从胆盐水解酶的特性出发,在干酪乳杆菌LC2W中过量表达Lactobacillus plantarum ST-III 4种胆盐水解酶同工酶,通过酶活性的测定研究胆盐水解酶对干酪乳杆菌水解胆盐的作用。结果表明:实现了4种胆盐水解酶在干酪乳杆菌LC2W的过表达;利用茚三酮显色法测定的4种重组菌胆盐水解酶活性较宿主LC2W都不同程度地降低;在干酪乳杆菌LC2W中过量表达L.plantarum ST-III的胆盐水解酶基因达不到提高该菌水解胆盐能力的目的。
Effects of different additives(sucrose and maltodextrin)on storage stability of colostral whey(CW)powders packaged in aluminium-laminated polyethylene pouches were investigated under different storage conditions(4℃and 40%-70%relative humidity(RH),25℃and 50%RH,and 50℃and 20%-60%RH).All the samples stored under 50℃and 20%-60%RH showed the highest levels of lipid oxidation,Maillard reaction,proteolysis,and color difference,and the lowest immunoglobulin G(IgG)retention.Moisture contents showed an increase trend with increasing RH.Addition of sucrose into CW powders increased water adsorption capacity and Maillard reaction,whereas addition of maltodextrin showed the opposite effects.Maltodextrin as drying aids was suitable for keeping quality during storage.Sucrose did not clearly play any roles in protecting denaturation of IgG during 90-day storage.The low storage temperature and RH were helpful for keeping storage stability of CW powders with different additives.
乳蛋白浓缩物(Milk protein concentrate,MPC)是近年来新兴的牛乳蛋白制品,在食品加工中有着广泛的应用。本试验采用薄膜蒸发浓缩牛乳超滤截留液至固形物含量为15.55%,18.17%和26.12%,研究了不同浓缩程度对MPC粉末的粒径,溶解性,流动性和喷流性指数等性质的影响。结果表明,浓缩至超滤截留液固形物含量为26.12%时,MPC具有较好的加工特性。
