Formulation optimisation of mixed sugar/protein/maltodextrin encapsulants for spray drying L. acidophilus using the response surface method

Three sugars (maltose, fructose, and lactose) have been combined in different formulations with three protein based powders (whey protein, skim milk, and soy protein) to assess the survivability of L. acidophilus after spray drying at 80°C followed by optional further exposure to simulated gastric intestinal juice (SGI) or bile solution. The results showed that the highest survival rate was found in a recipe consisting of 87.5% skim milk and 12.5% maltose, while the lowest rates were found in formulations containing no protein. Maltose and lactose provide higher survival rate than fructose which may reflect the higher glass transition temperature of maltose/lactose mixtures. Similar trends were found with cells rehydrated in SGI and bile solutions.