Study On Tartary Buckwheat Germination In Stress And Its Functional Components

Tartary buckwheat is an annual crop with abundant biological nutrition components.However, many nutritional elements in tartary buckwheat can not be directly utilized byhuman and its nutritional inhibitiors, rough taste, and poor processability disturb thepopularity of tartary buckwheat. The traditional germination method is inefficient andinsignificantly effective. In this study, germination in stress is adopted to arouse resistanceaction in plant and accelerate seeds germination. This process is beneficial to accumulate thefunctional elements and eliminate the nutrition inhibitors in tartary buckwheat in relativelyshort period.In this study, Al³⁺、Cu²⁺and Zn2+were chosen as the stress factors in germination, andthe technological process of germination was also determined. The effect of steeping solutionsin different concentrations on germination indexes, starch and protein contents was discussed.Metal ions had a significant influence on germination and growth indicators. The optimalmetal ion stress was1000mg/L Al₂（SO₄）₃. Compared to the control, germination in stresspromoted the amylolysis. However, no significant changes in protein content were observedduring germination.During0-120h, the flavonoids and D-chiro-Inositol （DCI） contents in germinated seedsshowed an upward trend. During48-84h, they both increased rapidly. Germinationtemperature played a vital role in their contents, and the optimal temperature was25oC. Allthe three metal ions could stimulate the secondary metabolite and accelerate accumulation offlavonoids. The maximum content of the total flavonoids presented at1000mg/L Al₂（SO₄）₃,30.12%higher than that in control. Moreover, a correlation analysis between these enzymesactivities and the total flavonoids and DCI contents revealed a significant correlation. Themaximum DCI content presented at CuSO460mg/L was65.94%higher than that in control.Based on the results above, an orthogonal experimental experiment was run. It revealed thatthe optimal germination condition was1000mg/L Al₂（SO₄）₃solution at25oC for84h, for thehighest yields of total flavonoids （1347.07mg/100g DW） and DCI （86.41mg/g DW）.Changes of the trypsin inhibitor activity （TIA） and in vitro protein digestibility in seedsgerminated in stress were studied. Under the stress of1000mg/L Al₂（SO₄）₃, TIA decreasedsignificantly with minimum values4.90U/g on the third day, compared to TIA in control withminimum values7.71U/g on the seventh day. The reduction of TIA showed a remarkablecorrelation with an increase of in vitro protein digestibility. Compared to the control, thehighest digestibility in Al³⁺steeped seeds was97.15%observed on the third day.The main preparation process of germinated tartary buckwheat tea was studied. Theoptimal parameters were: crushed dried sprout between40-80meshes, baked at200oC for10min, for the lowest loss rate of the total flavonids and DCI as well as brewing property. Themetallic residues in product were not out of limits. The germinated tartary buckwheat teaowned a better flavor, brewing and nutritional property than other similar products.