Effects Of Microbial Fermentation On The Antioxidant Activities Of Purple Wheat Bran

Pigmented wheat has different color in the kenel pericarp or aleuronic layer and is different from the common white wheat. Pigmented Wheat consist of blue, purple, black, pericarp ones. And they are precious new varieties of wheat. Many cultivars pigmented wheat have been showed to contain rich natural pigment, protein, amino acid and microelements or antioxidant substance which are beneficial to human health. And there are lots of natural phenolic acids in the wheat bran which having special physiological regulation and health care functions, high application value and development prospects.This study is based on using the bran of the Shandong Agricultural University self-cultivate purple wheat for materials. From Bacillus subtilis, Paenibacillus sp., Bacillus thermoliquefaciens, Saccharomyces cerevisiae and Aspergillus niger strains screened effect on purple coarse wheat bran solid state after fermentation, on which the total phenols and phenolic acids are extracted and measured and studied antioxidant activity. The main findings are as follows:(1) Screening of solid state mixed fermentation strains.By analyzing the antioxidant activity of extraction rate and liquid and solid fermented bran total phenols,Bacillus subtilis, Paenibacillus sp., and Aspergillus niger are Screened to ferment from five kinds of strains.(2) Process parameters regression equations of solid state fermentation conditions: Y=6.12+0.38X1-0.03X2+0.30X3-0.029X4+0.36X5-0.17X1X2-0.070X1X3+0.12XiX4+0.16X2X3-0.073X2X4+0.13X2X5+0.085X3X4+0.23X3X5-0.14X4X5-0.51X12-0.40X22-0.48X32-0.34X42-0.55X52。(3) According to the results of the regression analysis model. Optimum technological conditions are as follows:the temperature should be31℃, loading should be20g, fermentation time should be3.5d, inoculation quantity should be15%, material-liquid ratio should be1:0.5. Under the optimum conditionsn, the total phenol extraction rate was6.264mg/g.(4) Study on total phenolics extraction rate and antioxidant activity. The correlation coefficients between total phenol extraction rate and DPPH radical scavenging and between total phenol extraction rate and ABTS radical scavenging were greater than0.9, so that there was a significantly positive correlation between total phenol extraction rate and DPPH radical scavenging and ABTS radical scavenging.(5) Determination of phenolic acids species and content.The coarse wheat bran in purple which after a solid state fermentation, Gallic acid, coumaric acid, ferulic acid content, exclusive content, ferulic acid and salicylic acid was higher than the blank group, but the original catechin, p-hydroxy benzoic acid, clove acid content is reduced, the content of total phenolic acid increased more than two times than that of the blank group.