Determination of the effect of dairy powders on adherence of Streptococcus sobrinus and Streptococcus salivarius to hydroxylapatite and growth of these bacteria

Dental caries is a highly prevalent disease caused by colonisation of tooth surfaces by cariogenic bacteria, such as Streptococcus sobrinus and Streptococcus salivarius. Reducing initial adherence of such bacteria to teeth may delay onset of caries. Many foods, such as milk, can inhibit microbial adherence. In this investigation, the effect of untreated (UT) and enzyme-treated (ET) dairy powders on adherence of S. sobrinus and S. salivarius to hydroxylapatite (HA), an analogue of tooth enamel, was examined. Untreated (UT) acid whey protein concentrate (AWPC) 80 inhibited streptococcal adherence to phosphate-buffered saline-coated HA (PBS-HA) and saliva-coated HA (S-HA) by >80% at ⩾31.25 μg mL−1. UT sweet WPC80, buttermilk powder and cream powder also significantly reduced adherence (P < 0.05). Enzyme-treatment of all dairy powders reduced their anti-adhesion activity. However, ET sweet WPC80 significantly inhibited growth of these streptococci (P < 0.05) at ⩾0.6 mg mL−1. Therefore, dairy powders may reduce progression of dental caries by their anti-adhesion and/or antibacterial activity.

► We examined the effect of whey products pre- and post-hydrolysis on streptococcal adherence.
► We used two model systems; buffer-coated HA (PBS-HA) and saliva-coated HA (S-HA).
► We also determined the effect of one hydrolysate on growth of these streptococci.
► Our results show dairy powders can inhibit growth and adherence of these streptococci.
► We conclude that whey products may be useful in preventing onset of dental caries.