Weijuan Huang,Yingfei Zhan,Xiaowen Shi,Jiajia Chen,Hongbing Deng,Yumin Du
Electrospinning is a facile method to fabricate nanofibers, in terms of their high specific surface area and porous structure. Electrospun nanofibrous mats are excellent candidates for immobilization of enzymes . In this study, a simple route based on electrospinning and layer-by-layer (LBL) self-assembly processes has been developed to prepared naringinase/alginate multilayer coated electrospun cellulose acetate nanofibers. The content of immobilized naringinase could be tuned by adjusting the number of multilayers. XPS results indicated that naringinase was successfully immobilized on cellulose acetate nanofibers. SEM images showed the nanofibers maintain their sharp but became rougher after multilayer coating. Besides, the surface area of electrospun cellulose acetate nanofibers decreased and mesopores reduced. The major bitter components of grapefruit juice are naringin and limonin, naringin could be slightly removed by hydrolysis with naringinase and limonin might be removed by adsorption with cellulose acetate nanofibers.
The α- l -rhamnosidase ( rha 1) gene was homologously expressed in Aspergillus niger strains CCTCC 206047 and CCTCC 206047Δ pyr G, using hygromycin B and auxotrophic as selection markers. The engineered A. niger strains RHA001-1 and RHA003-1 were screened, yielding α- l -rhamnosidase activities of 20.81 ± 0.56 U/mL and 15.35 ± 0.87 U/mL, respectively. The copy numbers of the rha 1 gene in strains RHA001-1 and RHA003-1 were found to be 18 and 14, respectively. Correlation analysis between copy number and enzyme activity in the A. niger strains revealed that α- l -rhamnosidase activity increased with the copy number of the rha 1 gene. Recombinant α- l -rhamnosidase was utilized for the enzymatic debittering of Ougan juice, and its process conditions were optimized. Furthermore, the primary bitter substance neohesperidin (2.22 g/L) in Ougan juice was converted into hesperetin 7-O-glucoside (1.47 g/L) and hesperidin (0.143 g/L). This study presents a novel approach for the production of food-grade α- l -rhamnosidase and establishes a technical foundation for its application in the beverage industry.
Zheng-Fei Yan,Jia-Yu Chen,Jing Yang,Shuai Yuan,Xue-Yi Qiao,Bo Xu,Lingqia Su
Cod protein isolate (CPI), a by-product from the cod machining process, is a novel source of high value-added products. Off-flavors in cod protein, such as bitterness and fishy odor, reduce its acceptability for consumers. Here, CPI was first debited using Streptomyces canus aminopeptidase (ScAPase) and then deodorized through probiotic fermentation. This is the first report of completely removing the bitterness of CPI using ScAPase. Subsequently, Syn3 and Syn4, as aromatic CPI (ACPI), were prepared from debittered CPI (DCPI) using Lactobacillus acidophilus and Bifidobacterium longum, respectively, possessing non-fishy odor, no bitterness, strong aromatic odor, and good overall acceptance. These products (DCPI and ACPI) exhibited better physicochemical properties, such as higher oil-holding capacity, emulsifying activity, and digestion resistance, compared to untreated CPI. However, they showed significant differences in radical scavenging activity, and the highest scavenging activity was detected in Syn3 against DPPH· (63.5%) and·OH (79.2%), DCPI against O2- (32.0%), and post-digestion Syn4 against ABTS+· (95.2%). These products after digestion treatment, significantly promoted the proliferation of probiotics. Notably post-digestion Syn4 exhibited the most proliferation effect on Lactobacillus reuteri, Lactobacillus rhamnosus, and Bifidobacterium breve than other post-digestion samples. These results indicated that the treated CPI has potential for applications in health food products.
危险品化学品经营许可证（带存储）