Research On Pigment Content And Anthocyanin Extraction Technology Of Colored Rapeseed Germplasm

Rapeseed is an important oilseed crop in China.It has many applications,such as oil,flowers,feed,fertilizer,vegetables and honey.With the continuous deepening of the multi-function of rapeseed,the development and utilization of colored rapeseed has more potential.In this paper,six rapeseed materials with different color were studied.The pigment content of flower buds,involucres and petals of rapeseeds with different color were determined by spectrophotometry,and the change rule of pigment and coloration mechanism were preliminarily explored.There is a significant difference in pigment contents in the petals of six kinds of colored rapeseeds,and the anthocyanin contents in petals of purple,pink,red and orange were higher.Therefore,these four kinds of flower color materials were selected to optimize the ultrasonic-assisted extraction process of anthocyanin from rapeseed petals by response surface method,in order to obtain the maximum anthocyanin extraction amount and the best extraction process of each flower color material,and to study the antioxidant and stability of anthocyanin.Anthocyanins have many physiological functions and broad application prospects.It is of great significance to the study of anthocyanins,and also provides reference for color rapeseed breeding and multi-functional utilization.The test results are as follows:1.There are differences in the changes of pigment content in the petals of rapeseed with six flower colors during flowering,which reflects the coloring mechanism of rapeseed with different flower colors to a certain extent.Anthocyanins are closely related to the color of purple,pink,orange and red rapeseed flowers.The anthocyanin content of these four flower color materials gradually increased with the advancement of flower buds,gem to petals,and was significantly higher than that of white and yellow rapeseed lines.In addition,the carotenoid content in rapeseed orange blossom is rich and higher than other substances,reflecting that carotenoids are also related to the formation of orange blossom color.The pigments in yellow rapeseed petals were mainly composed of flavonoids and carotenoids,and the change trends of the two pigments were inconsistent.The former increased first and then decreased,while the latter decreased first and then increased.2.On the basis of single factor experiment,the extraction process of each flower color material was optimized by response surface test with the extraction amount of anthocyanin as the response value.The results showed that the ratio of material to liquid was 1:30g·m L^-1 and the ultrasonic power was 400w,and the three factors of ethanol concentration,temperature and time were selected for further optimization.Response surface methodology was used to optimize the extraction process of anthocyanins from the petals of purple,powdery,red and orange rapeseeds.The optimum extraction process was as follows:ethanol concentration 74.33%,79.28%,74.42%,80.02%（V/V）,extraction time50min,51min,50min,55min,temperature 62°C,68°C,68°C,66°C.Under these conditions,the extraction amount of anthocyanins reached the highest.They were 0.579±0.011 mg·g^-1,0.683±0.023mg·g^-1,1.275±0.019mg·g^-1 and1.032±0.040mg·g^-1,respectively.The relative error between the predicted value and the response surface fitting equation was less than3%.The extraction process had good repeatability and high feasibility.3.The scavenging effects of anthocyanin extracts on DPPH·,ABTS⁺,?OH free radicals and total reducing capacity were studied,and the antioxidant capacity was evaluated by membership function method.The results showed that the anthocyanins extracted from four rapeseed materials had certain antioxidant capacity,but there was still a gap compared with VC.In the concentration range of 1～8 mg·m L^-1,the scavenging effect of rapeseed anthocyanins on ABTS⁺free radicals increased first and then tended to be gentle with the increase of concentration.Among the four materials,the anthocyanin extracts from the petals of red rapeseed and orange rapeseed showed strong DPPH·and ABTS⁺free radical scavenging ability.In the range of 0.1～0.8 mg·m L^-1,there was a dose-effect relationship between the scavenging effect of?OH and the anthocyanin concentration in the petals of the tested materials.The anthocyanin extract of purple rapeseed had the strongest scavenging effect on?OH.The comprehensive evaluation of its antioxidant capacity showed that the antioxidant order was:red flower material>orange flower material>purple flower material>pink flower material.4.The effects of light,temperature,metal ions,oxidant H₂O₂,reducing agent Na₂SO₃and sugar on the stability of anthocyanin in rapeseed petals were investigated by using the preservation rates of anthocyanin as the detection index.The results showed that anthocyanin was suitable for storage in dark and low temperature（<40°C）.In the process of storage and processing,Na⁺,K⁺,Mg²⁺and Al³⁺can be added appropriately,but contact with Cu²⁺and Fe³⁺should be avoided.High concentration of glucose and sucrose can improve the stability of anthocyanin,and the effect of glucose on the stability of anthocyanin is better than that of sucrose,while the oxidant H₂O₂ and the reducing agent Na₂SO₃ have adverse effects on the stability of anthocyanin,and the anthocyanin is more sensitive to H₂O₂.