In vitro degradation of curcuminoids by faecal bacteria: Influence of method of addition of curcuminoids into buttermilk yoghurt.

The mode of delivery of curcuminoids in the manufacture of curcuminoid-fortified buttermilk yoghurts was investigated. Curcuminoids were added prior to the addition of yoghurt cultures as powdered curcuminoids or curcuminoids pre-dissolved in ethanol and added to buttermilk prior to or after yoghurt manufacture. Only a small portion (4.6-7.7%) of the total added curcuminoids in yoghurts (299 mg/100 g) was bioaccessible after sequential exposure to simulated gastric and intestinal fluids compared to 10.9% when curcuminoids in ethanolic buffer were delivered. The total potential curcuminoid bioavailability (i.e. bioaccessible curcuminoids + curcuminoids converted by faecal bacteria) delivered in yoghurts was 19-34%, depending on the delivery formats, compared to 37% for curcuminoids delivered in ethanolic buffer. The addition of powdered curcuminoids into buttermilk prior to yoghurt fermentation had 33% total potential bioavailability. This study demonstrated the feasibility of preparing curcuminoid-fortified yoghurt for the functional food market.