| In recent years,a large number of studies have shown that glucosinolates and degradation products in broccoli,radish seeds,mustard,etc.have anti-cancer,anti-oxidation,and anti-bacterial functions.The content of glucosinolate in rapeseed cake is high,but for a long time,it has been considered that glucosinolate in rapeseed cake is toxic,which has greatly restricted the development and utilization of rapeseed cake resources in China.Therefore,strengthening the research and development of glucosinolates in rapeseed cakes will not only improve the utilization value of rapeseed cakes,but also provide a basis for the further development of the traditional "poison" of glucosinolates,and provide a basis for human beings to health.Based on this,the thesis takes glucosinolates in rapeseed cake as the research object,and conducts extraction,separation,purification,structure identification,stability and antioxidant tests of glucosinolates.The main conclusions of the paper are as follows:(1)First,the traditional "detoxification" water and ethanol are used as the solvent for the comparison test,the best solvent is preferred,and then the ultrasonic enhanced extraction is performed.The results showed that the optimal extraction conditions for water extraction were: liquid-to-material ratio 6: 1(mL/g),60? water bath,25 min each time,three extractions.Under this condition,the yield of glucosinolate was 31.044 mg/g.The best conditions for extracting glucosinolates from rapeseed cake with ethanol are:liquid-to-material ratio 4: 1(mL/g),70% ethanol,80? water bath,30 min each time,extraction 4 times,under this condition,the yield of glucosinolate was 63.08 mg/g.Based on this,ethanol was selected for the ultrasonic enhanced extraction test.The optimal conditions were: ultrasonic power 150 W,liquid-to-material ratio 4: 1(mL/g),70% ethanol,60?,15 min each time,extraction 5 times.Under this condition,the yield of glucosinolate was 62.06 mg/g.It can be seen that ultrasound enhancement can achieve a similar yield,which can greatly shorten the extraction time,which is a better method.(2)The experiment adopted the method of adsorption and desorption separation,through the single factor of resin type,adsorption temperature,resin mass and glucosinolate volume ratio,adsorption time and desorption liquid type,resin quality and desorption liquid volume ratio,desorption time,pH factor.The optimization experiment showed that the best adsorbent was D201 GF resin.The optimal adsorption conditions were: temperature 40?,resin mass to glucosinolate volume ratio 1:10(g/mL),adsorption time 9 h;the optimaldesorption conditions are: the desorption liquid was 1 mol/L NaCl,the volume ratio of resin to desorption liquid was 1:10(g/mL),the desorption time was 45 min,and the pH was 6.The desorption solution was concentrated by rotary evaporation and then lyophilized to obtain the product.After measurement,the recovery of glucosinolate was 76% and the purity was 89%.(3)The effects of temperature,pH,ultrasonic power and time,and light on the stability of glucosinolates were studied.Tests show that ethanol extracts and water extracts have good stability in neutral environment below 80?,and are unstable under 80? and acidic and alkaline conditions;ultrasonic treatment,when the acoustic power was 200 W,the glucosinolate content in the alcohol extract and water extract was reduced by 30% to50%,while the purified product has a reduced content when the ultrasonic power was 300W;The lengthening of the ultrasonic action time reduces the glucosinolate content;light will also reduce the content of glucosinolates in alcohol extracts and water extracts.(4)The glucosinolate extract of rapeseed cake and the products of high temperature,strong acid,ultrasound,and light treatment were characterized by infrared structure.The results showed that although the glucosinolate content in the extract was reduced at high temperature,its infrared The spectrum has no obvious change compared with the low temperature;strong acid causes the content of glucosinolate to be reduced.Infrared shows that C=N,C-O-C and other groups have changed.After ultrasonic treatment,the characteristic absorption peak of N=C=S is produced;there is no obvious change between infrared display and avoiding light under light.Infrared,ultraviolet,nuclear magnetic resonance hydrogen spectroscopy,and nuclear magnetic resonance carbon spectroscopy were used to characterize the purified product and the high-temperature and acid-treated product.The results showed that under high temperature,the C-S of the purified product was partially decomposed to produce isothiocyanate and cyanate ester compound;under acid treatment,C-S,C-O-C and other groups change and isothiocyano is produced at the same time.(5)Antioxidant tests were carried out on alcohol extracts,water extracts and purified products of glucosinolates in rapeseed cake,and DPPH·,·OH,ABTS free radical scavenging rate,and the reducing ability of Fe were selected as indicators Measure antioxidant properties.The results show that no matter which antioxidant index is used,the antioxidant capacity of glucosinolates shows a dose-dependent effect.For the removal rate of DPPH·,when the concentration was 0.3 mg/mL,the alcohol extract was 76.9%,the water extract was less than 60%,the purified product was 68%,and Vc was 95%;When the concentration was 4 mg/mL,the three respectively reach 48.5%,75%,91.8%,and Vc wasclose to 100%;the reducing power of Fe,when the concentration was 5 mg/mL,alcohol extract and water extract are all around 0.5,and the purified product was 1.7,which exceeds Vc(1.2);the clearance rate of ABTS was 0.7 mg/mL.When the concentration was0.06 mg/mL,the clearance rate reaches 86%.It can be seen from the above test results that for the removal of DPPH·,the alcohol extract was the best,while for the removal of ·OH,ABTS radicals and the reducing power of Fe,the purified product was the best.In addition to the reducing power of Fe,the alcohol extract The antioxidants of the substance,water extract and purified product were worse than Vc. |
PDF Full Text Request