Effect of partially replacing skim milk powder with whey protein concentrate on buffering capacity of yoghurt

The effects of replacing skim milk powder (SMP) with whey protein concentrate (WPC) on the buffering capacity of yoghurt in both acidic and alkaline conditions were studied. At similar total solids level (18%) and protein content (8.3%), a control yoghurt with SMP and no added WPC showed less buffering capacity than the yoghurt which contained WPC replacing 20% of the SMP in its mix formulation. Partial replacement of SMP with WPC (WPC replaced 51% and 20% (w/w) of SMP in yoghurt mix formulations) produced yoghurts with high buffering capacity at low pH and low buffering capacity at high pH. The pH of the yoghurt samples did not change significantly (P<0.05) during a three week storage period. Hence, addition of WPC to yoghurt formulations could produce an enhanced buffered yoghurt to better withstand the low and high pH conditions of the gastrointestinal tract. This may increase the survival of live culture bacteria and their enzymic activity in vivo, which could help people with lactose maldigestion to more readily consume dairy products.