Extraction And Purification Technology Studies Of Blackberry Anthocyanins

Blackberry(Rubus fruticosus L.) is a species of fruit belonging to the Rubus genus in the Rosaceae family, native chiefly to North America, firstly introduced from the United States by the institute of botany, the Chinese academy of sciences in 1986. Anthocyanins are a species of natural water-soluble pigments belonging to the flavonoids, which widely exist in the plant. As playing an important role in human nutrition and pharmacological effects, anthocyanins, a natural antioxidant, has become one of the hot spot of research. Anthocyanins have been reported to have the anti-oxidative, anti-inflammatory, anti-tumor, anti-diabetic effects, protection against coronary heart disease, memory enhancement and other pharmacological effects. It has been shown that blackberry contains higher amounts of anthocyanins than other fruits. Blackberry anthocyanins as the natural pigment and dietary antioxidants, which are used in food, medicine, cosmetics and other fields.However, it has been widely acknowledged that stability of anthocyanins can be affected by large amounts of other compounds such as organic acids, sugars, sugar alcohols, amino acids and proteins and so on, so we have to purify the crude extract of anthocyanins. At present, Extraction and purification technology studies of blackberry anthocyanins in the domestic and overseas is not mature enough, to solve this problem, this paper intends to start from the extraction and purification of BBAC, to conduct the thorough research to the BBAC, to provide scientific data to support for its industrialization, comprehensive utilization and the value enhancement.The extraction and purification technology studies of BBAC were focused on the following four aspects. Firstly, by comparing a variety of ways to extract of BBAC including the enzyme transformation extraction, ethanol extraction, microwave assisted extraction, optimizing the best extraction method. Secondly, aimed at optimizing the extraction method, based on the extraction yield and antioxidant activity index, the best BBAC extraction process parameters are optimized by using response surface design method. Thirdly, by comparing the ion exchange resin and polyamide resin purification of a variety of ways for BBAC purification effect, optimizing the best purification methods. Finally, aiming at optimizing the purification methods, the best BBAC purification process parameters are optimized by the single factor experiment. The detailed results are as follows:1. The extraction process study of BBACThis study was compared the enzyme extraction(fruit pulp enzyme, wine enzyme, juice enzyme, pectinase, β-galactose glucoside enzyme, acid protease, hemicellulase, β-glucan enzyme, lysozyme, soluble enzyme, xylanase, β-glycosidase enzymes, saccharifying enzyme, cellulose enzyme, lyases, α-amylase, β-starch, glucamylase), water extraction and microwave assisted extraction method of BBAC. By comparing the three methods, we found the highest BBAC extraction yield was the microwave assisted extraction, so we finally choose microwave assisted extraction as the best way to extract.In order to optimize the best extraction process parameters of the blackberry anthocyanins, in this section, basing on BBAC extraction yield, levels of scavenging effects on ABTS·+ free radicals and DPPH· free radicals as the comprehensive evaluation indexes, the conditions for extraction of BBAC from BB were optimized by using microwave assisted assisted extraction, single-factor test, and the response surface methodology(RSM). A central composite design was adopted to investigate the effects of four independent variables including microwave power(W), solvent concentration(%), liquid-solid radio(g·mL-1), and microwave time(min) on the responses, BBAC yield. The optimized conditions of the extraction were as follows: microwave power 469 W, solvent concentration 52 %, liquid-solid radio 25 g·mL-1, and microwave time 4 min. Under this condition, the mean experimental value of extraction yield(2.18 ± 0.06 mg·g-1), ABTS assay(32.18 ± 1.54 μMTEAC·g-1) and DPPH assay(27.18 ± 1.33 μMTEAC·g-1) were achieved, respectively, which corresponds well with the predicted values and increased more than 120 % compared with the ethanol leaching extraction. 2. The purification study of BBACThe purification of BBAC with cation exchange resin was compared with the 60 ~ 100 mesh of polyamide resin, 60 ~ 100 mesh polyamide resin was founded as the best resin for purification BBAC. 60 ~ 100 mesh of polyamide resin showed highest adsorption capacity(4.41 mg·mL-1 of adsorbent) and desorption capacity(3.29 mg·mL-1 of adsorbent), among the all adsorbents studied. Adsorption of anthocyanins correlated best using Freundlich isotherm. Second order kinetic model was found to be most appropriate to explain the adsorption of anthocyanins onto the 60 ~ 100 mesh of polyamide resin. In the case of ethanol as eluent, optimal adsorption and desorption conditions for 60 ~ 100 mesh of polyamide resin purification of BBAC are obtained as follows conditions: initial concentration 0.75 mg·mL-1, the pH of adsorption liquid 1, the pH of eluent 3, and ethanol concentration 80 %. The dynamic adsorption process parameters for the puri?cation of anthocyanins using 60 ~ 100 mesh of polyamide resin arrived at were as follows: processing volume 5 BV, ?ow rate of adsorption 5 BV·h-1, temperature of adsorption 15 °C, eluent volume 3.5 BV and ?ow rate of desorption 5 BV·h-1. Under this condition, dynamic adsorption and desorption process parameters were successfully standardized. Polyamide resin adsorption resulted in a concentrated blackberry extract that contained 432 mg·g-1 anthocyanins which was superior to cation exchange resin adsorption(160 mg·g-1) and macroporous adsorbent resin adsorption(176 mg·g-1).