ABSTRACT
Beefy Meaty Peptide(BMP)，an thermostable octapeptide found in beef with beefy flavor，has a good potential for application in food industry as a new kind of flavor enhancer.In this paper, the inducing condition,stability,pretreatment and isolation methods of BMP were studied.
The optimized inducing condition was as follows: BSM was chosen as the inducing medium, added 0.5%(V:V) methanol,the nitrogen source (1%CA) per 24 hours,then incubated at 28℃, pH 3.0, rotating at 190rpm. The optimum inducing time was 96 hours.The secreted peptide quantity under the conditions in the flask fermentation had been obviously improved. The expressed peptide yield reached 623mg/L .
The stability of BMP in recombined Pichia pastoris yeast fermentation was studied.The results showed that the target peptide was still stable after heated at 90℃ within 5min, 10min, 15min, 20min,respectively.Also,it kept stable between pH3.0 and pH8.0 within 48 hours in room temperature.Besides,BMP can withstand pepsin, while was relative instable afer hydrolyzed by Neutrase and Alcalase.
It was revealed that heat-solution was not satisfying during the pretreatment, as the impurities were also thermostable. However, the active carbon adsorption was more effective at pH7.0-8.0,while the ethanol precipitation was better at pH 7.0.
Macroporus adsorption resin, ion-exchange and gel-filtration chromatography were performanced according to the standard protocols. The content of BMP was detected by RP-HPLC. It was found that the purification effect of the Sephadex G-25 gel filtration chromatography was better.
Finaly, BMP was gathered and analyzed by RP-HPLC, eluted with bi-gradient mobile solvents at a flow rate of 1.0 mL/min and UV detection at 230nm．The purity of BMP was 95.26%.
