Tartary Buckwheat Introduction

Tartary buckwheat (Fagopyrum tartaricum (L.) Gaertn.), one of the two cultivated buckwheats, is widely grown in high‐altitude and mountainous regions, such as southwest China, northern India, Bhutan, and Nepal 1. Many studies have shown that Tartary buckwheat has great potential utility in reducing the risk of chronic diseases such as hypertension, hyperlipidemia, and hyperglycemia, because of its abundant active compounds, especially its high content of polyphenols 2, 3. With growing attention to the prevention of chronic diseases, there is increasing interest in inclusion of Tartary buckwheat in a healthy diet, and various healthy foods have been developed from Tartary buckwheat, including Tartary buckwheat noodles, breads, and tea.

Starch is the predominant constituent of Tartary buckwheat flour (accounting for approximately 70%), and is responsible for the textural properties of Tartary buckwheat products in the absence of gluten protein 6, 7. Compared with wheat and corn starch, Tartary buckwheat starch (TBS) has a higher amylose content (20–28%), a better water‐binding capacity, more stable pasting properties, and lower percentage of retrogradation 8, 9. Interestingly, although there are few differences in the physical properties of TBS and common buckwheat starch 10, the textural properties of Tartary buckwheat products, which have a higher phenolic content, are reported to differ from those of common buckwheat products. For example, Tartary buckwheat noodles have lower tensility and hardness, but greater adhesiveness, than common buckwheat noodles, and steamed cakes made from Tartary buckwheat flour are softer and moister than those made from common buckwheat flour 11, 12. This suggests the physicochemical properties of TBS in Tartary buckwheat products are affected by other factors.

Tartary buckwheat is rich in phenolics and is an excellent healthy food source. To evaluate the endogenous phenolics affecting the physicochemical properties of the starch in Tartary buckwheat products during processing, varying concentrations (0.5, 1.0, and 1.5%) of the predominant phenols, rutin and quercetin, were co‐cooked with Tartary buckwheat starch (TBS). Rutin and quercetin reduced the peak and final temperatures and enthalpy of TBS during gelatinization, lowered the aging enthalpy of retrograded TBS, and increased the trough and final viscosity of TBS paste and reduced its breakdown. The two additives also reduced the hardness and cohesiveness of TBS gels, while improving their water‐binding capacity. The morphologies of gelatinized and retrograded TBS were greatly altered with the presence of rutin and quercetin. The interaction between rutin or quercetin and TBS may be responsible for these changes, and the starch–phenolic binding force was much weaker than that in the iodine–starch complex. Our study provides insight into the physicochemical effects of the phenol–starch interactions in the Tartary buckwheat food matrix in a model system.