Optimization of the ultrasonic-microwave assisted enzymatic hydrolysis of freshwater mussel meat

In the present study,the Ultrasonic-Microwave(US-MW)technique was applied for assisting enzymatic hydrolysis of freshwater mussel meat.The operating parameters of enzymatic hydrolysis were investigated and the properties and qualities of the freshwater mussel hydrolysates were also analyzed.The considerable optimum conditions for enzymatic hydrolysis of mussel meat were ratio of liquid to material of 10.36:1,power of 360.52 W,processing time of 6.91 min,enzymolysis time of 4 h.Under these conditions,a degree of hydrolysis(DH)of 48.40% was obtained.The hydrolysates produced under optimum conditions,were characterized in terms of electrophoretic profile,amino acid composition and infrared spectrum analysis.SDS-PAGE profiles of the hydrolysates revealed that several protein bands were cleaved and several light myosin chains(25 kDa and 15 kDa,respectively)and peptides of molecular weight lower than 6.5 kDa were identified.The infrared spectrum absorption peak of amide band A and band III shifted after US-MW pre-treatment,which indicated that the N-H(hydrogen bonding)stretching vibration and triple helix structure of samples were affected.The essential amino acids in hydrolysates with or without US-MW pre-treatment were 36.62 mg/100 g and 33.40 mg/100 g.It was proved that US-MW assisted enzymatic hydrolysis is an effective technology to utilize freshwater mussel meat.

The optimization of ultrasonic-microwave assisted synergistic extraction of Lotus plumule extract rich in flavonoids and its hypoglycemic activity

Lotus(Nelumbo nucifera Gaertn),a kind of perennial aquatic plant,is widely cultivated and consumed by people in Asian countries.Lotus plumule flavonoids(LPF)have been recognized as a hypoglycemic agent.LPF was optimally obtained using novel ultrasonic-microwave assisted synergistic extraction(UMSE)method by response surface methodology(RSM)on the basis of the results of single-factor experiments.Furthermore,the hypoglycemic activity of LPF was investigated by measuring the body weight,fasting blood glucose(FBG)level,and oral glucose tolerance test(OGTT)and analyzing the physiological indexes in streptozotocin-diabetic mice model.The optimum extraction conditions consisted of microwave power 355 W,ultrasonic power 423 W,extraction time 15 min,solid-liquid ratio 1:40,ultrasound/interval time 1/0,and ethanol concentration 70%with the maximum LPF yield of 2.62%.LPF supplementation significantly decreased the body weight,FBG,OGTT,serum total cholesterol(TC),serum total triglycerides(TG),and insulin levels,indicating the antidiabetic activity of LPF.This research verified that the UMSE technique was highly efficient to extract LPF to the maximum extent and the flavonoids from L.plumule exhibited hypoglycemic activity,which showed broad development and application prospects.

Ultrasonic Microwave Assisted Extraction of Polysaccharides from Sipunculus nudus

[Objectives] This study was conducted to optimize experimental conditions for extraction of polysaccharides from Sipunculus nudus.[Methods]With the Sipunculus nudus from Sanya as the experimental material,S.nudus polysaccharide was extracted by ultrasonic microwave assisted method,during which univariate factors including solid-liquid ratio,time,temperature,ultrasonic power,microwave power were investigated,to select optimal extracting conditions,which were also demonstrated and optimized by variance and response surface analysis.The optimized conditions were adopted to carry out a test,in which the absorbance of S.nudus polysaccharide was measured with an ultraviolet and visible spectrophotometer,followed by the calculation of the extracting amount of polysaccharide,and precision test and recovery test were also carried out to verify the experimental method.[Results]The standard solutions were determined at the maximum absorption wavelength of 486 nm,and the regression equation was A = 0.2677 C + 0.001 8,R^2= 0.999 8.Solid-liquid ratio,time,temperature,ultrasonic power and microwave power were investigated by univariate analysis and then optimized by response surface method as follows: solid-liquid ratio at 1:20( g/ml),time of 35 min,temperature at 50 ℃,ultrasonic power at 420 W and microwave power at 300 W,under which the measured extracting amount of S.nudus polysaccharide was1.37 mg/g.The RSD was 0.985% in precision experiment.In the repeatability test,the extracting amounts of polysaccharide were 1.41,1.43 and 1.38 mg/g for three parallel tests,respectively,with a RSD of 1.140%.The recovery test obtained following results: for group a( added with glucose standard) : the recovery of S.nudus polysaccharide was in the range of 100.3%-101.4%,RSD = 0.03%; and for group b( not added with glucose standard) : the recovery of S.nudus polysaccharide was in the range of 99.7%-100.3%,RSD = 0.02%.[Conclusions]The research method is stable and reliable.This study provides data basis and reference for follow-up study on S.nudus.