Study Of The Technology For Isothiocyanates Accumulation Produced From Cabbage (Brassica Oleracea L.) Seed During Germination

Glucosinolates (GLs), a group of plant secondary metabolites, are mainly found in the family of Cabbage (Brassica oleracea L.). Isothiocyanates is a type of products hydrolyzed from glucosinolates by myrosinase in Brassica plants. Isothiocyanates is a naturally occurring inducer of phase II emzymes in human and animal bodies to detoxify cancer-causing chemicals. Studies have shown that the dietary intake of Brassica vegetables can reduce the risks of chronic diseases such as atherosclerosis and cancer.Cabbage has a lot of characteristics such as wide adaptability, high yield, nutrition, storage tolerance and so on in the family of Brassica vegetables widely cultivated in China due to its cheap price. Cabbage is a good raw material to accumulate isothiocyanates. In this dissertation, the isothiocyanates and the glucosinolates were analyzed during cabbage seed germination using "training environment" and "applying amino acid" as interfering factors and effects of exogenous substances and cultivating methods on isothiocyanates accumulation were observed, in order to provide the theory for improving the content of isothiocyanates in cabbage seedling by a scientific approach. The research findings were summarized as follows:The testing method of total glucosinolates content with potassium ferricyanide spectrophotometric was established. The analyzing conditions were:the glucosinolates in cabbage seed and sprouts were extracted with phosphate buffer solution (0.2 mol/L, pH 7.0) and then heated in 80 ℃ water bath for 15 min to inactivate enzyme activity. The polyvinylpyrrolidone, lead acetate/acetic acid buffer solution and saturated solution of sodium sulfate were added in succession and then oscillating centrifugation was carried out, the supernatant was collected as glucosinolates extraction liquid. The extraction liquid was furthmore hydrolyzed with NaOH solution. The hydrolyzed product was reacted with potassium ferricyanide solution, and then centrifugated. The supernatant was taken for determination of the light absorption value in 420 nm. The results showed that this method has good precision and repeatability. Comparision with HPLC method, it is simple and low cost.In the paper, the effects of different incubation time, temperature and light conditions on the content of isothiocyanates and glucosinolates during cabbage seed germination were investigated. Results showed that:the length of seedlings, germination rate, respiration rate, consume in dry matter content and other indexes had significantly changed during cabbage seed germination. On the other side, the content of isothiocyanates and glucosinolates increased significantly. Under the blue light irradiation, cabbage seed was incubuated at 30℃ for 3 h, glucosinolates content was increased at the first stage and then leveled off. At the germination time of 12 h, its glucosinolates content reached the highest, up to 34.78 μmol/g FW.The length of seedlings, germination rate, respiration rate and consume in dry matter content and other indexes had no significantly changed with applying methionine, phenylalanine and cysteine during 0-5 d of cabbage seed germination. On the other side, the isothiocyanates and glucosinolates were significantly affected. The 0.02 mol/L cysteine medium treatment improved the respiration rate, reducing sugars and ascorbic acid, glucosinolates content also increased significantly. The content of isothiocyanates did not change significantly.