| Isothiocyanates (ITCs) refers to molecules which containing-N=C=S conjugated double bond, has a strong biological activity of antibacterial, anti-mildew and destroy of the parasite. However, the using highly toxic raw materials in the synthesis process and a strong instability were limited its application. Extraction of active ingredients from natural products avoid the use of toxic materials, and complex coacervation can be effectively protected unstable components. The curing agent of complex coacervation microcapsules were toxic formaldehyde and glutaraldehyde, severely limited the application of this method.In this paper, the mixture mainly composed of isothiocyanates were extraction from mustard seed and wasabi by simultaneous distillation and extraction (SDE), the composition of the mixtures were identified by gas chromatography-mass spectrometry (GC-MS), and its antibacterial activity were tested, further utilized gelatin/gum arabic as wall material, natural product genipin as curing agent, the wasabi extraction complex coacervation were prepared. The curing process, physical and chemical properties and and storage stability were studied. Main contents and results are listed as follows:The extraction rate of isothiocyanate mixture extracted from Mustard seed and Wasabi were0.6-0.8%and0.4-0.6%, respectively.14compounds were identified from mustard extraction, including six kinds isothiocyanate (the relative content of86.33%),22kinds of compounds were detected from Wasabi extraction, including eight kinds of isothiocyanates (the relative content of69.58%).Isothiocyanate extraction obtained from Mustard seed and Wasabi were both inhibited Staphylococcus aureus, Sarcina lutea, Staphylococcus, Bacillus subtilis, Pseudomonas aeruginosa, Salmonella, Pseudomonas fluorescens and Shigella sonnei, and inhibition ability of Gram-positive bacteria were stronger than Gram-negative bacteria’s. The antimicrobial activity of Wasabi extraction was stronger than Mustard seed extraction, the minimum inhibitory concentration (MIC) range of8kinds of tested strains were128-512μg/mL and512-1024μg/mL, respectively.In the study, the optimal curing process optimization parameters:time8h, temperature40℃, pH10.0, the amount of curing agent added0.075g Genipin/g gelatin. The laser particle size analyzer results showed that particle size of genipin cross-linked isothiocyanate microcapsules was widely distributed in the range5-10μm, and the average volume diameter was6.080μm The particle size of microcapsules prepared under optimum curing conditions have relatively uniform size observed by fluorescence microscopy and scanning electron microscopy. Microcapsules have spherical distribution after drying, no obvious cracks and shrinkage on the surface of microcapsules, which can form a stable protection of core material. It was proved by FT-IR that the ester group of the genipin and the amino group of gelatin to form an amide bond in the curing stage, resulting in cross-linking.The glass transition temperature (Tg) was31.62℃of microcapsules analyzed by differential scanning calorimetry (DSC), so the microcapsules at room temperature in a glassy state, has good stability. Studies have shown that the microcapsules are stable at low humidity conditions (relative humidity54%), when the relative humidity rised to84%, the retention rate of microcapsule is greatly reduced; microcapsules were stable in25℃, but the stability was reduced in40℃. Compared with the untreated isothiocyanates, the stability of isothiocyanates which encapsulated has improved significantly irrespective of the storage conditions. |
PDF Full Text Request