End of Project ReportTraditionally, yoghurt is produced in a hydrated form and, thus, possesses a
limited shelf-life even when refrigerated. Consumption within a short time
of production is advisable, particularly if advantage is to be taken of the
putative benefits associated with the ingestion of live yoghurt cultures.
The production of an instant yoghurt powder would, thus, provide benefits
of shelf-life extension and convenience of preparation and storage.
However, the drying of such products is difficult due to low pH, which
causes stickiness in drier chambers and makes powder recovery difficult.
Furthermore, key flavour components formed by fermentation such as
acetaldehyde and diacetyl which contribute to the unique flavour of natural
yoghurt are sensitive to heat and easily lost during spray-drying.
Hence, a major challenge of this project was to investigate the processing
technologies and conditions necessary for the minimisation of flavour losses
during the spray-drying of acidified/fermented milk bases, to monitor the
effects on drier performance such as powder adhesion to drier walls, and to
develop functional forms of the spray-dried ingredients. The main aims of the project were to:
- improve yoghurt powder spray-drying efficiency through optimisation of
concentrate solids,
- investigate the effect of spray-drying conditions on flavour losses of
sensitive products such as dehydrated yoghurt and fermented creams,- apply technological approaches for the reduction of flavour losses: a)
ingredient formulation, b) modification of fermentation conditions,
- investigate the production of agglomerated forms of spray-dried yoghurt
powders,
- study factors affecting the physical properties such as rheological
characteristics and powder bulk density, and
- adapt technology to ensure greater viability of culture cell numbers at the
end of the drying process.Department of Agriculture, Food and the Marin
