| Anthocyanins is a kind of nonpoisonous and abounding natural pigment. It has greatprospects in foods, cosmetics and medicine because of its nutritional and the pharmacologicalfunctions. Compared with the ordinary red skin peanut, the black skin peanut has highercontents of anthocyanins which color is deeper and easier to extract. Developing the pigmentfrom black peanut skin can provide high quality, multi-nutritional edible natural pigment forfood industry.The peanut skin was the by-products of peanut processing and it has high value ofcomprehensive utilization with the merit of huge amount and low price. The output of blackpeanut has no difference with common peanut, but the nutritional value of black peanut washigher than the common peanut. With the deeper researches of black peanut (including blackpeanut skin), it will be helpful to enlarge cultivation area of the good cultivar, and improve thepeanut culture structure and benefit to increase the income of farmers. Furthermore, with thelarge scale culture of black peanut, there will be a plenty of black peanut skin inevitably. Inorder to developing the ideal anthocyanins resources, it has very vital significance to study thepigment's structure, properties and stability of black peanut skin.The aqueous ethanol was used as the extractant of black peanut skin pigment andorthogonal design method was applyed in studing the parameters of the extract technology ofthe black peanut skin pigment (BPSP). Using static absorption and dynamatic absorptionmethod, screened the suitable macroporous resin to purify the BPSP, and studied thepurification conditions. Application of XAD-7HP macroporous resin, polyamide and sephedexLH20 as packed column chromatography (CC) materials in refinement of BPSP, and studiedthe suitable technology to separate BPSP. Using ultraviolet visible spectrum scan, HPLC-MSand nuclear magnetic resonance (NMR), identified the structure of black peanut skin pigment,and explored the particular type and molecular structure. This article also studied the effects ofthe pH, temperature, common food additives and oxidant on the stability of black peanut skinpigment and studied the thermal decomposition kinetics on BPSP as well. Using several kindsof organic acid to studied the effect of copigmentation on BPSP, developed one kind ofcompound copigment which helped BPSP solution become more stable, and broadened itsapplication scope.Black peanut skin contained high amount of anthocyanins(4.93mg/g). Aqueous ethanolwas suitable extractant when we extracted BPSP. During extracting BPSP, under thecircumstance as followed was suitable, about 50% concentration Aqueous ethanol as extractant;about 60℃as extractive temperature; about 1:40 as the mixture ratio of the black peanutskin to the extractant; about 80 min as extractive time. Through orthogonal experiment, theresults showed the optimum extractive technique parameters that aqueous ethanolconcentration was 50%, extractive temperature was at 60℃, the mixture ratio of the black peanut skin to the extractant was 1:50 and the extractive time was 80 min.Nonpolar and weak polar macroporous resin has the higher adsorption capacity to BPSP.Among several kinds of macroporous resin be tested, HP20 resin was significantly better thanthe others in saturation ratio, adsorption ratio, elution ratio. When pH=1, the anthocyaninsconcentration of 10mg/mL in sample and the work temperature of 20℃, HP20 resin hasgood adsorption capacity. When using 80% ethanol as eluent, and the amount of eluentsreached 14BV, the desorption achieves better result.After column chromatography separation of XAD-7HP macroporous resin, polyamide,Sephedex LH20, two kinds of anthocyanin monomer RF1 and RF2 was obtained and theirpurity was over 95%. The results of structure determination of RF1 and RF2 indicate that RF1is cyanidin-3-sophoroside, RF2 is Cyanidin-3-sambubioside.Value of pH was a significant factor on the stability of BPSP and it should be used underthe acid circumstance; The absorbency of BPSP solution increased after added sucrose and salt;Low concentration of Benzoic Acid and Potassium sorbate have little influence on the stabilityof BPSP. Ascorbic Acid and H2O2 enhanced the fading of BPSP solution. Sodium pyrosulfitelead to fade of color of BPSP solution. Fe3+ was able to cause dark/brown precipitation inBPSP solution, Mn2+ and Mg2+ lowed the absorbency of BPSP. The existence of oxygen insolution enhanced the degradation of BPSP.Additive of malonic acid, maleic acid and oxalic acid into the BPSP solution were able toincrease the absorbency significantly and multiple using of the three kinds of organic acid, theinfluence on the absorbency will be more prominent. Through tribasic-quardratic regressionrrthogonal rotational combination design and Multiple regression analysis, the regressionequation of the influence of three organic acids on black peanut clothing pigment absorbancewas obtained, Y=0.759527508+3.410167410X1+1.4647540984X2-35.70003476X1*X1Regression equation has Statistical significance that the model can be applied. Itsforecast accuracy is up to 93.98% with high accuracy and reliability. |
