Study Of Millet Bran Stabilization And Millet Bran Oil Extraction Technology

Millet is one of the oldest cultivated crops with abundant nutrition substance.And millet bran,a byproduct of millet milling process,is also rich in variety of nutrient substance.Millet bran oil which is the high value-added vegetable oil extracted from millet bran contains rich unsaturated fatty acid,and it has been recorded that millet bran oil has medical functions.Therefore,millet bran oil has greatly development and utilization value.First of all,we study the issue of millet bran stabilization in this paper.With the peroxidase residual energy as indexes,we treat millet bran in different treatment,such as dry heating,moist heating and extrusion.And we get the better result of the three treatment as follows,dry heating?120 ?,60min?;moist heating?120 ?,30min?;extrusion?110-120?,moisture content of material 12-16%?.Then with the millet bran fatty acid as indexes,the millet bran obtained from above method is stored under the condition of 37?,we draw the conclusion that the treatment effect of extrusion and moist heating are better than dry heating,in contrast,extrusion is the best.To achieve the aim of ensure millet bran stabilization and extraction of millet bran oil at the same time,we get the suitable conditions that moisture content of material is 14-16%,extrusion temperature is 110-120?.It is noteworthy that excessively high extrusion temperature can singe miller bran which could affect subsequent oil extraction.Secondly,to solve the problem of the extracting of millet bran oil,ultra-wave soaking and supercritical CO₂ extraction are compared in this aspects of extraction rate,acid value,peroxide value and fatty acid composition in this paper.Compared with supercritical CO₂ extraction,the millet bran oil extraction yield of ultra-wave soaking is advantageous,but acid value and peroxide value are higher.The fatty acid composition of millet bran oil extracted by these two method both are linoleic acid,oleic acid,plamitic acid,stearic acid and eicosanoic acid,while total content of linoleic acid and oleic acid occupy over 83%.Then,supercritical CO₂ extraction is optimized by three factors of extracting temperature,pressure and time.According to the result of the orthogonal experiment,the important order who influence on millet bran oil extraction yield is,pressure>temperature>time.And then,the optimal extracting condition obtained is,extracting pressure 30 MPa,extracting temperature 40?,extracting time 120 min.Lastly,oxidation stability of millet bran oil is discussed in this paper.The whole extraction process is combined from pretreatment to extraction and some physicochemical index of the extracted oil is analyzed.Meanwhile,with the peroxide value as indexes,the oxidation experiment of millet brain oil is designed at different temperature,such as 30?,50? and 70?.At the beginning of oil oxidation,we speculate that it has much to do with oxidation induction time.With the peroxide value as indexes,TBHQ,BHA and VE antioxidants add to millet bran oil with addition of 0.02% under the condition of 50?,respectively.From the data,the important order of these three antioxidants influence on oxidation stability of millet bran oil is,TBHQ>VE > BHA.At the same condition,antioxidants of BHA+VE,VE+TBHQ and BHA+TBHQ are added to oil with addition of 0.01%.Statistics indicate that the combined antioxidant BHA+TBHQ exhibited more remarkable antioxidative activity than the others.