Preparation And Characterization Of Nanocapsules Containing Isothiocyanates

Isothiocyanates are found in cruciferous plants widely, which are glucosinolate subsequent enzymatic conversion to breakdown products, secondary metabolites. There are two methods to get isothiocyanates, one is extraction the volatile oil from the cruciferous plants, another is synthesis method by use of chemical meterials. Isothiocyanates and their derivatives are widely used in pesticides, chemical industry, and pharmaceutical industry because of their strong biological activity.The quantity of glucosinolates in Hainan mustard is analysised. In this experiment, solvent method was used to extract glucosinolates from Hainan mustard. The existence of glucosinolates in the crude extracts was preliminarily detected by the infrared spectrometer scanning. The quantity of glucosinolates in the crude extracts was determined by barium sulfate precipitation, and methanol or ethanol was adopted as solvent. The quantity of glucosinolates was 1.060μmol/g in the Hainan mustard using of methanol extraction, but it was 5.553μmol/g using of ethanol extraction. The result indicated that the higher extraction rate of ethanol solvent.The isothiocyanates are extracted from Hainan mustard. The process was extraction the volatile oil from Hainan mustard by CO2 supercritical extraction and stream distillation, the volatile oil is isothiocyanate analysised by GC-MS, the mainly component is allyl isothiocyanate. The temperature, time, and pressure were selected to design orthogonal experiments and a better CO2 supercritical extraction condition was found, it was that 250Mp, 50℃,4h. The two anti-oxidants, Vc and TBHQ were added seperately in Hainan mustard when the volatile mustard oil was extracted by stream distillation, the results show that the extraction rate of addition Vc or TBHQ was not obviously different.The stability of allyl isothiocyanate in an aqueous solution are studied. In order to investigate the stability of allyl isothiocyanate in water, four important factors, temperature, time, pH and ultrasonic frequency were selected to design orthogonal experiments. The isothiocyanate was dissolved in an aqueous solution containing a small amount of methanol. The effects of the different factors on its stability were characterized by the changes of allyl isothiocyanate degradation were most significant, followed by ultrasonic freguency, temperature and pH. After petroleum ether was used to extract the degradation mixture. The LC-MS and GC-MS analysis data suggested that allyl thiocyanate and cyclopropyl isothiocyanate were main products of allyl isothiocyanate degradation, and with the degradation of allyl isothiocyanate, their quantity increased.The nanocapsule containing isothiocyanates is prepared and characterized. The nanocapsulation is based on a simple coavercation process. Isothiocyanates are the capsule-core, with an alginate biopolymer coating, crosslinking with calcium chloride, and the size of the nanocapsule is 50±5nm. The size and uniformaty of nanocapsule were detected by TEM, the encapsulation rate was judged by HPLC, and the changes of nanocapsule weight during heating was analysised by TG. At the same time, the concentration and amount of isothiocyanates, dripping speed, mixing time, the addition of calcium chloride and other factors on encapsulation rate and size of nanocapsule were studied. The results showed that encapsulation rate was higher by the method of lower concentration of isothiocyanates, dropping more slowly, mixing longer time. Besides in this case the size of nanocapsule was small and relatively uniform. Additive amount of calcium chloride had little effect on the the size and embedding rate of nanocapsule.