Study on Extraction of Glucosinolates from Broccoli and Its Degradation Products Antibacterial Activity
|School||Zhejiang Technology and Business University|
|Course||Food Science and Engineering|
|Keywords||broccoli glucosinolates extraction purification degradationproduct antibacterial|
Glucosinolates are an important sulfur-containing secondary metabolites in cruciferous plants, especially in broccoli, cauliflower, cabbage and so on. In the presence of myrosinase, glucosinolate hydrolysis reaction will occur, or under conditions of mutative temperature and pressure it will occur non-enzymatic degradation. A large number of studies have found that eating more cruciferous vegetables can prevent many cancers. Therefore, the research and development of glucosinolates in cruciferous plants should play a major influence on the human production of valuable health products.Broccoli, also known as broccoli cauliflower, is cruciferous cabbage Brassica varieties. Glucosinolates of broccoli are very rich, which contain a large number of active glucoraphanin (4-methylsulfinyl butyric alkenyl glucosinolates). Many researchers have found in cruciferous vegetables that sulforaphane, the major degradation products of glucoraphanin is the most promising anti-cancer substances.This paper mainly studied the enzyme inactivation and effect of drying conditions on the loss of glucosinolates in the procces of extraction of glucosinolates from broccoli, extraction and purification of glucosinolate as well as the preliminary antibacterial activity of its degradation products. It would provide some information for further study on glucosinolates in broccoli, but also provide a theoretical basis for the clinical treatment and health care products research and provide an initial research base for fermented food preservative applications. The following conclusions:1. This study was comparing microwave treatment, heat treatment, beating treatment, soaking treatment and ultrasonic treatment effect of inactivating enzymes, to obtain optimum conditions of75℃95%ethanol was heated to80℃keeping20min. Comparing blast drying, microwave drying and natural drying for dring after raw materials enzyme inactivation treatment, microwave drying time is short, which is240s, less glucosinolate loss and is worth using.2. By single factor experiments and response surface optimization test, the optimum conditions of the ethanol solvent extraction glucosinolate broccoli were: extraction temperature:80℃, solid-liquid ratio:1:12, extraction time:30min, extraction times:4times to obtain the broccoli crude extract powder of21.79mg/g glucosinolate content, whose crude extract powder yield was20.21%. And then they were purified by ethanol precipitation and solid-phase adsorption elution. It was obvious for the purification of glucosinolates by ethanol precipitation method, especially under0℃and100%ethanol, whose glucosinolate content was up to91.5%in precipitation. Finally ethanol purified extract was33.78mg/g of glucosinolate content, which increased72.02%; glucosinolate content of the solid powder was23.75mg/g in the experiments of extract solution was added1:2deionized water by centrifugation, which increased8.72%. On the other hand,10kinds of food grade fillers columns were compared by the static method, PVP/P、kaolin、diatomaceous earth and silica had very low adsorption capacity, which were2.16%,1.93%,0.08%and1.99%. As a solid-phase adsorbent, adsorption broccoli extract glucosinolates for interference, to obtain a solid powder whose glucosinolate contents were28.81mg/g,25.79mg/g,30.73mg/g,27.47mg/g, respectively increased32.11%,18.35%,40.83%and26.15%. Granular and powdered activated carbon, ion resin extract had the strongest adsorption capacity of glucosinolates, which were91.92%,99.99%and98.11%. After selecting ion resin as adsorbent, the results could be found that0.5mol/L calcium chloride solution several times eluate was the best, then removed chlorine and calcium ions by chitosan and CO2. In the several purification methods were improved glucosinolate content, which provide a basis for theoretical methods of the production of health products.3. This thesis studied the antimicrobial effect of degradation products of broccoli seed glucosinolates on E. coli, S. aureus, B. subtilis, L. sake and L. brevis. The results showed that the antibacterial effect of the extract liquid (3.645mg/g),12MIC (2.734mg/mL) on E. coli、S. aureus and B. subtilis had reached the extremely sensitive level, and it is the most obvious glucosinolates degradation products inhibitory effect on E. coli,8MIC (1.823mg/mL) also achieved a extreme sensitivity level, but reached a highly sensitive level of the antibacterial action on S. aureus, B. subtilis; while extracts had no antibacterial effect on L. sake and L. brevis. It selected preservative that had weaker toxicity lactic acid bacterias but strong to other bacterias.