酪蛋白胶束粉的陶瓷膜分离生产工艺

摘要

为尽快建立酪蛋白胶束粉(micellar casein concentrate, MCC)的中试生产线，实现MCC在国内的工业化生产，该研究通过测定牛乳蛋白粒径，选取孔径40和100 nm的中空纤维陶瓷膜进行膜分离效果的对比，并选用膜分离效果较佳的陶瓷膜进行最佳操作参数的确定及稀释过滤工艺的研究，最后将自制MCC和进口MCC进行品质特性对比并分析其工业化生产的可能性。结果表明：孔径40 nm中空纤维陶瓷膜与孔径100 nm中空纤维陶瓷膜相比，渗透液中不含酪蛋白，能够减少酪蛋白损失，更适合于酪蛋白和乳清蛋白的分离，孔径40nm中空纤维陶瓷膜的最佳操作参数为操作压力2×105 Pa，料液温度50℃；采用四段式的连续稀释过滤工艺，可使料液中酪蛋白占真蛋白的比例从69.39%提升至93.34%，真蛋白占干物质的比例从38.45%提升至88.15%；稀释过滤完毕后膜的纯水通量衰减了39.98%，经生物酶清洗液清洗后膜的纯水通量恢复至初始的98.02%；自制MCC在成分组成上与加拿大Proteinco公司生产的MCC相比差异不显著（p<0.05），但在溶解度和粉粒的微观形态上优于Proteinco MCC；生产1 kg MCC需要原料乳46.24 L，成本为244.58元，可实现其国内工业化生产。研究结果为实现MCC在国内工业化生产及其应用性研究提供参考。%Micellar casein concentrate (MCC) powder, a new milk protein product produced by a combination of processes including membrane separation, evaporation and spray drying has potential applications in cheese making, whipped topping, coffee whitener and yogurt making. It is becoming more and more popular in the food processing industry, but currently China depends on imported MCC mainly from developed countries. The main objective of this study was to successfully develop a pilot scale production process for micellar casein concentrate powder and facilitate its rapid adoption and manufacturing in China’s dairy plants. Preliminary studies involved the selection of a suitable hollow fiber ceramic membrane for the separation of casein micellar and serum protein between 100 nm and 40 nm pore size hollow fiber ceramic membranes (InoCep, Hyflux Ltd, Singapore). The 40nm pore size hollow fiber ceramic membrane, which had better separation performance, was chosen for further investigation on optimum operating parameters, mainly temperature and pressure. A four-stage diafiltration process was employed, in which chemical composition and flux changes were measured at the end of every stage in the production line. Finally, the micellar casein concentrate powder made after evaporation and spray drying process was compared with commercial MCC (Proteinco Inc., Quebec, Canada) in terms of their physical characteristics and chemical compositions. The yield rate and the production costs were also calculated. The results showed that:(1) the permeate of 100 nm pore size membrane was cloudy but the permeate of 40 nm pore size membrane was clear in appearance and the proportion of casein in the true protein of the permeate for the 100 and 40 nm pore size membrane were 40.03%and 17.48%, respectively. Therefore, the 40nm pore size membrane was found to be more suitable for the separation of casein micellar and serum protein and its average permeate flux during a 3×concentration at the optimal operating conditions (temperature 50℃, pressure 2×105 Pa) was above 60 L/(m2·h);(2) the best time for adding water during the whole diafiltration process was when the volume concentration factor was equal to 3, which reduced membrane fouling and enhanced average stage flux. After four stages of the continuous diafiltration process, the casein micellar purity and the pure protein content (on a dry basis) reached 93.34%and 88.15%, respectively;(3) at the end of the diafiltration process, the water flux declined by 39.98%, and when a biological-enzyme cleaning agent was used, water flux recovery was 98.02%of the initial;(4) The solubility of the pilot scale produced MCC was significantly different from that of the commercial MCC. The solubility was better in the pilot scale produced than commercial MCC, which may be due to the difference of the inlet temperature of spray drying. Additionally, the particle morphologies of the pilot scale-produced MCC, as observed by a scanning electron microscope, appeared spherical and smaller in size, whereas the commercial MCC had wrinkled particle surfaces and large particle sizes. (5) From the chemical analyses, determinations of total solids, lactose, minerals, total protein, true protein, casein protein and serum protein content were done but there were no significant differences (p<0.05) between the pilot scale produced and the commercial MCC. (6) In order to produce 1 kg MCC, 46.24 L raw milk was required and the production cost of MCC was calculated as 244.58 Yuan/kg, which was deemed profitable and therefore can be transformed to the industrialized production stage. The methods and data stated in this study are valuable and useful to the industry and as a benchmark for further studies. They can also be used both as a reference and guide for MCC production in China.