In Vitro Starch Digestibility And Antioxidant Property Of Cooked Buckwheat Noodles

Buckwheat is known as a medical and edible dual-purpose plant in China, which is richin nutrients and bioactive compounds. Extruded buckwheat noodle is a kind of food madefrom buckwheat flour and commonly consumed in North China. Studies on buckwheat foodare of great practical significance. The current study selected several common and tartarybuckwheat cultivars, and made extruded buckwheat noodle from their flour. The noodles ofdifferent cultivars were investigated into cooking and edible quality, in-vitro starchdigestibility, content and antioxidant property of polyphenols and antioxidant activity ofpolysaccharides in buckwheat noodles. The main results of the study were as follows:(1) The cultivars of buckwheat had a significant effect on cooking and edible quality,in-vitro starch digestibility, content and type of polyphenols and antioxidant activity ofbuckwheat noodles.(2) Common buckwheat noodles were better in textural quality (adhesiveness andtensility) and sensorial evaluation. Among the cultivars tested, Yuqiao4#performed best inthe two parts with the highest sensory scores, low adhesiveness and high tensility. Also, theestimated glycemic index (EGI) buckwheat noodles in five cultivars were significantly lowerthan wheat noodle. Within the different buckwheat cultivars, Yuqiao4#has the highest EGIvalue and that of other four noodles were below75which is belonging to medium-EGI valuefood, expecially Wensha, whose EGI value was as low as69.53. The result indicated thatbuckwheat noodle can be served as good alternative food to wheat noodle for people withdiabetes.(3) Tartary buckwheat noodle contained remarkably higher total phenolic content andantioxidant activity than common one, while both of them showed stronger antioxidantquality than wheat noodle. The level of total phenolic and total flavonoids content inbuckwheat noodle varied from182.65to1362.74mg GAE/100g DW and183.33to600.76mg RE/100g DW, respectively. With regard to the results in HPLC analysis,12polyphenolcompounds (gallic acid, p-hydroxybenzoic acid, chlorogenic acid, syringic acid, p-coumaricacid, ferulic acid, ellagic acid, cinnamic acid, protocatechuic acid, catechin, rutin and quercetin) were identified and quantified and revealed that rutin and quercetin were thedominant phenolic compounds. The content of rutin and quercetin ranged from1.2to48.2mg/100g DW and2.1to455.5mg/100g DW, respectively.(4) Both polysaccharides extracted from buckwheat noodles and wheat noodle exhibitedantioxidant capacity to varying degrees and the former was better than the latter. Theantioxidant capacity ranking of buckwheat noodles of five cultivars in different antioxidantsystems showed obvious variation. Additionally, the antioxidant activity grew along with theincrease of concentration of crude polysaccharides, and it reached a peak and remained stableat high concentration. Moreover, the antioxidant capacity of crude polysaccharides in tartarybuckwheat noodle was better than common buckwheat noodle, and Xinong9940wasconsidered as the best.