| Vaccinium bracteatum Thunb. (VBT), which is also known as Nan Zhu or Wu Fan Zi, is widely grown throughout China with abundant resources. It is medicinal and edible plants which belongs to family Ericaceae genus Vaccinium. It is named after whose leaves are used to stain cooked rice by Chinese. However, the use of VBT is very limited, which brought a lot of waste. In this paper, extraction process for VBT leaves (VBTL) pigment was studied. The stability of pigment extract under the different conditions was also studied. At the same time, antimicrobial and antioxidant activities of extract were tested, to provide the basis for its practical application. The further analysis was to research the utilization of extract. The purpose of this study was to provide theoretical basis for further development and application of VBTL.The main results of this study are as follow:(1) Pigment from VBTL was extracted by solvent extraction, enzymatic extraction and ultrasound-assisted extraction method. The results showed that a maximum pigment yield of 26.09% was obtained under the optimal extraction conditions of enzymatic extraction method as follows:material-liquid ratio of 1:80 g/mL, cellulase of 1.5 mg/g, temperature of 50℃, pH 5.0 and extraction time of 0.5 h.(2) The influencing factors on stability of pigment extract were investigated, such as solubility, temperature, illumination, sweeteners, oxidant, reducing agent, pH and metal ions. Stability experiment showed that this pigment extract was sensitive to oxidant, and had good thermal stability. Under illumination, reducing agent, acid/alkaline environment, glucose and fructose existing, the pigment extract was stable. Na+, K+, Ca2+ and Al3+ had little effect on the stability of pigment, but Fe3+, Mg2+, Cu2+ and Fe2+ would decrease the stability.(3) The antioxidant activity and antimicrobial activity of the pigment extract were investigated by three normal antioxidant model in vitro, measuring antibacterial circle diameter and mycelium growth rate, respectively. The results indicated that pigment had good DPPH-,-OH scavenging activities and the IC50 values were 0.68 and 0.17 mg/mL, respectively; moreover, it was found to have reducing ability. Meanwhile, the results showed that the pigment extract had antimicrobial effects on Staphylococcus aureus, Escherichia colli, Bacillus subtilis and Aspergillus niger. Hydrogen ion concentration (pH) had some effects on the antimicrobial activity. Moreover in the acid and neutral condition, the extracts showed good antimicrobial activity on bacteria and Aspergillus niger, respectively.(4) The component analysis of pigment extract were investigated by HPLC and LC-MS. The results showed that combined with the relative molecular mass and standard control, three phenolic compositions (ferulic acid, caffeic acid and rutin) were identified in which ferulic acid was the main component with 48.9 percent of total phenols. The content of caffeic acid and rutin was 5.34%,2.21%, respectively.(5) Some properties of pigment extracted including dyeing ability and preservation effect were determined. The pigment is used to dye rice and flour, and titratable acidity contents were tested. Compared with experimental group, titratable acid contents of control group were increased 20%,25% after 96 h storage at room temperature, respectively. It showed that pigment extract having potential dyeing ability and preservation effect. The results of present study indicate that extract can be used to fresh-keeping of grapes. Compared to control group (grapes treated with distilled water), the weight loss rate, decay rate and shattering trait of experimental group (grapes treated with pigment) were decreased 4.3%,73.1%,62.9% after 10 days storage at room temperature, respectively. Under the same conditions, SSC and firmness were increased 4.2%,11.7%, respectively. Compared with control group, the weight loss rate of experimental group were decreased 14.9% after 13 days storage at 4℃. Meanwhile, SSC and firmness was increased 4.8%,20.6%, respectively. |
PDF Full Text Request