Study Of The Preparation And Gel Properties Of Low Ash Plasma Protein Powder

In order to provide data support for quality evaluating,standard-setting and production technology research of plasma protein powder,14 main kinds of plasma protein powder were collected for study including food grade and feed grade.The product chromaticity,conventional ingredients,texture and water-holding capacity of protein gels,protein composition,content of mineral elements were measured,and then the present situation and differences of plasma protein powder quality were determined.The results showed that there were significant differences in appearance(quality of protein powder and chromaticity)and quality(moisture,crude protein,crude ash,insoluble substance,texture and water-holding capacity of protein gels,protein composition,content of mineral elements)among different products of plasma protein powder from different companies(P<0.05).Besides,there was a difference between food grade and feed grade powder.Generally,the ash of plasma protein powder was high(7.02% ~ 14.27%),the main source of which was Na element.Different separating technique,concentration technique and spray drying technique were investigated in this study in order to utilize animal blood effectively and optimize the preparation technique of plasma protein powder.First,the effects of different centrifugal speeds and times on the concentration of total plasma protein,hemoglobin residues and yield were studied.Besides,the effects of different ultrafiltration pressure and pH of plasma on moisture content,protein content and ash content of plasma protein powder were analyzed.Finally,the effects of different inlet temperatures and feeding rates on moisture content,protein content,extraction ratio and nitrogen soluble index of plasma protein powder were investigated.The results indicated that the best centrifugal condition was at 5000 r/min(corresponding centrifugal force was 2437 ×g)for 10 min.For the ultrafiltration membrane material was polyether sulfone and intercept molecular weight was 10000 Da,the best ultrafiltration condition was at 0.6 MPa airflow pressure,and the pH of plasma was 9.The best spray drying technique was under inlet temperature 150? feeding rate 0.178 mL/s and outlet temperature 81.38?.After this optimization technique,the ash content of plasma protein powder decreased to 6%.Effects of different drying method and ash content on properties of plasma protein powder gels were investigated.Water-holding capacity,texture,microstructure,protein polymerization,thermostability of different drying methods and water-holding capacity,texture,microstructure,secondary structure of different ash content of plasma gels were measured.The results indicated that different drying method had no significant impact on water-holding capacity and elasticity.The hardness of gels from Spray-dried plasma was below that from freeze-drying plasma,and both were below that from liquid plasma.Besides,both methods could decreased the thermostability of plasma powder.The microstructures of dehydrated plasma were more dense and the holes were smaller.The polymerizing time of spray-dried plasma was early than that of freeze-drying plasma.Compared with the gels of high ash plasma protein,the water-holding capacity of the gels of low ash plasma protein powder(ash content 5%)were the largest and the hardness and elasticity of which were the minimum.However,the gel microstructure,the composition and content of protein secondary structure were no differences between the gels from low ash and high ash plasma protein powder.