Intra-oral lactic acid production during clearance of different foods containing various carbohydrates.

Oral carbohydrate clearance and acid production were monitored over a two hour time period following the ingestion of six foods (chocolate bar, potato chip, oreo cookie, sugar cube, raisin and jelly bean). Each food was evaluated intra-orally in eight volunteers. Oral fluid samples were obtained from each volunteer at 30 min intervals at five different tooth sites using absorbent paper points. The oral fluid samples were analyzed qualitatively and quantitatively for carbohydrates and organic acids using high performance liquid chromatography. Data obtained for each food were averaged and subjected to statistical analysis. The quantity of lactic acid produced 30 min after ingestion was found to be in the following order: (highest) raisin > chocolate bar > sugar cube > jelly bean > oreo cookie > potato chip (least). Two hours after food intake the order had changed significantly: potato chip > jelly bean > sugar cube > chocolate bar > oreo cookie > raisin. A direct linear relationship existed between lactic acid production and the presence of glucose. In foods containing cooked starch prolonged clearance occurs via the intermediate metabolites maltotriose, maltose and glucose. Results indicated that the term 'stickiness', when used to label certain foods such as jelly bean and chocolate bar, should be used cautiously. Foods containing only cooked starch or cooked starch and sugars can be considered as 'sticky', since glucose arising from their intra-oral degradation contributed to acid production over prolonged periods of time.