There is increasing evidence that whey protein isolates (WPI), can be utilised to encapsulate and protect
bioactive substances, including lactic acid bacteria, due to their physicochemical properties. However, little
is known about what happens in the immediate vicinity of the cells. This study examined the protective
behaviour of WPI for two strains of Lactobacillus plantarum, A17 and B21, during spray drying. B21
was found to be more hydrophobic than A17 and required 50% of the amount of WPI to provide comparably
high survival (90%). We hypothesise that WPI protects the hydrophobic bacteria by initial attachment
to the unfolded whey protein due to hydrophobic interactions followed by adhesion to the proteins,
resulting in cells being embedded within the walls of the capsules. The encapsulated strains had a moisture
content of approximately 5.5% and during storage trials at 20 C retained viability for at least eight
weeks.