Using repeated ingestion to determine the effect of sweetness, viscosity and oiliness on temporal perception of soymilk astringency

Astringency is a persistent sensation which increases upon repeated ingestion. To evaluate the effect of viscosity, sucrose and oil on perception of astringency during consumption of soymilk, a sequential sipping time¯intensity (TI) procedure was utilized. For each soymilk, judges sipped the first of four ingestions and initiated the continuous recording of astringency intensity. Each sip was expectorated at 10 s after ingestion, and sipped 10 s after expectoration of the previous stimulus. After the fourth sample, judges rated astringency for 30 s. Traditional TI parameters, as well as rate of onset for each sip and increase in maximum intensity per sip were extracted from the TI curves. Maximum astringency (IMAX) increased significantly with successive sips as did the astringency at the time of sipping. Time to IMAX decreased from sip 1 to 3, but was longer for sip 4, which may be an artifact of the rapid test pace. Although addition of 60 g l-1 canola oil had no affect on astringency, adding 40 g l-1 sucrose or increasing viscosity by 5 cp with CMC significantly lowered all astringency parameters. The reduction in astringency by CMC may result from restoration of salivary lubrication and in part by chelation or hydrogen bonding of CMC to the astringents reducing their ability to bind to salivary proteins. The reduction in astringency produced by sucrose is more probably due to a cognitive process.