Sensory evaluation of different stirred yoghurt samples containing
ATS clearly showed that ATS is a four times more effective
creaminess enhancer in low-fat stirred yoghurt compared with setyoghurt.
Creaminess of a full-fat yoghurt (3%) was obtained by the
addition of 0.5% ATS to 1.5% fat yoghurt and 0.8% ATS to 0.5% fat
yoghurt. The replacement ratio of the 3% fat reference in stirred
yoghurt based on their creaminess is 3:1 (fat:ATS). The sensorial
functionality of ATS in stirred yoghurt resulted from discrete
domains of ATS in the yoghurt microstructure, as observed by
CLSM, formed during the first days of storage at 5 C after processing.
The ATS domains act as fillers with fat mimicking properties
as the ATS domains are enclosed in the protein network among
protein aggregates. Time is the driving factor in the domain
formation after stirring and cooling. The viscosity build-up due to
domain formation requires two days of refrigerated storage to
match the viscosity of the reference. ATS domains are formed at low
concentration (0.1%) in a yoghurt system of 4.5% protein. ATS is
functional as a non-charged polysaccharide during yoghurt
fermentation and affects the break-up of the protein network after
fermentation, during pumping and filling. No phase separationwas
observed at the studied time and length scales during fermentation
at 42 C. ATS is expected to be present in its dissolved state and will
only affect the aggregation of the milk proteins by occupying
a specific volume, and thereby affect the break-up of the yoghurt
gel during stirring. Domain formation of ATS takes place on a larger
time scale than aggregation of the protein and requires refrigerated
storage. This resulted in an unique functionality of ATS compared
with current existing stabilisers.