Key Technologies Of The Stability Protection In The Preparation Of Colostrum Powder

This thesis has been funded by the subject of Office of Science and Technology of Jilin Province- "Colostrum-end liquid dairy production and processing key technology research"(project number: 20140204009NY). The immunoglobulin G in the colostrum is easily denatured when heated, which results decrease of antigen-binding ability, and affects the immune regulatory function in vivo. Therefore,this studyaims to research two major studies which are the largest destruction of the immunoglobulin G sterilization and spray drying technology among the colostrum powdered process. First, regarded the residual value of bacteria and immunoglobulin G modified ratio as indexes, through sterilized membrane separation, high voltage pulsed electric field sterilization and water bath heat sterilization separately, the sterilization process was to determine the optimal conditions; Secondly, set the extraction rate, immunoglobulin G retention, moisture content and reconstitution of the evaluation score as an indicator to determine the optimum parameters for preparing spray-dried colostrum powder; Finally, for the spray drying process can maximize the protection of immunoglobulin G, regarded immunoglobulin G as retention rate targets, and screened for spray drying the composite thermal protection agents, thenmeasured the colostrum powder sensory indicators, the physical and chemical indicators and microbial indicators. The main findings are as follows:(1) The study on the membrane separation sterilization, high-voltage pulsed electric field sterilization and heat sterilization:(1) Membrane separation sterilization: Set the value of the residual bacteria,immunoglobulin G retention rate as the indexes, measured the effects of feed rate and feed temperature in the sterilization process of membrane separation, and determined membrane separation optimum conditions: feed rate was 2.4m · s-1, the feed temperature was 40 ℃. Under these conditions, the measured value of the residual strain was 2.71, and the immunoglobulin G retention rate was 83.8%.(2) High-voltage pulsed electric field sterilization: Set the value of the residual bacteria, immunoglobulin G retention rate as indexes, and measured the effects of the electric field strength, pulses and feed temperature three factors to determine the optimal sterilization condition: electric field strength of 50 kV ? cm-1, the number of pulses is 6, the feed temperature was 30 ℃. Based on the single factor, experimented the L9(34) orthogonal, set the residual value of the bacteria, immunoglobulin G retention rate as indicators to determine the high-voltage pulsed electric field sterilization optimum parameters: electric field strength of 50 kV? cm-1, pulse number was 7, the feed temperature was 40 ℃, on the sterilization condition, the measured value of the residual strain was 3.57, immunoglobulin G retention rate was 90.67%.(3)Heat sterilization: Through single factor, the study researched the influence of heating temperature and heating time on the total number of colonies, the number of E.coli, and the immunoglobulin G retention rate, and determined the optimum condition of heat sterilization: the heating temperature was 65 ℃, heating time was30 min, at this time the residual bacteria value was 4.78, immunoglobulin G retention rate was 74.7%.Considering the bactericidal effect of immunoglobulin G and retention,membrane sterilization was best.(2) Spray drying bovine colostrum: Set the colostrum to go through membrane separation after sterilization as experimental materials to study the influence of inlet air temperature, feed concentration, feed rate, drying effects of air traffic on the spray,and obtained on each factor spray-dried optimum condition: inlet air temperature was170 ℃, feed concentration was 25%, the feed rate was 10 ml · min-1, air flow was473L·h-1. Based on the single factor experiment, used L9(34) orthogonal experimental method to immunoglobulin G retention, set the extraction rate, moisture content and reconstitution of the evaluation score as indexes to determine the optimal spray drying process parameters: inlet air temperature was 170 ℃, feed concentration was 25%,feed rate was 11ml·min-1. Under these conditions the preparation of bovine colostrum immunoglobulin G retention rate was 22.26%, rate of powder collector was 73.88%,moisture content was 3.79%, prepared and evaluation score was 4.91.(3) Screening the spray drying protective agents: Under optimum spray drying conditions to set the immunoglobulin G retention rate as index to measure the effects of plant polysaccharides, food additives, amino acids on the protective effect of immunoglobulin G. Screened optimal single protection agents were: 10% of polysaccharides, 0.3% of calcium lactate, and 5% of glycine. On the basis of single factor experiment, began the response surface analysis,setthe immunoglobulin G retention rate as indicators to determine the optimal formulation of composite thermal protection agents: Pachymaran was 56.43%, calcium lactate was 0.20%, glycine was41.55%, based on the optimal formulation, the study has done the spray drying verification experiment to measure the immunoglobulin G retention rate which was62.14%, increase 179%. The resulting products were in line with sensory indicators,physical and chemical indicators and microbiological testing standards indicators.