Separation Of Rapeseed Meal Protein By Flat Sieve And Preparation Of High Bioavailability Products By Ultrasonic Assisted Enzymatic Method

Rapeseed meal contains 35%-45% protein,which includs a large number of essential amino acids,such as lysine and methionine.Therefore,high value utilization of rapeseed protein is of great significance.At present,the common solvent extraction methods of rapeseed concentrate protein are complex,inefficient and harmful to the environment.The anti-nutrient factors in rapeseed meal and protein denaturation caused by traditional pressing process reduce the digestion and absorption of rapeseed protein,which greatly restricte production and application of rapeseed protein.The purpose of this study was to improve the production efficiency of rapeseed protein and protein content.Firstly,the efficiency of preparation of rapeseed concentrate protein using high performance flat sieve was studied.Then,the effect of hydrolysis degree of rapeseed protein on bioavailability was explored.Finally,in order to improve the efficiency of rapeseed protein enzymolysis with high bioavailability,the effect on enzyme pretreated with the S five frequency ultrasound,sweep frequency ultrasound and triple frequency ultrasound was further studied.The contents and main conclusions of this paper are below:(1)Using rapeseed meal as raw material to produce concentrated protein with high performance flat sieve.The R-R distribution function of the particle size distribution and the correlation between the protein and phytic acid in the raw material were analyzed.The single well high efficiency flat sieve was used to produce protein concentrate.The effects of feed rate and rotation speed on the screening effect were studied with the ratio of the screened material and the content of the protein under the sieve.The particle size distribution and the composition of the different sizes of the raw materials were also analyzed.The optimum conditions for the preparation of rapeseed concentrated protein were as follows: the flow rate of the inlet was 2 kg/min,the rotation speed of the flat screen was 260 r/min,the protein content of the rapeseed protein was 56.99%(dry basis)and yield was 26.66%.The protein content of rapeseed protein concentrate obtained by alcohol elution was up to 60.15%(dry basis).(2)In order to improve the bioavailability of the protein in double-low rapeseed meal,proteolysis was carried out.Rapeseed peptides were selected as the research object and the utilization of rapeseed meal protein with different hydrolysate in organisms was studied.Experiments of growth and nitrogen metabolism in rats were done with nitrogen free group,casein group,hydrolytic group(4%,8%,12%,16%,20%),including seven groups of three groups.Animal experimental results showed that the enzymatic hydrolysis significantly improves the bioavailability of rapeseed protein.Weight gain of rats in the group of hydrolysis degree of 8% was higher than other group.Apparent and true digestibility,net protein utilization and biological value were significantly higher than that of the other group(p <0.05).Therefore,hydrolysis degree of 8% has the highest bioavailability.(3)To improve the efficiency of rapeseed meal protein enzymolysis with high bioavailability,raw materials were pretreated by S five frequency ultrasound,sweeping frequency and pulsed ultrasound,triple frequency ultrasound.The ultrasonic mode,initial temperature,ultrasonic time and power density were optimized respectively.The ultrasonic parameter optimization experiment results showed that the S shaped ultrasonic device could significantly improve the efficiency of enzymatic hydrolysis and the protein transformation rate of supernatant(p <0.05).Pretreated by S shaped ultrasonic device could also increase the inhibition rate of ACE in the enzymatic hydrolysate.The optimal mode of ultrasound is equential work of dual frequency 50/28 kHz.The time of enzymatic hydrolysis is 25 min,the initial temperature is 40 degrees,and the power density is 80 W/L.Under these conditions,the efficiency of enzymatic hydrolysis is 36.20%,the protein transformation rate of supernatant is 62.76%,which was increased by 86.22% compared with the non ultrasonic group;ACE inhibition rate of enzyme hydrolysates is 67.90%,which was increased by 35.28% compared with the non ultrasonic group.