Experimental Study On Multi Frequency Ultrasound Assisted Enzymatic Hydrolysis Of Livestock And Poultry

China is a big country of animal husbandry,the annual mortality rate of pigs caused by various diseases is higher than that of developed countries.Mortality of livestock and poultry has a wide range of characteristics.If the carcasses of dead are not treated properly,they seriously affect the harmonious development of society.At present,the harmless disposal methods of the animal carcasses include incineration,burying,alkaline hydrolysis fermentation and rendering,these methods have their own shortcomings,it is necessary to explore a kind of efficient,energy saving,environmental protection,economic,harmless treatment technology to pathogenic animal carcasses,In this paper,a method of multi frequency ultrasound assisted enzymatic hydrolysis to livestock and poultry is proposed.Pork,pigskin,lard oil as raw materials,with degree of hydrolysis or lipolytic rate as index,amount of enzyme,substrate concentration,temperature and p H as influence factors on screening test using enzyme,and using response surface method on optimizing process parameters.Ultrasonic frequency combination,power and pretreatment time are as influence factors,using orthogonal experiment to optimize the ultrasonic pretreatment process parameters.Scanning electron microscope was used to observe the changes of micro structure of the surface before and after ultrasonic pretreatment.Liquid chromatograph was used to analyze the types and contents of amino acids in enzymatic hydrolysate before and after ultrasonic pretreatment.The main conclusions of this study are as follows:1.Through the contrast of trypsin,neutral protease,pepsin,bromelain for pork enzymolysis,trypsin is screened more suitable for enzymatic hydrolysis of pork.Through the contrast of alkaline proteinase,neutral protease,flavorzyme,trypsin for pigskin enzymolysis,alkaline proteinase is screened more suitable for enzymatic hydrolysis of pigskin.2.The experiment of single factor and response surface optimization shows that the optimum conditions for trypsin hydrolysis of pork is as follows: enzyme quantity 1.15%,substrate concentration 80.5g/L,p H 7.96,temperature 40.6 ℃,optimal hydrolysis time 6h,the degree of hydrolysis is 28.91%;the optimum conditions of pigskin alkaline protease,proportions of enzyme to substratum 16006U/g,temperature 48.92℃,substrate concentration 59.76g/L,p H 10.43,optimal hydrolysis time 8h,the degree of hydrolysis is 18.73%;the optimum conditions of lard oil enzyme PPL: temperature 41.76℃,p H 6.92,enzyme quantity 1.04%(w/w),substrate concentration 42.39%(w/w),optimal hydrolysis time 7h,the lipolytic rate is 48.87%.3.The test of ultrasonic single factor and orthogonal shows that the optimal ultrasonic pretreatment parameters of trypsin hydrolysis of pork: frequencies(20k Hz,20 h Kz,40 k Hz),power 500 W,pretreatment time 20 min,the optimal time for hydrolysis is 4h,it can shorten the hydrolysis cycle of 2h;the best ultrasonic pretreatment parameters of alkaline proteinase hydrolysis of pigskin: frequencies(20k Hz,40 k Hz,40 k Hz),power 600 W,pretreatment time 25 min,the optimal hydrolysis time is 5h,it can shorten the hydrolysis cycle of 2h;the best ultrasonic pretreatment parameters of PPL hydrolysis of lard oil: frequencies(20k Hz,20 k Hz,40 k Hz),power 500 W,pretreatment time 20 min,the optimum hydrolysis time is 5h,it can shorten the hydrolysis cycle of 2h.