin in the noodles were determined to be about 250-500 mg/100 g which corresponded to the recommended daily dose of rutin. While frying temperatures (150-190 °C) and times (1-3 min) did not negatively affect the level of rutin in the instant fried noodles, the distinct loss of rutin was observed after cooking. Furthermore, REM did not significantly affect the oil uptake and mechanical property of instant fried noodles. The strong antioxidant activity of rutin in REM contributed to retarding the oxidative deterioration of the noodles during storage.