Research On Accumulation Characteristics Of Pigment And Antioxidant Activity Of Different Colored Pericarp Of Weedy Rice

In this paper, three colored weedy rice were used as experimental materials and Shenyang black rice was used as cantrast.The color changes of glume,caryopsis,pericarp,seed coat and endosperm of weedy rice were observed during the development process. The polyphenol content and clearance rate of 2,2-diphenyl-1-picrylhydrazyl (DPPH)and hydroxyl free radicals (·OH) of different colored weedy rice in different periods were determined. High performance liquid chromatography (HPLC) coupled with tandem mass spectrometry (MS) were applied to determination of main components of pigment in weedy rice. The main results are shown as follow:1. The pigment of colored weedy rice gathers at the mesocarp cells. The color changing time of different caryopsis colored weedy rice are different. The caryopsis of black weedy rice WR07-14 and red-black weedy rice WR03-32 begin change color 8 days after flower, the caryopsis of red weedy rice WR07-141 begin change color 12 days after flower. The dorsal and both sides of caryopsis of different colored weedy rice are the first part to appear pigment. Gradually pigment proliferated to the whole pericarp. Glume color change low of three colored weedy rice cultivars is inconsistent. Glume of WR07-14 and WR03-32 discolor later than caryopsis, mature glume is golden which is similar to the cultivated rice. And glume of WR07-141 discolor before caryopsis, mature glume is red, not fade.The accumulation of pigment of weedy rice is in pericarp mainly,and seed coat and endosperm are not found.2. Total phenol content of different colored weedy rice during the caryopsis development period are not identical. After the earing and flowering, total phenol content of black weedy rice in the presence of the dynamic changes in different periods, which range between 65.27 mg GAE/100g and 225.14 mg GAE/100g; total phenol content of red weedy rice range between 59.57 mg GAE/100g and 77.23 mg GAE/100g; total phenol content of red-black weedy rice range between60.47 mg GAE/100g and 102.10 mg GAE/100g. The minimum total phenol content at maturity is red weedy rice(60.40 mg GAE/100g), the maximum total phenol content at maturity is black weedy rice(89.49 mg GAE/100g).3. Anthocyanin content to the weedy rice change is first will later in the mass. The anthocyanin content increase is consistent with caryopsis color change. Anthocyanin content of black weedy rice is significantly higher at 5～15 days after flowering, the highest anthocyanin content at 15 days is 150.30 mg C3G/100g; Anthocyanin content of red weedy rice is significantly higher at 5～20 days after flowering, the highest anthocyanin content at 20 days is 17.10 mg C3G/100g;Anthocyanin content of red-black weedy rice is significantly higher at 5～20 days after flowering, the highest anthocyanin content at 20 days is 72.33 mg C3G/100g. The minimum anthocyanin content at maturity is red weedy rice(12.17 mg C3G/100g), the maximum anthocyanin content at maturity is red-black weedy rice(51.57 mg C3G/100g). Procyanidins content of red weedy rice at maturity is 16.41 mg Catechin/100g.4. The antioxidant test in vitro result show, the DPPH free radical and hydroxyl radical removal ability of red weedy rice at maturity is higher than black and red-black weedy rice.5. Ingredients of pigment extract in different colored weedy rice are different. The main components of the extract of black weedy rice are cyanidin-3-glucoside and pconidin-3-glucoside; the main components of the extract of red weedy rice is cyanidin-3-glucoside, pconidin-3-glucoside is not contain; the main components of the extract of red-black weedy rice is cyanidin-3-glucoside. Procyanidin is only detected in the red weedy rice.