Process Optimization Of Lactic Acid Bacteria Fermented Buckwheat Sprouts Juice And Study Of Its Effect On The Removal Of DPPH Free Radical

Buckwheat have a high antioxidant activity, due to the nutrients in buckwheat, and theexistence of a variety of phenolics. The process of germination can improve the content ofantioxidants and the antioxidant activity of buckwheat. But at present, the study of buckwheatsprouts mainly concentrated on the content of active material, the health care function, theextraction method optimization of buckwheat sprouts and so on. This study used differentconcentrations of ethanol to extract the antioxidant components from buckwheat sprouts in thedifferent germination time, analyze the DPPH radical scavenging effect of extracts; then usedthe microorganisms adhered to the surface of buckwheat sprouts buckwheat sprouts, start thespontaneous fermentation of buckwheat sprouts juice; selected the lactic acid bacteria fromspontaneous fermentation of buckwheat sprouts juice, optimize the fermentation conditions ofprocess of lactic acid bacteria fermented buckwheat sprouts juice by the response surfacemethod.The main conclusions of this study are as follows:1.60%ethanol solution had a higher extraction yield, but antioxidant activity of extractswas low; while40%ethanol extracts from buckwheat sprouts showed a higher DPPH radicalscavenging ability, the antioxidant capacity increased when germination for a longer time,germination in6days had the maximum clearance rate; comprehensive consideration of DPPHfree radical clearance rate and the extraction yield, the buckwheat sprout germinated for9dayshad the strongest DPPH radical scavenging ability.2. In the process of spontaneous fermentation of buckwheat sprouts juice, when thefermentation time was extended, total flavonoid content in the fermented liquid showed aascendant trend, peaked in9day, and then slow down. After fermentation, of the DPPH freeradical scavenging effect of buckwheat sprouts obvious increased, along with the extension offermentation time, when fermented for9days reached the highest clearance.3. Strain L9was isolated from buckwheat sprouts juice fermented for9days spontaneousfermentation. After morphological identification and physiological and biochemical testevaluation, proved that L9strain had high similarity with the ones belonged to Lactobacillusbrevis.4. On the basis of single factor experiment, the fermentation conditions of Lactic acid bacteria fermented buckwheat sprouts juice were optimized. Selected the fermentation time,initial pH and the inoculum size as three factors, each factor select three levels. Responsesurface analysis was used to determine the best fermentation conditions of buckwheat sproutsjuice. The results showed that the optimum fermentation conditions: inoculum size was6.5%,fermentation time was6d, initial pH was6.1.Under the optimum fermentation conditions, theDPPH free radical clearance rate of buckwheat sprouts juice was84.68%, was close to thatfermented for9days in spontaneous fermentation, but the fermentation time was shortened for3days.