| Buckwheat is not a cereal but is usually grouped with cereals due to its ways of cultivation and utilization,it has been used both as a food and a traditional medicine.Buckwheat is abundant in nutrients,such as protein,amino acids,and minerals.According to the published reports , buckwheat has been shown to exhibit antioxidative,anti-inflammatory, anticarcinogenic,hypoglycemic and hypolipidemic effects for its abundance in flavonoids.The content of flavonoids in buckwheat is higher than most plants,especially in tartary buckwheat,so tartary buckwheat is an excellent material for functional food developing.Tartary buckwheat bran is the mainly byproduct in tartary buckwheat processing,and it has high content of flavonoids.Generally,tartary buckwheat bran is used as feedstuff and waste.In order to make full use of tartary buckwheat,the extraction technology of total flavonoids in tartary buckwheat bran was investigated in this paper.Ethanol-extraction technology,microwave-assisted extraction technology and ultrasonic wave-assisted extraction technology were optimized and compared.The compositions of total flavonoids in 11 kings of tartary buckwheat were analyzed by HPLC-MS and the HPLC-MS fingerprint of total flavonoids in tartary buckwheat bran was established.The main contents of this paper:(1) Study on ethanol-extraction technology;(2) Study on microwave-assisted extraction technology;(3) Study on ultrasonic wave-assisted extraction technology;(4) Study on HPLC-MS fingerprint.The main results of this paper:(1) The results showed that the content of total flavonoids in tartary buckwheat bran was 6.01% by soxhlet extraction.The optimum conditions of ethanol-extraction were obtained as follows:the concentration of ethanol was 80%,the temperature of extraction was 80℃,the ratio of material to solvent was 1:50 and the time of extraction was 2.5h.With this technological conditions,the extraction yield was 5.65%,extraction rate was 94.01%.(2) The microwave-assisted extraction technology of total flavonoids in tartary buckwheat bran was studied,and all experiments were designed and optimized with Box-Behnken concept of response surface methodology(RSM).The optimum conditions of the extraction technology were obtained as follows:treatment time 120s,the concentration of ethanol 86%,the ratio of material to solvent 1:50,using the technological conditions,the extraction yield of total flavonoids was 5.81%,the extraction rate was 96.67%.(3) The ultrasonic wave-assisted extraction technology of total flavonoids in the bran were studied,and all experiments were designed and optimized with Box-Behnken concept of response surface methodology(RSM).The significant order of the factors in this experiment was as follows:concentration of ethanol,ratio of material to solvent,time,temperature.The optimum conditions of the extraction technology were obtained as follows:90% ethanol as extraction solvent at 65℃for 30min,and the ratio of material to solvent was 1:40.Using this technology,the extraction yield was 5.72%,extraction rate was 95.10%.(4) According to the results of HPLC-MS,four main flavonoids were detected:quercetin-3-rutinose-glucoside,rutin,kaempferol-3-rutinoside,quercetin.The HPLC-MS fingerprint of total flavonoids in tartary buckwheat bran was established,the parameters were obtained as follows(No.of common peak(relative area)):1(0.04),2(1),3(0.64),4(0.38).The main conclusions of this paper:(1) According to the results mentioned above,the ultrasonic wave-assisted extraction technology was timesaving,at the same time,it was convenient and efficient with low treatment temperature,so it was the best extraction technology in this study.(2) The best varieties for flavonoids extraction were:Chuanqiao 1,Zhaoku 1 and Xinong 9909.The innovative points of this paper:(1) Microwave technology and ultrasonic wave technology were used to extract flavonoids in tartary buckwheat bran and response surface methodology was utilized to design experiment.(2) The mian flavonoids in 11 kinds of tartary buckwheat bran were characterized by HPLC-MS.(3) The HPLC-MS fingerprint of total flavonoids in tartary buckwheat bran was established and was applied to screen tartary buckwheat variety. |
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