Study On Controllable Degradation Of Thioglucoside In Papaya Seed

The heat treatment,ultrasonic and microwave assisted enzymatic degradation,environmental factors and exogenous myrosinase were taken as the object of the study.The purpose was to explore the controllable degradation of glucosinolates(GS)in papaya seeds,improving the yield of benzyl isothiocyanate(BITC).Firstly,the heat treatment of glucosinolates in papaya seeds was studied.The results shown that the yield of benzyl isothiocyanate and the degradation products produced by glucosinolates are different at different thermal degradation temperature.When the thermal degradation temperature was 100 ℃,the yield of benzyl isothiocyanate was 2.64 ‰,and the degradation rate of glucosinolates was 20.63%.When the thermal degradation temperature was 160 ℃,the yield of benzyl isothiocyanate was 0.67‰,and the degradation rate of glucosinolates was 62.24%.The degradation products of thermal degradation were detected by GC-MS analysis at different temperature.It was found that besides benzyl isothiocyanate,benzoyl isothiocyanate and benzyl chloride,benzyl isocyanate,benzyl cyanide,benzyl isocyanide and benzyl thiocyanate were the thermal degradation products of glucosinolates.With the changing of thermal degradation temperature,the proportion of benzyl isothiocyanate,the degradation product of glucosinolates,showed a difference.At 100 ℃,the proportion of benzyl isothiocyanate reached the highest.Secondly,ultrasonic assisted extraction was studied,performed on the basis of hydrolysis of glucosinolates by endogenous enzymes.On the basis of single factor,The optimization of response surface optimization was designed,three factors,ultrasonic time,ultrasonic power and ultrasonic temperature,were optimized.With the highest yield of benzyl isothiocyanate as the optimization target,the results shown that ultrasonic time,ultrasonic power and ultrasonic temperature had some interaction effects.The optimum ultrasonic time was 16.17 min,ultrasonic power was 60 W,ultrasonic temperature was 38 ℃,and the yield of benzyl isothiocyanate was 5.58‰.In addition,if the degradation rate of GS was taken as the optimization target,ultrasonic time,ultrasonic power and ultrasonic temperature also had some interaction effects.The optimum result showed that the degradation rate of glucosinolates was 77.36%,and the yield of benzyl isothiocyanate was 4.46‰.The results showed that when the degradation rate of GS reached the highest,the yield of BITC could not achieved the peak.Maybe it was caused that the reaction occurred in the direction of producing other products during the degradation process.Thirdly,in this study,the effect of microwave time and microwave power on the degradation of glucosinolates in Carica papaya seeds was investigated by microwave assisted extraction.The yield of benzyl isothiocyanate was regarded as the optimization objective,The effect of microwave time on the yield of BITC is greater than that of microwave power.Microwave time had significant effect on the rate of benzyl isothiocyanate.The highest yield of benzyl isothiocyanate was as follows:microwave time was 10 s,microwave power was 420 W,and the yield of BITC was 5.42 per thousand at this time.The degradation rate of GS was 65.14%at this time.Then the environmental effects of Vc concentration,magnesium ion,calcium ion and EDTA on the degradation of glucosinolates in papaya seeds were investigated.The result showed that the yield of benzyl isothiocyanate was gradually increased with the increase of Vc concentration.When the concentration of Vc was 3 mmol/L,the yield of BITC reached 5.33 per thousand,while the degradation rate of GS was 70.49%;Magnesium ion and calcium ion had no effect on benzyl isothiocyanate,on the contrary,they brought even a certain inhibitory effect,when the concentration of ion is 0 mmolL,the yield of BITC reached 4.28 per thousand,the degradation rate of GS was 61.62%;The proper concentration of EDTA could promote the degradation of glucosinolates in papaya seed,with the increase of EDTA concentration,the benzyl isothiocyanate was increased,while the EDTA concentration is 0.5 mmol/L,the yield of benzyl isothiocyanate run up to5.45 per thousand,the degradation rate of GS was 63.31%.To sum up,when the papaya seed was treated in different ways,the degradation effect of GS was different.With the comprehensive analysis of the effect of these degradation methods of GS,it as showed that ultrasonic assisted enzymatic degradation was the best way to prepare BITC.