CSIRO Materials Science and Engineering, Normanby Road, Clayton, Victoria 3168, Australia.
Food Funct. 2013 Sep;4(9):1376-86. doi: 10.1039/c3fo60112a.
The moisture uptake and molecular mobility of freeze-dried powders containing whey protein isolate-carbohydrate matrices (1WPI:2maltodextrin; 1WPI:1maltodextrin:1d-glucose; and 1WPI:1maltodextrin:1l-glucose) and encapsulated Lactobacillus rhamnosus GG (LGG) in these matrices were investigated at 25 °C and 33% and 70% relative humidity (RH). The inactivation rate constant for probiotics in freeze-dried matrices were positively correlated (R(2) = 0.98) to moisture uptake and molecular mobility measured by NMR relaxometry. The stability of probiotics in glassy protein-carbohydrate matrices was dependent on the composition of the matrix. The partial substitution of maltodextrin with glucose (d- or l-) which improved microbial survival at 33% RH was related to the reduced molecular mobility and lower water uptake of the matrix. This study suggests that moisture uptake properties and molecular mobility of the matrix composition, as opposed to the relative humidity of the environment, are better determinants of probiotic viability during storage. Dynamic vapour sorption and NMR relaxometry are promising tools to assist in the selection of protein-carbohydrate matrices for enhancing probiotic viability during storage.
研究了乳清蛋白分离物-碳水化合物基质（1WPI：2 麦芽糊精；1WPI：1 麦芽糊精：1d-葡萄糖；和 1WPI：1 麦芽糊精：1l-葡萄糖）中含有乳双歧杆菌 GG（LGG）的冻干粉末的水分吸收和分子迁移率，在 25°C 和 33%和 70%相对湿度（RH）下进行。通过 NMR 弛豫测量，益生菌在冻干基质中的失活动力学常数与水分吸收和分子迁移率呈正相关（R(2) = 0.98）。益生菌在玻璃态蛋白质-碳水化合物基质中的稳定性取决于基质的组成。用葡萄糖（d-或 l-）部分替代麦芽糊精，提高了在 33%RH 下的微生物存活率，这与基质的分子迁移率降低和吸水率降低有关。本研究表明，在储存过程中，相对于环境的相对湿度，基质组成的水分吸收特性和分子迁移率是更好的益生菌生存能力的决定因素。动态蒸汽吸附和 NMR 弛豫是有前途的工具，可以帮助选择蛋白质-碳水化合物基质，以提高益生菌在储存过程中的存活率。
