| In this paper,the whey protein concentrated(WPC100)containing?-lactalbumin(?-La)and ?-lactoglobulin(?-Lg)is used as the raw material,and through systematic research,three key processes including rapid centrifugal removal of lipid impurities,rapid separation of ?-La and ?-Lg by isoelectric point method,and two-step salt washing purification of ?-La were realized.In this research,the recovery rate and purity of a-La reached 67.75%and 94.31 wt%respectively.There hasn't denaturation of ?-La during the experiment,and its properties meet the requirements of infant formula.Based on that,an experimental device capable of rapid and continuous separation and purification of ?-La was designed,which overcomes the shortcomings of unstable product quality such as intermittent operation.The specific research content and research results of this paper are as follows.First,the skimmed milk was used as the raw material to remove the impurities by centrifugation,by which the liposomes in WPC100 can be removed.The separation effect is reflected by the absorbance A of the supernatant,and the skimmed milk is centrifuged by changing the centrifugal operating conditions which is relative centrifugal force G,centrifugal time T,relative centrifugal force and centrifugal time product GT.The results show that the separation efficiency increases linearly with the increase of G,T and GT.Based on this,the WPC100 was centrifuged to remove the lipid impurities.The results show that when G=6000g,the removal effect of lipid impurities is better,and the removal rate is close to 100%.The isoelectric point method was used to conduct a rapid preliminary separation study of ?-La and ?-Lg on the degreased WPC100.Using citric acid as a pH adjuster,by observing the influence of the pH value of the solution on the precipitation amount and precipitation time of ?-La,the isoelectric point for rapid separation is obtained,which is the pH value with better separation effect.The experimental results show that when pH=3.96,?-La precipitates quickly,has the largest amount and is easy to separate.The purity of the obtained ?-La is 37.65%,and the recovery rate is 81.83%.According to the sensitivity of ?-La and ?-Lg to the formation of reversible precipitation by cation combination,a two-step salt washing method was used to purify ?-La.NaCl and CaCl2 solutions were used as salt lotions to purify ?-La crude products separately.The effects of factors such as the concentration salt washing agent,salt washing time and times on ?-La purification effect were systematically studied.The experimental results show that when the NaCl solution concentration is 7 wt%,the salt washing time is 60 min,repeat the salt washing twice,then with 0.2mol/L CaCl2 solution at pH=7.4,temperature is 50?,after washing once,the purity and recovery rate of the obtained ?-La reach the maximum value,which are 94.31 wt%and 67.75%.The ?-La slurry obtained by salt washing was lyophilized to analyze its physical and chemical properties.The results showed that the purity and structural stability of ?-La both met the requirements of infant formula.A set of ?-La continuous separation and purification device was designed and produced.Preliminary experimental results show that the device can realize the rapid continuous operation process of isoelectric point method combined with salt washing method for separating ?-La from WPC100 The separation effect provides basic data for further method experiments. |
PDF Full Text Request