Study On Germination Of Tartary Buckwheat And Antioxidant Activity In Its Sprouts Under Microwave Treatment

Microwave is a type of electromagnetic waves,microwave technology is a new and efficient and environmental protection physical processing methods which widely used in food processing,storage and sterilization and other fields.In recent years,many studies have found that microwave has a variety of biological effects,and it has been used in the field of life science.It is reported that microwave stimulation has a positive effect on seed germination.Low-power and short-time microwave can accelerate germination speed,improve the quality of seedlings,and increase the synthesis of flavonoids,phenols and other important biological active ingredients in plants,thereby enhancing the antioxidant capacity of plant sprouts.Tartary buckwheat(Fagopyrum tataricum Gaertn.)is a type of herbaceous plant belonging to the family polygonaceae.It grows mostly in cold and dry areas with high sea waves.Tartary buckwheat is a kind of medicine and food crop with rich nutrition function.The amino acid composition is relatively balanced.It has more edible fiber and flavonoids than common buckwheat.In this study,tartary buckwheat seeds were used as experimental materials to study the effects of microwave technology on seed germination characteristics,phenolic and flavonoid enrichment in seedlings,determining the best germination technology of microwave treatment,and analyzing the relationship between microwave treatment parameters and the antioxidant capacity,antioxidant enzyme activity of tatary buckwheat seedlings in order to provide the theoretical basis for the development of nutritious tartary buckwheat food.The major research results are as follows:The optimum technology of microwave treatment to promote the germination of tartary buckwheat seeds was determined:microwave power of 300 W,microwave time of 75 s.Under these conditions,the final germination rate of tartary buckwheat was 96.00%.The effects of microwave treatment on seed germination,the seedling growth and the vigour index of tartary buckwheat were studied.The results showed that different microwave power and time had significant effects on the germination potential,germination index,average germination time,germination length,stem length,promotion rate and the vigour index of tartary buckwheat(P<0.05).The germination potential,germination index,stem length and vigour index of germination length were increased by 3.66%,10.36%,37.37%and 28.14%respectively,while the the average germination time was shortened by 7.54%.The changes of total phenols and flavonoids in tartary buckwheat germinated under different microwave treatments were studied.The contents of several flavonoids in tartary buckwheat germinated with microwave treatment were determined by HPLC.The results showed that microwave had a significant effect on total phenol and total flavone content of tartary buckwheat(P<0.05).The total phenol,total flavone and rutin content of 7-day-old tartary buckwheat sprouts and seedlings reached 23.26 mg GAE/g,3.88 g/100 g,23.3 mg/g respectively at 300 W and 75 s of microwave,but the contents of chlorogenic acid,vitexin and orientin were increased after germination compared with that of the seeds,but there was no significant effect compared with the control(P<0.05).The effects of different microwave treatments on antioxidant capacity of tartary buckwheat seedlings were analyzed and the correlation between total phenol,total flavonoids content and antioxidant capacity.The results showed that microwave could significantly improve the scavenging capacity of buckwheat malt seedlings on DPPH,ABTS,superoxide anion(O2-)and hydroxyl radical(·OH),thereby significantly improving their antioxidant capacity.The total reducing power of buckwheat seedlings germinated for 7 d reached 866.67 ?mol VC/g,68.53%higher than that of the control,which was 4.12 times higher than that of the seeds.There was a significant positive correlation between the content of total phenols and flavonoids of tartary buckwheat sprouts under microwave treatment and the antioxidant capacity.The effects of different microwave treatments on the activities of superoxide dismutase(SOD),catalase(CAT),peroxidase(POD)and ascorbic acid peroxidase(APX)in tartary buckwheat sprouts were studied.The results showed that the activities of SOD,CAT,POD and APX were significantly increased(P<0.05).When the microwave treatment at a power of 300 W for 75 s,the CAT activity of the tartary buckwheat sprout germinated for 7 d was the highest(7555.56 U/g FW/min),which was 99.22%higher than that of the control.Meanwhile,the highest SOD and APX activities were 846.11 U/g FW/h and 2.04 umol VC/g FW/h,which were 12.84%and 55.73%higher than the control in the tartary buckwheat sprout germinated for 5 d,respectively.When the seed treated by microwave of 250 W for 75 s,the highest POD activity of tartary buckwheat sprout germinated for 7 d was 64.89 U/g FW/min,which was 52.07%higher than that of the control.